Thursday, June 30, 2011

On some alleged quantifier shift fallacies, Part I

If every reader of this blog owns a computer, it doesn’t follow that there is some one computer that every reader of this blog owns.  To think otherwise is to commit what is known as a quantifier shift fallacy.  A reader asks me to comment on the following passage from the second edition of Harry Gensler’s Introduction to Logic:  

Some great minds have committed this quantifier shift fallacy.  Aristotle argued, “Every agent acts for an end, so there must be some (one) end for which every agent acts.”  St Thomas Aquinas argued, “If everything at some time fails to exist, then there must be some (one) time at which everything fails to exist.”  And John Locke argued, “Everything is caused by something, so there must be some (one) thing that caused everything.”  (p. 220) 

Such claims about Aristotle, Aquinas, and Locke are often made.  Are they true?  The answer, in my view, is that they are not true – certainly not in the cases of Aristotle and Aquinas, and arguably not in the case of Locke either.

Let’s begin by reminding ourselves of some apposite remarks made by Christopher Martin, which I had reason to quote not too long ago: 

As [Peter] Geach points out, if we wish to show that an argument is invalid, it is not sufficient to show that it can be represented as instantiating an invalid form. It might instantiate an invalid form and at the same time instantiate a valid form: and for an argument to be valid it is sufficient that it should instantiate a valid form. The potentially vast numbers of invalid forms which it may instantiate are completely irrelevant.  (Thomas Aquinas: God and Explanations, p. 161) 

There is no doubt that Aristotle, Aquinas, and Locke could be read in the way Gensler and so many others suggest.  (Gensler is not actually quoting them, by the way, but paraphrasing what he is assumes is the gist of what they had to say.)  What is at issue is whether they should be read that way, whether it is plausible that they meant to say what Gensler thinks they did.  And in fact there are other plausible readings of the relevant texts that do not involve any quantifier shift fallacy.  Given that these readings are available, and that the writers in question are, as Gensler says, “great minds” who would surely be unlikely to commit so blatant a fallacy, the reasonable conclusion to draw is that they did not in fact commit it. 

Consider first the case of Aquinas.  The fallacy in question is allegedly committed in the last sentence of this passage from the Third Way: 

We find in nature things that are possible to be and not to be, since they are found to be generated, and to corrupt, and consequently, they are possible to be and not to be.  But it is impossible for these always to exist, for that which is possible not to be at some time is not.  Therefore, if everything is possible not to be, then at one time there could have been nothing in existence. 

Now since I dealt with the present objection in my book Aquinas, I have the luxury of quoting the relevant material here.  What I have to say is best understood in the context of what I say about another objection sometimes raised against this passage (in particular, against the claim made in its second sentence), so the paragraphs that follow (from pp. 91-95) address that separate objection first: 

One common objection to the Third Way… is the suggestion that Aquinas commits an obvious fallacy when he claims that “that which is possible not to be at some time is not,” for even if it is possible for something to go out of existence, it simply doesn’t follow that it will actually do so.  This objection would clearly be correct if by “possible not to be” Aquinas meant “non-existent in some possible world” or “the non-existence of which is logically possible,” for it is obvious that neither the fact that there is a possible world in which something doesn’t exist nor the fact that there is no self-contradiction involved in denying its existence entails anything about its longevity in the actual world.  Similarly, it is sometimes claimed against cosmological arguments that only propositions can be necessary, and not things.  This too might be a good objection to Aquinas if by “necessary” he meant “logically necessary.”  But again, Aquinas does not in fact mean “possible” or “necessary” in any of these modern senses, so these objections are irrelevant.  

