From background to default: the epistemic role of the unmarked

A great deal of our epistemic life takes place beneath the surface. In forming our beliefs, adjudicating truth, distributing trust, and disseminating knowledge, we oftentimes rely on criteria, assumptions, and requirements, which are seldom openly expressed in our discourse. It is little more than a commonplace to say that we cannot state everything or be aware of everything, but the juicier point is that what we do not state tends to play a more important epistemic role than we think or would like to allow. This is not necessarily a problem, though, or, at any rate, it has not been traditionally treated as such. In this article, we discuss some of the more relevant manifestations of the unmarked in contemporary epistemology. Our survey follows a historical trajectory, but we aim at more than just an account of what has been said about what is not said. We argue that one can single out two main conceptions of the unmarked in epistemology. First, many writers claimed that our cognitive activities always happen within the contours of a certain background knowledge which, as the name suggests, remains silent albeit present. The idea of background knowledge, which – we suggest – is shaped after the model of Euclid’s geometry, has two remarkable features. On the one hand, it has a constructive role: like in Euclid’s geometry, we need a firm starting point to create new thoughts. On the other hand, it is under our full control: we, as epistemic agents, are able to choose what stays in the background and what comes to the fore. This contention started to become increasingly more suspicious in the postwar period when more and more philosophers pointed out that our hidden presuppositions are so entrenched with the marked part of our epistemic life that a clear separation between the two is impossible in practical terms. This is what we dub ‘default knowledge’ and we argue that it raises a number of ethical questions which were unthinkable from the perspective of background knowledge.