Is constructive empiricism systematic?

In his article "Practical Inadequacy: Bas Van Fraassen's Failures of Systematicity", Curtis Forbes argues that constructive empiricism fails to provide a systematic account of science. An account of science is systematic when it is "able to account for the uses, methods, goals, and place of actual human science, as it exists within its institutional and industrial context." Forbes takes it, and I agree, that any acceptable philosophy of science must be systematic in this sense.

Forbes's case against the constructive empiricist begins with the famous conjunction argument. Scientists routinely conjoin theories; if scientists accept two theories T1 and T2, they will also be prepared to accepted the conjunction (T1 & T2). The realist can easily account for this since truth is preserved under conjunction: if both T1 and T2 are true, then the conjunction (T1 & T2) is also true. The constructive empiricist supposedly runs into trouble here because empirical adequacy is not preserved under conjunction. Indeed, one of the main reasons why conjoining theories is useful is that (T1 & T2) may entail some observable consequence E that is not entailed by either T1 or T2 separately. So the fact that T1 is empirically adequate and T2 is empirically adequate doesn't entail that (T1 & T2) is empirically adequate. So how does the constructive empiricist account for theory conjunction?

As Forbes points out, van Fraassen has a simple response to this. Scientists conjoin theories in order to test the empirical adequacy of the conjunction. They don't need to believe that the conjunction is empirically adequate. Ultimately scientists aim for empirically adequate theories, but when a theory conjunction entails a novel consequence, belief in the empirical adequacy of the conjunction can be withheld until after testing. Conjoining-to-test accounts for theory conjunction just as well as conjoining-to-believe.

Forbes argues that this response is inadequate, and leaves a failure of systematicity in constructive empiricism. The problem arises from the fact that science plays an important role in public policy, where we use science to make predictions about the future and guide our actions. Forbes cites the example of global warming research. Global warming theory is a conjunction of a variety of theories concerning the composition of the atmosphere, the properties of emissions released through fossil fuel burning, the impact of solar radiation on Earth's temperature, etc. These conjuncts have each individually been well-tested but, says Forbes, the conjunction in the form of global warming theory has not been. Indeed, global warming theory makes a variety of novel predictions concerning catastrophic climate change that no scientist intends to test. We don't want to test what will happen if we continue to burn fossil fuels at the current rates for another 50 years. Instead, we want to avoid such catastrophic outcomes.

So in this case, scientists must be conjoining-to-believe the empirical adequacy of global warming theory, not conjoining-to-test it. If scientists only ever conjoin-to-test, they would advise us to continue burning fossil fuels to check the novel predictions of global warming theory. This would be disastrous. In general then, constructive empiricism fails to account for the role science plays in informing public policy, where theory conjunctions are used to predict and then try to avoid certain outcomes.

There are three problems with Forbes's objection to constructive empiricism:

(1) The example of global warming theory depends on the claim that this theory as a whole has not been well-tested, only the conjuncts (e.g. theories about atmospheric composition) have been well-tested. This is simply false. Global warming theory has existed for decades, and many of its novel predictions have been tested and confirmed: glacial retreat and Arctic sea ice decline, accelerated sea level rise, increasing numbers of record high temperatures, etc. Of course, we haven't yet tested all the predictions of the theory. But that is never possible for any theory. Conjoining-to-test requires only that we specify some novel consequences of the theory conjunction and test them. Given the many confirmed novel predictions of global warming theory, we are by constructive empiricist lights entirely justified in treating the theory as well-tested, and applying it in policy decisions.

Suppose global warming theory did not exhibit such successes. Suppose it were a new theory, and scientists had not yet tested its novel predictions. In this case, it's not at all obvious that we should use it to inform important policies. After all, new theories are proposed all the time, many of which fail to be accepted by the scientific community. In the 1970s it was conjectured by a minority of climatologists that the emission of aerosols would increase Earth's albedo and induce global cooling and extensive glaciation. How should policy makers decide which theories to adopt to predict and respond to potential problems? Surely they should adopt just those theories that have passed a sufficient number of tests. That is the difference between global warming and global cooling.

(2) The second problem with Forbes's argument is that it is possible for a constructive empiricist to hold that scientists sometimes conjoin-to-believe, not just conjoin-to-test. As Andre Kukla points out in chapter 3 of "Studies in Scientific Realism", we can distinguish two forms of constructive empiricism. In Van Fraassen's original form, to accept some theory T involves believing only that T is empirically adequate. But we can modify this slightly to "conjunctive" constructive empiricism, where to accept T involves believing that T, in conjunction with any other accepted theories, is empirically adequate. When the conjunctive empiricist accepts a theory, she believes it to be empirically adequate and also believes that a new theory generated by conjoining T with any other accepted theory will also be empirically adequate. Obviously, conjoining-to-believe empirical adequacy is entirely compatible with conjunctive empiricism.

Note that there are independent reasons to favour this form of constructive empiricism. Scientists seem to aim for a unified view of the world; they want theories from different fields to provide a coherent world-picture. On van Fraassen's original formulation of constructive empiricism, it would be no problem for scientists to accept mutually inconsistent theories provided each theory is thought to be empirically adequate in its domain. By contrast the conjunctive empiricist will need to ensure that all accepted theories are, at minimum, consistent with each other. Aiming for conjunctive empirical adequacy seems to be more in line with scientific practice.

(3) If the conjunction argument is successful, it also refutes all plausible forms of realism. The sensible realist does not say that our best theories are true. She says that our best theories are approximately true. This qualification is necessary because nobody thinks that science has given us a complete, final, and unified theory of everything, and we all expect that even our best theories are likely to change somewhat in the future. So the realist asserts the approximate truth of our best theories, not truth period. But the conjunction of two approximately true theories need not be approximately true. In particular, the conjunction of two approximately true theories need not entail approximately true claims about observables. Even if we assume that the individual conjuncts of global warming theory are approximately true, this is no guarantee that global warming theory itself will provide reliable predictions about the future.

A brief catalogue of solutions to Newcomb's Problem

The One-Boxer: “Take only box B.”

The Two-Boxer: “Take both boxes.”

The Dialetheist: “Take only box B and take both boxes.”

The Fundamentalist Teenager: “Until we’re married, take only box A.”

The G.E. Moore: “Here is £500,000. Here is another £500,000. Therefore, take only box B.”

The Schroedinger: “Take only box B, but never open it.”

The Radical Skeptic: “What boxes?”

The Rational Skeptic: “When I appeared alongside this so-called “predictor” on Larry King Live, I invited it to take my One Million Dollar Paranormal Challenge, and it accepted. Unfortunately, when I approached it after the show to arrange a date, it made a quick exit without responding to me, and my subsequent attempts to contact it have all been ignored.”

The Modal Realist: “In some possible world, you take both boxes and receive £1,001,000.”

The Talking Heads: “And you may find yourself taking both boxes. And you may say to yourself, MY GOD, WHAT HAVE I DONE?!”

The Behaviourist: “I can see that you’re keen on two-boxing; how do I feel about it?”

The Humean: “One box or two boxes? I prefer to just scratch my finger.”

The Nihilist: “Vere iz dat money, Lebowski? Ve vant da money, Lebowski! Ya zink ve are kidding?!”

The Neutrino Physicist: “Take two boxes. Then do the same again another hundred trillion trillion times.”

The Heisenberg: “I worked out exactly what’s in box B, but now I have no idea where it is.”

The Penn & Teller: “This time, we’ll do Newcomb’s problem with both boxes transparent!” [Naturally you take two boxes, but as you leave you notice that the all the money has disappeared from both of them.]

The Timothy Leary: “Take all three boxes.”

The Kaczynski: “Run away from box B.”

The Donald: “We’re gonna open boxes, okay? Because I know boxes. I have the best boxes. Tremendous boxes. We’re gonna open so many boxes, you’re gonna get sick of opening boxes. Believe me, I’ve opened boxes many times. Look, having boxes - my uncle, good genes, very smart, okay, very smart - he opened so many boxes, you wouldn’t believe it. Crooked Hillary, she couldn’t open even one box – it’s true, it’s true. Lots of people are saying that. Sad!”

The John Cage: “Music for Two Boxes for solo performer. Flip a coin. If heads, take box B. If tails, take both boxes. To be performed with maximum amplification.”

The Nicolas Cage: “No, not the boxes! NOT THE BOXES! AAAHHHHH!! AHH, MY EYES, MY EYES!!”

Against manifestationalism

I recently read Asay and Bordner's (A&B) interesting paper "A modest defense of manifestationalism". Last week I discussed a stricter form of constructive empiricism which holds that we should believe that our best theories correctly describe not observable phenomena but only observed phenomena. A&B explore the same view under the name "manifestationalism". More precisely, they given the following taxonomy:

Scientific realism (SR): Science aims to give us theories that are literally true; acceptance of a theory involves the belief that it is literally true.

Constructive empiricism (CE): Science aims to give us theories that are empirically adequate; acceptance of a theory involves only the belief that it is empirically adequate.

Manifestationalism (M): Science aims to give us theories that are comprehensively manifestly adequate; acceptance of a theory involves only the belief that it is comprehensively manifestly adequate. (A theory is manifestly adequate just in case it correctly describes all observed phenomena.)

I have already mentioned that I don't think it's particularly helpful to frame the realism debate in terms of the aim of science. The interesting position is that of the manifestationalist who believes that scientific theories correctly describe only observed phenomena, and who is agnostic about the unobservable and the observabled-but-unobserved.

