The Meditator next looks at the source of his errors. They depend simultaneously upon the intellect (the faculty of knowledge) and the will (the faculty of choice, or freedom of the will). The intellect, however, only allows us to perceive ideas, not to make judgments on them, and so in this strict sense, it cannot be the source of error. In contrast to the intellect, which he knows is limited, the Meditator reflects that he could not conceive of his will as being any greater or more perfect. In all his other mental faculties-- memory, imagination, understanding, etc.--the Meditator realizes that God is endowed to a much greater degree than he is. But in freedom of choice, or the will, the Meditator realizes he is unlimited, and in this respect more than any other he resembles her creator. God's will may be greater in that it is accompanied by a greater knowledge and power and that it ranges over everything, but when considering the will in the strict sense, the Meditator concludes that his will is just as great as God's. Exercising the will consists simply in affirming or denying, pursuing or avoiding. The feeling of indifference is not a weakness in will but rather a lack of knowledge of what is the true or right course to pursue. Thus, God's will is only superior to our own in that God has supreme knowledge and can always will what is good.
Since the will is perfect and unlimited, it cannot be the source of error. Similarly, since his understanding, or intellect, was created by God, it can never be wrong either. The Meditator concludes that error results not from imperfections in either of these faculties, but from the fact that the will has a far wider scope than the understanding. As a result, the will often passes judgments on matters that are not fully understood and toward which it is indifferent. For instance, the Meditator has such a clear and distinct perception that he exists that he cannot help but judge (will) that this is true. However, he is as yet uncertain about his relationship to the corporeal body that he normally assumes is his. Since he does not have a proper understanding of the relationship between mind and body, he is indifferent as to whether he should assent or deny that the mind and the body are identical and is liable to make a false judgment. In all matters of the intellect except for clear and distinct perceptions, there is some level of conjecture and uncertainty, and so the will is liable to make a false judgment. The correct use of the will in cases of uncertainty is simply to refrain from judgment. When "I" affirm or deny in cases of uncertainty, "I" will either be in error or "I" will arrive at the truth purely by chance.
The Meditator concludes that he cannot complain that God has created him imperfectly. It is only natural that he has a finite intellect, and the will is indivisible, so it cannot be anything less than complete. He cannot complain about the imperfections in him that lead to false judgment, since he is only a small part of God's larger creation, and his role in that creation is perfect even if he may seem imperfect when considered alone. He concludes he can also avoid error completely by suspending judgment in cases where he is uncertain, and only passing judgments on clear and distinct perceptions.
This section draws an important distinction between the intellect and the will. The intellect is the faculty that not only understands and thinks, but also senses and imagines. All these are value-neutral acts in themselves. The will is responsible for affirming and denying, and it is in the will that value and the possibility for error manifest themselves. For instance, my visual perception of a tree is created in the intellect, but it is the will that either affirms that it is indeed a tree, or suspends judgment because I might be dreaming. Thus, even if I am just hallucinating and there is no tree, my intellect is not mistaken in reporting this perception to me, but my will would be mistaken in judging that it is indeed a tree.
The intellect is finite and limited because there are varying degrees at which perceptions and understanding can function. For instance, some of us can only do simple arithmetic, while some of us can calculate differential equations in a snap, while none of us can understand all the mysteries of the universe. The will, on the other hand, is not finite because its efficacy is not a matter of degree. Because I have a free will, I can affirm or deny any proposition put to me by my intellect. The fact that we do not always affirm or deny, the Meditator asserts, is not due to a weakness in the will, but due to a weakness in the intellect. Often, the intellect does not understand a matter well enough to allow the will to make an informed judgment and so the will suspends judgment instead.
The source of error, then, lies in this disparity between the scope of the will and the scope of the intellect. The will is unlimited and can affirm or deny any proposition, while the intellect is limited and can only clearly and distinctly perceive a small number of propositions. Most of what the intellect perceives is confused and obscure, like our sensory perceptions. The only time that we can be certain that we are judging correctly is in cases of clear and distinct perception. The question then arises of how we can know which perceptions are clear and distinct. Descartes' answer is that clear and distinct perceptions are those that the will cannot help but affirm. For instance, the Meditator finds it impossible to deny that he exists, since his every thought confirms his existence. On the other hand, he can doubt what he sees, as the Dream Argument (in the First Meditation) shows. Therefore, visual perceptions are not clear and distinct.