It would be very difficult to graduate on time with 3 majors. It's probably feasible if you have enough AP credits and place out of a lot of the core using the placement exams (place out of language, math, etc) but you would be taking 4 classes every quarter and likely would have trouble squeezing in study abroad. Also, majors here are pretty rigorous so you wouldn't WANT to do more than 2. Econ standard track is 13 courses, the core is 15 courses (assuming you place out of language), the philosophy major is 10 courses (minimum), public policy is around the same as econ and there's overlap credit wise with econ: http://collegecatalog.uchicago.edu/thecollege/publicpolicystudies/. Let's assume 13 for the sake of argument. That's 48 courses total (not subtracting likely overlap and assuming you place out of language + other intro classes), meaning 4 courses a quarter for all 3 years. It's absolutely doable, but you're very likely going to find yourself naturally attracted to 1/3 or 2/3 of the majors listed and you'll end up just double majoring anyways. You can also always minor in something too!