Season 2, Episode 3 - The One Where Heckles Dies
Ross the palaeontologist, and Phoebe the new-age free spirit, argue about Evolution. (Sorry for the quality, this video is very old now, I'm trying to upload a HD version).
Update: Thanks for being so nice and curious, commenters of YouTube! I've really enjoyed all of our conversations.
Video Commentary: Real scientists will balk at both Ross's strident approach to explaining science to a lay-person and Phoebe's dualist irrationale. Both are very funny characters, though, and it's a good little example of where these sorts of conversations can go off the rails. (Evolution is true, though).
Copyright notice: Warner Bros. -owned clips fairly used, in part only, to promote the show, and for entertainment, commentary and education. No ownership is claimed by the poster of this video compilation.