What Aquinas does mean is indicated by the reason he gives for saying that some things are possibly either existent or non-existent, namely that we observe them to be generated and corrupted.  Now as we saw in chapter 2, for Aquinas generation and corruption, coming into being and passing away, characterize the things of our experience because they are composites of form and matter.  Their coming to be is just the acquisition by a certain parcel of matter of a certain form, and their passing away is just the loss by a certain parcel of matter of a certain form.  Hence it is ultimately this composite, hylemorphic nature that makes it the case that they are “possible to be and not to be” (ST I.2.3); it has nothing to do with possible worlds, with there being no self-contradiction involved in denying their existence, or any other such thing.  The “possibility” in question is not some abstract logical possibility but rather something “inherent,” a tendency “to be corrupted” rooted “in the nature of those things… whose matter is subject to contrariety of forms” (QDP 5.3).  In other words, given that the matter out of which the things of our experience is composed is always inherently capable of taking on forms different from the ones it happens currently to instantiate, these things have a kind of inherent metaphysical instability that guarantees that they will at some point fail to exist.  They have no potency or potential for changeless, indefinite existence; hence they cannot exist indefinitely. 

By “possible not to be,” then, what Aquinas means is something like “having a tendency to stop existing,”  “inherently transitory,” or “impermanent”; and by “necessary” he just means something that is not like this, something that is everlasting, permanent, or non-transitory.  Thus there is no fallacy in his inference from “such-and-such is possible not to be” to “such-and-such at some time is not,” for this would follow given an Aristotelian understanding of the nature of material substances.  Given enough time, such a substance would, if left to itself, have to go out of existence eventually.  There is no sense to be made of the idea that it might be “possible” for it not to exist and yet that it never in fact goes out of existence no matter how much time passes and even if nothing acts to frustrate its tendency toward corruption, for in that case the claim that it has an inherent tendency toward corruption would be unintelligible.  Something that always exists would by that very fact show that it is something whose nature does not include any inherent tendency toward corruption, and thus that it is necessary (In DC I.29). 

However, this still leaves untouched an apparently more serious difficulty with the Third Way.  Even if it is granted that Aquinas is justified in holding that whatever is “possible not to be” will at some time go out of existence, it is widely held that his further inference to the effect that if everything were “possible not to be” or contingent, then at one time nothing would have existed, is clearly fallacious.  Specifically, it is claimed that he is guilty here of a “quantifier shift” fallacy, of inferring from “Everything has some time at which it does not exist” to “There is some time at which everything does not exist.”  This is called a “quantifier shift” fallacy because the quantifying expression “everything” shifts position from the first statement to the second.  That it is a fallacy can be seen by comparing the argument above with parallel arguments that are clearly fallacious.  If every student in the room owns a pencil, it does not follow that there is a certain pencil that every student in the room owns; if every human being has someone as a mother, it does not follow that there is someone who is the mother of every human being; and so forth.  Similarly, even if every contingent thing goes out of existence at some time, it does not follow that there is some time when they all go out of existence together.  An alternative possibility is that even though every contingent thing goes out of existence at some point, there is always at least one other contingent thing that continues to exist in the meantime, and this overlapping series of contingent things could continue on infinitely.  (Certainly Aquinas could not rule such an infinite regress out, since it would involve a causal series ordered per accidens extending backward in time, and as we have seen, Aquinas concedes for the sake of argument that such a series might not have a first member.)  In this case, though, Aquinas’s conclusion to the effect that if everything were contingent than nothing would exist now would be blocked, and the Third Way would fail. 

But common though this objection is, it is not in fact fatal to Aquinas’s argument, for he need not be interpreted as arguing in the fallacious manner described.  As several commentators have suggested, what Aquinas really seems to be getting at is the idea that given an infinite stretch of time, and given also the Aristotelian conception of necessity and possibility described above, then if it is even possible for every contingent thing to go out of existence together (which even Aquinas’s critic must concede), this possibility must actually come about.  For (again, at least given an Aristotelian conception of possibility) it would be absurd to suggest both that it is possible for every contingent thing to go out of existence together, and yet that over even an infinite amount of time this will never in fact occur.  “Possibility” here entails an inherent tendency, which must manifest itself given sufficient time, and an infinite amount of time is obviously more than sufficient.  Hence if everything really were contingent, there would have been some time in the past at which nothing existed, in which case nothing would exist now, which is absurd, etc., and Aquinas’s argument would (up to this stage in the proof at least) be vindicated.  (Note that it would not help the critic to suggest that the series of contingent things had a beginning in time after all rather than being infinite, for in that case Aquinas could simply say that given the principle of causality this beginning must then have had a cause and that this cause would have to be something non-contingent, i.e. necessary, which is of course what he has been trying to prove the existence of all along.) 

