TANG & TAG

INTERLOCUTOR SAID:

"Your definition seems, to me at least, to perfectly state TAG as I've heard and read it explained in the past. Are there supporters of TAG that would formulate it in a significantly different way?"

Not that I'm aware of. But I don't keep tabs on all these intramural debates. I tend to go my own way.

"I guess this could be true for those who actively attempt to argue that the statement, "There is no God," is true. What about the so-called "weak atheist," though, who says she disbelieves simply because she has not been presented with sufficient reason to believe?"

Okay, but you're now changing your example. Your original illustration was a Quinean. Quine had a carefully formulated secular ontology and epistemology. So he, for one, did implicitly assume his own burden of proof.

You're welcome to pose a different question. But my answer was responsive to your original question. As for the rest, see below.

"[I guess, though, your theology denies that these people truly exist. I find that hard to swallow, however, because this is how I feel--i.e. I simply don't believe because I don't feel there is sufficient reason to believe. Perhaps you believe that I am deceiving myself, but it doesn't feel like deception to me (but I guess it wouldn't if I were doing a good enough job at my self deception, right?)]"

True, but that's not an argument I'd use with the unbeliever. It affects my expectations, and it affects the way I will structure my argument, but it is not, of itself, an apologetic argument.

It's a presupposition rather than an argument. And it's not a presupposition I'd bother to argue for in that particular setting.

"Anyway, do you believe that the unbeliever who does NOT argue that the statement, "There is no God," is true, but rather that there does not seem to be enough evidence to believe the statement, 'There is a God,' is true, 'face the same gargantuan task in reverse'? In other words, do these atheists have a burden in the argument other than challenging theistic arguments put forth?"

Yes, I do think they face the same burden of proof. And it's not just a question of whether unbelievers "really" exist.

Rather, there's more to unbelief than lack of evidence. Rather, especially among, say, philosophically or scientifically astute unbelievers, they have certain intellectual investments which positively conflict with Christian theism. They believe some things that are directly inconsistent with Christian belief. So it's more than sheer, passive unbelief. It's contrary belief.

Now, that may come in degrees. It may be very tentative.

"I'm not so sure that this is so. At least it does not seem logically necessary. Let's say that there is phenomenon X. Isn't it logically possible that two theories consistently and completely explain/account for phenomenon X, but that only one is 'true'?"

Depends on whether we're talking about local or global explanations. You're talking about a local explanation while I'm talking about a global explanation.

"It sounds as if you are saying that, at this time, TAG is not a completed argument, that it's premises (at least as it pertains to laws of logic) are not yet supported/supportable. Perhaps, you are committed to the belief that the right work can be done by the right team of Christians to support these beliefs, but that it is not at this point yet. (Or maybe I've misrepresenting you)."

1. It's not a completed argument, but then, there's no such thing as a completed argument.

2. It's supportable.

3. To some extent, it also supported. I'll be giving some examples (see below).

4. But you might say it's undersupported.

5. This is not a question that admits a definitive answer, for it's a correlative question rather than a discrete question.

By this I mean that how well-supported the argument for Christian theism happens to be is, in some measure, correlative with how well-supported the counterargument for atheism happens to be.

So there's a dialectical relation between opposing positions. In practice, for every Christian argument there's an anti-Christian counterargument, followed by a Christian counter-counter argument, &c.

In other words, you don't know what the counterargument will look like before the argument is given. One can't respond to something that isn't on the table.

And once the counterargument is presented, it may be necessary to make various adjustments to the original argument to address the objections of the counterargument.

I'm not suggesting that everything reduces to relativism, as if all arguments and counterarguments are on an epistemic par.

But, as a practical matter, an argument that was well-supported in the absence of a counterargument may need some reinforcements in light of the counterargument. TAG and TANG are, to some degree, symbiotic. The development of the one demands a corresponding adjustment in the development of the other.

"Is this somewhat close to what you are saying? Are you saying that, right now, there is not sufficient material to support the premises of TAG, that the project is so large that it has yet to be completed?"

My answer here will piggyback on my answer above. Both sides are in process of rebuilding their ship after it left dry dock.

There are some excellent preexisting arguments to support the premises of TAG. Are they "sufficient"? Depends on what you mean:

1. The present state of the TAG argument may be sufficient to overturn the present state of the TANG argument. Indeed, I believe that's already the case.

2. But it's insufficient in the dual sense that:

i) It could be further elaborated and refined;

ii) If TANG improves, then TAG will need to improve to retain a level of sufficiency adequate to rebut a more sophisticated version of TANG--and vice versa.

