The Fourth Way, fire, and entropy

The Fourth Way makes the claim that because things are more or less hot there is something maximally hot. This was based on STA’s idea that fire was a chemical released by burning, meaning that a campfire took fire out of logs just like a still takes alcohol out of fermented things. His example was incorrect but the principle remains as a valuable though unarticulated postulate for chemists, which is assumed in their long list of separation processes. If we wanted to update the fire example we could do so with any property of pure substances: e.g. given that some drinks are more and less intoxicating, there is something maximally intoxicating.

Digging deeper in the Fourth Way one finds STA’s reliance on the idea that every act communicates itself so far as possible. “Communicates” is a transliteration, not a translation – what he means by the term is the complementary description to participation. Participation is the dependence of a part on something that it common, the way players participate on teams or interlocutors participate in discussions. This generalizes to the fact that matter participates in form, and then further generalizes to potency participating in act. The reverse activity from act to potency is what STA calls communicatio, though there is no corresponding technical term in English.*

So why STA was wrong about fire being a chemical existing in either a pure or mixed state, he was right that heat is an act of some potency, and that this act communicates itself or diffuses itself as far as possible. The communicatio of heat is familiar from the phenomena that we label entropy, though we give an accidental description of it as a tendency to disorder. Nothing about the phenomena changes if you view nature as diffusive self-giving or dissipating tendency to disorder, but these are completely different views of what nature is and what it is up to. Our description is equivalent to describing a car as an exhaust-making tool, or breathing as a process that seeks to make carbon dioxide.

On the communicatio account of entropy the closest analogue to the Fourth Way, ironically enough, is Sean Carroll’s argument that the cascade of entropy is necessarily infinite. Reformulated in STA’s terms, this is nothing but an application of the principle that all finite diffusions or communications of act are participants in an infinite and unlimited act. I’d agree with Carroll, of course, and he might even have a whole shelf full of models that point to the need for some time with infinite energy, but I’m pretty sure that if we took the idea seriously then, just like Aristotle did in Physics VIII, we’d find that there’s a limit to how much energy we could hope to find in any given physical system. So what if your theory demands more actuality than a physical system can provide? That’s a pretty good account of what a cosmological argument is.


*One synonym for communicatio is “diffusio” which is the term STA tends to apply to the communicatio of the good (cf. “the good is diffusive of itself”).

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