The Falliciousness of Conceivability Arguments

Why philosophers should not care about philosophical zombies

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Scientifically, a zombie apocalypse like the ones depicted in films aren’t inconceivable. Typically, the origin of science fiction zombies is some contagion or another that is at first brutally fatal, and subsequentially alarming as the person is reincarnated as a cannibal. However, just because something is inconsiderable doesn’t mean that it is likely to happen. Thus, it would be exceedingly imprudent to prepare for a zombie apocalypse, precisely because of its improbability of occurring. What is conceivable isn’t necessarily plausible, and conceivability alone is not enough to bolster an argument. The substantiation of a claim must entail tangible evidence, not merely a supposition of possibility.

What about philosophical zombies? Philosophical zombies are quite different from the standard science fiction zombies in a few important respects. For starters, philosophical zombies are not undead cannibals sprung from a disease outbreak. Rather, philosophical zombies are no different from everyday people in almost all respects. In other words, simply picture a different world out in the universe that resembles Earth in all of its important aspects: a world crowded with a multitude of life forms, each of which bearing resemblance to Earth’s.

The one respect in which they differ, however, is that they lack consciousness. It is a world full of life, but void of any experience. Specifically, philosophical zombies are humans that function and behave in all of the same ways that humans do, but without any experiences of such behaviors or functions. What may the philosophical import of philosophical zombies be?

The philosophical zombie argument

According to New York University philosopher David Chalmers’ book The Conscious Mind, the concept of philosophical zombies threatens what is known in the philosophy of mind as ‘physicalism.’ Physicalism runs counter to the traditional idea that the mind is somehow distinct from the body –a view known as ‘mind-body dualism.’ Mind-body dualism takes it to be the case that the mind is immaterial (i.e., not physical), and the body is material (i.e., physical) and that the two couldn’t be more different from one another. Thus, physicalism is the view that the mind is, at bottom, physical. That is, for the physicalist, the fundamental basis of consciousness is the world of natural laws, the forces of evolution, and atomic particles coming together over the course of history to form what we now know as consciousness.

Molecule for molecule identical to me, and identical in all the low-level properties postulated by a completed physics, but he lacks conscious experience entirely….he is embedded in an identical environment. He will certainly be identical to me functionally; he will be processing the same sort of information, reacting in a similar way to inputs, with his internal configurations being modified appropriately and with indistinguishable behavior resulting….he will be awake, able to report the contents of his internal states, able to focus attention in various places and so on. It is just that none of this functioning will be accompanied by any real conscious experience. There will be no phenomenal feel. There is nothing it is like to be a zombie. (1996, p. 95)

What is it about philosophical zombies that threaten the validity of physicalism? The crux of dualism –which Chalmers claims is proven by the zombie argument — is the idea that it is possible for the mind to exist without the body, and vice-versa. The zombie argument distills this, focusing on the implications of bodies existing without minds. What does it say about the nature of the mind if minds can exist without bodies?

Now, just like science fiction zombies, it is conceivable that philosophical zombies exist. That is, the possibility of philosophical zombies is something we are capable of conjuring up in our mind’s eye in a coherent manner. Logically, therefore, philosophical zombies are possible. According to Chalmers, the conceivability, and therefore, possibility of philosophical zombies is a meaningful substantiation of dualism. If it is possible for a body to exist without a mind, then the two are separate entities –as opposed to the physicalist view, where mind and body are inextricably physically connected. Thus, whatever the essence of consciousness might be, it isn’t physical. We can, according to such reasoning, begin from using our imagination to conceive of something, to positing its possibility, and, finally, using such possibility as a basis for the validity of a theory. This is what is called a ‘conceivability argument.’

Conceivability arguments fail to stand on their own two feet

But does the conceivability of philosophical zombies disprove physicalism and prove dualism? There are many good reasons answer, ‘no.’ On the one hand, if conceivability arguments are valid, we need to be capable of conceiving philosophical zombies. But is this even possible? It is unclear that philosophical zombies can be conceived in any reliable manner.

How can we conceptualize a creature that is like us in every way, except that this creature doesn’t have any conscious experience? The only conscious experience we have any direct evidence for is our own. When it comes to other people having consciousness, this is something we just take for granted –an axiom that we all accept. Other people look and act similarly to us, and we ourselves have consciousness, so why shouldn’t others? Aside from this, what other evidence do we have for the existence of consciousness in other humans? None, and so too is the case with philosophical zombies and their lack of consciousness.

This is especially salient when we pay close attention to the folk psychological terms Chalmers uses to describe philosophical zombies. What would it mean to report on internal states, to use one’s attentional faculties, and all other salient features of consciousness, without any such features being themselves conscious? As the philosopher, Daniel Dennett amusingly puts it, if we were to duplicate Chalmers and have a Chalmers-zombie, whose reports ought we to believe? We would not be able to distinguish between the two, but if we were under the presumption that at least one of them was a zombie, we’d need to make an arbitrary decision as to which Chalmers we should treat as a human and which we should treat as a non-human. Let’s say we accidentally treat the real-Chalmers as a zombie, and he reports to us, ‘hey! I’m the real David Chalmers! The other one is an imposter.’ And — as Chalmers actually does — he can appeal to his “direct evidence” of his 1st-person mental states, which the so-called zombie lacks. From the 3rd-person, however, the zombie can do exactly the same thing. Only if we are to completely discount the validity of 3rd-person access to others’ mental states are we to take the zombie argument as compelling. But we have no reason to do that — indeed, we have far greater reasons to take our 1st-person access as unreliable, as we are often not the best authorities on what mental states we are actually in. That’s the point of psychoanalysis, for instance — to illuminate to you your own mind. The notion that one’s 1st-person perspective on their own mental states is the final word is not just empirically invalid, but it is also profoundly unpragmatic — many people really need to be told from some outside observer what their mental states are, even though it is socially frowned upon in most contexts to do so.

Moreover, the jump from conceivability to possibility, and the jump from possibility to justifying an entire metaphysical theory, seems logically over the top. After all, there are plenty of things we can conceive of using our imaginations. I can, for example, conceive of a centaur that pilots for delta airlines. Does this mean that it is possible that a centaur indeed does pilot for delta –that a centaur can fly? Well, centaurs –as far as we know — do not exist –just like philosophical zombies. Things that do not exist have no possibility outside of the imagination. Of course, many actual things can have their origin in imaginative possibility –cars existed in human minds before they existed in the material world!

There are literally infinite things you can conceive of that are completely absurd and non-existent outside of the imagination. Moreover, you can conceive of things that are patently false. For example, if you are unaware that there are infinite prime numbers, you can conceive of prime numbers stopping at some point. This doesn’t mean, however, that prime numbers are thereby not infinite. Rather, it means that you used your imagination to conceive of something that is unalterably false.

So too is the case with philosophical zombies, just as much as it is with science fiction zombies. In the case of philosophical zombies, their conceivability is not enough proof to disprove physicalism and thereby prove dualism. We would need to discover philosophical zombies in the real world in order to justify such a proof –and even then, we would never know whether or not such zombies truly had no experience. Until we have better methods for ‘measuring’ whether or not a creature is conscious, the possibility of philosophical zombies is truly up in the air!