When writing your responses, imagine your audience is a fellow student who is not in our class, and think about what you'd need to say in order to answer these questions in a way they could fully understand. Be sure to organize your essays well, define important terms, and make your wording as clear and direct as possible. I will be looking for clear, concise expression of ideas; complete answers to each question; evidence of your comprehension of the material; well-structured arguments where called for (not just assertions); as well as proper grammar, punctuation, and spelling. Explain why Descartes thinks he cannot doubt his own existence, even though he can doubt the existence of the external world, his knowledge of it, and so on. Why is one doubtable and the other not? Clarify how Descartes’ arguments on this matter demonstrate his rationalist approach to philosophy.