What did William Stanley Jevons think caused the business cycle? Was he right?

William Jevons Stanley was wrong in his assumption.

In economics, the term sunspot is used to refer to extrinsic random variables. The term sunspot was coined by an English economist and logician named William Jevons Stanely. An extrinsic random variable is one that cannot influence, fundamentally, an economic model. For example, social and psychological factors can be classified as sunspots.

Like Jevons, some economists believed that there existed a relationship between the business cycle and real sunspots. This is mainly because the economies of their time were mainly agrarian. Jevon and his colleagues opined that since sunspots directly impact the weather, a change in the productions of crops would impact the economy. Later, economists proved that Jevon's theory was statistically insignificant.