Obviously there are other questions that might be raised about the Third Way and its Aristotelian metaphysical background, and I address them in the book.  For example (to quote now from pp. 95-96): 

[A] critic might… suggest (as J. L. Mackie does) that even if individual contingent things all go out of existence, there might still be some underlying stuff out of which they are made (a “permanent stock of matter,” in Mackie’s words) which persists throughout every generation and corruption.  Now if this were so, then what would follow, given the Aristotelian conception of necessity we’ve been describing, is that this stock of material stuff would itself count as a necessary being.  But (so the suggestion continues) the critic could happily accept this (as Mackie does) given that such a “necessary being” would, in view of its material nature, clearly not be divine.  

The trouble with this reply, though, is that it falsely purports to be asserting something that Aquinas would deny.  In fact, surprising as it might seem, Aquinas would be quite happy, at least for the sake of argument, to concede that the material world as a whole might be a kind of necessary being, in the relevant sense of being everlasting or non-transitory.  After all, as we have repeated many times, Aquinas does not think that proving the existence of God requires showing that the material world had a beginning.  Moreover, as we noted in our discussion of hylemorphism in chapter 2, Aquinas himself insists that while individual material things are generated and corrupted, matter and form themselves are (apart from special divine creation, to which he would not appeal for the purposes of the argument at hand lest he argue in a circle) not susceptible of generation and corruption.  Far from regarding the notion of the material world as necessary as a blow to the project of the Third Way, Aquinas would in fact regard it as a vindication of his claim that there must be a necessary being.  Indeed, he recognizes the existence of other non-divine necessary beings as well, such as angels and even heavenly bodies (which, given the astronomical knowledge then available, the medievals mistakenly regarded as not undergoing corruption). 

That this should not be surprising, and in particular that it should not be regarded as damaging to the aim of proving the existence of God specifically, should be evident when we remember that proving the existence of a necessary being is only one component of the overall argumentative strategy of the Third Way.  For recall that at this stage of the argument Aquinas immediately goes on to say that “every necessary thing either has its necessity caused by another, or not” and then argues that a series of necessary beings cannot go on to infinity… 

In particular (as I go on to explain), given a hylemorphic analysis of material objects, neither matter nor form nor a composite of matter and form could have its necessity in itself (if it has any necessity at all), but would have to derive it from something else.  Only that which is pure actuality could even in principle have its necessity of itself.  But as they say, read the whole thing.  What has been said here suffices to show that there is no good reason to think Aquinas guilty of a quantifier shift fallacy. 

We’ll look at Locke and Aristotle in two further posts.

20 comments:

DNW said...

"The “possibility” in question is not some abstract logical possibility but rather something “inherent,” a tendency “to be corrupted” rooted “in the nature of those things… whose matter is subject to contrariety of forms” (QDP 5.3). In other words, given that the matter out of which the things of our experience is composed is always inherently capable of taking on forms different from the ones it happens currently to instantiate, these things have a kind of inherent metaphysical instability that guarantees that they will at some point fail to exist. "


I think it is pretty obvious that you are right even taking the paraphrases (for why are the parenthetical "one"s included if that is the self-evident and default sense of any such passage?) and it's that likely Aquinas does not intend an exercise in modal logic, but is rather referencing how certain kinds of things are actually observed in a common sense manner to come into being and pass away, and what, if anything, that this observation might imply.

In following the link you provided to the intro text I also noticed what for me having been brought up on Copi's Intro, was a kind of surprise: an apparent serious delving into Deontic logic, belief logic, and "A formalized ethical theory" in an "Intro".

I'm not sure what to make of it. He seems to be some kind of Kantian teaching at a Jesuit University.

Patrick said...

Dr. Feser,

Your response to the second common criticism seems at odds with your response to the first: pace your phrase, "given also the Aristotelian conception of necessity and possibility described above," in the second response you seem to depend upon precisely the "abstract logical possibility" (e.g., so-called possible worlds or states of affairs) which you rightly reject in the first response as foreign to the Aristotelian sense of possibility operative here, viz., potentiality for substantial change in some substance.

