This result may not seem especially substantive or surprising—that we cannot doubt the existence of our minds. Descartes is being a little bit sneaky, however, as perhaps is Searle. Both are right to hold that we cannot doubt the existence of the highly conscious and highly reflective activity of attempting to doubt our beliefs, but that does not mean that our minds are to be equated with consciousness. There might be other parts of a person’s mind that she does not know as well, and whose existence is not so indubitable, but that again are still components of her mind. Descartes does not agree: At last I have discovered it—thought; this alone is inseparable from me. I am, I exist, that is certain. But for how long? For as long as I am thinking. At present I am not admitting anything but what is necessarily true. I am, then, in the strict sense only a thing that thinks; that is, I am a mind, or intelligence, or intellect, or reason. .25 As to the fact that there can be nothing in the mind, in so far as it is a thinking thing, of which it is not aware, this seems to me to be self-evident. [W]e cannot have any thought of which we are not aware at the very moment when it is in us.26 Descartes is correct that the existence of highly conscious thinking is indubitable while we are engaging in it, but that does not mean that there are not other elements of the mind whose existence is less well known, and it does not mean that the mind is to be identified with those of its elements that are well known. Are thoughts immaterial? 20 Thus far we have considered some arguments for the view that thinking is material, along with some of the possible extensions and implications of that view. There are also a number of compelling arguments for the view that minds are immaterial. One is that bodies are always composite and divisible into parts, but minds are simple and indivisible. Minds and bodies are therefore different kinds of things. Socrates puts forward a version of this argument: Is not anything that is composite and a compound by nature liable to be split up into its component parts, and only that which is noncomposite, if anything, is not likely to be split up? . The soul is most like the divine, deathless, intelligible, uniform, indissoluble, always the same as itself, whereas the body is most like that which is human, mortal, multiform, unintelligible, soluble, and never consistently the same.27 We find the same argument later in Descartes: [T]he body is by its very nature always divisible, while the mind is utterly indivisible. For when I consider the mind, . I am unable to distinguish any parts within myself. I understand myself to be quite single and complete. Although the whole mind seems to be united to the whole body, I recognize that if a foot or arm or any other part of the body is cut off, nothing has thereby been taken away from the mind.28 The two philosophers are defending the doctrine of substance dualism—the view that there are two kinds of things or substances in the universe. According to this view, there exist mental substances that are intangible and indivisible, and also physical substances that have dimension and are divisible. Minds are things that think and have ideas, and because they do not have dimension they cannot be decomposed into parts. Socrates adds that minds are different from bodies in that they are invisible.29 So minds appear to be very different from bodies: they are invisible and indivisible, and hence indestructible and deathless, or at the very least they do not perish as a result of the death of the body. 21 A potential problem for this argument is that there appears to be evidence that if some parts of the body are cut off or damaged, then—to use Descartes’ language —something is taken away from the mind. Socrates and Descartes may be correct that minds are not decomposable into parts, but when our brains shut down it appears that thinking shuts down as well. Socrates and Descartes would say that thinking may seem to shut down from an outsider’s perspective, but in fact it does not.30 22 Another argument for the view that minds are immaterial substances is that minds are free and independent in a way that they would not be if thinking was material. We make choices and are (at least in part) the author of our own trajectory. If our thinking was due entirely to the cells of our nervous system, we would have no more independence or autonomy than anything else in nature. 23 A variant of this argument appears in Socrates. In Phaedo, there is a discussion of the relationship between harp strings and the music that they produce. The discussion begins when Socrates’ interlocutor insists that just because a thing is invisible, that does not mean that it is immaterial: One might make the same argument about harmony, lyre and strings, that a harmony is something invisible, without body, beautiful and divine in the attuned lyre, whereas the lyre itself and its strings are physical, bodily, composite, earthly, and akin to what is mortal. If then the soul is a kind of harmony or attunement, clearly, when our body is relaxed or stretched without due measure by diseases and other evils, the soul must be immediately destroyed, even if it be most divine, as are the other harmonies found in music and all the works of artists.31 Socrates responds with the claim that a harmony is very different from a mind. A harmony depends for its existence on the instrument that produces it; a harmony cannot go off in its own direction, independent of the strings, and if it did we would look for another musician hiding in the bushes. Nor can a harmony have an impact on the strings that produce it and make the strings proceed in a different order. Or perhaps a harmony can affect the strings, but only if it was produced and then guided by the vibrations of the strings to begin with. A mind is different: it is able to direct its body independently of the way that the body (or the brain) is behaving. Socrates writes, Do you think it natural for a harmony, or any other composite, to be in a different state from that of the elements of which it is composed? . Nor, as I think, can it act or be acted upon in a different way than its elements? . One must therefore suppose that a harmony does not direct its components, but is directed by them.32 Socrates has put his finger exactly on the problem. He is assuming that the dependence relation between thinking and the brain is very different from the dependence relation between music and an instrument. It sure seems to be different—if we are autonomous agents—and it seems outrageous to deny that we are autonomous at least to some degree. 24 We are at a critical juncture in the debate about whether or not thinking is material. One view is that all of our mental life is dependent on the brain and that if our ideas and decisions are able to guide our bodies, it is because our brains produced those states to begin with. Another view is that we have a kind of control and autonomy that would not be possible if the entirety of our mental life depended on the underlying cellular activity of the nervous system, and so it doesn’t. 25 Things come to a head in cases like that of the impressive politician and actor, Ronald Reagan. The reason why the case of President Reagan is so central is that a pillar of his political platform was to argue that individuals should exercise mind over matter and use willpower to pull themselves up from difficult circumstances. Reagan was a remarkable human being. His energy and charisma, the thoughts that came to him at just the right time, and his charm and poise—on the view that thinking is physical, every aspect of his mental life depended entirely on the underlying neuronal activity in his brain. On that view, Mr Reagan could not have summoned up willpower to neutralize the symptoms of his Alzheimer’s disease; the very faculty that he would need to employ to do that—his will—was among the things that the disease was holding hostage. On the view of Socrates and Descartes, minds are not the product of the nervous system. The original self and mind of an Alzheimer’s victim is still present somewhere, even if it appears to an outside observer that it has disappeared. The decisions of a person are not produced by the antecedent states of their brain, and no matter the configuration of their brain at any given moment, a lot of different decisions are possible for them. On this second view, our ideas and decisions are not like the music of a harp but are autonomous and have a life of their own. 26 We have to be very careful here. If we accept the first view (that thinking is produced in the brain), we might feel inclined to criticize our opponent. We might suggest that our opponent is wrong and that they should be held accountable for their blunder. But in that case we would be supposing that human beings do have control over their mental lives.