Avicenna’s argument from contingency, Part II

In a previous post we looked at an outline of Avicenna’s argument from contingency for a Necessary Existent.  Suppose the argument does indeed establish that much.  Is there any good reason to identify the Necessary Existent with God?  Does Avicenna spring for any divine attributes?  You betcha.  Jon McGinnis’s book Avicenna, cited in the previous post, provides a useful overview of the relevant arguments.  I will summarize some of them briefly.

The Necessary Existent, Avicenna holds, must be unique.  For suppose there were two or more Necessary Existents.  Then each would have to have some aspect by which it differ s from the other -- something that this Necessary Existent has that that one does not.  In that case they would have to have parts.  But a thing that has parts is not necessary in itself, since it exists through its parts and would thus be necessary only through them.  Since the Necessary Existent is necessary in itself, it does not have parts, and thus lacks anything by which one Necessary Existent could even in principle differ from another.  So there cannot be more than one.

Obviously, it follows also that the Necessary Existent, being without parts, is simple or non-composite.  The Necessary Existent must also be immaterial, and thus incorporeal.  For matter exists only insofar as it has form, and what is composed of form and matter is not simple but composite.  Here Avicenna’s Aristotelianism is evident.

It is evident also in an argument he gives for the goodness of the Necessary Existent.  Goodness, for the Aristotelian, is to be defined in terms of the end toward which a thing points as to a final cause.  Now part of Avicenna’s more general metaphysics is the thesis that every existing thing “desires” or aims toward approximating necessary existence as far as it can (not necessarily consciously, of course -- a thing’s final cause need not be something of which it is consciously aware).  But then what it desires or aims at is approximating the Necessary Existent, which qua object of this desiring or aiming is (given the Aristotelian analysis of the good) the highest good.

The Necessary Existent must also be perfect insofar as for Avicenna, perfection is a matter of what completes a thing with respect to its existence.  An acorn is more perfect the closer it is to being an oak, the Venus de Milo would be more perfect if it had its arms, and so forth.  But the Necessary Existent, being absolutely necessary in itself, is lacking in nothing with respect to its existence.

It is also part of Avicenna’s background metaphysics that what makes a thing intelligible -- that is, what makes it the proper object of an intellect, a concept -- is separation from matter.  (This is a common theme in ancient and medieval philosophy.  See my ACPQ paper “Kripke, Ross, and the Immaterial Aspects of Thought” for a detailed defense of the immateriality of strictly intellectual activity, as opposed to mere sensation or imagination.)  Moreover, the further a thing is from matter, the more intelligible it is.  Avicenna also thinks of an intellect as just that which has something essentially intelligible.  Now the Necessary Existent has its existence essentially, and being an immaterial kind of existence its existence is something essentially intelligible.  Hence the Necessary Existent, Avicenna concludes, is an intellect.

Much more could be said, both about these attributes -- again, this is just a brief sketch -- and about other aspects of Avicenna’s conception of God’s nature and relationship to the world.  Saying much more would require getting into Avicenna’s general metaphysics in more depth.  But this much gives a sense of how he would expand on his argument from contingency.

What should we think about that argument itself, as summarized in the previous post?  Naturally I am sympathetic, similar as the argument is in some respects to Aquinas’s Third Way (which Avicenna’s argument arguably had an influence on, and which I defend at length at pp. 90-99 of Aquinas).  There are differences, though.  For one thing, the notion that there cannot be an infinite regress of (essentially ordered) causes does play a role in the Third Way, but not in Avicenna’s argument.  For another, though both arguments concern contingency and necessity, the notions of contingency and necessity involved are importantly different.  Aquinas begins with the difference between things which are contingent in the sense of being generated and corrupted, argues for something that is necessary in the sense of being permanent or neither generated nor corrupted, and from there argues in turn to the existence of that which is necessary in the stronger sense of deriving its permanence from nothing else (where on analysis, as I argue in Aquinas and in my ACPQ article “Existential Inertia and the Five Ways,” only what is in no way composite can be permanent or necessary in this strong sense).  Angels and human souls are “necessary” in the weaker sense, which is why Aquinas needs a further stage in the argument to get to that which is “necessary” in a stronger sense that applies only to God.