"Do you believe there are any completed arguments that do not need to be 'further refined' or that are not awaiting completion that do demonstrate the existence of the Christian God?"

1. Arguments are capable of infinite refinement. The argument can always be extended to incorporate related truths.

2. However, there's also the possibility of evidentiary overkill.

For example, I could have sufficient evidence, or more than sufficient evidence, to correctly conclude that the butler killed the rich old geezer even though there is a lot more potentially or actually available evidence to corroborate or substantiate that conclusion.

There can be multiple lines of evidence for a given proposition, any one of which may be adequate to implicate the proposition.

"Further, and I don't mean to but you in a difficult spot with the other contributors and supporters here, how do you feel about people like Paul Manata and Peter Pike/Calvindude who seem to think that TAG is a done deal? It seems they believe this pretty dogmatically."

I honestly don't have time to keep up with everyone else's arguments. Manata will have to speak for himself, but in my experience, he's fairly flexible and eclectic.

"Further, and I don't mean to but you in a difficult spot with the other contributors and supporters here, how do you feel about people like Paul Manata and Peter Pike/Calvindude who seem to think that TAG is a done deal? It seems they believe this pretty dogmatically. You, as I understand it, are a close personal friend of John Frame, the living guru of presuppositionalism. Do you believe the view of TAG that you have presented here is more representative of his views or do you think Manata and Pike are closer?"

I think that Frame would probably agree with me, but I haven't attempted a comparative analysis, and I haven't consciously modeled my position on his. So if our positions happen to intersect or coincide, that's a case of independent convergence.

"Do you think that past presuppositionalists (e.g. Bahnsen) overstated the case for TAG or do you think they aligned with your beliefs presented here?"

I think that Bahnsen overstated the case for TAG. And I think my positions differs from his.

Bahnsen seemed to view TAG as a silver bullet. But even if it's a silver bullet, there's a lot of metaphysical gunsmithing that goes into the six-shooter and the gunpowder to turn an ordinary bullet into a silver bullet. And Bahnsen strikes me as having been rather naive about the amount of metaphysical machinery and supporting arguments thereof which were needed to silver-plate this particular bullet.

Mind you, Bahnsen was far more sophisticated than Gordon Stein, or even Michael Martin and/or George Smith. A rubberband would do the trick.

My impression is that some Van Tilians like Mike Butler or David Byron are somewhat closer to Bahnsen's position than Frame's.

However, they're well aware of the need to develop Van Til's embryonic argument, and they are by no means hostile to Frame.

I can't speak for Peter Pike. However, Peter isn't dealing with some ideal, hypothetical opponent.

Rather, he's dealing with real opponents like Daniel Morgan and John Loftus.

We can only debate the people who debate us, and not some Olympian abstraction.

And, from what I've read of him, Peter Pike doesn't have any great difficulty getting the better of the argument.

So even assuming, for the sake of argument, that he's pretty dogmatic about the sufficiency of TAG, it's not as if his opponents have given him much occasion to doubt his dogmatism. If anything, prolonged exposure to the general level of the opposition simply confirms his operating assumptions. But he will have to speak for himself--and he's more than welcome to do so.

Finally, below are some concrete examples (from Welty and Pruss) of the direction which subsidiary arguments for TAG might take:

Theistic conceptual realism claims that (at least some of) the divine thoughts
can be regarded as functionally equivalent to abstract objects, due to the unique
and determinative relation they sustain to any created realm.

As a version of realism, TCR asserts that abstract objects (such as
propositions, properties, possible worlds, logical relations) are real objects. They
are not (as in creative antirealism) mere products of human intellective activity,
but have extramental existence relative to finite minds. However, as a version of
conceptual realism, TCR asserts that such objects are ultimately mental in
character. This is because what is being considered is a theistic version of
conceptual realism, where the abstract objects in question are uncreated ideas in
the divine mind; i.e. God’s thoughts.

So what follows from this joint affirmation of divine aseity and necessary
omniscience (where the latter is construed as divine self-knowledge)? The
preceding considerations can be brought together to produce a model of abstract
objects as divine ideas. If due to the divine aseity God’s knowledge of all
possibilities (of everything that he can bring about) is completely independent of
the creature, then a whole range of God’s thoughts can be seen to function as
abstract objects in relation to the created realm. In addition, abstract objects will
differ in kind according to how the divine thoughts function in relation to the
world. And, finally, the three fundamental characteristics of all abstract objects
(on a realist conception) will have been satisfied: (a) real existence outside space
and time, (b) ability to be exemplified, (c) real existence independent of
exemplification. Let us see how this model accounts for properties, and for
possible worlds.

