The adjective philosophic is used to describe the study of deep thinking. If you have a philosophic attitude, you face trouble with a level head, like a deep thinker.
To some extent, you can use philosophic interchangeably with the more widely-used philosophical whenever you're talking about philosophy. It's more common, though, to save philosophic for the academic discipline rather than a more general context. So you might discuss the philosophic texts in your ethics class or Marx's philosophic thoughts on a particular subject. The word philosophic can also describe being calm in the face of defeat or loss. Philosophic comes from the Greek philosophia, "love of knowledge."