A&B clarify that manifest adequacy is not simply truth to the phenomena observed so far, but truth to all phenomena that have ever been or will ever be observed, including those observations that take place outside a scientific context (this is what they mean by comprehensive manifest adequacy). This clarification is important. Belief in nothing more than what has been observed so far entails radical scepticism about the future, a position which is not just implausible but probably psychologically impossible to adopt. M avoids this radical scepticism. M endorses the belief, for example, that I will continue observing my computer screen for as long as I sit here typing; that when I go downstairs to get some food I will observe some bananas in the fruit bowl; etc.

The case for manifestationalism

A&B do not attempt to present a conclusive case for M. They merely try to show that it is not absurd or irrational, but a serious contender in the philosophy of science. I will argue that they fail. Much of A&B's paper is devoted to answering a criticism of M based on the aim of science, which I discussed briefly in my previous post; I will focus on their arguments for M, of which there are three:

1. One possible argument for M appeals to van Fraassen's "vulnerability criterion" of belief, expressed in this passage:

If I believe the theory to be true and not just empirically adequate, my risk of being shown wrong is exactly the risk that the weaker, entailed belief will conflict with actual experience. Meanwhile, by avowing the stronger belief, I place myself in the position of being able to answer more questions, of having a richer, fuller picture of the world, a wealth of opinion so to say, that I can dole out to those who wonder. But, since the extra opinion is not additionally vulnerable, the risk is — in human terms — illusory, and therefore so is the wealth. ... What can I do except express disdain for this appearance of greater courage in embracing additional beliefs which will ex hypothesi never brave a more serious test?

Given two theories that are equally vulnerable, we should believe the logically weaker theory. Van Fraassen uses this to argue for CE, but A&B claim that this argument is really an argument for M, not for CE. We will only ever be able to test our theories against those phenomena that are actually observed; we will never obtain any evidence that could decide between two rival manifestly adequate theories. If I believe a theory to be empirically adequate and not just manifestly adequate, my risk of being shown wrong is exactly the risk that the weaker, entailed belief will conflict with actual experience... M and CE are equally vulnerable and M is logically weaker than CE. So we should accept M.

Of course, the force of this argument for M depends on whether we accept van Fraassen's vulnerability criterion of belief. I won't discuss the case for or against this here. Another question is, are CE and M equally vulnerable? Once the end of science occurs, and all the observations we will ever make have been made, the answer is clearly "yes". However the situation is somewhat trickier from our current position. We can see the problem clearly by asking, exactly which aspects of our best theories should we believe? It's easy for the constructive empiricist to answer this. CE tells us to believe what our theories tell us about the observable world. But M tells us to believe what our theories tell us about the observed world - observed in the past, the present, and the future.

The obvious difficulty here is that we don't know what observations will be made in the future. Consider the following case. My friend Frank has an apparently normal chicken egg. Nobody has ever observed the interior of this egg. Frank decides to put the egg in a box and throw it into a volcano, so that nobody will ever observe its interior (suppose this is part of some bizarre religious ritual). Well, if I accept M, then I must be agnostic about what it in the interior of the egg. Its interior will, in all likelihood, never be observed. But then suppose that while carrying the egg to the volcano, Frank drops it and it breaks, revealing the yolk and egg white.

The point, in the context of the "vulnerability criterion" argument for M, is that since we don't know what will be observed in the future, it's not at all clear that, at the present time, CE and M are equally vulnerable. The manifestationalist believes only that theories are true for what will be observed - if we don't know whether X will be observed, or we have good reason to believe that X won't be observed, then we must be agnostic about X. For this reason the manifestionalist, but not the constructive empiricist, must be agnostic about many things that will ultimately end up being observed. CE is therefore riskier than M, and this pushes us towards CE.

2. A&B suggest that M better captures the spirit of empiricism, which counsels us to limit belief to what in principle to tested against experience. The observations that we can make are constrained by our spatiotemporal location. CE involves belief in entities and processes billions of light-years distant or billions of years in the past, that we could not possibly observe. M offers a more modest position based on the specific position of humans in the universe and the epistemic limits entailed by this.

With this argument, I think that A&B have identified a genuine problem with van Fraassen's formulation of CE, but other versions of CE are less vulnerable to their criticism. We simply need to reconceive what is meant by "observable". I offer one suggestion in this post. The constructive empiricist hold the observable is what could in practice be detected by the unaided senses, given the technology of the time; and no feasible technology currently available would allow us to travel to distant quasars. This conception of observable is of course not precise - there is no absolutely clear line between the observable and unobservable - but this is equally true of van Fraassen's way of drawing the distinction.

3. Finally, A&B argue that the aim of an enterprise should be related to "what an ideal community of practitioners of that enterprise would accomplish under ideal circumstances." The aim of an enterprise should be attainable at least in ideal circumstances. A&B then suggest that the ideal scientific community is a community of people just like us, with the same sensory capacities and occupying the same spatiotemporal location in the universe, but who are devoted exclusively to the development of science. They meticulously and flawless record every observation. They generate theories that perfectly fit the observations. What will the final product of this community be? They will have a theories that are manifestly adequate - but not necessarily true or even empirically adequate. Rival empirically adequate theories will fit the data equally well. Even in ideal circumstances, there is no guarantee that we would produce empirically adequate theories, but we would produce manifestly adequate theories. This favours M.

I have two objections to this argument. First, why should the aim of an enterprise be decided by what an ideal community would achieve? Consider games with impossible aims. The aim of Klondike solitaire is to move all cards to their foundation piles; however, this is not possible even in principle for about 20% of deals. An ideal community of Klondike solitaire players could not move all the cards to their foundation piles in those deals - nevertheless, the aim remains the same.

Second, why suppose that there is a definable "ideal community" of scientists? A&B suppose that the ideal community is limited to our place in space and time; but why? Surely an even better scientific community would be one that existed as soon as complex life was possible, and had been meticulously collecting observations ever since. Would all members of the ideal community have perfectly functioning sensory capacities, e.g. 20/20 vision? Perhaps they would have superhuman capacities, 20/10 or even 20/1 vision perhaps. It isn't at all clear what counts as ideal in this respect.

It's clear that the ideal community will need some superhuman capacities. A&B suggest that ideal community would devote all their time to science, and they record every observation they make. Neither of these things is possible for humans. We need to devote time to other enterprises such as eating food, and we wouldn't be able to record every observation even if we tried. There are simply too many observations, and in any case, a person could not record observations while at the same time generating theories to account for those observations.

The problem for A&B is that in order to ensure that the ideal community generates manifestly adequate theories, they must suppose that this ideal community is capable of feats that go far beyond human capacities - indeed, feats that go far beyond the capacities of any conceivable organism. But then why not say that the ideal community is one that observes every observable? This community would produce empirically adequate theories - and this would give us an argument for CE.

What's wrong with manifestationalism?

There are many objections we might raise against M. I want to outline what I regard as a knock-down argument against it. Consider again Frank and his egg. We saw that Frank broke the first egg. So now he goes and out and purchases a second one, which again he intends to put in a box and throw into a volcane. This time, he takes many precautions to avoid breaking the egg, such as wrapping it thickly with bubble wrap. If I accept M, I must be agnostic about the interior of the egg, since I have good reason to believe that this will never be observed.

But now suppose that on the trip up the volcano, Frank gets hungry, and decides he wants to eat the egg. Well, now I have good reason to believe that Frank will observe the interior of the egg, and since our best theories tell us that he will observe a yolk and egg white, I should believe that he will observe a yolk and egg white. Of course, this example can be run in reverse as well, where Frank initially intends to eat the egg, and then intends to throw it into the volcano: in this case, I first believe that he will observe a yolk and egg white, and then I must give up that belief and become agnostic.

This is of course an absurd conclusion, absurd enough in my view that it's enough in itself to remove M from serious consideration. One response to this is to hold that we should remain agnostic about anything that has not yet been observed - even if we have good reason to think that Frank will open the egg, we should remain agnostic about the interior of the egg until he actually does it. But this entails radical scepticism about the future, which is no less absurd; and as I noted earlier, M was supposed to avoid radical scepticism.

Ultimately, it seems to me that A&B fail to show that M is a serious contender. There are very serious, very obvious problems with M, and no plausible arguments in its favour.

Constructive empiricism and the past

Derek Turner argues, in chapter 7 of Making Prehistory, that van Fraassen's constructive empiricism entails radical scepticism of the past. Here is Turner's argument:

(P1) All of our knowledge is limited to that which we can observe.
(P2) We cannot observe things which no longer exist or events which occurred in the past.
(C) Therefore, we cannot know anything about past things and events.

The constructive empiricist must suspend belief in dinosaurs, the Black Death, WWII, even what she had for breakfast this morning. Turner takes this conclusion to be far too radical, hence a good reason to reject constructive empiricism. I agree with him that such radical scepticism should be avoided, but I'm not convinced that the constructive empiricist is committed to it.

It seems clear that the constructive empiricist is committed to (P1), since this merely expresses the constructive empiricist's scepticism about unobservables. Van Fraassen would presumably want to reject (P2), but as Turner argues, it's not clear how he could do so. The natural response for van Fraassen is to say that some past entities such as dinosaurs were such that, if they were around today, we would see them. So dinosaurs are observable. The problem with this move, as I discuss in this earlier post, is that we may as well also say that if we stepped into a miniaturization machine, we would see bacteria.

In any case, the interesting question is not whether past things and events are observable per some definition, but whether there is good justification for believing in past things and events. My point is, we can surely draw the observable/unobservable distinction so that some past things and events count as observable - but similarly, we can draw that distinction so that electrons and neutrinos count as observable (we might say that to observe something is simply to detect it either with the senses or with instruments). In practice, dinosaurs are just as inaccessible to us as electrons and neutrinos - indeed, as Turner argues, dinosaurs are if anything even less accessible, since if electrons and neutrinos do exist we might interact with them and manipulate them instrumentally.