It seems to me that the reason the Third Way is not guilty of a quantifier shift fallacy is that, just like the First Way, it implicitly depends upon a hierarchical view of the cosmos which Thomas could take for granted but which moderns do not—the very reason the First and Second Ways are so often misunderstood as denying a infinite temporal regress in univocal agents, whereas actually they are denying an infinite regress in simultaneous, non-univocal agents. (In short, they are tracing a causal chain up through the Ptolemaic cosmos, not back through time.)

Likewise the Third Way. The critique that only contingent things have existed, and yet at no time has nothing existed, is quite valid if the contingent things in question have no hierarchical interdependency; but Thomas certainly took it for granted that they do, and in that case "overlapping" may be insufficient. For among the known substances of which we are asking, "Is any of these a necessary being?" is the sun. If we call it necessary, we have completed the first stage of the argument, and can move on to asking if its necessity is derived from another. If we call it contingent, then we must grant that (given infinite past time) at some time it did not exist. No big deal; the time during which the sun did not exist can be "covered" by other contingent things, trees, horses… Oh, wait—it's the bleeping sun. When it doesn't exist, nothing which depends upon it for existence can exist. If the present existence of these things is to be explained then there must at that time have existed something independent of the sun and capable of generating it. Of course this argument must take on a very different form for the modern view of the cosmos, if it can even survive; but for the Ptolemaic view it is straightforward. This is the consideration which will drive you to necessary being, not the supposition that given infinite time any "possible state of affairs" must be realized.

What do you think?

DNW said...

Gee, Gensler's a Jesuit.

The Godel book on his website looks interesting.

Anonymous said...

I've been a lurker on your site for a few weeks and have been reading some of your back logs. Forgive me if you've already addressed this point, but how do you deal with the issue of cause and effect?

I think I think I understand how you can argue that God is necessary to maintain being even absent of a temporal chain.

But I'm not quite sure on the details of this maintenance outside of a temporal understanding.

Cause and effect seem to me to be properties of time. They are series of events.

So how can God cause being absent some sort of origin point?

Will said...

I read your book; thank you for the introduction to Aquinas. I don't know how I got to my 40's w/o knowing this stuff.

But maybe I still don't. One problem I had with Aquinas's arguments as I understood them did relate to this type of fallacy. Everything that is contingent has, in any given moment, a cause; if that cause is also contingent, it must have a cause, and so on till we get to a primary cause. My arm motion, the motion of trees in the wind, the boiling of the teakettle. OK.

But why would these things have the *same* primary cause? And why would they have the same primary cause moment to moment? That is, why is there *a* primary cause, rather than massive numbers of them? (And if it's massive numbers, we don't have *a* prime mover, do we?)

E.R. Bourne said...

Will, to be contingent is to be able to either exist or not exist. Contingent things must, therefore, be a composite of the potency of essence with the act of existence since existence, by definition, cannot belong to any contingent thing essentially.

Following this, we can say that that which ultimately gives existence to things cannot itself possess this distinction between essence and existence; if it did it would also be contingent and composite and therefore caused by another. So all things which exist contingently must be caused by something non-contingent, meaning something that does not receive existence from another but has it essentially.

Finally, we must say something about this being whose essence it is to exist or whose essence and existence are not really distinguished from one another. Why is it impossible that there be more than one? In creatures, species are unified by essence and distinguished by existence. Men share a common essence but each one has a different act of existence. Notice, this can only be the case in composite or contingent things, since, in them, essence and existence must really be distinguished and not identical to one another. God, then, cannot be a species predicated of many individuals because what he is and that he is are the same thing. There can be no plurality of prime movers who share an essence “prime mover” yet are differentiated by their individual acts of existence.

From Aquinas' Compendium of Theology:

CHAPTER 68

THE EFFECTS PRODUCED BY GOD

After considering the truths which pertain to the unity of the divine essence and to the Trinity of persons, we turn to a study of the effects produced by the Trinity. The first effect wrought by God in things is existence itself, which all other effects presuppose, and on which they are based. Anything that exists in any way must necessarily have its origin from God. In all things that are arranged in orderly fashion, we find universally that what is first and most perfect in any order, is the cause of whatever follows in that order. Thus fire, which is hot in the highest degree, is the cause of heat in all other heated bodies. Imperfect objects are always found to have their origin from perfect things; seeds, for instance, come from animals and plants. But, as we proved above, God is the first and most perfect Being. Therefore He must be the cause of being in all things that have being.

