Most of the students who choose to pursue a concentration in philosophy did not have any background in philosophy when they entered Harvard. And those students who have had encounters with philosophy tend to find that academic philosophy at the college level is quite different from what has come before. In other words, just about everyone starts from the same position.
The philosophy concentration is non-linear. There is no set sequence of courses that students need, or even should, follow as they make their way through the concentration. Very few of our courses have explicit pre-requisites (really only the logic courses), so students can take courses in whatever order makes sense to them, given their intellectual goals and interests.
Very broadly speaking, the undergraduate curriculum falls into three parts. We offer introductory level courses, numbered between 1 and 90; tutorials, numbered 97 and 98; and more advanced courses for undergraduates and beginning graduate students, numbered 101-199. There are also two special courses, PHIL 91r and PHIL 99. You can read more about all of these below.