British philosopher Nigel Warburton says the same thing in his books. Emboldenings are mine. I know that some French literature syllabi include Camus and Sartre. But at least in English, I have never seen philosophy books in any school or university literature syllabus!
What exactly does Warburton mean by great, significant literary work? How can philosophy texts be literature too?
The history of political philosophy includes many of the greatest and most widely studied works of philosophy, from Plato's Republic through to John Rawls's A Theory of Justice. In this book we are focusing on seven works by indisputably great thinkers. These books are intrinsically interesting, in some cases qualify as significant works of literature, and, most importantly, contain ideas that have a continuing relevance beyond their original contexts of composition. Our book has been written in the firm belief that studying the history of philosophy should not be like a visit to a dusty museum of superseded thought, but rather a challenging and invigorating engagement with the ideas of the great thinkers of the past.
Reading Political Philosophy Machiavelli to Mill, page vii.
These are known as the Platonic Dialogues and are great works of literature as well as of philosophy – in some ways Plato was the Shakespeare of his day.
A Little History of Philosophy, 2011, page 4.
The history of philosophy is a fascinating and important subject in its own right, and many of the classic philosophical texts are also great works of literature: Plato’s Socratic dialogues, René Descartes’s Meditations, David Hume’s Enquiry Concerning Human Understanding, and Friedrich Nietzsche’s Thus Spake Zarathustra, to take just a few examples, all stand out as compelling pieces of writing by any standards.
Philosophy: The Basics, 2012 5th Edition, page 2.
This book consists of thirty-two chapters, each focused on a single great philosophical book. The point is to introduce each book, bringing out its most important themes. The books dealt with here are worth reading today because they engage with philosophical problems that are still worth discussing, and because they continue to offer insights. Apart from that, many of them hold their own as great works of literature.
Philosophy: The Classics, 2014 4th edition, page 1.