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.

Biological Diversity

Modern biology provides an abundance of empirical evidence that things like populations and ecosystems need diversity to flourish. Inbreeding leads to all sorts of genetic defects; monoculture crops and other simplified environments are more vulnerable to pests, and generally far less able to recover on their own when disturbed.

In a more reflective, interpretive vein closer to ordinary experience, Aristotle already documented the tremendous variety exhibited in nature. Species are not somehow pre-given, but rather to be discerned and understood in terms of specific ways of meeting very general needs.

The fact that there is a superabundance of such ways in nature is one of the most basic observations we can make. Nature as we concretely experience it is much more characterized by this superabundance and diversity than by univocal necessity of the kind we find in mathematics. For Aristotle, an emphasis on this superabundance and diversity goes hand-in-hand with a perspective that looks to purely natural ends and means as more primary in the order of explanation than mechanical metaphors.

This suggests a broader paradigm of intelligibility, reason, and objectivity than the one grounded in mathematics, univocity, and simple necessity. Emotional reasonableness is a real thing that is not at all reducible to formal logic. Similarly, intelligibility, reason, and objectivity in general have a practical reality that should not be understood as requiring a univocal foundation. (See also Bounty of Nature; Equivocal Determination; Multiple Explanations.)