Measure of Change: The Adjectival Core of Degree Achievements

Christopher Kennedy and Beth Levin

Current theories of aspect acknowledge the pervasiveness of verbs of variable telicity, and are designed to account both for why these verbs show such variability and for the complex conditions that give rise to telic and atelic interpretations. Previous work has identified several sets of such verbs, including incremental theme verbs, such as eat and destroy; degree achievements, such as cool and {\em widen}; and (a)telic directed motion verbs, such as ascend and descend. As the diversity in descriptive labels suggests, most previous work has taken these classes to embody distinct phenomena and to have distinct lexical semantic analyses. We believe that it is possible to provide a unified analysis in which the behavior of all of these verbs stems from a single shared element of their meanings: a function that measures the degree to which an object changes relative to some scalar dimension over the course of an event. We claim that such 'measures of change' are based on the more general kinds of measure functions that are lexicalized in many languages by gradable adjectives, and that map an object to a scalar value that represents the degree to which it manifests some gradable property at a time. In this paper we focus on the analysis of degree achievements, which provide the first step towards this goal. As verbs for the most part derived from gradable adjectives, they most transparently illustrate the semantic components that we claim are involved in determining variable telicity.