This book investigates the distribution and interpretation of Covert Modality. Covert Modality is modality which we interpret but which is not associated with any lexical item in the structure that we are interpreting. This dissertation investigates a class of environments that involves covert modality. Examples of covert modality include wh-infinitival complements, infinitival relative clauses, purpose clauses, the 'have to' construction, and the 'is to' construction (cf. 1):

1a. Tim knows how to solve the problem]. ("Tim knows how one/he could/should solve the problem.")
1b....