Books on Philosophy fall largely into the "B" call numbers, which also hold Psychology and Religion. Important subcategories include:
The Library of Congress offers a full listing of philosophy call numbers. You don't need to memorize all of these in order to find books on your subject, but understanding how the Library of Congress organizes Philosophy and it's sub-categories can help you find more materials for your own research.
Some examples of books from our catalog on various philosophical subjects are listed below.