So you're looking for a person who's ideas (not necessarily due to their own merit) had the most positive effect on science and philosophy in the future?
Well, I'm not sure why you're interested... Although I'll add that does seen to exclude people currently alive like Nick Bostrom, who's effect upon the future is currently unknown to us (I would assume that calculating his effects upon the probability of saving the whole human race and the future, and thus causing a near infinite amount of science, might make him beat any others I know).
I'm interested because one of the things I am meant to be studying is the history of philosophy and I consider it best practice when studying a topic to do one's best to properly understand it.
(In case it isn't obvious, I'm asking Lesswrong because although I disagree on some things I think the aggregate of forum opinion more accurate on this sort of question than my own)
Since LessWrong is a major congregation point for certain philosophical ideas, and because people here tend to be more objective (in the sense of not being self-deluded) than elsewhere, I thought I'd ask people's views.
To be clear, by "Greatest Philosopher" I am referring not to the most correct philosopher in human history but the one who deserves the most credit for advancing human philosophy towards being more true.
Off the top of my head I would say that a prime candidate would be Hume- amongst other things he rejected the idea of a soul, realised to a much greater extent than his predecessors the limits of human knowledge, and opposed the idea that reason is somehow an objective force that can make priorities independent of emotions.
Aristotle deserves considerable credit relative for his time but doesn't make the list because although it wasn't his fault his ideas were dogmatically accepted and held back both science and philosophy later on.
Your thoughts?