Understanding is amongst the highest cognitive achievements we, humans, can attain. It is hardly surprising, then, that recent epistemol-ogy has witnessed a surge of interest in the nature of understanding. However, this line of epistemological inquiry meets with complications from the very start. The reason for this is that understanding is such a complex matter. For starters, understanding is not only one of the highest but also one of the most complex cognitive achievements we may hope to attain. Moreover one can understand a variety of different things, including that something is the case, why it is the case and how to do something. One can also understand various phenomena in the world, including persons, events, theories and so on. In order to make this complexity more tractable, I would first like to introduce a distinction, familiar from the literature on the subject, between two broad types of understanding in accordance with two broad categories of objects of understanding: propositional understanding—such as understanding that p and understanding why p—on the one hand and objectual understanding—that is, understanding of various phenomena (persons, theories and events)—on the other. 1 I would also like to point out that, in this chapter at least, I will focus exclusively on objectual understanding (henceforth simply ‘understanding’).