I personally think Descartes wasn't really a great philosopher. I really don't have much trust for many of the Catholic philosophers since they seem to always just try to backwards rationalize things from the standpoint of there being a god (I can perceive there is a god so there must be a god. I can think of perfection so there must be perfection which is automatically embodied by this god). His duality argument was also kind of weak. I didn't dislike Aquinas though. I may not have read enough but I thought his stuff was pretty good.
My favorites were Hume (On Benevolence), Albert Camus (Absurdism), RW Emerson (his philosophies on power... great stuff, applicable today), his friend HD Thoreau (Civil Disobedience), and who can forget Immanuel Kant (Categorical Imperative stuff mostly)?
I also didn't like JS Mill's amoral philosophy at all, preferred Pojman's response to Rand's Ethical Egoism, and Plato really just rubbed me the wrong way, especially with The Republic (it seems he and I agree on a lot of the same stuff, but what he says just aggravates me... I like his predecessor and prodigy, just not him
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I really enjoyed my philosophy class on one hand, but on the other I found it really dumb. After reading the Tao Te Ching, I found all the answers I had and all of the philosophy stuff was mostly just people feeding their egos.