[morelisp]

There are plenty of uncontroversial polymaths in the 20th century alone - von Neumann (hopefully no need to list here), Chomsky (political science, linguistics, computer science), and Nabokov (literature, chess, entomology) come to mind quickly.

In retrospect, many polymaths look like an expert in only one field because they more or less invented it. (Chomsky synthesized computation and lingustics into computational linguistics; Helmhotz synthesized physics, medicine, psychology, and philosophy to help found modern psychophysics; Frege, Russell, and Whitehead synthesized logic and mathematics into, uh, mathematics.)

Another issue seems to be assuming that all or at least one of the fields is a science (or even a hard science), but this isn't the case. Paul Robeson has been cited as a polymath due to his contribution across several dramatic arts, law degree, his political activism, and football career.

[tux1968]

I like the one Bill Burr made a point of highlighting: Arnold Schwarzenegger. Body building champion, movie star, and governor of California.