Aristotle develops his theory of economic justice in Nicomachean Ethics and Politics. The theory is interesting because his discussion of economic justice is connected to his larger concern about the relationship between the commensurable and incommensurable. Commodities are mutually incommensurable from the viewpoint of their use value but commensurable from that of exchange value. They are reduced to be mutually commensurable on the basis of “need (chreia)”. The medium of this quantitative comparison is money, which is introduced by“convention (hypothesis)”. There have been various interpretations concerning the meaning of “need”, but little discussion about the meaning of “convention”. I propose in this paper that Hume’s analysis of convention in The Treatise of Human Nature could be profitably made use of for understanding the Aristotelian idea of convention.
