ESHS/HSS Annual Meeting

Something that Can Stand for Anything: The Unknown Against the Backdrop of 14th-Century Accounts of Quantity

• In Event: Rewriting the Histories of Algebra

English Abstract

In a fourteenth-century algebraic textbook (edited by R. Franci and M. Pancanti), an anonymous Florentine abacus master characterizes the unknown—the cosa, litt. the thing—as a distinct kind of mathematical entity, capable of representing multiple types of quantity, both discrete and continuous. In the same period, another Florentine abacus master, Dardi, explicitly states in his albegra textbook (edited by R. Franci) that the unknown is called cosa (thing) because such a name can stand for anything in the world. These two definitions of the unknown appear to rest on complex philosophical commitments and thus demand careful conceptual analysis. In my paper, I will examine these, and hopefully other, accounts of the unknown in relation to contemporary understandings of quantity developed in the same milieu as these abacus masters, namely, fourteenth-century Florence.

Author

• Clelia Crialesi