Assertions and Their Justification: Demonstration and Self-Evidence

In Frege’s epistemic account of logic, the notions assertion, justification and being evident play a central role. Although the notion of judging agent plays an important role in the explanation of these notions, this does not mean that Frege’s logic is committed to a form of psychologism. How can we use Frege’s account of these notions to illuminate the notions of demonstration and being evident in Constructive Type Theory (CTT)? As the judging agent also plays a role in CTT, how can it prevent a form of psychologism? Although the notion of demonstration cannot be understood without invoking a judging agent, such a judging agent is a first person, which is not to be understood as an empirical subject. And similarly for being evident. The latter notion is often taken to imply a form of psychologism. Although the appeal to the notion of being evident involves a form of fallibilism, the notion is normative, and therefore not psychological. It can thus be used to account for a justification of the inference rules.