The book proposes a novel account of perceptual justification, indebted to Wittgenstein's idea that justifaction always takes place within a system of assumptions, which play the role of hinges for our empirical inquiries. It shows how it can be coupled with an anti-sceptical strategy, whereby epistemic rationality extends to its conditions of possibility as well as to justified propositions. It shows why endorsing a hinge epistemology should not lead to epistemic relativism. It then shows how these views can be extended beyond the case of perceptual justification, to the cases of testimonial justification, justification of basic logical laws, and hinges such as "there is a past", "there are other minds" and the Principle of the uniformity of nature.