The dumbing down of mechanism

Jessica Riskin, Alive and ticking, in Aeon.

The model of nature as a complex, clockwork mechanism has been central to modern science ever since the 17th century. It continues to appear regularly throughout the sciences, from quantum mechanics to evolutionary biology. But for Descartes and his contemporaries, ‘mechanism’ did not signify the sort of inert, regular, predictable functioning that the word connotes today. Instead, it often suggested the very opposite: responsiveness, engagement, caprice. Yet over the course of the 17th century, the idea of machinery narrowed into something passive, without agency or force of its own life. The earlier notion of active, responsive mechanism largely gave way to a new, brute mechanism.

Brute mechanism first developed as part of the ‘argument from design’, in which theologians found evidence for the existence of God in the rational design of nature, and therefore began treating nature as an artefact. The natural world of late-medieval and early Renaissance Europe had contained its own spirits and agencies; but arguments from design evacuated these to a location decisively outside the physical realm – leaving a fundamentally passive machinery behind. Since theology and natural science were not yet distinct fields of inquiry, brute mechanist ideas pervaded both. Between the mid-17th and early 19th centuries, the principle of passive matter became a foundational axiom in science, to the point that few people today recall its theological origins.

A key moment in the establishment of brute mechanism in science took place one Sunday evening in Edinburgh, in November 1868. The English naturalist Thomas Henry Huxley – friend and defender of Charles Darwin, as well as a professor of natural history, anatomy and physiology – gave a lecture. He chose the subject of protoplasm, or, as he defined it for the uninitiated, ‘the physical basis of life’. Huxley’s main point was simple: we should be able to understand what brings something to life simply by reducing it to its component parts. There should be no need to invoke any special something, any force or power such as ‘vitality’. After all, Huxley quipped, water has extraordinary properties too; but we needn’t rely on something called ‘aquosity’ to explain how hydrogen and oxygen produce water under certain conditions. To be sure, Huxley couldn’t say how the properties of either protoplasm or water arose from their composition; but he was confident that science would find its way to the answer, as clearly as ‘we are now able to deduce the operations of a watch from the form of its parts and the manner in which they are put together’.