The constructive empiricist must accept (P1) and (P2), and the conclusion straightforwardly follows. However, the significance of the conclusion depends on how we interpret the word "we". Turner seems to assume that "we" refers to presently existing humans. I think we should resist this interpretation. To explain why, consider this very similar argument, which suggests that constructive empiricist to an even more extreme form of scepticism:

(P3) All of my knowledge is limited to that which I can observe.
(P4) I cannot observe anything other than my immediate surroundings.
(C) Therefore, I cannot know anything abuot that which is not in my immediate surroundings.

The problem with this argument is that science is fundamentally a human and communal activity. Perhaps there could in principle be one lone scientist, who correctly applies the scientific method (whatever that is) but who never communicates with any other people - clearly, however, her investigations wouldn't get very far. Every scientist relies on the testimony of others, and although testimony is often unreliable, there are circumstances where we can trust it. Science depends on this because a single scientist can't test everything. The vast majority of beliefs that a scientist holds even about the observable world will never have been tested by her. Speaking as a layperson, I've never observed the planet Neptune. I rely on the testimony of other people, who claim to have seen it through their telescopes. We work as a community to generate scientific knowledge; if you reject that community aspect, you undermine the very conditions of modern science.

Observability is relativized to the epistemic community. Who counts as part of that community? Not just contemporary people, but people in general - past, present, and future - and all their observations count. The Black Death was not simply observable, it was actually observed by hundreds of thousands of people, and we have numerous reports of it, many of which are reliable. So we should believe that the Black Death occurred. Of course, the people who observed the Black Death no longer exist. But why would that matter? Science is something that develops across many times and places. Indeed, building and testing theories can only be done over time, sometimes only over literally decades.

My point is that the existence of human communities over time, and certain conditions under which we can reasonably rely on the testimony of others, is simply taken for granted in any philosophy of science, because if this assumption rejected there is no reason to think that anything resembling science actually takes place. Having made this assumption, there is then an additional question about what else we should believe: for example, does science require us to extend belief beyond human observation?

Of course, a question remains about what justifies this assumption. Why should I believe that other people exist, that I can sometimes rely on what they say, etc? This questions arises when we "step back" from philosophy of science and it is, of course, a familiar question of philosophical scepticism. Perhaps it will turn out that whatever justifies belief in the existence of other people will also justify belief in some unobservable entities such as electrons. This would refute constructive empiricism, or at least it would make the constructive empiricist's selective scepticism of unobservables arbitrary. But in principle, the constructive empiricist need not be committed to scepticism of human history.

What about prehistory? Can the constructive empiricist believe in dinosaurs? On this point, I'm inclined to agree with Turner: constructive empiricism implies total scepticism about the distant past. I don't, however, share Turner's feeling that this is an especially extreme position. Indeed, it's curious that Turner regards such scepticism as so repugnant, because he devotes a great deal of his book to defending an epistemic asymmetry thesis that we have better access to the microscopic and microphysical than to the distant past; as he puts it, "there is a rough sense in which we can know more about the tiny than about the past" (pg 25). However, Turner is rather sanguine about the constructive empiricist's scepticism of microphysical unobservables; he sees this as a fairly modest feature of the theory. If we have better access to the tiny than to the past, and if scepticism of the tiny is at least reasonable (though perhaps not rationally compelled), why would scepticism of the past be repugnant?

Observable or observed?

In my previous post I discussed some difficulties with the observable/unobservable distinction in constructive empiricism (CE). Here I'll focus on a related problem, the distinction between the observable and the observed.

Extreme constructive empiricism

In accepting that our best scientific theories correctly describe all observable phenomena, CE goes far beyond the empirical evidence. Most of what is observable will never be observed. Consider this position, which I will call "extreme constructive empiricism" or "ECE" for short: our best theories are true for the observed phenomena, but we should be agnostic about everything else. Why not adopt this more sceptical position? There are some obvious benefits to ECE. In holding that science delivers truth about the observable, two common arguments for antirealism are unavailable to CE:

(1) The pessimistic induction. Put briefly, this argument goes as follows: (P1) Most scientific theories accepted in the past have been rejected; (C) so, most currently accepted theories will be rejected in the future.

However, every case in which claims about unobservables have been rejected has also involved rejection of claims about observables. Those theories that we rejected in the past were rejected because they conflicted with observations. If our current theories are going to be rejected in the future, this will presumably be because they confront new observations that contradict them. So no antirealist who takes current accepted theories to be true for observable phenomena could endorse the pessimistic induction. Obviously this difficulty doesn't arise for the ECEist who only takes those theories to be true of the observed phenomena.

(2) The underdetermination argument. This argument rests on the claim that for any theory that correctly describes observable phenomena, there are numerous other theories that also correctly describe observable phenomena but that make different claims about unobservables. Again, it is easy to see that this can be run against CE, because for any theory that correctly describes what has been observed, there are numerous other theories that also correctly describe what has been observed but that make different claims about observable-but-as-yet-unobserved phenomena.

So what is the justification for belief in the observable over the merely observed? I will discuss two arguments.

The aim of science

First, Van Fraassen and Monton argue that CE is an attempt to describe the aim of science, with an assumption that the behaviour of scientists is rational. If the aim of science were truth about the merely observed, rather than the observable, then:

there would be no scientific reason for someone to do an experiment which would generate a phenomenon that had never been observed before. But one of the hallmarks of good scientists is that they perform experiments pushing beyond the limits of what has been observed so far.

Suppose I develop a theory of galaxy evolution that accommodates all that has been observed so far. I could derive further predictions from this theory, and then probe the sky to check if those predictions are accurate. But if the aim of science is simply truth about what has been observed, why bother? My theory already achieves this aim; it is therefore as good as any theory could possibly be. It would be unreasonable to risk turning an perfect theory into an imperfect one by making further observations that could contradict it. By contrast, in holding that the aim of science is truth about the observable, CE accommodates the fact that scientists spend so much time generating new observations.

There are a couple of things to say about this. First, assuming that it even makes sense to talk of the aim of science as a whole (as opposed to the aims of particular scientists or particular research groups), why would we suppose that science has only one aim? Two others goals that science plausibly aims at are the discovery of new phenomena and the manipulation and control of natural phenomena. If science aims at discovery, that immediately makes it rational for scientists to make new observations. If science aims at control and manipulation, new observations are always worthwhile because the more we know about the world, the better we are at controlling and manipulating it.

Second, we must distinguish the aim of science from the epistemology of science. Just because science aims at empirical adequacy, it doesn't follow that we should believe that our best theories are empirically adequate. Perhaps science sometimes falls short of its aims. After all, we all know that science has developed over time, and we hope that it will continue to develop in the future, that in the future it will be closer to achieving its aims than it is today. So the question remains, why suppose that our scientific theories save the observable phenomena, rather than merely save the observed phenomena?

Epistemic risk

A second argument for belief in the observable is hinted at by van Fraassen in his contribution to Churchland & Hooker's Images of Science. Although this is stated as an argument against realism, we can use the ideas here to support CE over ECE:

If I believe the theory to be true and not just empirically adequate, my risk of being shown wrong is exactly the risk that the weaker, entailed belief will conflict with actual experience. Meanwhile, by avowing the stronger belief, I place myself in the position of being able to answer more questions, of having a richer, fuller picture of the world, a wealth of opinion so to say, that I can dole out to those who wonder. But, since the extra opinion is not additionally vulnerable, the risk is — in human terms — illusory, and therefore so is the wealth. ... What can I do except express disdain for this appearance of greater courage in embracing additional beliefs which will ex hypothesi never brave a more serious test?

The realist believes everything the CEist believes, but the realist also holds additional beliefs that cannot face any additional tests. As Kukla (pg 98) puts it, van Fraassen seems to adopt a "vulnerability criterion of belief". Two theories are equivalently vulnerable when they are disconfirmed by precisely the same observations. Van Fraassen holds that if two theories are equivalently vulnerable, we should believe the theory that is logically weaker.

CE is obviously riskier than ECE, since the CEist is committed to beliefs about what has not yet been observed whereas the ECEist is agnostic about this. The two positions are not equally vulnerable. Of course, this is not yet an argument for CE. Indeed, if anything this looks like an argument against CE: intuitively, if a belief is riskier, if it is more likely to be wrong, then that is a reason not to hold that belief.

But notice that if our goal is simply to minimize the risk of holding false beliefs, then we should become radical sceptics and believe nothing at all (or perhaps we should believe a few propositions that we think are beyond doubt, but certainly we should believe nothing substantial about the world). Clearly we have other goals. There are, broadly speaking, two types of epistemic error: type I errors consist in believing what is false; type II errors consist in failing to believe what is true. Attempting to avoid one type of error pulls us in a different direction than attempting to avoid the other type, and an important question in epistemology and philosophy of science is how to balance these two goals.

Here is a simple suggestion: We avoid type I errors through the vulnerability criterion of belief; don't hold beliefs that go beyond what can be tested empirically. We avoid type II errors by holding the strongest possible beliefs given the vulnerability constraint. This is exactly what CE does. ECE makes very severe type II errors: to be agnostic about everything beyond what has been observed entails total agnosticism about the future, and this would be disastrous even assuming that it's psychologically possible. ECE undoubtedly commits fewer type I errors than CE, but the price in type II errors is simply too high.

