We have had some rather vigorous discussions on platonism in our BA Seminar. Recently the discussion centered on the existence of “natural kinds” — the question, for instance, of whether biological species are arbitrary distinctions or grounded in reality. In a famous passage from the Phaedrus, Plato talks about dividing things into forms “following the objective articulation; we are not to attempt to hack off parts like a clumsy butcher. . .” (265e) Most of our students, it seems, tend to be nominalists rather than realists [which is not meant to imply that they are clumsy butchers]. Thinking about platonism reminded me of the following cartoon — linked in a comment to our GRE post. It is from a nice site, xkcd: A Webcomic of Romance, Sarcasm, Math and Language.