Again, whatever has some perfection by participation, is traced back, as to its principle and cause, to what possesses that perfection essentially. Thus molten iron has its incandescence from that which is fire by its essence. We showed above that God is existence itself; hence existence belongs to Him in virtue of His essence, but pertains to all other things by way of participation. The essence of no other thing is its existence, for being that is absolute and per se subsistent cannot be more than one, as was brought out above. Therefore God must be the cause of existence of all things that are.

George R. said...

I’m completely confused.

Harry Gensler wrote:

“St Thomas Aquinas argued, ‘If everything at some time fails to exist, then there must be some (one) time at which everything fails to exist.’”

Then Ed says that the passage that Gensler is referring to is the following:

“Therefore, if everything is possible not to be, then at one time there could have been nothing in existence.”

But these two arguments are clearly not the same. So if this, in fact, is the passage that Gensler is referring to, then it seems to me that he just screwed up, and that’s all there really is to say about it. I see absolutely no reason why we must show that all contingent things must eventually cease to exist in order to defend Thomas from the charge of arguing fallaciously; for his argument is in no way predicated on such an assumption. But Ed seems to be suggesting that it somehow is.

Can someone help clarify this for me?

Bilbo said...

Patrick: "Your response to the second common criticism seems at odds with your response to the first: pace your phrase, "given also the Aristotelian conception of necessity and possibility described above," in the second response you seem to depend upon precisely the "abstract logical possibility" (e.g., so-called possible worlds or states of affairs) which you rightly reject in the first response as foreign to the Aristotelian sense of possibility operative here, viz., potentiality for substantial change in some substance.

I agree with Patrick. I don't know enough about Aquinas to know if Patrick has succeeded in rescuing the Third Way, but it sounds reasonable.

Oliver Xxii said...

Dr. Feser, I post this here today because I wouldnt know where else to get this to you or your readers. This entry has little to do with the link im posting, so I wouldnt want to take the discussion away from the subject.

Anyhow, here is a link to a site which claims to argue against dualism, though the format is somewhat difficult the text seems intriguing. Because my ability in the field is very limited I wanted to see if you, or some of your readers, would be willing to tackle it.

Here is the link: http://www.wakingthedragon.org/page24.html

Thank you in advace.
Keep up the good work.

Ismael said...

@ Oliver Xxii

I will let Prof. Feser reply properly (he's after all a professiona philosopher), but I might say that Thomism and A-T in general ALSO refutes Descartes' dualism in favor for hylomorphic dualism (which are quite different).

Prof. Feser does discuss this topic both in The Las Superstition (TLS) and Aquinas.

Actually one of the criticism Prof. Feser moves towards modern philosphy is directed towards modern dualism which stems from Cartesian dualism.

I am more than sure he discusses it in 'Philosophy of Mind' as well but I still have to read that one :P

Edward Feser said...

Hello all, some brief responses (out of order):

George,

"Possible not to be," as Aquinas means it, entails "will go out of existence eventually." Hence it is not surprising that Gensler reads the passage in question the way he does.

Will,

For reasons given in Aquinas, only what is purely actual can be a true first cause. But when we unpack the idea of pure actuality, it follows (again for reasons stated in the book) that there can in principle be only one thing that is pure actuality. Hence there can be only one first cause.

Patrick,

There's no conflict. I never said that Aquinas or a Thomist would never under any circumstances appeal to abstract possibilities of any sort. What I said is that Aquinas's argument presupposes a specifically hylemorphic conception of material objects and that his points are grounded in that, not in thought experiments about what a material object might or might not be like in some possible world. For Aquinas, we start with what things are actually like, and work out possibilities -- maybe even very abstract ones -- from that. We don't start from abstract possibilities and then work from them to a conception of what things are actually like.

