Wednesday, October 6, 2021

A cosmological argument from a PSR for ordinary truths

Often in cosmological arguments the Principle of Sufficient Reason (PSR) is cleverly applied to vast propositions like the conjunction of all contingent truths or to highly philosophical claims like that there is something rather than nothing or that there is a positive contingent fact. But at the same time, the rhetoric that is used to argue for the PSR is often based on much more ordinary propositions, such as Rescher’s example of an airplane crash which I re-use at the start of my PSR book. And this can feel like a bait-and-switch.

To avoid this criticism, let’s suppose a PSR limited to “ordinary” propositions, i.e., the kind that occur in scientific practice or daily life.

  1. Necessarily we have the Ordinary PSR that every contingent ordinary truth has an explanation. (Premise)

  2. That there is an electron is an ordinary proposition. (Premise)

  3. It is possible that there is exactly one contingent being, an electron. (Premise)

  4. Necessarily, if no electron is a necessary being, then any explanation of why there is an electron involves the causal activity of a non-electron. (Premise)

  5. Let w be a possible world where there is exactly one contingent being, an electron. (By 3)

  6. At w, there is an explanation of why there is an electron. (By 1, 2 and 4)

  7. At w, there is a non-electron that engages in causal activity. (By 4, 5 and 6)

  8. At w, every non-electron is a necessary being. (By 5)

  9. At w, there is a necessary being that engages in causal activity. (By 7 and 8)

  10. So, there is a necessary being that possibly engages in causal activity. (By 9 and S5)

So, we have a cosmological argument from the necessity of the Ordinary PSR.

Objection: All that the ordinary cases of the PSR show is that actually the Ordinary PSR is true, not that it is necessarily true.

Response: If the Ordinary PSR is merely contingently true, then it looks like we are immensely lucky that there are no exceptions whatsoever to the Ordinary PSR. In other words, if the Ordinary PSR is merely contingently true, we really shouldn’t believe it to be true—we shouldn’t think ourselves this lucky. So if we are justified in believing the Ordinary PSR to be at least contingently true, we are justified in believing it to be necessarily true.


Mikhail said...

Hi Dr. Pruss, what do you think of the objection that the grounds for accepting the PSR also justify us in accepting the principle that every contingent being comes (partly) from previously existing material? If so, we have to deny creation ex nihilo.

Walter Van den Acker said...


I am not sure that someone who thinks (1) is true should accept (5).

Walter Van den Acker said...


If ex nihilo nihil fit, then creatio ex nihilo is impossible anyway.

Wesley C. said...


I've been thinking about the skeptical implications of brute facts as related to them lacking any meaningful probability, and noticed that when compared to other sources of no probability such as non-measurable sets or even causal powers that by definition (or by nature, or due to their substantial form) produce their effects with no probability attached to any of them, brute facts imply a much greater threat to our ordinary intuitions than even those do.

In fact, the very possibility of brute facts implies an immediate and universal threat to having any justified expectations about reality. Unlike those other sources of no-probability, accepting brute facts seems to entail accepting that we can NEVER have justified expectations about reality, not just that it's possible for us to lack justified expectations if some condition is true, or that it's possible for there to be causal powers with no probability due to their nature.

So if it's very plausible to deny that we can never have justified / rational expectations, or if it can even be proven with certainty, this would inevitably entail a denial of brute facts as a possibility. I also think one of the reasons for this is that brute facts are like a poison that infects modality specifically - it isn't one specific possibility among others, but a universal whose mere logical possibility entails the above in all possible worlds. This is why it's immediate and universal, and since bruteness can apply to all possibilities insofar as anything can happen for no reason, it's also universal in this sense as well.

What do you think of this argument?

Wesley C. said...

Here's a possible argument form from the above as well:

1) If brute facts are possible, then necessarily we can never have justified rational expectations about reality. Or ~JRE.

2) We can have JRE about reality.

3) So brute facts aren't possible.

I think the idea that ~JRE follows necessarily from brute facts might be important as well. You could rephrase 1), or make an additional argument for it, by saying that

1') Necessarily, if brute facts are possible then we can never have JRE about reality.

So if we use axiom S5 to argue that brute facts are necessarily possible, this also means ~JRE is a necessary truth, perhaps?

swaggerswaggmann said...
This comment has been removed by the author.
swaggerswaggmann said...

