We don’t read Descartes so we can find out if we exist, or what the mind is. His methods in those areas border on bizarre. Descartes, however, did do a fine job in clarifying the issues under discussion. He mainstreamed several powerful philosophical concepts and tools. First Meditation: the things that are doubtable How do I know an evil genius or a demon isn’t deceiving my senses about the external world, my existence, etc.? Or to put it in modern parlance: how do I know I am not a “brain in a vat” with memories that were pre-programmed five minutes ago? Second Meditation: The Nature of the Human Mind Descartes’ initial answer to the problem: in order for me to doubt, I have to first exist in order to doubt. What am I? I am a thinking thing. What is a thinking thing? It is a thing that doubts, understands, affirms, etc. While my senses may deceive me that I am seeing red et al, it is quite certain that I seem to be seeing red et al. In other words, I am being appeared to redly. Third Meditation: Of God, that he exists Descartes advances Anselm’s ontological argument. It’s not as profound as Anselm’s nor as powerful as Plantinga’s. I have ideas imprinted on my mind which are not in the senses (and so Descartes rightly rejects the old scholastic dictum). Therefore, a greater, yet immaterial, reality must exist. Meditation Six: Of the existence of material things; mind and body Bodies are divisible. Minds aren’t. I can’t cut up the mind into will, faculty, reason, etc.