Descartes insists that there is no analogy between walking and thinking since the notions of “a walk” and “a thought” are different in essence. Following the philosopher, one can claim that “a walk” is nothing but “the act of walking,” i.e. a physical human ability, which does not require any mental efforts and exists independently from the mind. “A thought,” on the contrary, is a broader notion since it can be applied at three distinct levels: it may refer to “the faculty, to the thing, which possesses the faculty, and to the act itself.” From this standpoint, Descartes endows a thought with the potential for a broader circle of functions. However, he does not exclude the possibility that “a thought” may stand for “the act of walking” or the ability to walk, which makes his distinction rather vague.
In simple terms, there is really no analogy between walking and thinking since the first is a physical process and the second – a mental, but Descartes complicates the matter. Saying that “a thought” may stand for “the act of walking” or the ability to walk, he admits that both notions can be equal, at the same time rejecting this. Further, the philosopher argues that he can be sure only about his thoughts rather than any actions. “Metaphysical certainty,” in this case, should imply a human cognitive ability to make logical inferences, i.e. the cogito, and it is embarrassing why he is sure about his thoughts and unsure about his actions as if the latter were not controlled or predetermined by our brain.
Probably, Descartes’ position is defensible if one considers his arguments in the Second Meditation, where he wonders if there is any absolutely certain truth. He gives an affirmative answer since even if his experience is illusory, it is still real because it takes place. Therefore, the person who experiences really exists. The single argument proving that the philosopher exists is that he is thinking (or experiencing), which presupposes that he is a thing that experiences (thinks) – a mind. Descartes knows for sure that he is a mind since he is not yet sure if his body and the physical world exist. What is more, he is more certain that his mind exists since exactly the intellect represents a truthful state of physical things, and the senses themselves are unable to do it (Descartes). As Descartes exemplifies the matter, even if “he seems to himself to be walking, his body may not move at all, as in dreams.” Consequently, we should trust our mind rather than our senses. It follows from this that if Descartes considers walking as a sensual experience, he may not make the inference “I am walking, therefore I exist,” unless “the awareness of walking is a thought.”
In the given context, it is noteworthy to mention Descartes’ ideas about mind/body dualism. According to the philosopher, a human is a distinctly “thinking thing.” Although he, as every human, does have a body, with which he [his mind] is tightly connected and which is an “unthinking thing,” he [his mind] is entirely different from his body and may exist without it (Descartes 5). The philosopher exemplifies how his body is intimately conjoined with his mind: when his body is hurt, he does not perceive the wound “by the understanding alone” but feels pain; likewise, he feels hungry or thirsty when his body needs food or drink. Therefore, there exists “the union and apparent fusion of mind and body” (Descartes 7). Despite this apparent fusion, another difference between the mind and body is that the body is inherently divisible, whereas the mind is completely indivisible. Indeed, Descartes can think of distinct parts of his body like foot, arm, head, etc., but he can distinguish no parts in himself as a thinking thing. One more distinctive feature is that the mind receives the immediate impression not from all the parts of the body but only from the brain or some its part. Movements of the brain, in turn, immediately impress the mind only with that sensation which is the most important at the moment.
Nevertheless, such distinction between the mind and body seems rather vague to me. Descartes rejects the idea of a “thinking body,” claiming that he is a mind. It looks like he disregards the fact that human brain is a physical entity, and exactly this physical entity enables humans to think, which makes his argument unconvincing. To make his standpoint more convincing, and, therefore, rebut Hobbes’ and Gassendi’s arguments in a more reasonable way, he should explain his position in terms of rationalism. Rationalism argues that a person is born already with knowledge, i.e. knowledge is inherent, and learning stems from intuition. Following Rationalists like Plato and Descartes, who are concerned with absolute universal truths, one can assert that the mind is the single source of knowledge (Empiricism v. Rationalism. n.d.; Rationalism: Some similarities between Plato and Descartes, 17 Mar. 2001).
In this connection, it becomes clear why Descartes argues that there is no analogy between walking and thinking and why a person is “a thinking thing.” Nonetheless, a person can walk, breathe, or eat without thinking, i.e. he or she can perform purely physiological functions without thinking. If, however, one starts to think what to eat or where to go (or in which direction), these actions become impossible without thinking. Likewise, a person can think without doing anything; the only prerequisite for thinking is being alive. All in all, such questions are rather entangled and seem to be of a little practical value. The issues mentioned above may be good for philosophers, who aim at discovering human essence, but ordinary people are not likely to ponder on them.