Observables in constructive empiricism

Constructive empiricists such as Bas van Fraassen hold that we should take our best scientific theories not to be true but merely empirically adequate, where a theory is empirically adequate when what it claims about observable phenomena is true. We should believe what our best theories tell us about the observable world, but remain agnostic about any unobservable phenomena they postulate. For the constructive empiricist, something is observable just in case it can in principle be detected by the unaided senses. So we should be agnostic about electrons, mitochondria, the strong nuclear force, the tricarboxylic acid cycle, etc.

Obviously, the cogency of constructive empiricism depends on whether the observable/unobservable distinction can be made to work. Van Fraassen treats observability as a property of entities. Some types of entities are such that they produce certain changes in our perceptual systems, provided we have the right kind of relation to them; these entities are observable. For example, Jupiter's moons are observable. From Earth, of course, we require telescopes to detect them, but they are in principle detectable with the unaided senses because we could travel to them, and then they would impinge on our senses in certain ways. So van Fraassen isn't agnostic about Jupiter's moons; he believes they exist.

The question is, how should the "in principle" be interpreted? What kind of relation to an entity is the "right" kind of relation? Van Fraassen, as far as I know, is fairly dismissive of this kind of problem. He thinks that "observable" is a vague predicate so there is no precise distinction between the observable and the unobservable, but this is no threat to constructive empiricism because even with a vague boundary we can still specify entities that are unambiguously unobservable. It seems to me, however, that without an answer to those questions, it isn't at all clear that there are any unambiguously unobservable entities - or at least, that the class of them becomes so small that constructive empiricism fades into realism.

Van Fraassen is happy to count distant astronomical objects such as quasars as observable, because we would detect them unaided if we travelled billions of light-years in their direction. Similarly, past entities such as dinosaurs are observable, because we would detect them unaided them if we went back into the past. The observable is not just what is detectable unaided given current technology, as Jupiter's moons are. We can also imagine technology that violates the laws of physics, that can take us millions of years into the past or billions of light-years distant.

There are various problems with this treatment of observability, but the constructive empiricist in particular surely can't accept it. Once we're allowed to imagine totally speculative technology, we might say that in principle I could see a bacterium with my unaided senses, because I could enter a miniaturization machine and be shrunk down to the bacterium's size. Indeed, it's worth noting that miniaturization appears to be more plausible than travelling to the most distant quasars, since miniaturization doesn't violate any laws of physics as far as I'm aware. So on this view, a whole host of phenomena become observable and the distinction between constructive empiricism and realism fades. One fix is to say:

(A) The observable is what is detectable with the unaided senses given current technology, here in 2017.

But now consider the situation for astronomers working, say, 300 years ago. Given the technology at the time, both Jupiter's moons and bacteria were equally inaccessible. It later turned out that space travel was feasible whereas miniaturization was not, but surely there was no justification available in the 1700s for expecting technology to develop that way. If we accept (A), then the constructive empiricist has the curious conclusion that, in the 1700s, it was reasonable to believe in Jupiter's moons even though there was good reason to think that Jupiter's moons were unobservable in the same way that microbes were unobservable.

A similar problem arises when we consider future technological developments. Maybe we will in fact develop miniaturization machines and people will directly interact with microbes. If observability is determined by current technology, then microbes will still count as unobservable and therefore our miniature descendents should remain agnostic about microbes. With these points in mind, it seems we have to drop (A) in favour of:

(B) The observable at time t is what is detectable with the unaided senses given the technology at t.

However, technology can regress. If a nuclear holocaust occurs and we lose our ability to construct telescopes, then Jupiter's moons will become unobservable again. The constructive empiricist would have to conclude that we must once again be agnostic about the existence of Jupiter's moon. To avoid this conclusion we can modify (B):

(B*) The observable at time t is what is detectable with the unaided senses given the technology at t and any time before t.

This doesn't seem to face any obvious problems. However, an interesting consequence of (B*) is that it can be used to strengthen the case against the constructive empiricist by supporting an "optimistic induction" argument for realism about unobservables. This is because (B*) allows that unobservable entities can become observable as technology develops. Briefly, the argument is that numerous entities postulated by our best theories were initially unobservable but later became observable, thus vindicating those believed in such entities; so we can similarly expect that those who believe in currently unobservable entities will be vindicated in the future if the technology develops to make those entities potentially observable.

Jupiter's moons were once unobservable. Over the past few decades we have sent machines to Jupiter, and we could probably even send a person there, though that might be a waste of time and money. In any case, Jupiter's moons clearly do exist. The astronomers of the past who believed in these objects have been vindicated. Numerous other examples can be found from astronomy: (a) Other planets and moons and their properties. We can now see directly that the Moon's surface is disfigured by craters, that Venus undergoes phases similar to the Moon, that Mars has a tenuous carbon dioxide atmosphere, etc. (b) The true properties of the Sun, such as its size and sunspots. (c) The asteroid belt. (d) Comets. (e) Certain properties of the gravitational force. We feel a particular gravitational force on the surface of the Earth; now we can ascend to space in rockets and directly feel that the force is lesser there. (f) The shape of the Earth: predicted to be an oblate spheroid on theoretical grounds, its shape can now be directly seen.

Of course, this is an inductive argument, and van Fraassen rejects induction. However, as far as I can tell, this is not a necessary feature of constructive empiricism. In any case, anybody who accepts induction has an additional reason to be wary of constructive empiricism.

Philosophy of extraterrestrials: an unfairly neglected subject

Philosophers have devoted very little attention to the subject of extraterrestrial life. Cirkovic, Kukla, and Lamb are the only recent philosophical monographs on the subject that I'm aware of. The lack of philosophical engagement with the extraterrestrial question is puzzling for several reasons:

(1) As is demonstrated by Dick and Crowe, there is a long history of philosophical discussion of extraterrestrials. The early atomists were optimistic about extraterrestrials. They proposed an infinitely large universe, consisting solely of "atoms and the void", with different arrangements of atoms producing the diversity of objects we see around us. On this view, our planet and the organisms inhabiting it were created by chance collisions of atoms. Given this metaphysics, we can expect that other worlds with other living creatures will have arisen elsewhere. Lucretius, for example, says (quote taken from Kukla):

it is in the highest degree unlikely that this earth and sky is the only one to have been created … This follows from the fact that our world has been made by nature through the spontaneous and causal collision and the multifarious, accidental, random and purposeless congregation and coalescence of atoms whose suddenly formed combinations could serve on each occasion as the starting-point of substantial fabrics – earth and sea and sky and the races of living creatures.

Following the Copernican revolution, the scholarly discussion of extraterrestrial life snowballed, and optimism was the dominant position. There were two primary justifications for belief in extraterrestrials. First, most scientists accepted the Copernican Principle, which claimed, to put it simply, that there is nothing special about the Earth (versions of this principle are still accepted today). The stars are suns just like our own; and all areas of the universe are subject to the same laws of nature. Thus it was expected that planets similar to the Earth would be prevalent throughout the universe. Studies of other solar system bodies seemed to confirm the similarity to the Earth: astronomers observed clouds on Jupiter and mountains on the Moon. Second, abundance of extraterrestrial life was held to follow from religious commitments. God would not be wasteful; he would not have created a vast universe filled with stars and planets for no reason. Obviously such other worlds were not created for the benefit of humankind, so their purpose must be to house other intelligent species. Many scholars, such as William Herschel, went as far as to suggest that the Moon, the comets, Saturn's rings, and even the interior of the Sun, were inhabited.

Against this optimism were those who held that extraterrestrial life, even if it does not explicitly contradict anything in the Bible, is at least in some tension with a religion that is structured around humanity's unique experience and history. Should we suppose that Jesus died and was resurrected on an infinite number of planets? This seems absurd. Or perhaps extraterrestrials have not fallen and so are in no need of redemption? But now we are supposing that the Earth is uniquely evil. Along with these religious concerns, by the mid-1800s scholars such as William Whewell were emphasizing scientific studies showing significant differences between the planets, such as spectroscopic studies of the Moon that revealed its lack of appreciable atmosphere. Philosophers engaged in a great debate about extraterrestrials throughout the 19th century.

(2) The scientific study of extraterrestrial life, which is part of the field of astrobiology, is a highly interdisciplinary field currently undergoing rapid progress, however its conceptual foundations have yet to be fully developed. For exmaple, what is the status of principles such as the anthropic principle and the aforementioned Copernican principle, and how should they be applied? How much can we learn from the Drake equation? So far, much of this work has been left to the scientists themselves. Philosophical study of extraterrestrials will allow philosophers to work closely with an increasingly powerful science, and on a topic that is of great interest to many people even outside of academia.

(3) The problem of extraterrestrials is connected with a variety of topics in philosophy of biology, philosophy of language, philosophy of mind, ethics, and so on. For example:

-- One of the first questions that arises in the search for extraterrestrial life is, what exactly are we looking for? What is life? This is, of course, a central problem in philosophy of biology.

-- Assuming that life does exist on other planets, how similar should we expect it to be to life on this planet? There has been a great deal of debate in philosophy of biology about the degree to which the evolutionary process is contingent, or is instead driven by trends that tend to produce convergence on the same solutions. A similar question is, does civilization require a humanoid form? Dolphins, octopi, and crows are intelligent animals, but it's difficult to see how they could build a civilization due to the limits of their morphologies - they simply cannot manipulate tools in the precise ways that humans hands can.

-- A number of authors have suggested that SETI is in some sense unscientific. To take Popper's criterion of falsifiability, for example, it seems that SETI research is organized around a proposition that is unfalsifiable, namely: there exist detectable extraterrestrial civilizations. SETI may therefore provide a good case study for discussion of the demarcation problem of how to distinguish science from non-science.

