Do you think _Zen and the Art of Motorcycle Maintenance_ is categorically a philosophy book, or because it's a novel, it cannot be in that classification? Marty C.

To add to Kalynne's answer, once you have identified a work of philosophy "broadly speaking," a useful thing to do is to reflect on whether or not that specific work is likely to meet your specific objectives for engaging with philosophy -- that question can be much more useful, I think, than simply understanding whether a given work can rightly be categorized as a work of philosophy. Reading and reflecting on Pirsig, working your way through an introductory text, browsing within the Stanford Encyclopedia of Philosophy, and reading a set of specialized journal articles on a narrow topic each involve engagement with philosophy under one or another conception of what philosophy is, and each offer different opportunities for learning and growth. As you read around, you will get a sense of which types of texts offer which kinds of opportunities, and you may also get a better sense of which opportunities matter the most to you.