In René Descartes’s Second Meditation, he claims that reasoned deduction is a more reliable source of information than either sensory induction or imagination, and that the existence of the mind is more certain than the existence of physical objects. To prove this, he gives us the case of a ball of wax which is exposed to a fire. The pre- and post-fire waxes have completely different physical properties, but any reasonable person would say that they are the same object. The essence of the wax is not the sum of its properties; it is the continuity of its individuality through space and time. Properties, according to Descartes, have a lesser ontological status than objects. The wax could change into anything, and as long as there is something there to change, its new form will still be the same object as the fresh, sweet-smelling ball of wax it once was.
Descartes could not realize this truth if he relied on his senses alone. Senses can give him information, but they cannot interpret it. His eyes show him the old wax and the new but cannot connect the two because they look completely different. Without reason, he sees changes, but he cannot comprehend them. A mindless sensory animal would never learn lessons from the past; it would only see what exists now. Thus, the mind is more valuable than the senses.
Descartes cannot use his imagination to fully understand the wax, either. While his imagination is part of his mind, it cannot draw any conclusions on its own. It can merely recall past sensations and synthesize them in new ways. For an object as malleable as wax, there is an infinite number of potential forms. Without reason, he would not comprehend this limitlessness, however. His imagination, left to its own devices, would simply load image upon image for the rest of time. Reason recognizes the wax’s potential and directs the imagination towards useful purposes for it. Of the two, reason provides the most illumination.
Using reason in conjunction with the senses, Descartes knows what the wax was and is. Using reason in conjunction with imagination, he knows what the wax can be. Therefore, he achieves full understanding of objects through thought alone. If he examines his mind long enough, he can find the solution to any problem. Furthermore, since thinking is an action, each new thought he has about the wax reaffirms his own existence. Since he has been thinking for his entire life, and he has spent only a minority of that time pondering any one subject, he must be more comfortable with his mind’s existence than he is with anything else.
Descartes’s argument is strong. I see two points that need clarification, however. First, he must not forget that the process of understanding, though impossible without reason, would also be impossible without the senses and imagination. Without his mind, he would not know the wax, but without his senses, he would never be aware of its existence, and without his imagination, he would not be able to picture its potential forms or remember its sensible properties. Sense, imagination, and reason are all indispensable.
Second, though we can be most certain of the existence of the mind, we understand it, in a relative sense, far less than we understand simple objects like wax. Wax generally behaves in a predictable fashion. It changes because other forces shape it. People, however, are always doing things that they can’t explain, having thoughts that they can’t control, and disregarding the advice of their minds. Confused young men go on long quests to “find themselves.” Many poets attribute their works not to the mind but to the Muse because they do not understand what they have written. Some minds break for no apparent reason, and we put their owners in sanitariums. If we know our minds better than we know anything else, then we don’t know much at all.