Re: the Ptolemaic conception of the cosmos, you are right that he was thinking concretely in terms of that, but as I argue in the book, neither the Third Way nor any other of the Five Ways actually depends on this outdated cosmology. In general, none of the arguments depends on any thesis of physics or the other sciences as we understand those disciplines today. Rather, they depend on deeper theses in what Scholastics call the philosophy of nature, which deals with the metaphysical presuppositions of any possible physical science.

Anonymous,

For Aristotelians, (a) it is an error (albeit these days a common one) to think of causation primarily in terms of events, and (b) the most important instances of efficient causation involve causes which are simultaneous with their effects. I discuss all this in Aquinas and The Last Superstition.

Mr. Green said...

George R.: But these two arguments are clearly not the same. So if this, in fact, is the passage that Gensler is referring to, then it seems to me that he just screwed up, and that’s all there really is to say about it. I see absolutely no reason why we must show that all contingent things must eventually cease to exist in order to defend Thomas from the charge of arguing fallaciously; for his argument is in no way predicated on such an assumption.

I'm not sure how you're interpreting each cited passage, because they do look the same. Gensler says, "If everything at some time fails to exist, then there must be some (one) time at which everything fails to exist.". Ed says, "Therefore, if everything is possible not to be, then at one time there could have been nothing in existence." Now from the context, Thomas is clearly talking about "possibility" and "necessity" across time (rather than, say, across possible worlds), so I shall use the terms "finite" (i.e. existing for only a temporary period) and "everlasting" (existing at all points in time), in hopes of avoiding confusion from our more usual meanings of logical possibility and necessity.

Thus Gensler's account is: "If everything is finite [=non-existent at some point(s) in time], then there must be some time t at which everything is non-existent." Feser's version is: "If everything is finite, then at some time t, there could not be anything existent." They both amount to the same thing: there must be at least one time, t, at which nothing exists. And Thomas must certainly be arguing for this conclusion because he goes on to say that hence nothing would exist now, since nothing could come out of a previously-existing nothing (at time t).

So the question is how does Aquinas conclude that finite/contingent/possible objects would all be out of existence at some time t? I do not think that he was assuming some sort of "combinatorial time" in which every possibility must eventually come to pass. Even with Aristotelian act and potency, there is no reason why a corruptible body must actually get corrupted — perhaps some other things continually maintain it. (Our bodies have an inherent tendency to decay, but we can keep them alive with food and so on; now there is a limit to how long we can maintain our bodies given the present state of the world, but God could easily create a world with different laws of physics in which this process could continue forever (indeed, maybe that was how physics operated in Eden before the fall?).)

But recall that we are talking not about logical possibilities, but temporal possibilities. Thomas wants to show that something is everlasting (something that is potentially corruptible but never corrupted is good enough for his purposes). At this point in the argument, he is supposing that each and every particular thing does in fact cease to exist, and trying to show that, given infinite time, there would be nothing left. Prof. Feser points out that finite beings certainly can continue on indefinitely — not individually, of course, or else they would be everlasting ("necessary"), but rather consecutively. A finite-lived man can beget a son, who exists for a finite time but begets another son, and so on ad infinitum. There is nothing to indicate that such a series must have to come to an end; indeed, since Aquinas happily allowed (for the sake of argument) that the world might be infinitely old, he clearly accepted such eventualities.

(continued...)

Mr. Green said...

(cont'd)

OK, so if Aquinas is not making a quantifier fallacy, and he's not making a multiverse fallacy ("anything you want can happen if you just allow enough time and/or space"), then how does he conclude that nothing would exist now [given the hypothetical assumption that everything is a temporally finite object]? It turns out that it is the critics who have the misplaced quantifier. The Third Way is claimed to say, "But it is impossible for these [finite things] always to exist, for that which is possible not to be at some time is not." What it really says is, "Impossibile est autem omnia quae sunt, talia esse, quia quod possibile est non esse, quandoque non est." It's necessary to go back to the Latin here, because we've got a mistranslation. This is the standard translation from the Dominican Fathers (1920), and it's not obviously wrong in a word-for-word sense, but since it doesn't work philosophically, it cannot be what Aquinas really meant.

