What did Descartes discover in the 2nd Meditation that he cannot doubt? Explain why he cannot doubt this. What is the latin expression for his famous claim?

Descartes discovers that the physical world does not exist, but because he can doubt the physicality of the world, he must exist.

Explanation:

In the second Meditation Descartes discovers that the Physical world is not real, or does not exist as it is believed to exist in its permanence. This would imply that Descartes himself does not exist in himself, as he is part of the physical world too.

This leads him to think about his doubts too. The fact that he is able to doubt this existence means that he can see that his existence cannot be doubted.

His existence is thus different from his physical existence.

Then the Latin phrase was come up with that is 'cogito ergo sum' or meaning 'I think, therefore I am.'