Properties

With respect to properties, we could say that if God creates any world which
exists, and if any created world exemplifies (a particular subset of) the ideas of the
divine mind, then at least some of God’s thoughts function as properties in the
realist sense, insofar as they are nonspatial, nontemporal, exemplifiable entities
which actually exist (in the divine mind), entities that explain all cases of
attribute-agreement in any created universe, and which exist independently of any
created universe.

The existence of a property is due to the divine power, since God has the
power to bring such-and-such about. The form of a property is due to the divine
omniscience, because it is God’s knowledge of his power that serves as the
blueprint for all possible worlds. Thus, the property of ‘being red’ exists, precisely
because God has the power to bring about the existence of things that are red. But
the property of ‘being red’ exists in the form of a concept in God’s mind;
specifically, God’s idea of his power to bring about the existence of red things.
This concept or idea which is in God’s possession exists outside space and time, is
exemplifiable, but exists independently of any of its exemplifications. Indeed, it
could exist wholly unexemplified.5

Notice here that TCR can still adapt M&M’s distinction between human
concepts and divine concepts: ‘Human concepts [are]... graspings of properties
that exist ontologically distinct from and independent of those graspings,’ whereas
‘divine concepts are those very properties themselves’ (Morris and Menzel 1986:
166). TCR just rejects M&M’s account of God creating his concepts and all other
abstract objects via an intellectual activity, since (as argued in Chapter 2) it
regards such creation as incoherent.

Possible worlds

God is an omniscient being. One consequence of this is that God perfectly
knows the capacities of his own power, and therefore all possibilities. From
knowledge of possibility is derived knowledge of impossibility, necessity, and
contingency. For instance, the impossible is what is not possible. The necessary is
what is not possibly not. And the contingent is what is possible but not necessary.6
Thus, possible worlds are simply God’s knowledge of his own power, of what
he is able to instantiate. God’s knowledge is not just a useful fiction, and so
neither are possible worlds. God truly has this knowledge – it is as real as his own
thoughts – and he creates in accordance with it. This naturally leads to a theistic
version of an ‘actualist’ conception of possible worlds, akin to the actualism
embraced by Alvin Plantinga, Robert Adams, and Robert Stalnaker, and rejected
by David Lewis. On this conception, existence claims about nonactual possible
worlds are reducible to existence claims about things in the actual world, for
God’s knowledge of his own power is after all a mental item in the actual world.7
modal facts about God ground modal facts about the world.

In this connection it is crucial to remember that,
because of the divine aseity, it is simply a ‘brute fact’ that God is the kind of God
he is, with the powers that he has. There is no cause of God’s nature and
existence, and thus no cause or ultimate explanation of why God’s knowledge of
his nature has the content that it does. This is significant, because it follows that
what God is able to do (the possible), and his knowledge of what he is able to do,
is not dependent in any way upon the existence of anything distinct from God
(such as, for instance, human sentences). To be sure, in order for humans to
describe these and other facts about God, they must use human sentences. But the
order of our knowing does not determine, and is completely independent of, the
order of God’s being and knowing. Thus, God’s knowledge of a whole host of
necessary truths about himself – for instance, the range of possible universes he
could create – is a function of who God is in and of himself, not a function of our
contingent ability to describe such knowledge.8

Thus, the essential argument is that if God exists and has thoughts, then
everything significant which realists have wanted to say about abstract objects can
be said about (at least some of) the divine thoughts. The argument doesn’t
presuppose the existence of abstract objects at the outset, but only the existence of
the divine thoughts. It then proceeds to characterise those thoughts as abstract
objects.

Thus, I want to deny that God’s thoughts are abstract objects simpliciter.
Instead, I want to endorse the claim that while God’s thoughts are numerically the
same thoughts in relation to the creation and to God, God’s thoughts function as
abstract objects only with respect to the creation, and not with respect to God. For
example, God’s thoughts determine attribute agreement with respect to the
creation, not with respect to God.

To illustrate. God and I can have the same thought, ‘2+2=4’, in terms of
content. But my thought doesn’t function in the same way that God’s thought
does. My thought doesn’t determine or delimit anything about the actual world, or
about any possible world. But God’s thought does. Thus, it plays a completely
different role in the scheme of things, even though God and I have the same
thought in terms of content. Thus, God’s thought uniquely functions as an abstract
object, because of his role as creator of any possible world. I am not the creator of
the actual world (much less, any possible world), and thus my thoughts, though
they are in many cases the same thoughts as God’s, don’t function as abstract
objects in any relevant sense.

