Radical Interpretation and The Aggregation Problem

Abstract

This paper takes issue with Lewis’ influential argument for the supervenience of the semantic on the non‐semantic based on the possibility of radical interpretation. Radical interpretation is possible only if an ideal being, who is omniscient about the non‐semantic truths, can deduce the semantic truths a priori. The radical interpreter appeals to a set of criteria of interpretation choice, such as most notably some kind of Principle of Charity.It is argued in this paper that the radical interpreter faces an insoluble aggregation problem: the radical interpreter must jointly apply several criteria for evaluating interpretations in order to determine which interpretation is best overall. First, the situation of the radical interpreter is formally modeled using the machinery of social choice theory. Second, it is argued that either Arrow's impossibility theorem or a variant of it applies to the situation of the radical interpreter. The upshot is that radical interpretation is impossible, and Lewis’ argument for semantic supervenience fails.