Abstract. — In this paper I present a formal model of concept possession and use it to identify constraints that cognitively plausible processes of conceptual amelioration must typically meet. Concepts are to be thought of as lossily compressed encodings of the state of the world. It turns out that optimal solutions to this compression problem, in ecologically realistic contexts, rely on encoding-decoding strategies that fit the bill of what psychologists call ‘concepts’. The application to the amelioration program comes from noticing that lossy compression requires the formulation of distortion criteria, which measure the closeness or fidelity of a reconstructed source sequence to the original. An amelioration program can be formally reconstructed as stemming from the perception that the compression scheme embodied by the currently available conceptual repertoire is suboptimal, as judged by a certain distortion criterion. With this formal redescription in hand, I discuss several soft constraints amelioration programs should observe.