Friday, January 10, 2020

Simultaneous actualization of potentiality

I will argue, on Aristotelian grounds, for the following thesis:

  • There are cases of actualization of potentials that are simultaneous with the possession of the potentials.

In particular, it follows that Aristotelian arguments against eternalism on the grounds that eternalism makes potentials co-real with their actualities fail, because every Aristotelian has to admit that there are potentials that are co-real with their actualities.

Here is the argument for the thesis.

  1. All ordinary substances have first moments of existence.

It follows from Causal Finitism that all temporal substances have a first moment of existence. By “ordinary” substances, I mean things like dogs, cats and oak trees. I am excluding weirder candidates like the wavefunction of the universe or the universe itself, as well as extraordinary substances such as angels.

Now we add this premise:

  1. Every ordinary substance always actualizes a potential of itself.

For instance, ordinary substances are always emitting electromagnetic radiation, and on Aristotelian grounds such activity had better be the actualization of a potential.

Now, while time travel and backwards causation might turn out to be possible, they are extraordinary. Thus:

  1. An ordinary substance never actualizes a future potential.

Moreover, transsubstantiation is also extraordinary and:

  1. Every potential that an ordinary substance has is one that it has at a time at which it exists.

From 1-4, it follows that:

  1. An ordinary substance in the first moment of its existence actualizes a potential that it has then.

For suppose Alice is an ordinary substance and it’s now the first moment of her existence (she has such a moment by (1)). Alice actaulizes a potential of herself by (2). That potential which she is actualizing must be had by her in the present or the future by (4), since this is the first moment of her existence. She isn’t actualizing a future potential by (3). So she must be actualizing a present one.

And (5) gives us the thesis about potentiality being sometimes simultaneous with its actuality.


Jonathan D. Jacobs said...

Why does simultaneity follow from 5? Suppose that when a substance actualizes a potential, that *just is* to cause an actuality at some later time. Am I wrong to think that simultaneity would not follow?

Alexander R Pruss said...


Well, I am just arguing that actualizing is simultaneous with the having of the potential. I guess you're suggesting that it is possible that one is actualizing a potential at t1 but there is no actuality at t1: i.e., that actualizing isn't an actuality. This sounds wrong. For the sake of argument, let's suppose that time is discrete and that at each moment of time t, Alice has the potential to make Bob smile at t+1. Suppose that at times 1, 2 and 3 she is not actualizing this potential. Then at time 4 she actualizes the potential, and at time 5 Bob smiles.

Alice has got to be different between times 3 and 4 if at 3 she is to count as not actualizing the potential but at 4 she is actualizing the potential. And it seems to me that this difference has got to be one where at 4 something is actual that wasn't actual at 3. Otherwise, it would be a difference between potentials, either Alice losing some potential she had at 3 or gaining some new potential. It doesn't seem like a case of mere loss of a potential. So there has to be a gain. But if it's a gain of a potential P, then having P, on Aristotelian grounds, is presumably the actualization of some other potential, say Q. (Compare how a second potentiality is the actualization of a first potentiality in Aristotle.)