-- Putting aside the practical problem of the vast distances, is it possible even in principle to communicate with extraterrestrials? Translating human languages, such as Egyptian hieroglyphics, is often hard enough; the difficulties facing any interpreters of extraterrestrial signals will be orders of magnitude greater. Is there anything that could serve as a "universal langauge" - mathematics, for example? (I discuss the problem of extraterrestrial communication in this video.

-- Active SETI is a branch of SETI that attempts to contact extraterrestrials directly by sending messages into space. Various authors have argued that while listening for extraterrestrials is acceptable, we should refrain from sending messages ourselves because it poses potentially catastrhopic risks. We don't know the character or the capabilities of the civilizations we are attempting to contant. For all we know, they may well be able to do us great harm. (I discuss these risks in this video.

-- What will be the impact on our culture of discovering extraterrestrial life? Are contemporary religions such as Christianity compatible with the existence of extraterrestrials?

-- We may well discover simple microbial life elsewhere in the solar system; Mars and Europa, for example, remain possible abodes of life. What moral obligations would we have to such life? What kind of planetary protection policies should we adopt? How can we extend contemporary theories in environmental ethics to cover extraterrestrial life?


Why did philosophers lose interest in extraterrestrials? I don't have the historical competence to answer this definitively, but it's worth noting a few points. By the early 1900s, the scientific justification for belief in extensive extraterrestrial life had collapsed. Closer studies of the other planets of the solar system revealed them to be barren, desolate worlds, wholly unsuitable for life. The "canals of Mars" controversy had brought disrepute to the study of extraterrestrials. Furthermore, by this time the dominant view of the origin of the solar system was the Chamberlin-Moulton encounter hypothesis, which proposed that the solar system formed when another star passed close to the Sun and gravitational interaction drew out huge filaments of material that coalesced to form the planets. Planets were therefore likely to be extremely rare. Whereas the Copernican revolution had initially seemed to provide a scientific basis for optimism, extraterrestrials now once again entered the realm of mere speculation.

At around the same time, philosophy became dominated by the logical positivists, who held that philosophy cannot make empirical claims and instead focused on technical problems of meaning of scientific terms, theory reduction, the nature of scientific confirmation, etc. They saw little value in philosophical speculation on grand topics such as extraterrestrials. In later decades, into the 1940s and beyond, outlandish reports of UFOs and alien abductions have sullied the topic of extraterrestrials still further in the eyes of serious philosophers.

Whatever the reasons for the absence of philosophical study of extraterrestrials, I hope, in light of the great scientific progress on the problem and the wide range of philosophical issues it connects with, that more philosophers turn their attention to it in the near future.

Entity realism and experimental failure

Entity realism, defended most famously by Ian Hacking, is the view that we should be sceptical of scientific theories, but we should believe in unobservable entities that scientists can manipulate and use as tools to study other phenomena. Nobody will ever observe an electron, but we should believe in electrons because we can spray them onto deuterium to help study weak neutral currents. As Hacking says, "When we use entities as tools, as instruments of inquiry, we are entitled to regard them as real."

Discussions of entity realism often assume that experimental or manipulative success is the entity realist's criterion for belief in unobservable entities; Gelfert, for example, says: "In its original form due to Ian Hacking, entity realism postulates a criterion of manipulative success which replaces explanatory virtue as the criterion of justified scientific belief." I suggest that the entity realist would be better off dropping this criterion. Experimental failure often provides just as strong reason for belief as experimental success.

Consider the following case from solar astronomy. Thermonuclear fusion in the core of the Sun occurs by the proton-proton chain, where four protons are converted into a helium nucleus, two positrons, and two electron neutrinos:

4p → ⁴He + 2e⁺ + 2ν_e

Neutrinos interact with matter extremely rarely; a piece of lead one light-year thick would stop only 50% of any neutrinos passing through it. The vast majority of neutrinos produced in thermonuclear fusion pass straight through the Sun unimpeded. So studying neutrino flux gives us a direct view into the core of the Sun. The challenge is how to detect the flux of these particles that interact so weakly with matter.

The first experiment to detect solar neutrinos was developed in the mid-60s by Ray Davis using a tank of perchloroethylene, C2Cl4. Very rarely, a neutrino collided with a chlorine nucleus, converting it into radioactive argon by converting a neutron into a proton. The radioactive argon was then captured by bubbling helium through the tank. Davis used the rate of argon production to measure the neutrino flux. Unfortunately, the Davis experiment was a failure; he detected only 1/4 of predicted neutrino flux (figures are from Longair's The Cosmic Century, p.180):

Predicted flux: 7.9 +/- 2.6 solar neutrino units
Observed flux: 2.1 +/- 0.9 solar neutrino units

What went wrong? Different reactions in the p-p chain produce electron neutrinos of different energies. It was proposed that Davis was detecting only the high-energy neutrinos. Further experiments, such as GALLEX and SAGE, which were based on neutrino collisions converting gallium into radioactive germanium, were designed to detect the low-energy neutrinos. These experiments also failed; they detected only about half of the predicted low-energy neutrino flux. Another suggestion was that something was wrong with the solar models – perhaps we were mistaken about the temperature in the core of the Sun, for example – however, by the 90s experiments in helioseismology were providing robust confirmation of these models, and it became clear that the problem lay with our understanding of the nuclear physics relating to neutrinos (see Longair p.182).

The problem was finally resolved in the early 2000s by the discovery of neutrino oscillation: some of the electron neutrinos produced in the p-p chain spontaneously converted into tau and muon neutrinos, which were not detected by any of the original experiments. However, what is interesting in the context of entity realism is the situation in the decades prior to this. From the mid-60s to the early-00s, across numerous different experiments, predictions failed and experiments did not work as intended. So any argument from experimental success could not apply to neutrinos. Yet it remains the case that scientists used neutrinos as tools, as "instruments of inquiry", in their investigations of the core of the Sun, which seems to be what Hacking requires to justify belief in neutrinos. Indeed, few, if any, scientists working on solar physics doubted that neutrinos were being detected.

This case suggests that there is nothing especially important about experimental success. By analogy, we use hammers to drive nails into walls. There are many ways we might fail: we might smash a hole in the wall, or we might be using a dud nail that snaps when we hit it. None of this would lead us to doubt the existence of the hammer. We don't infer the hammer's existence from its success at driving nails into walls; the fact that we can use and manipulate the hammer in certain ways is enough.

One reason why it's worth exploring cases of experimental failure is that these may provide the entity realist with the resources to answer the persistent objection that entity realism collapses into standard scientific realism. Believing in some entity X, so the objection goes, requires believing theories about X. As Alan Musgrave puts it:

To believe in an entity, while believing nothing else about that entity, is to believe nothing or next to nothing. I tell you that I believe in hobgoblins. "So", you say, "You think there are little people who creep into houses at night and do the housework." To which I reply that I do not believe that, or anything else about what hobgoblins do or what they are like - I just believe in them.

Hacking, as is well known, has claimed that while we shouldn't believe scientific theories about e.g. electrons, there are basic "home truths" about electrons, a basic "common lore" about electrons, that we should all accept. Such home truths include that electrons have negative charge, that they "orbit" (in some sense) atomic nuclei, that they have a rest mass of about 9.1x10-31kg, that certain materials transmit electrons more readily than others, etc. This is enough to give us a substantial belief in electrons, and to allow us to use electrons in scientific experiments.

Theories change but home truths remain. This is illustrated very nicely by the neutrino experiments. Since the neutrino detection experiments failed to confirm the theoretical predictions, it was clear that some part of the theory was wrong. Initially this was attributed to inaccuracies in the solar models, but by the 1990s most scientists turned their attention to the nuclear physics. Neutrino theory was wrong. Arguably then, belief in neutrinos could not be justified by appealing to this theory. Nevertheless, scientists retained certain low-level assumptions or "home truths" about the causal powers of neutrinos, such as that neutrinos are produced by reactions in the p-p chain, and that they can very occasionally collide with chlorine converting it into argon. Perhaps entity realists should turn their attention to examples of experimental failure.

An interesting follow-up question for the entity realist would be, how do we distinguish cases of failed prediction where we nevertheless assume that the experimenters were using a certain unobservable, as occurred in neutrino astronomy, from those cases where we think that nothing important was detected? Joseph Weber's research into gravitational waves might be an example of the latter case.

Quine on unactualized possibilia

I'd like to examine some arguments from Quine's On What There Is, one of the most famous papers in modern philosophy. In particular, I want to focus on Quine's comments concerning the Platonic riddle of nonbeing.

As Quine puts it: "Non-being must in some sense be, otherwise what is it that there is not?" In asserting, for instance, "Pegasus does not exist", I appear to commit myself to the existence, or to the being, of Pegasus. What is it that I'm saying doesn't exist? If Pegasus is nothing, then when we use the word "Pegasus", we're not talking about anything, which would render any statements containing the word nonsensical. "Pegasus does not exist" would amount to "_ does not exist". So, Pegasus, along with other nonexistent things, must have being of some sort, in order to account for the intelligibility of our discourse about nonexistents.

We might formalize the argument like so:

(P1) If "Pegasus" names nothing, then statements about Pegasus are nonsensical.
(P2) Statements about Pegasus are not nonsensical.
(C) So, "Pegasus" must name something.

Another way to see the problem is that it would appear that, if "Pegasus" and "Santa Claus" name nothing, than "Pegasus does not exist" and "Santa Claus does not exist" are each saying exactly the same thing. In each case, we're referring to nothing, and saying it doesn't exist.

(P3) If "Pegasus" names nothing and "Santa Claus" names nothing, then "Pegasus does not exist" and "Santa Claus does not exist" both say the same thing.
(P4) "Pegasus does not exist" and "Santa Claus does not exist" do not say the same thing.
(C) "Pegasus" and "Santa Claus" must each name something.

