Does anything actually exist outside of the human mind? Does the world make sense? Is everything relative? Do human beings have a free will? We show that these questions, as well as other fundamental philosophical problems, lead to contradiction - and that this contradiction is their truth. Followed by a dialogue with Loïc Maréchalen, a Hegelian, to discuss the similarities and differences between Hegel's dialectics and the method used in this book. ----------------------------------- Léonor Franc holds an agrégation in philosophy and teaches philosophy in France. In 2022, he co-founded Éditions Skhedia with Romuald Bidault.