3 and 4 are wrong. Due to the loops happening in quantum mechanics.

Alexander R Pruss said...

Even if there are loops, they aren't explanatory.

swaggerswaggmann said...

Non sequitur...

swaggerswaggmann said...

Also related is that in our vast real world the fact that there is an electron could be due to a PSR, as our world is vast and nothing remain of the beginning ( if there was one), but to extrapolate that same psr to a world only made of one electron is a strong leap of faith.

In short : no ordinary psr in your extraordinary world.

RunDec said...

"the objection that the grounds for accepting the PSR also justify us in accepting the principle that every contingent being comes (partly) from previously existing material?"

If the universe had a beginning, which is plausible, we have a counter-example to that principle, so the inductive evidence is overturned.
And if PSR is true and all contingent things have causes anyway, we have another counter-example, since it's implausible that a necessary a se being would be material.
So the two ideas are not on the same epistemic pairing, I'd say.

Moreover, I think that what would ground (and/or explain) such an idea of material causation would be something like the Principle of Proportionate Causality: nothing can give what it does not have; the effect cannot be greater than the cause; the cause must have at least the same amount of reality that the effect has, etc. So every power or actuality that an effect has, must be present in the cause in either the same degree or a greater degree (say, in its most basic constituents if the power or reality is reducible to something else). I accept this, and most classical philosophers accept it as well. But then it's really disputable whether matter would be a positive reality that doesn't reduce to something more fundamental (which the cause could have). Aquinas and Aristotle thought matter was pure potentiality. Samuel Clarke thought matter was negative, just a form of limitation. While a cause cannot give *more* than what it has, it can give *less* than what it has.

Finally: Josh Rasmussen thinks theists could potentially accept the idea, check out his discussion with Felipe Leon in "Is God the best explanation?"

Wesley C. said...


I think it's important to distinguish prime matter from secondary matter, or signature matter, or whatever terminology is used. Prime matter is the underlying substrate, but it doesn't fully specify the exact traits of the material substance - at least that's how Aquinas may explain it, IIRC. And Aristotle did put quantity into the ten categories of being, along with location, meaning that these things at least aren't purely negations or limitations.

And not even all scholastics agree that prime matter is pure potency; Scotus held that it does have some actuality of its own, though intrinsically dependent on form to exist.

Another important point though is that matter is an accident of finite beings - specifically, material things like size or extension as accidents can't exist on their own but always inhere in a substance, whose unity or substantial actuality isn't material. So in this sense they are lesser in being since they don't have being in themselves, like substances do. Something analogous can be said of God - since He is highest when it comes to being, it's not surprising He isn't material, and transcends it without thereby being unnable to create or interact with it.

IanS said...

One could doubt (2). On our best current physics, an electron is a concept in the ‘standard model’ of particle physics, which is a QFT. But there is no generally accepted interpretation of QFTs. There is no generally accepted understanding of what, beyond the mathematical formalism, an electron actually ‘is’, or what it would mean for one to exist. So it is at least arguable that ‘there is an electron’ is not a proposition.

One could take a more operationalist view: electrons are the negatively charged particles emitted in beta decay, the particles that leave spiral tracks in bubble chambers, etc. But this would make (3) doubtful: a putative world with just one electron would lack unstable nuclei, bubble chambers, etc .

RunDec said...

Wesley C.,

Well, yeah, the idea I was trying to give (by just mentioning some very brief illustrations) was that matter (the aspect which material things have and God traditionally doesn't) could be reducible to something non-real/a limitation/something which is not a pure perfection. The idea is just that even for those who think a Cause must possess any reality an Effect has at least in the same degree that it is present in the Effect (something accepted by most historical theists - Ari, Plotinus and all the Neoplatonists, Aquinas, Clarke, Descartes, Berkeley, etc.), "matter" could be reducible to something more fundamental which God has (just being, I would say). There are many different ways to cash out this idea, but at the end it's something along the lines of "God has any perfections that are present in material beings without any of the limitations".

Wesley C. said...

@Alex, What do you think of my first two comment above about why brute facts are worse than other sources of no meaningful probability, and entail that we necessarily can never have JREs?

Alexander R Pruss said...


It sounds right.