Özet:

Descartes claims that he can doubt the existence of everything sensible, but he cannot doubt his own existence. Because, according to him, the existence of things outside ourselves is not directly perceived by our senses, on the contrary, it is based on some sort of inference. On the other hand, Kant sees as a logically wrong inference to conclude that all external things are doubtful because the existence of external appearances is also based on inference, based on the fact that things whose existence is based on inference are doubtful. According to Kant, a logical fallacy in an inference occurs only because the middle term is used with a double meaning in the premises. However, the expression "outside us", which Kant sees as ambiguous in this inference, is not a middle term, nor is the real middle term ambiguous. Kant also develops an argument based on transcendental idealism and empirical realism against skepticism towards the existence of the external world. Accordingly, if the existence of external things beyond our perception is denied and only the reality of our perception is accepted, skepticism towards external things will be eliminated. Because the appearances outside of us also exist only in our consciousness as a perception. Therefore if we do not doubt ourselves, we cannot doubt the things in our consciousness. However, Kant's epistemological distinction between our consciousness and the knowledge of things outside of us can be seen as an obstacle to this solution. Moreover, this solution may require accepting the perceptual reality of dreams and hallucinations as well. Finally, Kant deduces as the cause of our perception, the existence of a noumenon that does not occupy space and does not think and accepts it as the cause of our consciousness. But the fact that this noumenal cause lacks the qualities in the result can be seen as an inconsistency for Kant.