This is not what is going on in Avicenna’s argument, even though like Aquinas (and as we saw in the previous post) he does have a distinction between two kinds of necessity, viz. that which has its necessity in itself and that which has its necessity through another.  For generation and corruption play no role in Avicenna’s reasoning.  As we saw, he takes his notions of “necessity” and “possibility” to be basic, evidently in a way that he wouldn’t think needs elucidation in terms of our experience of things coming into being or passing away.  In this regard his argument might seem closer to Leibniz’s rationalist brand of cosmological argument than to Aquinas’s Third Way.

But I wouldn’t put Avicenna in the rationalist, as opposed to Aristotelian, camp.  He appeals (in what I labeled step (4) of his argument) to a variation on the principle of causality -- which, unlike Leibniz’s Principle of Sufficient Reason, is about things themselves, not about our demand for an explanation of things.  (I have discussed the difference between these principles and the more general metaphysical and epistemological assumptions they reflect here and here.)  His notions of possibility and necessity are related to the distinction between that which has an essence distinct from its existence and that which does not -- an Avicennan idea that clearly had an influence on Aquinas, and forms the starting point of the “existential proof” for God’s existence in Aquinas’s De ente et essentia (which I also discuss in Aquinas). 

So, I would say that those aspects of the argument that rest on these ideas that Avicenna shares with Aquinas are correct, since I think those ideas are independently defensible.  And the aspects that are different from anything Aquinas says also seem plausible to me, so that while I do not have a settled view on Avicenna’s basic argument, I am inclined to think it is sound.  (I would be more cautious about some of what he says about the divine attributes -- those arguments would have to be treated on a case by case basis.  And unsurprisingly, I don’t agree with Avicenna’s views about the eternity of the world, which I have not discussed here.)

Let me turn briefly to some objections raised in the combox after my previous post (which you might want to re-read if you haven’t already, in order to follow the remarks below -- it’s brief).  One reader asked:

A mathematical platonist would say that the infinite sequence of whole numbers exists necessarily, but isn't it true that this series exists only through the existence of its members?

That is consistent with Avicenna’s argument, though, since he distinguishes between what is necessary in itself and what is necessary only through another.  He could say that the series is necessary, but only through another.  In any event, Aristotelians wouldn’t accept Platonism in the first place, for reasons independent of the topic at hand.  (Not that mathematical truths are not necessary, but since they exist -- for Thomists, anyway -- as ideas in the divine intellect, their necessity is derivative.) 

Another reader wrote:

If there's a flaw in the argument, here's it: the totality of all possible things is not a thing, so the premise that all things are either possible or necessary does not apply to it. And without this, the rest of the argument fails.

But why isn’t it a “thing”?  Obviously it’s a thing in at least the very loose sense that a pile of random junk is a thing.  True, it’s not a “thing” in the stronger sense of being a substance.  But why would Avicenna need it to be a “thing” in that stronger sense?  Why wouldn’t the looser sense suffice?

A third objection went as follows:

Having difficulty with premise 4. I can think of two readings:

4a Every existent possible being has a cause.

and

4b Every possibly existent being has a cause.

4a looks equivalent to the familiarly disputed claim that everything that exists contingently has a cause, since something exists contingently iff it is possible (in Avicenna's unusual sense) and exists.

4b looks too strong: after all, possible beings that lack existence lack causes too.

End quote.  I’m inclined to read (4) along the lines of the reader’s suggested (4a).  But I’m also inclined to read “possible” as entailing “that which has an essence distinct from its act of existence,” where the essence in question is merely in potency until actualized by an act of existence.  So, ultimately (4) depends on the idea that any actualized potency is actualized by something already actual (my preferred formulation of the principle of causality, which I’ve defended in Aquinas and elsewhere).

A fourth objection was:

7 seems to be the most controversial. Whether or not one thinks that the totality of the parts of the universe is contingent depends on whether or not one thinks the universe is contingent. Although I disagree with the man who holds the material universe to be necessary, if he does so he certainly has no problem agreeing that all of the universe's parts follow necessarily from the universe's existence as well. Of course this position is absurd, because it would mean that we exist necessarily (as do our thoughts and actions). But absurdity alone won't convince the anti-realist committed to the idea that the world just truly is absurd.

I think this misses Avicenna’s point.  The “totality” in (7) refers not to “the universe” but rather to “the totality of possible things” referred to in the previous step.  Avicenna isn’t making any assumptions about what the universe of our experience is really like.  His argument is more abstract than that.  He’s just arguing from the fact that something or other exists together with the notions of possibility and necessity.

