The Meditator tries to clarify precisely what this "I" is, this "thing that thinks." He concludes that he is not only something that thinks, understands, and wills, but is also something that imagines and senses. After all, he may be dreaming or deceived by an evil demon, but he can still imagine things and he still seems to hear and see things. His sensory perceptions may not be veridical, but they are certainly a part of the same mind that thinks.

The Meditator then moves on to ask how he comes to know of this "I." The senses, as we have seen, cannot be trusted. Similarly, he concludes, he cannot trust the imagination. The imagination can conjure up ideas of all sorts of things that are not real, so it cannot be the guide to knowing his own essence. Still, the Meditator remains puzzled. If, as he has concluded, he is a thinking thing, why is it that he has such a distinct grasp of what his body is and has such a difficult time identifying what is this "I" that thinks? In order to understand this difficulty he considers how we come to know of a piece of wax just taken from a honeycomb: through the senses or by some other means?

He first considers what he can know about the piece of wax by means of the senses: its taste, smell, color, shape, size, hardness, etc. The Meditator then asks what happens when the piece of wax is placed near the fire and melted. All of these sensible qualities change, so that, for instance, it is now soft when before it was hard. Nonetheless, the same piece of wax still remains. Our knowledge that the solid piece of wax and the melted piece of wax are the same cannot come through the senses since all of its sensible properties have changed.

The Meditator considers what he can know about the piece of wax, and concludes that he can know only that it is extended, flexible, and changeable. He does not come to know this through the senses, and realizes that it is impossible that he comes to know the wax by means of the imagination: the wax can change into an infinite number of different shapes and he cannot run through all these shapes in his imagination. Instead, he concludes, he knows the wax by means of the intellect alone. His mental perception of it can either be imperfect and confused—as when he allowed herself to be led by his senses and imagination—or it can be clear and distinct—as it is when he applies only careful mental scrutiny to his perception of it.

The Meditator reflects on how easy it is to be deceived regarding these matters. After all, we might say "I see the wax," though in saying that we refer to the wax as the intellect perceives it, rather than to its color or shape. This is similar to the way in which we might "see" people down in the street when all we really see are coats and hats. Our intellect—and not our eyes—judges that there are people, and not automata, under those coats and hats.

The Meditator concludes that, contrary to his initial impulses, the mind is a far better knower than the body. Further, he suggests, he must know his mind far better than other things. After all, as he has admitted, he may not be perceiving the piece of wax at all: it may be a dream or an illusion. But when he is perceiving the piece of wax, he cannot doubt that he is perceiving nor that he is judging what he perceives to be a piece of wax, and both of these acts of thought imply that he exists. Every thought we might have about the world outside us can only doubtfully be true of the outside world, but it must with certainty confirm our own existence and establish the nature of our own mind.

The Meditator happily concludes that he can know at least that he exists, that he is a thinking thing, that his mind is better known than his body, and that all clear and distinct perceptions come by means of the intellect alone, and not the senses or the imagination.


The first paragraph of the above summary covers the ninth paragraph of the Second Meditation. We could identify this moment as the invention of the modern mind. The Aristotelian conception of the mind separates intellection and understanding as attributes of a soul that survive death. Sensing, imagining, willing, etc., are all attached to the sensory world and are therefore distinct, according to Aristotle. In the Cartesian conception of mind, there is a sharp distinction between mind and world, where all those activities—like sensing and imagining—that could take place in dreams or in disembodied minds are considered mental activities, and exist only in the mind. Things in the world such as trees or light waves are then totally separate from things in the mind, and it becomes a major concern for modern philosophy to determine how the two connect. For instance, there seems to be some connection between my visual sensations and the objects in the world that I see, but since visual sensations are a part of the mind and the objects I see are a part of the world, it is very difficult to determine what that connection is. This picture of mind may seem intuitive to us now, but it and the theories of mind that have sprung from it originate in Descartes. Only in the 20th century have philosophers like Wittgenstein, William James, and J. L. Austin come to question Descartes' sharp distinction between mind and world.

The rest of the Second Meditation concentrates on the "Wax Argument" with which Descartes hopes to show definitively that we come to know things through the intellect rather than through the senses and that we know the mind better than anything else. His argument focuses on the process of change by which solid wax melts into a liquid puddle. The senses seem to tell us things about the world, and Descartes admits that what we know about the solid piece of wax we know through the senses. The senses can similarly inform us about the melted wax, but they cannot tell us that the melted wax and the solid wax are one and the same. Nor, Descartes argues, can the imagination. Only the intellect can organize and make sense of what we perceive. The senses only perceive a disconnected jumble of information: the intellect is what helps us to understand it.

This argument is another move against the Aristotelian theory of knowledge, according to which all knowledge comes from the senses. Descartes acknowledges that the senses inform us about the world, but asserts that the senses can only give us disorganized information. Without the intellect, we could make no sense of what we perceive. Descartes thus places himself firmly in the rationalist camp, as compared to empiricists such as Aristotle or Locke who argue for a sense-based theory of knowledge.

Descartes' next move is a little more questionable. He asserts that "I" cannot know with certainty that what "I" perceive is real (as per the doubts of the First Meditation), but that sensory perception, as a form of thought, confirms that "I" exist ("I" being the mind.) Every time "I" perceive "I" am thinking, and in thinking "I" am enacting the cogito. Every perception confirms the existence of "my" mind and only gives dubitable evidence for the existence of the world. Thus, Descartes concludes, the mind is better known than the body.

This argument is plausible if Descartes means that the existence of the mind is better known than the existence of the body, but it seems that he wants to say that the nature of the mind is better known than the nature of the body. That is, Descartes wants to say that "I" know not only that the mind exists, but also "I" know more about the mind than about the world outside the mind. This argument would only hold if every thought, perception, imagination, etc., told "me" something new about the mind. But, according to the cogito, all these thoughts tell "me" only one and the same thing: that "I" exist, and that "I" am a thing that thinks. Descartes is not as clear as we might like him to be as to what and how exactly each new thought makes the mind better known than the body.

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