I can say unequivocally that the Origin is the best 490-page argument I’ve ever read. His conclusion in particular is a work of art, and is worth rereading more than once. I was struck by just how subtle and sophisticated Darwin’s actual claims are, compared to the gross caricatures of his views you might be subjected to, both by those who argue for and those who argue against his view. Also, it is funny how some modern creationists (‘intelligent designers’) are just rehearsing objections which Darwin himself brought up in 1859, and fully answered.Perhaps the one thing that will stick in my mind the longest is just how anti-essentialist Darwin was about species. Species, for Darwin, were NOT essentially different from varieties; in fact, varieties could be seen as incipient species. I don't want to put words in his mouth, but he seems very conventionalist: surely there are groups of animals which differ more or less from other groups, but there is no magic criterion which marks groups as different in kind from others - our labels are just that, and our labelling system may be more or less useful. Wonderful!
I won’t rant on and on here about the quality of this book. But I just have to say that I was pleasantly surprised at how accessible it was to me, a non-biologist (there is very little jargon), and that I really think it would be impossible to read it without feeling the full force of the theory of evolution by natural selection; that is, just how many facts it predicts and explains. Darwin took pains to amass ridiculous amounts of evidence for his theory before publishing it, and remember, this book is just an abstract of what he really wanted to say! Darwin himself said that the person who is more impressed by the problems of a theory than with its solutions may at once reject his theory, but of course this would have turned out to be to their detriment in this case. The ‘problems’ have turned into entire (fruitful) research programs, all elucidating and confirming (if we want to be realists) the theory of evolution via natural selection that much more.
Thanks to Jeremy and the other class members for putting up with a philosopher for an entire semester; I feel like I am a much better person for having been able to share the experience of reading the original Origin with you all.