"Pegasus" names something, but what? One option is to hold that Pegasus has a kind of being as an unactualized possible object (Quine attributes this view to a character called "Wyman"). Reality consists of existent, actual objects; and also various nonexistent, merely possible objects.


Quine's objections to unactualized possibilia

1. First, how do we individuate such entities? What are their conditions of identity? The moment we try to analyze possible objects in any detail, we find that we can't answer simple questions about them:

Take, for instance, the possible fat man in that doorway, and, again, the possible bald man in that doorway. Are they the same possible man, or two possible men? How do we decide? How many possible men are there in that doorway? Are there more possible thin ones than fat ones? How many of them are alike? Or would their being alike make them one? Are no two possible things alike? Is this is the same as saying that it is impossible for two things to be alike? Or, finally, is the concept of identity simply inapplicable to unactualized possibles? But what sense can be found in talking of entities which cannot meaningfully be said to be identical with themselves and distinct from one another?

2. A second objection, related to the first, not explicitly stated by Quine but I think implicit in his paper, is that due to the problem of individuating possible objects, postulating possible objects doesn't actually solve the problem of referring to non-existent things. For if we can't individuate possible objects, we can't ever know what is being referred to when people use the term "Pegasus".

I don't think Wyman should be too troubled by these first two objections. In the first place, over the last few decades very detailed theories of modal metaphysics have been worked out that make answering questions such as these perfectly straightforward. Consider, for instance, Lewis's modal realism. Lewis would deny that there is a possible fat man in that doorway. Rather, at some possible world, a fat man is standing in the counterpart of that doorway. At some other possible world, a bald man is standing in the counterpart of that doorway. At some other world, a fat, bald man is standing in the counterpart of that doorway; at some other world, two fat, bald men are standing in the counterpart of that doorway; etc. Re whether any two possible men are alike, we evaluate the similarity of different possible objects in just the same way we evaluate the similarity of actual objects. Re identity, again, this is essentially just the same as for actual objects. (This is not to suggest that Lewis's theory, or any other realist theory of possibilia, is particularly plausible. But I think that Wyman could appeal to such developments to defuse Quine's objection.)

Second, as Richard Routley argues in his paper "On What There Isn't", precisely the same sort of difficulties arise for existing objects. Routley parodies the passage from Quine:

Take, for instance, the cloud in the sky above; and again, the adjacent cloud in the sky. Are they the same cloud or two clouds? How are we to decide? How many clouds are there in the sky? Are there more cumulus than nimbus? How many of them are alike? Or would their being alike make them one? ... is the concept of identity simply inapplicable to clouds? But what sense can be found in talking of entities which cannot meaningfully be said to be identical with themselves and distinct from one another?

Perhaps Routley isn't entirely fair here - surely there must be more difficulties with possible objects, if only because possible objects are so much more extensive, and include many stranger things, than actual ones - but the basic point is, I think, correct: just because it turns out to be difficult to answer seemingly simple questions about a certain class of objects, it hardly follows that we have reason to believe that there are no such objects. Reality is full of strange, difficult things. It's also full of perfectly straightforward things that turn out to be puzzling when subjected to certain questions, as when we try to come up with clear criteria for individuating clouds.

3. The notion of a possible object rests on a confusion. Modality, Quine suggests, applies to whole sentences, not to particular things. "It is possible there is a man in the doorway" is perfectly acceptable, the possibility in this case attaching to the sentence "there is a fat man in the doorway"; but it's illegitimate to infer from this to "there is a possible man in the doorway", with the possibility attaching to an entity, the fat man. (Quine doesn't present his reasoning for this in this paper. His arguments here are complex and I won't go into them here. I did start a video series on this, which I never got around to finishing. Michael Morris's An Introduction to Philosophy of Language also covers it.)

Quine suggests that the main motive for expanding possibility from sentences to objects is to deal with the riddle of nonbeing. I'm not convinced. I suspect that the main motive is the problem of explaining what the truthmakers of modal sentences are. The Nazis could have won WWII, I could have become a research chemist, nothing can exceed the speed of light, Frank couldn't have done any better in the exam, etc - in virtue of what, exactly, are such sentences true? Positing possible worlds is one way to deal with this.

4. Even putting aside the above problems, Wyman's account is simply incomplete. The postulation of unactualized possible objects doesn't help at all when we consider terms that apparently refer to impossible objects, such as "the round square cupola on Berkeley college". Quine suggests that one option for Wyman would be to hold that such terms are meaningless. So, regarding our riddle of nonbeing:

(P1) If "round square" names nothing, then statements about round squares are nonsensical.
(P2) Statements about round squares are not nonsensical.
(C) So, "round squares" must name something.

Wyman could reject (P2), accepting that "round square" names nothing and hence that statements about round squares are meaningless. Quine has two objections to this move. First, he argues, the claim that statements about round squares are meaningless "has no intrinsic appeal"; i.e. it's an unattractive and ad hoc hypothesis proposed simply to save the theory. Now, I'm not sure I agree with Quine here. To me, at any rate, "round square" does indeed seem to be meaningless, in some important sense. Of course, I can use the phrase "round square"; and I know what round things are and I know what square things are, so I might think that I'm able to make some inferences about what properties we might attribute to a round square. On the other hand, when I try to think about it in any detail, it slips out of my grasp. Can I really make inferences about it? Here's an easy one: it's a square, and square things have four sides, so it must have four sides. But this just ignores that we're talking about a round square. Round things don't have any sides.

It may be objected that "round square" is obviously contradictory, and this is why we struggle to assign any meaning to it. Sometimes however contradictions are disguised. Only on analysis do we realize that a proposed object is contradictory. Consider the suggestion that God, at least as conceived in Western monotheistic traditions, is contradictory, re arguments that properties such as omnipotence and omniscience lead to irresolvable paradoxes. Even if the atheist is correct about this, it's still the case that people have been able to talk about God in detail, and structure their lives around their belief in God, and even believe that they can have a personal relationship with God. Surely then we can't insist that the concept of God is simply meaningless.

There are two ways Wyman might deal with this. First, he could simply bite the bullet. Any concept that can be shown to entail contradictions is thereby meaningless. This is not such a radical position. The logical positivists held that a statement is meaningful only if it's analytically true or empirically verifiable; with this criterion they attempted to show that a whole host of apparently meaningful statements aren't meaningful after all, including statements about God (see e.g. Ayer's Language, Truth and Logic, chapter 6). Our ability to talk about God, to hold detailed religious beliefs, etc, can be explained by appealing to meaning in a weaker sense, e.g. emotional or poetic meaning. "Colourless green ideas sleep furiously" has no literal meaning, but we might say that it's meaningful in some extended, metaphorical sense.

Second, Wyman could reduce the force of the problem by suggesting that some contradictions are possible. Consider contradictory objects like the Penrose triangle or Penrose stairs.

Are these impossible? Round squares are simply inconceivable and can't be intelligibly talked about, but staircases that keep going up without ever getting higher can actually be visualized. By allowing that some contradictions are possible, Wyman significantly reduces the number of apparently meaningful statements he has to consign to meaninglessness. Of course, this option genuinely would be radical, but the ground has been prepared by dialetheism and paraconsistent logics.

Quine's second objection to the suggestion that statements apparently about impossible objects are meaningless is that this "makes it impossible, in principle, ever to devise an effective test of what is meaningful and what is not." Quine says: "it follows from a discovery in mathematical logic, due to Church, that there can be no generally applicable test of contradictoriness." I assume that what Quine actually has in mind is Gödel's second incompleteness theorem, which demonstrates, essentially, that any consistent formal system cannot prove its own consistency. So put simply: if contradictory objects are impossible, and statements about impossible objects are meaningless, then since there's no test for determining contradictoriness, there's no test for determining meaninglessness.

I have two comments about Quine's objection: (a) Why exactly do we need a strict, systematic way of determining what's meaningful? Why wouldn't it be good enough just to have a few basic rules of thumb? (It's not as though Quine is any stranger to indeterminacy of meaning!) (b) Again, Quine's criticism evaporates if Wyman severes the link between possibility and consistency, and holds that contradictory objects can be possible. Then he doesn't need to say that all contradictory statements are meaningless. In which case, it doesn't follow from the fact that there can be no effective test of what's contradictory that there can be no effective test of what's meaningful.

Ultimately then, it seems to me that rejecting (P2) is a much more plausible move than Quine suggests. Let me make one final comment here. Another obvious option for Wyman is simply to accept both (P1) and (P2), and draw the conclusion that there are unactualized impossibles, in just the same way as there are unactualized possibles. Quine objects to this move that if Wyman admits unactualized impossibles, then he will be trapped in contradictions. But why would this trouble Wyman? After all, he's openly admitting impossibles. Why wouldn't he also admit that some of those impossibles are contradictory?

5. Fifth, Quine suggests that the puzzle of nonbeing rests on a confusion between meaning and naming. Consider again (P1) and (P3):

(P1) If "Pegasus" names nothing, then statements about Pegasus are nonsensical.
(P3) If "Pegasus" names nothing and "Santa Claus" names nothing, then "Pegasus does not exist" and "Santa Claus does not exist" both say the same thing.

These claims seem to rest on the assumption that the meaning of a name is simply is referent (called direct reference theory or Millianism). If names have meanings above and beyond their referents, then "Pegasus" can be perfectly meaningful despite failing to refer to anything (and "Santa Claus" can also be perfectly meaningful, and can mean something different from "Pegasus", despite failing to refer). But Millianism has been subjected to a number of serious objections. Quine appeals to the famous problem of "Frege's Puzzle". Consider the following propositions:

(1) The Morning Star is the Morning Star.
(2) The Morning Star is the Evening Star.

