Constructive and Classical Models for Results in Economics and Game Theory

A standard approach in economic theory is to use a formal language to prove results about an economy or a game. In this paper, model theory is used to examine interpretations of such results. The particular focus is on constructive theorems, since results established by constructive methods are valid for many different interpretations, whereas classical theorems are valid more narrowly. I discuss why non-classical models may be of interest and also describe applications of model theory to economics in classical contexts, e.g. non-standard analysis. The paper advocates a viewpoint suggesting that constructive models are tools for studying worlds in which agents' knowledge of the world is incomplete. Copyright Blackwell Publishing Ltd 2004.