Thomas Nagel is correct to argue that, ‘dualism....is usually adopted on the grounds that it must be true, and rejected on the grounds that it can’t be.’ Such a seemingly paradoxical statement, which exists within what I will call the ontological common-senseness of the human experience, represents my position with regard to dualism, as will be argued within this essay. Acknowledging but notwithstanding the natural attraction to some sort of dualism, I will i) state that my case rests on two suppositions, ii) argue that the problem of causal interaction deals a fatal blow to Cartesian dualism, iii) argue that other types of dualism have inherent difficulties and iv), briefly, bring attention to an argument contending that the mind-body problem might actually be beyond solution due to the ontological apparatus borne by the human being.
There are two important contextual considerations which are pertinent to my argument. The first inescapable condition is that of what I will call the problem of arguing from within. The verb ‘to be’ appears within the very title of this essay, and it is the case, as Searle might argue, that any position on the mind/body problem cannot help but be advanced from within that very mind/body ontological perspective. Whilst Churchland is anxious to dismiss such introspective judgement from having ‘any special status’, it is difficult to ascertain what privileged external position he has been able to find from where to make such a statement. Thus it is that I have some sympathy with the Cartesian project which posits the internal as being the only place within which knowledge is certain. However, it is precisely because of the limitations of the way in which this internal field just ‘is’, that critique of substance dualism has to be given on scientific grounds, as arguing only from within the complex mind/body seems precisely to beg the question about the complex mind/body problem.
Thus, the second necessary consideration is that the critique I will make of Cartesian dualism rests on scientific and not philosophical ground. I would argue that the scientific explanation of a closed physical world is valid, and, under a Kuhnian-type move, contend that there are enough anomalies within the Cartesian position for it to be replaced, which allows a move towards attempting a better, as in more explanatory, model or models. I am prepared to accept that this is a scientific and not necessarily philosophical shift. This is a case where the knowledge gained within physics has provided useful ground for a movement within metaphysical understandings, but I contend that philosophical statements wishing to affirm any more than that are beyond reach.
And thus to Cartesian dualism. In a radical shift away from both the Aristotelian tradition of the soul as de anima, and from the view of religious authority as the source of truth, Descartes, through the process of hyperbolic doubt, concludes that the only knowledge of which he can be certain is the fact that he is a thinking thing. He cannot doubt that he is thinking as such doubts actually cannot be in place if he were not in the process of thinking; he can, however, doubt he has a body as this is not necessary to the thinking process and thus exists separately to the mind. Accordingly, Descartes posits the mind and body as ‘substances’, which have very different properties. The mind, the indubitable seat of certain knowledge is immaterial, indivisible, eternal, non-extended; the body is that which is corruptible, material, sensory, divisible and extended in nature. Descartes argues that these two substances interact with one another and in doing so the mind controls the body, but the body can influence the mind, through such things as the passions.
I want to stress here that the juxtaposition yet interaction of the substances as the sine qua non of the entire argument, and...