Speaking of Possibility and Time
Ignorance and the passage of time are among the most fundamental and pervasive aspects of human life. People draw conclusions from unreliable evidence, revise their beliefs in view of new information, and base their plans and decisions on expectations about likely outcomes. People also talk about knowledge and ignorance, past and future, best guesses and their factual basis. All languages provide speakers with means to be explicit about varying degrees of confidence and hypotheticality, and to specify the temporal locations of the events they talk about, relative to each other and to the time of utterance. In English, conditional (‘if-then’) sentences and modal expressions like ‘must’, ‘may’, and ‘probably’ are typical examples of the former. Tenses (e.g., past ‘-ed’) and aspectual forms (e.g., Perfect, Progressive) are instances of the latter. The value of modal and temporal linguistic expressions as an object of study goes far beyond purely linguistic concerns. They reflect the way we represent and reason about a wide range of extralinguistic concepts such as causality, (non)determinism, the relation between subjective uncertainty and objective chance, mutual beliefs and common ground, and the ontology of states and events. These notions are of interest to researchers across many disciplines, including philosophy, psychology, and artificial intelligence. This project is aimed at deepening our understanding of the meaning and use of modal and temporal expressions, the inferences involved in their interpretation, and their semantic interactions with each other and with other grammatical categories. Both the extralinguistic concepts behind modal and temporal discourse and the linguistic expressions used in such discourse interact with each other in intricate ways. For instance, our talk of past possibilities reflects the interplay between likelihood and causal dependencies. Temporal expressions whose ordinary use is in referring to different times are recruited for reference to alternative hypothetical states of affairs. Similar interactions between the two realms are attested across a wide range of genetically diverse languages. The commonalities and differences in the ways in which such interactions manifest themselves provide invaluable evidence about universal patterns in cognition.