I have made this point a few times in various discussions, but I’d like to make it here again. Often the Naturalist will argue that we have never observed minds without brains. For every mind we observe, we observe a brain. There are two conclusions often drawn from this, one more modest than the other:
(i) We have no justification for believing that there are any brainless minds.
(ii) We cannot have any coherent concept of a mind apart from a brain.
The second conclusion is argued to be justified precisely because coherent concepts are formed by empirical experience, and there is no empirical experience of a mind without a brain. I want to offer a response to these two conclusions in turn, starting with the second.
To say that we cannot make sense of a mind without a brain is to say that the concept of a mind is bound up with the concept of a brain. We may be able to imagine a brain without a mind, as in the case of a cadaver’s brain, but the reverse, the (hypothetical) Naturalist tells us, is not imaginable or intelligible. So far the Naturalist hasn’t committed herself to reductive materialism about the mind, so we cannot simply dismiss the Naturalist on those grounds. However, I think we all know a priori that the claim that the concept of the mind is conceptually bound up with the concept of a brain is simply false. Construed as a psychological fact about ourselves (i.e., that we cannot conceive of a mind apart from a brain) it is simply and obviously false. What is more, it is empirically false. The response I anticipate is that many people think they can make sense of a mind apart from matter or material extension, but that when pushed and pressed we find that they do not have any coherent concept of such a thing. What this really amounts to, however, is a disagreement about the philosophy of mind.
Allow me to illustrate with an analogy. When we think of grass we may naturally think ‘green’ for the same reasons that when we think of dogs we think of tails wagging. Our experience of grass is generally of green grass (perhaps sometimes it is brown). However, even if our experience of grass is such that it is never not green (or brown or whatever), we find no particular difficulty in imagining purple grass. Our ability to imagine purple grass demonstrates to us that our concept of grass is not conceptually bound-up with our concept of greenness, as though the latter were a necessary condition of the first. Even if we have never observed purple grass, it is completely intelligible to us that there be purple grass precisely because our concept of ‘grass’ does not essentially involve being green. On the other hand, when we are asked to imagine immaterial grass we do have trouble. It isn’t difficult just because we’ve never observed it, but rather because being material is a necessary condition of being grass. The concept of grass involves being material.
Note that the problem with imagining immaterial grass isn’t a problem of imagining (or perhaps better ‘conceiving’) of immaterial things – concepts of things immaterial. Consider, for instance, when we think of the number two, or when we think of the concept of the number two. We really do, I insist, have something in mind. However, we would be as hard pressed to imagine/conceive a material number two, or a material concept of the number two, as we would be to imagine/conceive of immaterial grass.
What is this thought experiment intended to show? It is intended to show that we can easily conceive of things which we have never experienced, like purple grass, and that the reason we can do this so easily is that we all understand that the association between grass and greenness is not a necessary one. The person who had lived their whole lives having never seen grass any colour but one single shade of green would still be able to imagine purple grass with ease. Similarly there is a meaningful distinction between the mind and the brain. Moreover, our concept of a brain is of a thing essentially material – we can no more conceive of an immaterial brain than we can conceive of a material number. Our concept of mind is of a thing essentially immaterial – we simply cannot make sense of a mind’s being material in the strictest sense. I think even a reductive materialist can admit this point – perhaps we can go on believing that the mind is just a material thing of some sort, but we can certainly make no sense of the concept ‘material mind’ anymore than we can make sense of ‘material concepts’. It’s just altogether bad grammar. However, if we can conceive of a mind being immaterial, which I think we must, and we cannot conceive of a brain being immaterial, then it seems to follow that we can conceive of a mind without conceiving of it ‘along with’ a brain. The concepts, qua concepts, are distinct.
I conclude, therefore, that we can not only conceive of a mind which is immaterial, but that our concept of mind is of a thing immaterial. Moreover, I believe that since the concepts of mind and brain are distinct in the relevant sense (i.e., since neither one is conceptually bound up with the other) we can conceive of a mind without a brain with relative ease. So long as we can just make sense of the idea that there be a mind without a brain we know that the claim that we cannot make sense of the idea of a brainless mind must be false. I know this to be false, and I think everyone else does too. To turn the tables; I think it is the materialist/Naturalist who thinks she has a coherent concept of the mind without actually having any coherent concept of the mind.
Well, that is my preferred response to (ii), but what of (i)? (i) is certainly a point about epistemology; it suggests that we cannot have a justified belief in brainless minds. The presumption seems to be that we can have justification for believing x if and only if we can have empirical justification for believing x. Thus, (i) should be more explicitly phrased as:
(i*) We have no empirical justification for believing that there are any brainless minds.
Perhaps (i*) is true. However (i*) does not entail (i) without the presumption that justification is empirical justification. It may also turn out that (i*) is false, depending on how one construes empiricism. For instance, if one construes empiricism as involving analytic truths known a priori then one may argue that since we know that it is logically possible for there to be a brainless mind we know with certainty that there may be such a thing. Moreover, even on a stricter version of empiricism, if there turns out to be some empirical proof of God’s existence (to the satisfaction of ’empiricism’ however construed), and if God turns out to be a mind without a brain, then there would be empirical justification for believing in at least one mind without a brain. I am inclined to think the real problem is that we have no justification for believing (i*) to be true in the first place! I am adamantly not an empiricist, at least not in any robust sense.
Maybe there is another way to accept (i*) along with believing that we have a justified belief in minds without brains. If one asks the question ‘under what conditions would the thesis that minds are independent of brains be verified’ and then proceeds to set up empirical tests to determine whether brainless minds exist, then we may find that we do have good evidence for minds being independent of brains. I have in mind here the growing body of evidence from out of body experiences, near death experiences and such like. The empiricist may dogmatically scoff, which she is entitled to do if she likes, but scoffing will do nothing to adjudicate the matter in her favor.
Finally, I want to end with the suggestion that we all apprehend ourselves to be immaterial minds. The fact that we are, at bottom, immaterial minds, seems to me to be clear and distinct in an almost Cartesian sense. It seems self evident to me, the contrary seems absurd. At very least it seems to me that it is a natural thing to believe, and more natural than its alternative(s), and thus that (being thus, presumably, properly basic) the burden is on the one who rejects it to offer us some defeater for it. I can see no realistic hope of doing that. Thus we should consider ourselves amply justified in believing in immaterial minds without brains. If we also find the arguments of thinkers like Plato and Leibniz convincing, that the mind must be a simple non-composite thing and that as such it cannot be destroyed (unless God miraculously annihilates it) then we will also be inclined to think that there are plenty of instances of minds without brains in the world (every time somebody dies that person’s mind continues to exist, and does so independently of that person’s brain).
To draw the point out any further would require that we enter into the philosophy of the mind explicitly, and I have avoided that on purpose, since I think one can make the aforementioned points as significant preliminaries to any and all more substantive points about the philosophy of mind. However, it may be worth advertising that when we actually do philosophy of mind what we find is that, by far and away, the better arguments are on the side of the possibility and plausibility of the mind’s being ontologically independent of the brain.
Caveat lector – I am adamantly not a substance dualist!