"The Morning Star" and "the Evening Star" both refer to the same object, namely Venus, which on Millianism seems to entail that the phrases have exactly the same meaning. Now, if "the Morning Star" and "the Evening Star" have the same meaning, then we should be able to substitute one for the other in a sentence without changing the meaning of the sentence, which entails that (1) and (2) have the same meaning. But surely this isn't right: (1) is simply trivial, whereas (2) is interesting and informative; (1) is a tautology, whereas (2) tells us something important about the world; (1) is knowable a priori, whereas it takes hands-on empirical investigation to confirm the truth of (2).

I don't have anything to say about this point. I agree with Quine that Millianism isn't adequate, and that if Millianism goes, the justification for (P1) and (P3) is undermined.

6. Finally, Quine appeals to Occam's Razor. Admitting unactualized possible objects massively expands our ontology without good reason. Quine thinks there's an alternative, more ontologically parsimonious solution to the riddle, which appeals to Russell's theory of descriptions. I won't discuss Quine's own solution here. I only note here that the view that there exist, or there are are in some sense unactualized possibilia, has a variety of motivations (cf. Lewis again). Quine's appeal to Occam's Razor is rather less convincing if we have to accept possibilia anyway for other reasons.

Richard Routley - Is There a Need for a New, an Environmental, Ethic?

In this famous 1973 paper, Routley attacks anthropocentrism and argues that ethics should recognize the intrinsic value of various nonhuman or even nonsentient items. ("Intrinsic" is intended to contrast with "instrumental".)

Anthropocentrism, the standard Western ethic

First, Routley discusses the traditional anthropocentric ethical tradition, and identifies three different strands of this tradition: (1) despotism: this views humans as the rulers of nature, so that humans have dominion over nature and can with it whatever they please; (2) stewardship: humans are the custodians or protectors of nature; (3) cooperation: humans are the perfectors of nature, with a duty to transform it into a more perfect state.

(1) is clearly unacceptable, but (2) or (3) prima facie seem better suited to an environmental perspective. However, Routley objects that both (2) and (3) "imply policies of complete interference", and hence are incompatible with environmentalism. I'm not convinced of this, especially with the notion of stewardship. Whether or not stewardship implies interference depends on what we take to be valuable; it depends on what exactly it is that we're trying to protect. I assume it's true that historically, stewardship views have called for a transformation of nature: nature is wild, having been put there by God to be perfected and developed by man, and ideally all of nature will be so developed. Seen in this way, the stewardship view and the environmental view will come into conflict. But nothing in the basic idea of stewardship implies anything like this.

Stewardship emphasizes responsible use. Even if our only concern is humans, there's obviously nothing responsible in pursuing a policy of "complete interference". Complete interference is clearly a bad move because interfering with ecosystems, even with a goal to "improving" them, has all sorts of unforeseeable consequences. There are substantial parts of the natural world that should be protected and, importantly, largely left alone. So Routley's objection to (2) misses the mark (as we'll see in the next section, he later offers a more powerful objection to (2), and all other anthropocentric approaches).

We can identify the core principles of an ethic. Any ethic that rejects one or more of the core principles of the standard Western ethic is a new ethic. Routley suggests that one of the core principles of the standard Western ethic is the "liberal principle":

The liberal principle: "One should be able to do what he wishes, providing (1) that he does not harm others and (2) that he is not likely to harm himself irreparably" (where "other" is of course intended to mean "other human" or, on recent animal rights ethics, perhaps "other sentient being").

Routley thinks that our moral judgements concerning the environment outstrip what can supported by the liberal principle. The liberal principle should be rejected, and that means that a new ethic is required.

Against anthropocentrism

Routley gives a number of examples that he takes to demonstrate the failure of the liberal principle:

(1) The last man: Imagine a man who has survived the collapse of society and the death of all other people. For some reason, perhaps just to pass the time until he dies or to take his mind off the loss of all his friends, he decides to go about destroying, as far as possible, every living thing and every item of value. On an environmental ethic such destructive behaviour is deplorable, but it's totally permissible on an anthropocentric ethic. Indeed, an anthropocentric ethic might even recommend it - for instance, if the Last Man finds his behaviour very satisfying and pleasurable, then an anthropocentric utilitarianism would recommend that he continue (since his pleasure is all that matters).

(2) The last people: Imagine a society who know that they're the last people, for instance because the effects of radiation have prevented any chance of reproduction. Since they're the last people, there's no longer any need to protect the environment for future generations, so they vastly accelerate production and consumption, putting all land under intensive cultivation, stripping away all the rainforests, farming all the fish out the seas, etc. Again, on an environmental ethic this destructive behaviour is deplorable, but it's totally permissible, perhaps even recommended, on an anthropocentric ethic. After all, they're simply doing what they can to improve their own lives before their inevitable extinction. If this vastly increased consumption spells disaster for the environment - well, who cares? No future people will be around to be negatively affected by it.

Routley also gives the examples of (3) the last man is an entrepreneur who damages the environment in pursuit of greater productivity and (4) the extermination of the blue whale to extract its oil and meat. I won't discuss these cases as (3) is a minor variation of (1) and (4) can, I think, be quite easily accommodated by standard ethical views. Even from an anthropocentric perspective the destruction of species is a bad idea for various reasons, including that they might be of significant scientific value, that they might play important roles in the ecosystems on which humans depend for their resources, etc. Also note that animal rights views would similarly condemn (4), but Routley wants to extend moral considerability not just to animals but also to nonsentient or even nonliving things. Scenarios (1) and (2) present the best case for this. Of course, animal rights views would similarly condemn the killing of sentient beings in (1) and (2), but we can simply modify the scenarios so that in (1) all other sentient beings save the Last Man are dead, and in (2) all other sentient species save humans are dead.

It's worth considering more carefully the structure of Routley's argument. First he identifies a moral principle that he takes to be at the core of Western ethics - the liberal principle. Then he offers a scenario in which this principle permits certain environmentally damaging actions that intuitively we consider morally impermissible on environmental grounds. Routley thinks that this necessitates the development of a new ethic that rejects the liberal principle and assigns intrinsic moral worth to various nonsentient or nonliving items. Let's try to formalize the argument:

(P1) The liberal principle is a core principle of standard Western ethics.
(P2) If the liberal principle is true, then forests have no intrinsic moral value.
(P3) If forests have no intrinsic moral value, then the Last Man's actions are morally permissible.
(P4) The Last Man's actions are not morally permissible.
(C1) Forests have intrinsic moral value.
(C2) The liberal principle is false.
(C3) Standard Western ethics must be rejected.

(Readers who, like myself, hold that moral claims aren't truth-apt can simply substitute e.g. "acceptable" and "unnacceptable" for "true" and "false".)

Responses

I will now consider three ways of defending the standard ethic. The first accepts Routley's conclusion about the worth of nature but rejects (P1), challenging his characterization of the standard Western ethic; the second attempts to show, contra (P3), that our condemnation of the Last Man's actions is compatible with an anthropocentric ethic; the third challenges (P4) and the underlying methodology of Routley's argument.

Reject (P1)
Routley claims to be offering a new ethic. But how new is it really? (We have already seen one form of this objection in my discussion of the stewardship position. Arguably, stewardship is not as inimical to environmentalism as Routley suggests. However, I think it would struggle to account for the judgement that the actions of the Last Man and the Last People are wrong.) According to Routley, one of the core principles of the Western ethic is the liberal principle: reject the liberal principle, and you reject Western ethics.

However, it's very questionable whether the liberal principle is in fact a core principle. Consider the traditional objections to homosexuality. For most of the history of Western society, homosexuals have been imprisoned or worse. This seems very much at odds with a principle allowing us to do as we wish providing we don't harm ourselves or others. Of course, perhaps some of the objections to homosexuality were based on this principle, since many people argued, indeed many people still argue, that homosexuality is harmful. There are physical harms of spreading disease (the association of homosexuality with AIDS) and "spiritual" harms in that God disapproves and will perhaps send you to a place of eternal punishment. However, I doubt that the persecution of homosexuals really had much to do with a worry that they might be harming themselves or others.

For a more modern example, consider incest. Incest is punishable by imprisonment in many enlightened Western nations. As with the persecution of homosexuals, this seems very difficult to reconcile with the liberal principle. Again, people do suggest that incest is harmful in various ways, but such arguments are clearly weak, ad hoc rationalizations. The real objection to incest, just like the real objection to homosexuality, has nothing to do with concerns about harm. The real objection is "ewwww, that's gross" (see this video for my arguments that incest is morally permissible).

A number of similar examples can be found in the work of Jonathan Haidt and his colleagues (e.g. Haidt, Koller, and Dias's article "Affect, Culture, and Morality"). Consider the following scenarios: (a) a woman cuts up her country's national flag and uses it to clean her bathroom; (b) a family's dog is killed in a car accident; the family hear that dog meat is tasty so decide to eat it; (c) a man who is about to hold a dinner party has sex with a dead chicken, which he then cleans thoroughly, cooks, and serves to his guests. Most people hold that these actions are morally wrong and perhaps even should be prevented if possible. Yet the scenarios are constructed to rule out the possibility of harm, and indeed people have great difficulty identifying a source of harm.

On the other hand, one notable thing about subjects who are then asked to justify their judgements is that they tend to search for harms (e.g., abusing the flag might erode respect for one's country, threatening social harmony; having sex with a dead chicken involves risks of disease; etc). This suggests that people's moral reasoning, if not their immediate moral intuitions, is guided by the liberal principle. But the point here is that our actual judgements, however we might try to justify those judgements, don't seem to conform to the liberal principle. In which case, it's very questionable whether this principle should be considered an essential core of Western ethics.

