Medieval Technology and Social Change is a collection of three essays by Lynn White published in 1962 on the economic influence of the stirrup, the development of a new and more productive technological system of agriculture, and the origins of mechanization. It is both a classic and a controversial book in the history of technology. Although White has been criticized for technological determinism, he states fairly clearly that “a new device merely opens a door” to new social forms.
White’s first essay argues that the introduction of the metal stirrup to Europe made cavalry much more effective because horsemen could swing swords without losing balance and channel the full force of a horse’s charge into a lance. Maintaining cavalry was expensive, leading rulers—in particular Charles Martel—to redistritute land to the nobles he expected to serve as knights. This redistribution was the foundation of feudalism.
The increased use of cavalry also led to the breeding of larger horses, one of several causes of a new agricultural system using horses in place of oxen. This transition also required the harness, the horseshoe, and the oats produced by the new triennial crop rotation. Farmers who used horses for tilling fields could also use them to commute to work, leading to a rapid urbanization process in which farmers continued to work the same land but moved from small, very local hamlets to larger, more remote villages. The triennial rotation also produced legumes, the protein from which White credits with a major role in the population growth of the late medieval period.
In his third essay, White traces the development of a number of machines, focusing on power sources like water, wind, steam, explosives, and gravity. He argues that a number of late medieval military machines—trebuchets, rockets, cannons—provided the engineering logic behind later socially revolutionary machines like spinning wheels and mechanical clocks.