A distinctive feature of modern capitalist societies is the tendency of the market to take over the production, maintenance, and distribution of goods that were previously produced, maintained, and distributed by nonmarket means. Yet, there is a wide range of disagreement regarding the proper extent of the market in providing many goods. Labor has been treated as a commodity since the advent of capitalism, but not without significant and continuing challenges to this arrangement. Other goods whose production for and distribution (...) on the market are currently the subject of dispute include sexual intercourse, human blood, and human body parts such as kidneys. How can we determine which goods are properly subjects of market transactions and which are not? The purpose of this article is to propose a theory of what makes economic goods differ from other kinds of goods, which can help to answer this question. (shrink)