Thick Concepts and Underdetermination

Thick terms and concepts in ethics somehow combine evaluation and non-evaluative description. The non-evaluative aspects of thick terms and concepts underdetermine their extensions. Many writers argue that this underdetermination point is best explained by supposing that thick terms and concepts are semantically evaluative in some way such that evaluation plays a role in determining their extensions. This paper argues that the extensions of thick terms and concepts are underdetermined by their meanings in toto, irrespective of whether their extensions are partly determined by evaluation; the underdetermination point can therefore be explained without supposing that thick terms and concepts are semantically evaluative. My argument applies general points about semantic gradability and context-sensitivity to the semantics of thick terms and concepts