An alternative translation, which can still be found in many places, reads: "It is impossible, however, that everything that exists should be such, for what can possibly not exist does not do so at some time." The other translation does look like a fallacy, because it's saying "finite things cannot exist forever" — when in fact they can, by putting them in an infinite series. (Hence the apparent mistake of misquantifying over all finite things vs. the series.) It is possible for finite things to be everlasting if they are consecutive; what's impossible is that all things belong to this set of finite objects. If you try to get around it by having an infinite series of finite parts, then you've broken the working assumption of "all things are finite". The series itself is not finite!

If there is an endless chain of men and sons, then mankind is everlasting. If the form of Humanity ceased to exist at any time t, then there could not be an individual man existing at that time. It doesn't matter what the thing is — it could be a form that exists at all times, or it could be prime matter (under different forms) — but if whatever is underlying the series is everlasting, then Aquinas has the "necessary" being he's looking for. And if the series itself is finite, then it too will come to an end eventually; if there are no everlasting individuals, and no everlasting series or combinations of individuals, then yes, at some point we'll be left with nothing at all.

Now that he has the preliminary step out of the way, Thomas can get on with the real argument. Unfortunately for the line in question, the misleading translation seems to be wide-spread. (Copleston, for example, attempts the same "eventually everything will happen" explanation.) The alternative translation makes perfect sense of Thomas's subsequent statements, and avoids fallacy-stricken interpretations. It would be interesting to see how this passage has been translated into other languages, and what interpretations are usually given by philosophers in those languages.

George R. said...

Mr. Greene,

Thanks for your response. Unfortunately, I can’t disagree more with what you’re saying. Gensler, Ed, and you all claim that Thomas predicates his Third Way on the proposition that all contingent things must necessarily go out of existence at some point in the future. I must, however, completely reject this interpretation for the following reasons.

1) Let’s look at what Thomas actually says:

We find in nature things that are possible to be and not to be, since they are found to be generated, and to corrupt, and consequently, they are possible to be and not to be. But it is impossible for these always to exist, for that which is possible not to be at some time is not. Therefore, if everything is possible not to be, then at one time there COULD HAVE BEEN nothing in existence.

Now I’m no expert grammarian, but I always thought the words “have been” referred to the past not the future; and that the word “could” implied possibility not certainty. So it seems pretty clear to me that Thomas is referring to a possibility in the past. Therefore, how, pray tell, can you claim that what Thomas is actually proposing is that all contingent things WILL DEFINITELY go out of existence? The plain meaning of his words simply do not allow such an interpretation

2) Moreover, Thomas himself denied that all contingent things must someday cease to exist. First of all, he considered angelic beings to be contingent, i.e., that they in themselves can be or not be, yet also naturally believed that they are to exist forever. Secondly, he (erroneously) believed the celestial bodies to be incorruptible, and, therefore, capable of existing forever. Thirdly, he believed that even some terrestrial beings, although naturally subject to corruption, can be maintained perpetually in existence by the will of God -- the point being that they do not necessarily go out of existence. Fourthly, if Thomas actually were to have claimed that in the future all contingent things must necessarily go out of existence, he would have been a complete heretic. To illustrate this last point, consider that the Virgin Mary is herself a contingent thing.

3) But even if one were to assume for the sake of argument that all contingent things might got out of existence in the future, and even if one were to assume that all contingent things definitely will go out of existence given infinite time, there is not reason to believe that all contingent things must actually go out of existence -- for the simple reason that the infinite time required for such a certainty can never be actually traversed. For posit any point in time you will for such an event to take place, the time between now and that point must of necessity be finite.

Mr. Green said...

George R.: Unfortunately, I can’t disagree more with what you’re saying. Gensler, Ed, and you all claim that Thomas predicates his Third Way on the proposition that all contingent things must necessarily go out of existence at some point in the future. I must, however, completely reject this interpretation for the following reasons.

Actually, I claim that the usual explanations are wrong in arguing that everything would have to go out of existence, for reasons like the ones you gave. However, Thomas does use a reductio as a sub-argument inside the Third Way where he argues that if everything were temporally finite, there would be nothing now.

