Typically, if I understand a sentence, then it expresses a proposition that I entertain. Nonsensical sentences don’t express propositions, but there are contexts in which we talk about understanding nonsensical sentences. For example, we accept various kinds of semantically defective sentences in fiction, philosophy, and everyday life. Furthermore, it is a standard assumption that if a sentence is nonsensical, then it makes no sense to say that it implies anything or is implied by other sentences. Semantically uninterpreted sentences don’t have (...) logical characteristics. Hence, the riddle of understanding nonsense arises. We seem to use nonsensical sentences in reasoning, thinking, judging, and drawing conclusions, but they convey no propositions, which are the vehicles of their semantic properties. In this article, I propose the pretence theory of understanding nonsense to explain the riddle of understanding nonsense, and discuss alternative frameworks that are insufficient to solve it. -/- . (shrink)