In this chapter I pull together the threads of discussion of the previous chapters to examine the different ways knowledge from non-knowledge may arise in the epistemologies of inference, testimony and memory. I offer a defeater-based explanatory framework for the various forms this phenomenon takes in the context of the three different epistemic sources and draw some conclusions about the picture that emerges.

This chapter introduces the received view in epistemology that inferential knowledge requires essential premises to be known. I formulate the principle of Knowledge Counter-Closure, which expresses the received view, and describe a schema for possible counterexamples to this principle.

A brief description of the book's aims and structure is provided.

I present the debate on testimonial knowledge from non-knowledge. After explaining Jennifer Lackey's challenges to the received view that a hearer can only come to know p testimonially if the speaker knows p, I raise several difficulties for Lizzie Fricker's view, according to which testimonial knowledge is necessarily second-hand knowledge, and reject it on the basis of these problems. I then argue that Sandy Goldberg's case of safe testimonial belief from unsafe testimony survives Lackey's criticism. I offer a first comparison between inferential and testimonial knowledge from non-knowledge in terms of defeaters.

In this chapter I present the received view in the epistemology of memory, according to which one only knows p via memory if one knew p at an earlier time. I discuss Jennifer Lackey's counterexamples to this view and address Thomas Señor's criticisms to Lackey's cases. I explain why factual-defeater-based cases of mnemonic knowledge from non-knowledge should not be expected.