In the three previous meditations, Descartes has discovered some important ideas. He now knows that God exists and is not a deceiver, he has reason to doubt everything, our senses deceive us, and he exists because he thinks. His most important revelation is that God does in fact exist and that he would not deceive. .
In the fourth meditation Descartes discovers a new problem that he has not thought of or come across before. The new problem involves his ability to make mistakes and human error. Descartes wonders that since God exists and is perfect, why would he create humans with the ability to make mistakes. Descartes knows that, "since God does not wish to deceive me, He surely did not give me the kind of faculty which would ever enable me to wrong while using it correctly." Descartes must find a solution to this problem without accusing God of deceiving us, since he has already established that God does not deceive, and he cannot deny that there is certain knowledge. According to Descartes, the concept of human error is any mistaken judgment. His solution to the problem must rest with us instead of with God.
Descartes goes through several solutions to he new problem, yet none of them seem to satisfy him. First, Descartes considers the solution that God is the cause of his mistakes and error. However, God can not be responsible for our mistakes because this would go against everything that Descartes has already determined; God is not a deceiver. Descartes" second solution is that his ability to form judgment is not perfect. This solution also turns out to be inadequate for Descartes. This would mean that the possibility of error would seem to be a defect that we can blame on our faculty of judgment. He says that a perfect God would not place an imperfect ability in him. Sometimes we cannot know God's purpose for allowing us to error because we are incapable of understanding God's wisdom since it is above our intelligence.