A question occurred to me as I was reflecting on an argument that the Shaykh al-Ra’is gives in his Risalah fi’l-Marifat al-Nafs for the distinction between the ‘self’ that each of us is and our bodies. The argument was the following:
Reflect O rational man that you are today in your self the same one who has existed throughout your life, also that you remember much of the states that have occurred to you. You are hence constant and continuous – there is no doubt about that – whereas your body with its parts is not constant and continuous but is ever in dissolution and diminution. For this reason man requires nourishment to replenish what has dissolved of his body. […]. You will thus know that in the period of twenty years, none of the parts your body remains. You, however, know the permanence of your self throughout the period, nay, throughout the entirety of your life. Your self hence is other than your body and its external and internal parts. This, then, is a great demonstration that opens for us the door of the unknown.
The issue I was mulling over is one on which the above argument significantly rests; that is, whether or not our bodies, as a whole and in its parts, however minute, change or ‘renew’ themselves continuously and in toto. That our bodies change in some ways throughout our lifetimes, e.g., in terms of growth (and the sub-changes that involves), etc., is I think fairly obvious. But the argument requires that the change be much more comprehensive; in fact, comprehensive enough, it seems, to either alter the numerical identity of our body or at least be close to doing so. So, I then naturally wonder if this is in fact the case, that our bodies are in fact continuously changing, ‘turning over’ at every level (cellular, chemical, molecular, atomic, etc.) throughout our lifetimes? Or is that not the case, which is to say that the matter of our bodies, at some fundamental level, retains its identity – because it does not change – which in turn, on a materialist view, would presumably account for a human beings’ identity throughout his lifetime?
If indeed it is the case that our bodies are constantly changing, then I think the Shaykh’s conclusion would go through. Let me try and make a bit more explicit why this is so with this syllogism:
The body is constantly changing
The self (or: the “I”) is stable
Therefore, the self is other than the body
The minor premise I take the Shaykh to have us explicitly understand as stating: ‘I am aware or know that I am the same ‘I’ that I was at any time in the past’ (despite all the bodily changes). The premise seems intuitively true; so, let it pass for now as in no need of any serious defense. Considering other aspects of the argument, someone may call attention to a suppressed premise it contains i.e., that ‘what is changing insofar as it is changing cannot be identical to what is stable insofar as it is stable’. But this premise is I think self-evident; for its denial would amount to a violation of the law of non-contradiction. Regarding the major, even though it appears controversial, it seems to me that biology pretty much establishes it. It’s now more or less common knowledge that the body changes throughout externally (e.g., in growth, etc.) and internally (e.g., the constant turning over of cells, etc.). However, I think this premise can still be doubted; suppose someone does so by pointing to the phenomenon of neurons. These kinds of cells, we are told, which exist in the central nervous system, particularly the brain, do not die and are present for the entire lifetime of an individual. Granted that, it then seems, on a materialist account, these neurons can plausibly ground the identity of our ‘selves’ throughout the period of our lives. Such identity cannot be grounded in other kinds of cells for the reason already stated i.e., they undergo constant renewal.
On reflection though, I think it will turn out that basing the identity of the self on nerve cells will turn out to be just plain nonsense. This is so, not only because there is change at sub-cellular levels in these cells, but also because (at least some of) these neurons themselves cease to exist. So the claim that such neurons all last throughout the lifetime of an individual is false. There are various accounts (here, here, and here, are just three) of how they do in fact die, although there are disagreements as to the precise cause of why they do so. Perhaps though, if we grant that not all neurons in fact end up dying, the materialist will then opt for basing the identity of the self on just the neurons that do in fact last. If he does take that route, then it seems to me he would have to base it on either (a) a single neuron that lasts our entire life time or (b) on multiple neurons that do so. But neither option is I think intelligible; option (a) isn’t because it makes no sense, if we accept that there are three classes of neurons (sensory, motor, interneuron) to say that the self should be identical with any one instance of them. Let me explain: what would it mean to say that the self that I am is identical to e.g., a sensory neuron which transmits information to the brain? If the self was identical with any one single sensory neuron, it would be identical with, say, a photoreceptor cell in the eye. But that’s just absurd! Or what would it mean to say that the self is identical to a (motor) neuron which the nervous system has carry signals to the muscles? And the same with so-called interneurons. Moreover, all such phenomena involve, it seems to me, many complex changes and therefore cannot account for the permanence and identity of ourselves. A similar problem I would say besets option (b); if the self was identical with multiple neurons, then the neurons which purportedly constitute the self would have to be either (b.1) of the same kind (e.g., all sensory neurons), or (b.2) a mixture of different kinds (e.g., a combination of sensory, motor, and interneurons). But both options I believe are false for this simple reason: the neurons that supposedly account for the identity of the self are numerically multiple, whereas the self is a unity – and that is precisely what it is that we are trying to account for in the first place i.e., the unity and identity of the self throughout time. Hence, on both (b.1) and (b.2) we would be holding that the cause of a unity and an identity is something that is a numerical multiplicity and diversity. That I think is equally, if not more, absurd. I am sure that many, many more objections can be raised against this sort of, to put it mildly, fanciful and bizarre view.
Granting the above, the materialist then, if he is to maintain his materialism, I think has two options at this point: either (1) he identifies the self with some other part or parts of the body (e.g., the brain as a whole) or (2) he altogether denies the experience of the identity of the self throughout time as illusory. I believe the Shaykh’s argument would equally hold good of (1); as for (2), I think that any reasonable man would agree that it entails many absurdities which we can just leave out at this point.