Mechanism and life

It’s non-controversial to call living things “machines” if you use the term in its literal sense of devices that change the direction and magnitude of a force: a jaws and elbows are obvious levers, ball sockets work like wheels and axles, etc. This is how Newton saw them (see the end of cor. 2 in the section of the laws of motion) and Descartes need not mean anything more by his physical mechanism (famously applied to animals).

One overlooked element in the scientific revolution is that it begins with motion already as given, and is only interested in the structures or rules that govern motion’s transference -i.e. things like machines. Newton’s first law,  for example, doesn’t explain motion as such but says that if there is motion it will continue indefinitely; and his second law describes changes of motions, i.e. exactly what machines do. The question of the origin or character of the motion simply cannot arise, and so the relevant difference between the living and the mechanical cannot arise. Modern physics is not the tool one uses for capturing the distinction between life and machines in the same way that a scale is not the tool one uses to capture the distinction between ten pounds of potatoes and ten pounds of steel.

Seen from this angle, Descartes’s “dualism” is just this: some systems consist only in activities where the relevant changes are just changes in the direction and magnitude of force and other systems involve activities where the relevant changes are not of this kind, sc. changes like the move from premises to the conclusion, from a function to its values, or from a goal or value to a choice. The first sort of system, however,  includes both a seesaw and an elbow joint, a wheel and a ball-socket, the living and non-living. We are not demoting animals, only giving a more helpful or useful way of articulating the Aristotelian difference of souls that cannot subsist without matter and souls that can. It’s not a repudiation of Aristotle’s idea but a way to open it up to a larger and more exact analysis.


1 Comment

  1. D.S. Thorne said,

    April 14, 2014 at 1:20 pm

    Gilson made the very interesting observation in _The Unity of Philosophical Experience_ that Descartes’ res extensa can’t even so much as allow for mechanical motion: if the only trait of two physical objects are their extension, and nothing else (i.e. devoid of all “properties”), they can’t interact with each other. Forget the mind-body problem – Descartes also gives us the body-body problem! Newton revises these physical objects, reintroducing properties in the form of mass, etc, so as to provide a grounding for their behavior. The only other option to fix this is the occasionalism of Malabranche…

    ~DS Thorne,

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