Bounded Rationality and Epistemic Blindspots

Abstract: Real-world agents do not know all consequences of what they know. But we are reluctant to say that a rational agent can fail to know some trivial consequence of what she knows. Since every consequence of what she knows can be reached via chains of trivial consequences of what she knows, we have a paradox. In this paper, I respond to the paradox in three stages. (i) I describe formal models which allow us to draw a distinction, at the level of content, between trivial (uninformative) and non-trivial (informative) inferences. (ii) I argue that agents can fail to know trivial consequences of what they know, but they can never do so determinately. Such cases are epistemic blindspots, and we are never in a position to assert that such-and-such constitutes a blindspot for agent i. (iii) I develop formal epistemic models on which the epistemic accessibility relations are vague. Given these models, we can show that epistemic blindspots always concern indeterminate cases of knowledge.