Reject (P3)
Can standard Western ethics condemn the Last Man? Must we attribute intrinsic moral value to e.g. forests to conclude that the Last Man's destruction of the forests is morally wrong? Here's an obvious response: what makes it wrong to destroy all life is that this destroys the potential for future sentient or rational life. There's nothing intrinsically valuable about a forest. But on a planet rich in life there's far more potential for a new sentient or rational species to emerge than there is on a barren planet. This kind of response would be especially attractive to classical utilitarians. If moral behaviour is simply a matter of doing what we can to maximize happiness or pleasure, it's easy to explain the wrongness of the Last Man's actions. The Last Man should try to promote the emergence of new sentient beings, or if there's nothing he can actively do to promote this, he should at least refrain from preventing it.

Our scenario can however be modified. Consider:

(1a) Imagine a man who has survived the death of all sentient beings. He decides to go about destroying, as far as possible, every living thing and every item of value. Furthermore, in 100,000 years, the Sun will die, so there's not enough time for new sentient life to evolve.

If we hold that the Last Man's actions are morally wrong in this case, we rule out the suggested response. Of course, one worry here is that with the scenario modified in this way, I expect that fewer people will be inclined to judge that his actions are wrong (we will return to this point when we consider rejecting (P4)).

A second response is to argue that the Last Man is in some sense harming himself. Virtue ethics might provide a basis for this. On traditional Aristotelian virtue ethics, for instance, the goal of human life is eudaimonia, which translates essentially to happiness or fulfillment or well-being, and we achieve eudaimonia by cultivating a virtuous character (classically, a virtuous character involves the virtues of temperance, practical wisdom, justice, and courage). Importantly for this context, virtues directly benefit the individual: the virtuous person has a better life, a more fulfilling life, than the vicious one, even if the virtuous has fewer possessions, fewer friends, achieves fewer goals, etc. Although ethics is usually taken to concern our behaviour towards others, on virtue ethics the good life is entirely in line with your own self-interest. Just because the Last Man is alone, it doesn't mean that no ethical questions arise for him.

Against this background, we might argue that the destructive behaviour of the Last Man evinces a vicious character. Following Robert Sparrow (see his "The Ethics of Terraforming"), two possible vices in the Last Man's character are: (1) aesthetic insensitivity, a kind of blindness to beauty; and (2) hubris, an excessive pride/arrogance or glorying in one's own powers, often exhibited when a person ignores their proper limits. The Last Man is both blind to the elegance and beauty in the world, and has a vastly inflated view of his own importance. He doesn't evince the appropriate respect and humility towards nature. From the perspective of virtue ethics, he's only harming himself; the wrongness of his actions lies in the fact that they evince a vicious character, a character incompatible with his achieving eudaimonia. Ask yourself: would you want to be the Last Man? Would you want to be the sort of person who chooses to spend his last days vandalizing everything of beauty? Regarding these points, I'm reminded of this lovely quote from Simon Blackburn:

If we visit the Grand Canyon and I am overawed by its grandeur, while you see it just as a good place for tourist concessions, then I may well think less of you. And if I learn that one day I shall become like you, I would be depressed and ashamed, just as I would if I learned that one day I might lose my love of my children, or my concern for truth. I may voice this by saying that the canyon demands the reaction of wonder. But of course it doesn't issue any demands - indeed its ageless, implacable, indifferent silence is part of what makes it sublime. It is we who demand these reactions from ourselves and others, and rightly so.

However, I'm not convinced that this response works in the present context, for two reasons. First, arguably virtue ethics itself is simply incompatible with the liberal principle, which emerged out of deontological and consequentialist approaches to ethics (indeed, virtue ethics is often seen as providing an "anti-theoretical" approach to ethics, emphasizing the messiness and imprecision of our ethical lives and hence resistant to any strict ethical principles). So even if this response undermines Routley's argument against the liberal principle, it's far from clear that it's consistent with a defence of the liberal principle. Virtue ethics may itself represent a "new ethic".

Second, recall that the point of this response is to show how even if the natural world has no intrinsic value, the Last Man's behaviour might still be morally wrong. The problem is that I very much doubt that negative evaluations of the Last Man's character really make much sense without supposing the natural world to be of intrinsic value. Why, exactly, does his destruction of the forests exhibit an insensitivity to beauty, and an inappropriate hubris? If the natural world is only valuable insofar as it has uses for humans, the Last Man may well object that he's simply doing what any of us would: using the natural world in the ways he thinks are best. In his view, he says, barren landscapes are far more beautiful than lush rainforests. And there are no more humans to answer to, so what's the problem?

Reject (P4)
(P4) says that the Last Man's actions are not morally permissible. Routley doesn't bother to defend this claim; evidently, he assumes it's simply obvious that we should condemn the Last Man's actions. But is this obvious? Well, I suspect that such pointlessly destructive behaviour would make most people rather uneasy, although as far as I know no empirical studies testing the common person's reaction to Last Man scenarios have ever been done. But let's grant that, at least intuitively, the Last Man's behaviour is wrong.

Recall the broad structure of Routley's argument. It has essentially three parts: (a) the liberal principle permits action X; (b) but intuitively, X is impermissible; (c) so the liberal principle must be rejected. This kind of argument - attempting to demonstrate that particular moral principles entail unacceptable conclusions - is fairly standard in moral philosophy. But as the famous phrase goes, one man's modus ponens is another's modus tollens. Rather than rejecting the principle, we may reason as follows: (a) the liberal principle permits X; (b) intuitively, X is impermissible; (c) so, our intuitions about X are wrong.

What we have here is a clash of intuitions. Intuitively, X is wrong. But intuitively, the liberal principle is right, and the liberal principle permits X. From this point of view, it's at least as reasonable to reject (P4) as it is to accept it. In fact, the problem for Routley is even more serious than this, for two reasons. First, the liberal principle arguably has more to recommend it than mere intuitive support. It's part of the core of much of our moral reasoning (Routley surely wouldn't deny that; after all, he identifies the liberal principle as the core of Western ethics). It has the virtue of simplicity, and it provides us with a straightforward way of resolving moral and legal dilemmas. Furthermore, if we reject it, we face the question of what exactly we replace it with, and note that Routley doesn't offer any specific proposals in his article.

Second, basic moral principles tend to be fairly resistant to counterexamples. Consider the resistance of utilitarianism to apparently outrageous conclusions. Utilitarianism seems to entail that we must give enormous amounts of money to charity, perhaps even to the extent that we won't be able to afford any luxuries for ourselves. The good that would be done by buying yourself a luxury, say a Grateful Dead t-shirt or a nice meal restaurant, is vastly outweighed by the good that would be done by using that money to help save starving children. So, it's morally wrong to buy a Grateful Dead t-shirt. You should only buy clothes you really need, and send the money you save away. This conclusion is outrageous. But many people who are attracted to utilitarianism simply bite the bullet and reject the intuition that there's nothing wrong with spending your money on luxuries.

Why shouldn't the defender of the liberal principle simply reject the Last Man intuition? Indeed, this response seems especially plausible in the present case. The Last Man scenario is outlandish. It's an extreme case, totally removed from the normal context of moral judgement. How much weight should we place on our intuitions about a case like this? It's not surprising that we can develop extreme scenarios in which there's a mismatch between our general principles and our specific judgements. Bear in mind that Routley is, by his own admission, pushing for a radical change in our moral attitudes - not just a modification of existing ethics, but a wholesale revolution. A few troublesome intuitions about strange scenarios that are almost certainly never going to happen is a rather weak basis for such a lofty goal.

I should note that despite my critical comments, I largely agree with Routley. I think that forests, salt marshes, mountains, oceans, etc are intrinsically valuable; I completely reject human chauvinism. However, I'm not so sure about how to argue for this. These "deep green" commitments are simply part of the foundations, the core, of my worldview. There may be rhetorical value in Last Man examples, and if you're inclined to think that the Last Man's behaviour is morally wrong, then I'd encourage you to consider deep green ethics. But ultimately, for committed human chauvinists, I think there are very plausible responses to Last Man cases.

This concludes the main parts of the paper. I'll also make some comments about Routley's discussion of rights.

Rights

If we accept an environmental ethic, must we say that e.g. trees have rights? No, says Routley: the mere fact that there are moral prohibitions against acting a certain way towards an object doesn't entail that the object has rights; i.e. just because it's morally wrong to clear-cut a forest, doesn't entail that the forest has a right not to be clear-cut.

Of course, this depends on just how we're using the term "rights". But I agree with Routley that on many uses of that term, there's no reason why assigning intrinsic value to natural items would entail assigning rights to them. On one popular view of rights, noted by Routley, rights are coupled to responsibilities and obligations; obviously, it would be absurd to hold that trees, salt marshes, mountains etc have any responsibilities or obligations. It's clear that on this view, moral prohibitions extend beyond objects to which rights are assigned. For instance, there is a moral prohibitions against killing babies, but if rights entail responsibilities then babies don't strictly speaking have rights.

Another popular view is that rights are in some sense inviolable. If P has a right not to be killed, it would be wrong to kill P even if killing P would e.g. improve the general utility. Now evidently, we also have plenty of duties towards others that aren't inviolable. I should return the money you lent me, unless I discover that you intend to use the money to finance terrorism. I should not steal, unless my children are literally starving. It's easy to proliferate examples like this.

So it can be perfectly reasonable to say that it's morally wrong to clear-cut a forest, that we have certain obligations towards the forest, without the forest thereby having rights (perhaps because if the circumstances were different, it would be acceptable to clear-cut the forest).