A fifth objection:

I’d object to #4 “whatever is possible has a cause”. I see no logical impossibility in X existing, not existing necessarily (i.e. not forming part of all possible worlds in the relevant sense of “possible worlds”), and not being caused by anything - but just simply being in some worlds but not in others...  [The reader’s objection continues in this vein.]

I don’t accept this way of framing the problem, though.  Like other Aristotelians, I don’t much like contemporary “possible worlds” talk, and certainly not in an argument for a claim about what is possible or necessary (as opposed to a claim about possible worlds which follows from what we independently have argued to be possible or necessary).  I don’t think Avicenna’s notion of possibility and necessity either requires making use of possible worlds, or can be challenged (in a non-question-begging way) by making use of that way of thinking about modality.  And if the above is just a variation on Humean objections to the principle of causality, I’ve dealt with that issue elsewhere (e.g. in Aquinas).

A sixth objection went as follows:

The step from 9 to 10 is invalid. Up to 9 "the totality of possible things" means the class of whatever is contingent, considered as a unit. In later steps, however, the cause of the totality of possible things has to mean not the class, but the members of the class, for the argument to hold. Specifically, in 13 the cause of the totality of possible things can be a member of the class without causing itself. Say I found a business partnership; the class of partners in the firm exists because of me, yet no member of the class exists because of me. And I do not become self-existent just because I am one of the partners, and thus a member of the class that I brought into existence.

Put differently, the step from 9 to 10 is a quantifier shift fallacy, going from "for everything in the totality, there is some cause" to "there is something that is the cause of everything in the totality."

End quote.  I don’t know why the reader thinks that (9) amounts to “For everything in the totality, there is some cause.”  Avicenna neither explicitly nor implicitly says that in (9).  What he means is that the totality considered as such (including each member but not just each member individually) requires a cause.  In other words, what he is saying in (9) is what the reader thinks he is saying in (10).  And what Avicenna actually says in (10) is not “There is something that is the cause of everything in the totality" -- again, he’s already said that in (9) -- but rather that that cause is itself either part of the totality or outside it.  So there is no quantifier shift fallacy.

Nor do I see how the reader’s analogy is supposed to work.  Avicenna is talking about what causes the totality and each part of it to exist at all, not merely to exist qua part of the totality.  But to found a business partnership is not to cause any of the participating persons to exist, but merely to cause them to come to have a certain institutional relationship to one another.  It just isn’t parallel to what Avicenna is talking about.  What would be parallel is a case where you bring both the individual members and their partnership into existence all at once (something which, of course, none of us can in fact do).  But then it is even harder to see how such an example is a problem for Avicenna, since it is hardly plausible to say that a member of the partnership could have brought each member (including himself) and the partnership into existence all together.

Finally, a reader wrote:

I would appreciate help in understanding the concept of "possibility" and "necessity" being employed here.

As I read the argument, the intuition at work here is contingent-on (X). Something is said to be "possible" if it is contingent-on-something-else. Something is said to be "necessary" if it is contingent-on-itself. [etc.]

This is a misunderstanding.  “Possible” as Avicenna uses it doesn’t mean “contingent on something else.”  It means something like “being the sort of thing which, given its essence, need not have existed.”  It follows from this in Avicenna’s view that it needs a cause outside itself, but that is a separate point rather than part of the definition.  And “necessary” doesn’t either mean or entail “contingent on itself.”  “Necessary in itself” essentially means something along the lines of what Aquinas would call something whose essence just is existence.   (Whether Avicenna would put it exactly that way is uncertain, since as McGinnis notes, he wavers a bit about whether to say that the Necessary Existent can be said to have an essence, precisely because there is nothing distinct from its existence.  But of course, Aquinas would not say that God’s essence and existence are distinct parts -- just the opposite.  So for present purposes they are saying essentially the same thing.) 

Anyway, precisely because there is no gap in what is “necessary in itself” between what it is and that it is, there is no sense to be made of it being “contingent” on anything, not even itself.  To say it is “contingent on itself” makes it sound like it had to add existence to its essence, and the whole point is that it doesn’t have any essence distinct from its existence, since it just is existence.  It doesn’t have something to which existence could be added in the first place (either by itself or by anything else).

What is “necessary through another,” meanwhile, can be said to be contingent, but not contingent on itself.  It rather depends for its necessity on another.  So again, the reader just misunderstands what Avicenna has in mind by “necessity,” in either of Avicenna’s senses of the term.