The following is a heavily edited transcript of a talk I gave for the Stanford Effective Altruism club on 19 Jan 2020. I had rev.com transcribe it, and then Linchuan Zhang, Rob Bensinger and I edited it for style and clarity, and also to occasionally have me say smarter things than I actually said. Linch and I both added a few notes throughout. Thanks also to Bill Zito, Ben Weinstein-Raun, and Howie Lempel for comments.