In this essay I will explore the syntactic expression of the notion ‘clause’ by focusing on some syntactic and semantic properties of bare infinitive (BI) complements to perception verbs in English. I shall argue briefly that perception BI complements must be clausal, and then turn in more detail to the issue of what sort of clause the BI complement must be. It will be established that the categorical nature of the perception BI complement as IP or VP is contingent on (...) selectional properties of the perception verb, properties which may be contextually influenced by modality and negation. More specifically, an interpretative distinction between ‘vision’ and ‘non-vision’see first suggested by Napoli (1988) will be shown, contrary to her proposal, to provide the key to the contrast in the selection of clausal types. The IP/VP distinction will be shown to correlate with the viability of interpretations for the BI clause that are ‘temporally independent’ of the matrix clause. Given the IP/VP distinction, it will be demonstrated further that the peculiarly limited distribution of the expletive formativethere in BI complements may be predicted from independently motivated syntactic principles that determine clausal structure. (shrink)