ABSTRACT
This chapter introduces three related notions: hinge, certainty, and trust. Each of these terms describes a peculiar feature of single beliefs and how they relate to other beliefs. These features are usually overlooked in epistemology because they are purely doxastic. They do not give any information about their own truth or falsehood. Instead, they describe psychological or doxastic mechanisms inside a subject’s belief system. These concepts play an important role in internalist epistemology. This chapter simply describes how agents structure their belief systems without taking any position on the beliefs’ epistemic status. Hinges are propositions that agents need to presuppose in order to have a coherent belief system. Certainty is the degree of confidence that we must have in a hinge. We have to trust these hinge certainties because we lack non-circular evidence for our hinges’ truth.
