Differential Rent: Its Changing Role in 19th Century Income Distribution Theory (by Michael J. Gootzeit) - ABSTRACT: The idea of economic rent started out in the early 1800’s as a differential surplus paid to agricultural landowners. During the later part of the century, it eventually evolved into more of a profit or excess return concept, also closely tied to wages and interest, as manufacturing came to dominate world economies. The merging of rent with the other three industrial income shares has so far been neglected in economics. This paper corrects this problem by illustrating how the concept of rent became part of the general theory of industrial income distribution as writers eventually debated the merits of the two competing views of distribution of that period: the wages-fund and the marginal productivity theories, with the latter gradually winning out.