Every once in a while, I get asked by students with a background in math (usually with an interest in logic) what they should do if they want to get into grad school in philosophy. I know there’s quite a number of accomplished philosophers who started out as math majors and then went on to top PhD programs in philosophy–but I don’t know what they did to get in. It may well be that you can take one upper-level logic course at MIT and get a letter from one of the philosophy profs there that’ll get you into a top philosophy PhD program. But if you’re not a math major at a top US school, how much philosophy should you have taken, and what kinds of courses, to stand a chance? How many letters from philosophy profs would it take? How technical can your writing sample be? And what if you’re in some other discipline (CS, physics, psych, etc) and you want to switch to a philosophy graduate program?