Abstract
Just as it’s possible to understand novel sentences without having heard them before, it’s possible to understand novel pictures without having seen them before. But these possibilities are often supposed to have totally different explanations: whereas the ability to understand novel sentences is supposed to be explained by tacit knowledge of a compositional theory of meaning for their language, the ability to understand novel pictures is supposed to be explained differently. In this paper I argue against this disanalogy: insofar as the ability to understand novel sentences is explained by tacit knowledge of a compositional theory, I argue, so is the ability to understand novel pictures.