The scholastic analysis of money, exchange, and market value, already well underway in the thirteenth century, continued to evolve over the fourteenth century, with the commentaries on Aristotle's Ethics and Politics providing the most important loci for this discussion. In this chapter I discuss the advances made within each of the six categories of connection between scholastic economic thought and proto-scientific speculation. I remind the reader that these categories are heuristic constructs. My use of them to isolate the core insights underlying the scholastic model of economic exchange should not obscure the consistent, even necessary connections between these insights in the writings considered in this chapter. Dynamic equilibrium, relativity, the measuring continuum, and common valuation all work together within the new social geometry of the fourteenth century.

EQUALITY, THE MEAN, AND EQUALIZATION IN EXCHANGE

Through the fourteenth century, the controlling principle in economic thought remained equality. Without exception, thinkers defined economic exchange as a process of equalization. In the restricted case of the loan or mutuum, ideal equality continued to be determined in most cases arithmetically – the sum lent determined the sum that could be required in return, with no allowance for proportionality. However, in the broader realm of economic exchange that included buying (emptio) and selling (venditio), traditional requirements for arithmetical equality came under increasing challenge. Thinkers began to question the knowability and even the existence of definable points of exchange equality.