Descartes's Method of Doubt

2. Descartes's Cogito

Book cover: Meditations and Other Metaphysical Writings by Rene Descartes

In his Meditations on First Philosophy [1641a: 67], the first indubitable proposition that Descartes arrived at is his now famous cogito ergo sum (I think, therefore I am). For Descartes, its utterance or conception in the mind renders it necessarily true. He recognized the difficulties in describing this demonstrative 'I'. Descartes [1641a: 71] candidly referred to it as '"this something I know not what", which does not fall under imagination'. To answer this problem, Descartes [1641a: 74] examined a piece of wax, after which he triumphantly exclaimed, 'For if I judge that wax exists from the fact that I see this wax, it is much clearer that I myself exist because of this same fact that I see it.'

Note, however, that Descartes could not tell us what it is that he 'sees'. Following this line of inquiry, he got no closer to a description of his 'self' than when he began. Descartes failing here, I think, lies in the fact that he never questioned the existence of a metaphysical substratum for consciousness; the elusive 'self'. He was fooled by his repeated usage of the common language grammatical term, 'I', into hastily and uncritically admitting that self-consciousness is possible. Self-consciousness is crucial for Descartes as it is the instantiation of self-consciousness that provides the rational basis for Descartes's 'self'.

David Hume was the first Enlightenment philosopher to question seriously the existence of a metaphysical, self-conscious self. He could find no conscious state that was conscious of its own consciousness. Moreover, for Hume, it was impossible to find one. This state would itself be a state of consciousness and, therefore, could not be indicative of its metaphysical substratum. Secondly, as Hume argued in his A Treatise of Human Nature [1739: 301], all of these conscious states exist separately from each other and have no need of a substratum.

Here, my experience mirrors Hume. I find it psychologically impossible to be conscious of a metaphysical 'self'. I cannot, no matter how hard I try, think of something and, at one and the same time, think that I am thinking of that something. As soon as I attempt this mental feat, my attention is immediately diverted from the thing I was originally thinking about. It seems the best we can say is that when one is thinking about thinking, it is always done about thoughts in the past. It may be thought that this counts as our conscious awareness of a metaphysical 'self'. Why this cannot be accepted as such, I will address in §4 below.

Book cover: A Treatise of Human Nature by David Hume

Hume [1739: 258], after rejecting the existence of a metaphysical 'self', found it necessary to define 'self' as a 'collection of different perceptions, united together by certain relations'. At the time, the common retort to this was, 'How can a series of conscious states be aware of itself as a series?' It was considered that Hume's [1739: 330] assumed answer to this, that we only feel a connection between conscious states, was inadequate. It was inadequate only because the question itself makes an unwarranted assumption and Hume's only shortcoming lies in the fact that he did not convince Descartes's supporters of the question's invalidity.

The misguided nature of the question becomes clearer when we pay more attention to what Hume wrote. Consider, for example, Hume's [1739: 330] statement that 'the thought alone feels personal identity, when reflecting on the train of past perceptions that compose a mind'. For Hume, since it is only in the present conscious state that we are aware, it is only in this present state that we are aware of past conscious states. The past states are simply relegated to memory. Therefore, it is not a series of conscious states that is aware of itself, but a present conscious state that is aware of past conscious states and which we call a 'memory state'. It is the experience of this memory that gives us a feeling of 'self'.

How do we know that such a series of past conscious states ever existed? The answer is that we can never know with logical certitude. The veracity of memory cannot be proved a priori, since the description of a present memory event is logically distinct from descriptions of all past events. There is no logical contradiction involved in postulating that the world came into being a moment ago, complete with all of our memories. Furthermore, the veracity of memory cannot be proved a posteriori, for the notion of direct access to the past, unmediated by mind, is logically incoherent. Inductive inference is also useless. As Aune [1970: 68] has pointed out, using the method of induction here requires one to assess the incidence of conjunctions between inaccessible past events and certain memory states.

Descartes [1641a: 66] conceded the fallibility of memory when he entertained the possibility that 'none of the things my lying memory represents to have happened really did so'. However, he acknowledged this lack of certainty only with regard to past events. He considered that when he remembered his previous conscious states, he was somehow epistemically privileged as it was himself that he was observing. As I have tried to show above, whether it be past events or previous conscious states, neither is immune from doubt.

Book cover: A History of Western Philosophy by Bertrand Russell

I think we must conclude that Descartes's metaphysical subject of consciousness, 'I', is not indubitably known. Self-consciousness is not, as he thought, a metaphysical act of mind-bending in which a non-material mind is aware of itself. 'Self-consciousness' is the name we give to that present conscious state which has, as its subject, past conscious states, remembering that the existence of these past conscious states is never guaranteed with certainty. One proposal that begs consideration is that the demonstrative 'I' is devoid of descriptive content and is used merely for grammatical convenience. For an early discussion of this view of the 'self' as a logical construct, see A. J. Ayer [1969: ch. 5, 1971: 166–8].

Bertrand Russell [1947: 550] contended that Descartes's basic premise should have been 'there are thoughts'. However, it seems that even this proposition is not indubitable. Hume's and Ayer's 'solipsism of the present moment' appears more defensible for, as I have argued above, memories of previous conscious states are never beyond reproach. Ayer's [1971: 63] basic proposition, 'there is a thought now', may appear to be the only proposition worthy of the title of indubitability in Descartes's sense of the term. Let us not accept this proposition too hastily, though, for it presents us with its own set of epistemological problems. The first of these is that the proposition takes more than an infinitesimal amount of time to express, thereby utilising our uncertain memory. The second issue is that it is not possible to entertain the meaning of this proposition with reference to our present thought. As I tried to show above, this kind of self-referential thinking is psychologically impossible. I will not attempt a solution to these outstanding problems here. My present purpose will be satisfied if I have successfully argued that Descartes had failed in consistently and rigorously applying his own method of doubt to his notion of the cogito.

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