Key Arguments

• The Cogito’s certainty rests solely on seeing clearly that thinking requires existing.
• Extending this insight yields a general epistemic principle about clear and distinct perception.
• He warns of the difficulty in correctly identifying distinct conceptions.

Source Quotes

After this I inquired in general into what is essential I to the truth and certainty of a proposition; for since I had discovered one which I knew to be true, I thought that I must likewise be able to discover the ground of this certitude. And as I observed that in the words I think, therefore I am, there is nothing at all which gives me assurance of their truth beyond this, that I see very clearly that in order to think it is necessary to exist, I concluded that I might take, as a general rule, the principle, that all the things which we very clearly and distinctly conceive are true, only observing, however, that there is some difficulty in rightly determining the objects which we distinctly conceive. In the next place, from reflecting on the circumstance that I doubted, and that consequently my being was not wholly perfect (for I clearly saw that it was a greater perfection to know than to doubt), I was led to inquire whence I had learned to think of something more perfect than myself; and I clearly recognized that I must hold this notion from some nature which in reality was more perfect.

Key Concepts

• in the words I think, therefore I am, there is nothing at all which gives me assurance of their truth beyond this, that I see very clearly that in order to think it is necessary to exist
• I might take, as a general rule, the principle, that all the things which we very clearly and distinctly conceive are true
• there is some difficulty in rightly determining the objects which we distinctly conceive

Context

Part 4: From the Cogito to the criterion of clear and distinct perception.