The Art of Conjecture: A Window into the Heart

Abstract

In 1561, Francesco Casoni published De arte, ac ratione in criminum causis disserendi, a dialogue that offered judges a rigorous method of investigation in criminal cases in which eyewitness testimony or a confession was lacking. Typically, in such cases, judges relied on their own personal arbitrium (discretion) in deciding whether to remand defendants to torture or sentence them to the gallows. Drawing not only on Aristotelian logic and classical rhetorical theory but also on the works of contemporary philosophers, Casoni used his dialogue to lay out a rigorous interpretative methodology. To Casoni, the careful elaboration of inferences, along with the proper use of loci, and a reasoned interpretation of signs (both natural signs and signs of conscience) enabled judges to read, through the opaque surfaces of the body, the interior states of those brought into their courts on suspicion of crimes—and to do so without resorting to torture.