Find research materials. These include the primary texts written by the philosopher you are studying, and secondary texts responding to these writings. Primary and secondary texts can be found by searching your campus or community library or an online scholarly journal; all must be cited according to the Chicago Manual of Style.
Narrow your topic. According to A Brief Guide to Writing Philosophy Papers, writing about Plato's philosophy as a whole, is too large a topic for a typical 15-20 page paper. You will need to find one aspect of the greater whole to discuss and argue for or against. Oftentimes, your philosophy instructor will have writing prompts giving you specific options to choose from for your topic.
Develop your thesis. Simply put, your thesis contains the main idea of your entire paper, and states the topic of your discussion and whether you are arguing for or against it. The first paragraph of your paper typically contains your thesis as well as an acknowledgment of the scholarship you will be addressing, both primary and secondary texts.
Compose the body of your paper. The body of your paper contains the bulk of the information you are presenting to the reader and also uses the most citations referencing the research materials you have gathered. Use pertinent quotes from primary and secondary texts in the body of your paper to support your argument.
Write the conclusion of your paper. The conclusion of the paper not only encapsulates the main ideas of your thesis and body into a few short phrases, but points to further possibilities for scholarship and addresses possible counterarguments against your ideas.