This sub-argument is actually pretty simple: if everything lasted for only a finite length of time, and — since for his reductio he's assuming that the universe is infinitely old — then obviously all the finite objects would have reached their limit. If anything exists after an infinite amount of time, well, then, we've got something that isn't temporally finite.
The bit translated as "if everything is [temporally finite], then at some time there could have been nothing in existence" does not indicate a possibility; it's saying, "there could not have been anything in existence", only it moves the "not" onto the "anything" to make it "nothing". (It is ambiguous that way, and a translation that wasn't a hundred years old would probably not phrase it like that, but the Latin is nihil fuit, "nothing existed".)
As to the tense, that's just a matter of whether we choose to imagine the situation before or after: if we start out with some finite objects, then they will all (eventually, in the future) go out of existence. Then, if we zoom along until an infinite amount of time has passed (so to speak!) and look back, everything will have gone out of existence.

Note however, that this is different from being "contingent". Aquinas does not use the word in the Third Way, and it is misleading here because, as you point out, there can be contingent beings that are nevertheless everlasting. The infinite time isn't a problem, because Thomas is just assuming that for the sake of argument — even if the world had always existed, his proof still works. But I do agree that there's no valid way to conclude that all contingent beings must go out of existence given even infinite time, and that's why I claim that the usual translation/interpretation is simply wrong. Aquinas is not talking about what's possible or contingent, only about what's everlasting vs. temporary.

Edward Feser said...

George,

1. Other translations typically have "would have" or some equivalent.

2. Angels and celestial bodies (as Aquinas understood them) are "contingent" in the sense that, like everything else, they depend on God for their being, but precisely because they have no natural tendency toward corruption the way material things do, they are still necessary in the sense of "necessary" in play in the Third Way. It's just that they have a derived necessity. Furthermore, the reason the Virgin Mary doesn't go out of existence in the future is that God prevents the natural decay of her body that would otherwise occur. What I was talking about was the way things would go if God did not specially act to prevent such corruption.

3. Whether an actually infinite amount of time really could ever have passed is irrelevant. Aquinas is granting for the sake of argument that it may have and arguing that even on that basis, we need to affirm the existence of an absolutely necessary being. (In any event, Aquinas himself did not think it could be proven that an actually infinite among of time has not already passed.)

Mr. Green said...

Prof. Feser: 2. […] precisely because they have no natural tendency toward corruption the way material things do, they are still necessary in the sense of "necessary" in play in the Third Way.

Yes, and I think that's the key point. In fact, that's all that Thomas is saying in the (allegedly fallacious) sub-argument. But since he isn't talking about logical necessity/possibility, this doesn't work:

For (again, at least given an Aristotelian conception of possibility) it would be absurd to suggest both that it is possible for every contingent thing to go out of existence together, and yet that over even an infinite amount of time this will never in fact occur.  “Possibility” here entails an inherent tendency, which must manifest itself given sufficient time, and an infinite amount of time is obviously more than sufficient."

To say "possible but never happens" is the "possible-worlds" sense which doesn't apply. If things are "possible" meaning "do get corrupted at some time", then of course each individual cannot survive infinite time. And you point out that an "overlapping series of contingent things could continue on infinitely," so clearly it isn't absurd! But as the better translation makes clear, the series itself would be a (contingent but) not-corrupting being, thus being necessary in the requisite manner.

Scott said...

Dr. Feser,

Thank you very much for your post. I had a question. You say, “If it is even possible for every contingent thing to go out of existence together (which even Aquinas’s critic must concede), this possibility must actually come about.”
I translated this given your prior comments to mean:
* If every contingent thing has a tendency to go out of existence together, this will actually come about.

If this is the correct translation, why should the critic grant this? You’ve claimed that every contingent thing has a tendency to go out of existence, not that the set of contingent things has a tendency to go out of existence together. What have I missed?

Thank you for your help,
Scott

Nueva Argentina said...

Concerning the quantifier shift in Aquinas' Third Way.
If Aquinas was asking the reader to derive on its own that the whole of all merely-possible beings is merely-possible from the fact that its parts are so, he was indeed demanding to commit composition fallacy.
So I don't see how the argument could be rescued that way.

Anonymous said...

Here's another look for interested readers (The link is to the first post in a series).

http://branemrys.blogspot.com/2010/08/modality-and-third-way.html