Thus, creatures exemplify properties in virtue of God’s own plan for them,
and this plan (and therefore the properties) exist independently of the creatures in
question. The propositions expressed by synonymous human sentences exist
independently of those sentences. Possible worlds exist (unexemplified, of course)
in the actual world. And due to the divine omniscience, what we call ‘creation’ on
the human level is just the first-tokening of an abstractly-existing type.10 We can
of course say that Beethoven created or invented the Ninth Symphony, but his
creativity is to be understood by saying that he was the first human person in
history to token that abstract object. He was not the first person to think of that
symphony, for it existed eternally in the mind of God.

5
I tie properties to the divine concepts, because properties and concepts are closely aligned. For
something to have a property means that it falls under a particular concept. And to have a concept
of X is to grasp or apprehend the property of being X. (cf. Plantinga 1980: 20-22; Plantinga 2000:
15)
6
Since all these notions are interdefinable, one can just as well start with something other than
possibility, such as necessity. ‘I shall take the central notion as the notion of necessity. The other
notions can be explained by means of it. The impossible is that which is necessarily not; the
possible is that which is not impossible, and the contingent is that which is neither necessary nor
impossible’ Swinburne (1994: 96).

Objection 3.1: TCR is philosophical ‘theft,’ not honest toil

However, this objection [of Rescher's] appears to be almost entirely prejudicial. If
theological concepts have substantive philosophical consequences, then why not
explore their explanatory power? If we are trying to find a coherent and satisfying
explanatory model for the ontology of unrealised possibilities, then we should find
one free of defects.

One can acknowledge the strength of Rescher’s arguments for ‘the ontological
status of the possible’ being ‘fundamentally mind-dependent, the domain of the
possible being a mental construct,’ while noting that a key defect of his
programme – that there are not nearly enough human conceivings to go around –
can be remedied by appeal to the omniscience of the divine mind. This preserves
Rescher’s conceptualist insights while avoiding an obvious difficulty with them.
If this is not ‘honest philosophical toil,’ then I don’t know what is.

http://www.ccir.ed.ac.uk/~jad/welty/mphil.pdf

An Aristotelian alternative

If one shares the Aristotelian intuition that this-worldly capacities, powers and dispositions can make modal statements true, one might opt for a fully Aristotelian definition of mere possibility: A non-actual state of affairs is possible if there actually was a substance capable of initiating a causal chain, perhaps non-deterministic, that could lead to the state of affairs that we claim is possible.  We can then say that something is possible if it is either actual or merely possible.

An approach like this has a number of benefits.  Capacities, powers and dispositions are probably the concepts closest to ordinary language notions of possibility.  They are things we arguably have direct experiential knowledge of, pace Hume, by ourselves being capable of producing effects, and we can at least point out by ostension what, say, a capacity is. Moreover, though while having modal force, they are concrete.  Reducing all possibility to this subclass of modal notions would thus increase the comprehensibility of what we mean in saying something is possible—at least if one finds Aristotelian intuitions appealing.  The account is not a full reduction, since powers and capacities are modal notions, but it does reduce all of modality to a more basic subclass.

There are, however, two closely related difficulties facing any such approach.  The first is that while this works fine for local possibilities, such as of my having been a biologist, it is difficult to see how one could get possible worlds out of it.

The second problem is the following argument.  Consider the set of all contingent beings in the universe, namely beings that could have failed to exist.  It is highly plausible that if we have a set of beings, every member of which is contingent, then it is a contingent fact that any of the beings in the set exist.  But if this is right, the Aristotelian has a problem.  For the possibility that none of those contingent beings that exist in the universe had existed cannot be grounded in the causal powers of any actual contingent being.  Note that we are talking here not about the controversial possibility that there should exist no contingent beings, but about the much less controversial one that those contingent beings that exist might not exist, though perhaps other ones might then exist in their stead.

Neither is it clear how the Aristotelian could account for the possibility of the laws of nature having been different.  Again, we see that the Aristotelian account has trouble with global possibilities.

Leibniz’s account

Consider now a somewhat different answer to the question of what possible worlds are.  Leibniz, who started the whole debate about possible worlds, argued that necessary truths, including modal truths such as that unicorns are possible, must exist somewhere.  Finding Platonic entities too queer, he wanted to locate these truths as acts of thought or ideas in the mind of an omniscient, necessarily existent God who contemplates them.  He then gave an account of possible worlds that matched this.  A Leibnizian possible world is a maximally specific consistent thought in the mind of God of a way for the world to be. 

