Carnegie Mellon University

The Rhetoric of Probability Mathematics

Author: Terri Palmer
Degree: Ph.D. in Rhetoric, Carnegie Mellon University, 2005

This dissertation discusses the rhetorical aspects of mathematical theory about the probable from a historical perspective. While today the term "probability" is considered a mathematical term, this is an historically recent development; before the mid-seventeenth century or so, the term was used extensively in forensic rhetoric but had no mathematical definition at all. I discuss the uses of this term as a specifically rhetorical term and then go on to discuss the history of probability mathematics, focusing on the earliest works of true probability mathematics, the mid-seventeenth century The Art of Thinking and Jakob Bernoulli's early eighteenth-century Ars Conjectandi. My contention is that handbooks of forensic rhetoric (such as the Ad Herennium, De Inventione, and parts of Quintilian's Institutio Oratoria) bore striking resemblances to the use of probability in Bernoulli and the Port-Royalists' texts and were texts that both parties were familiar with. My dissertation builds on previous research by arguing that these similarities are much more striking than had previously been noted.