Mechanical Metaphors

Perhaps the greatest contribution of the Italian physicist, astronomer, and engineer Galileo Galilei (1564-1642) — regarded by many as the single most important originator of modern, mathematically oriented natural science — was a unified explanation of both astronomical and earthly phenomena by the same set of mathematical principles for analysis of the behavior of physical bodies and matter. This was a generalized mechanics of solid bodies.

The tremendous power of this new way of understanding the physical behavior of bodies is undeniable. At least until the computer age, it has been the main basis of modern engineering and technology.

A historical side effect of this immensely successful development has been the promotion of solid-body mechanics as a kind of privileged metaphor for causality in general. I’ve several times discussed the transformation of Aristotle’s notion of efficient cause (most fundamentally, the means to actualization of an end) into the very different notion of “driving” cause or “motor” by medieval and early modern authors (see Efficient Cause, Again; Su├írez on Agents and Action; Effective vs “Driving”; Not Power and Action). In combination with a very un-Aristotelian tendency to reduce other causes to efficient causes, this created a ripe condition for the spread of a view of causality in general in terms of metaphors based on solid-body mechanics. We are now so used to this that it takes effort to imagine any other view.

But the solid-body interaction metaphor ultimately leads to an impoverished, overly narrow view of causality in general. (For an alternative, see Aristotelian Causes.) Even within mechanics proper, solid bodies are no longer the paradigmatic, privileged case. At scales that are too small or too large, analogies to the behavior of medium-sized solid bodies break down. In broader contexts, wave phenomena are as important as the analysis of solid bodies. The great Roman poet-physicist Lucretius already had the insight that in the general case, atoms in aggregate behave more like liquids than like solids.

Irreducible to any purely mechanical paradigm, disciplines like earth sciences, ecology, medicine, economics, and computer science provide many examples of more complex and subtle interactions and structures that suggest a new need for something more like an Aristotelian view of causality, as having more to do with forms of things than with force.


Previously, I objected to Althusser’s invocation of the clinamen (the mythical swerve of the atoms) in Lucretius when talking about historical contingency. (He, Deleuze, and the young Marx all seem to have fixated on what seems to me this most dubious — even if charming — aspect of Epicurean thought. I’m enough of a Leibnizian to believe in the principle of sufficient reason. I just don’t think that all determination takes the form of univocal causality.)

I actually enjoy Lucretius, and also found the strangely titled book about him, The Birth of Physics by Michel Serres, quite interesting. Lucretius is full of poetic descriptions of hydrodynamic phenomena. Serres argues that Lucretius considered the conceptual norm for matter in general to be liquid rather than solid; that he wanted to use hydrodynamic phenomena to model aggregate behavior of the atoms, always considering them in aggregate; and that this has widespread implications for thought. It is a not-so-atomistic atomism.