How so? The proposition that I am thinking is self evident. Surely the fact that I am thinking verifies the fact that it must be true. You can doubt absolutely anything, but yourself. The only way for something to be untrue is if we are being deceived, or we have a lack of knowledge and understanding. If I am being deceived, I must exist in order to be deceived or else there is nothing to deceive.
Give me one circumstance in which you can deny the existence of your own thought.
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