Gerolamo Cardano (1501-1576)

Gerolamo Cardano's mother already had three sons before Gerolamo was born and did not want another. At three months old, he, along with his three half-brothers and nurse, came down with the bubonic plague. Gerolamo was the only one of the five to survive. His father, Fazio Cardano, was a geometer and sometimes worked with Leonardo da Vinci, but never made much money, so the family's home life was difficult. Fazio started a business consulting in law and medicine. When Gerolamo was five years old, Fazio began taking him to meetings to carry books. Fazio reportedly had Gerolamo stop sometimes to use his head as a table.

As a young man, Gerolamo decided to study medicine, and began to save money by tutoring, reading horoscopes, and eventually gambling. At that time, games generally included a wager, no matter whether winning was based on strategy or luck. Gerolamo recognized patterns in the games of chance and began to use those to have an advantage in betting. Soon, he earned enough gambling to support himself as a medical student. Soon after Cardano began medical school, he recorded his observations and eventually published them in his Book on Games of Chance.

Cardano's work formed a good starting place for probability theory, but many of his explanations and assumptions were not correct. He attempted, but was unable to solve, the Problem of Points. Like those before him, he believed that luck affected chance processes. In Cardano's most influential work, Liber de Ludo Aleae written in the 1520s, he included a section called On Timidity in the Throw which includes this excerpt, explaining why many people at his time believed that throwing the dice timidly caused a less favorable roll:

For this reason it is natural to wonder why those who throw the dice timidly are defeated. Does the mind itself have a presentient of evil? But we must free men from error; for although this might be thought true, still we have a more manifest reason. For when anyone begins to succumb to adverse fortune, he is very often accustomed to throw the dice timidly; but if the adverse fortune, persists, it will necessarily fall unfavorably. Then, since he threw it timidly, people think that it fell unfavorably for that very reason; but this is not so. It is because fortune is adverse that the die falls unfavorably, and because the die falls unfavorably he loses, and because he loses he throws the die timidly (as cited in Tabak, 2005, pp. 18-19).

While his explanation that a person's luck affects the outcome of a dice roll is not accurate, he did recognize that this presumed association between timid rolls and unfavorable results was not a causal relationship. In addition to being limited by the common beliefs about chance processes at the time, he was also limited by the lack of algebraic notation fit for describing probability which was still developing. However, despite these challenges, he printed 131 works and had 111 books in manuscript by the time he died. He also said he burned 170 other manuscripts because they were not of interest.