These acts of thought are actual entities, then, and so Leibniz has an answer as to what possible worlds are.  Moreover, one might argue that Leibniz’s account makes some progress with respect to the question of how it is that the entities which are possible worlds represent concrete things.  Recall that one difficulty with the Platonic approach was that of picking out which relation between concrete things and propositions was to count as the relation of representation. If one takes the controversial view that our thoughts are innately representative, the Leibnizian account may get around this problem by saying that that relation between divine thoughts and concrete things counts as the relation of representation which is the relation produced by that faculty in God’s mind which is analogous to the faculty of intentionality in us, and we can perhaps point out which of our faculties is the faculty of intentionality by ostension.  There are many difficulties here, including first of all the Leibnizian’s very controversial commitment to thoughts being innately representative or to a faculty of intentionality.  But if we find appealing the intuition that we can have a better grasp of what thoughts are, even divine thoughts, than we can of Platonic entities, because thoughts are something that we after all have direct experiential knowledge of, then we might prefer the Leibnizian account.

However, this does not solve the main problem with the Platonic approach which was its failure to give an adequate account of what makes possibilities possible.  The Leibnizian account does not help there at all, since those divine ideas that are singled out for being dubbed “worlds” are singled out in virtue of being consistent, that is possible.  Their possibility is prior in the order of explanation to their being known by God to be possible (cf. Adams, 1994, p. 191).  And so this approach is not relevantly different from singling out some collections of propositions for being dubbed “worlds” on the grounds of their being consistent.  Positing a God who contemplates possible worlds as described above does not in any way help with Aristotelian intuitions about possibility being grounded in actuality, since, as far as the account goes, the thoughts could be just as causally inert as Platonic abstracta.

A combined account

But now go back to one of the arguments against the Aristotelian view.  The argument was that the Aristotelian cannot posit a contingent substance that would ground the possibility of our whole past history having been different. But if the Aristotelian is brave enough, she can say that what this shows is that if the Aristotelian notion of possibility is correct, and if we accept the intuition that none of those contingent beings that exist might have existed, then we are committed to the claim that there is a non-contingent being which grounds the possibility of none of the contingent beings having existed. In fact, with a littlework, this argument can be extended to show that the Aristotelian notion of possibility commits one to the existence of a necessary first cause (perhaps a non-unitary cause which is an aggregate of causes) that non-deterministically produces the historical universe and grounds the possibility of other histories, and indeed of there being other laws of nature.

To some, of course, this will count as a reductio ad absurdum of the Aristotelian approach.  However, if we do not count it as such, there is a natural way to combine this account with Leibniz’s, by identifying the Aristotelian first cause with Leibniz’s necessarily existent God.  Then, one could have both possible worlds, namely certain thoughts in the mind of God, and an answer to the problem of what makes these worlds possible, namely God’s power for initiating a causal chain capable of leading to their existence.  The God of this theory would not only be omniscient but also omnipotent, then.  Of course how attractive one will find this account will depend on one’s assessment of other evidence for and against the existence of such a God.

http://www.georgetown.edu/faculty/ap85/papers/ActualAndPossible.html

Section 1: Cost-benefit arguments for the Aristotelian-Leibnizian ontology of possible worlds
1.1: Modality
            
The Aristotelian-Leibnizian (AL) model does give an account of the existent realities that are spoken of when we make modal claims.  Moreover, it succeeds in doing this without making any implausible distinction between being-in-this-world and being-existent as Lewis does and without invoking any objectionable primitive modality as the ersatz views were seen to.  In a precise sense, the possible worlds exist in the actual world: it is true at the actual world that possible worlds exist.  But this is not paradoxical: The possible worlds are just divine ideas, one of which is actualized, and the actualized one contains within itself an account of all the other divine ideas.  (Obviously, they must be infinite lest the regress prove vicious.)

Moreover, the account squares nicely with the intuition that attributions of the possibility of doing something should be claims precisely about the beings to whom this possibility is attributed, something which neither Lewisian nor ersatzist approaches allow for.

1.2: Explanation of what propositions are

As a non-modal bonus, the AL model provides us with a deeper insight into the nature of propositions, which it says are divine ideas.  Admittedly, the nature of divine ideas is somewhat unclear, and so this clarification is only partial.  However, we do have an analogical grasp of the nature of divine ideas based on our grasp of our own ideas, and this provides us with a better understanding of what propositions are than just considering them to be bare Platonic abstracta that represent realities in some mysterious way.  Divine ideas represent realities analogously to the way that our ideas represent realities.

It is true that David Lewis’s EMR also purports to give an account of the nature of propositions.  Unfortunately, his reduction of propositions to collections of worlds is unacceptable whereas his “structured propositions” involve too much arbitrariness (see Section 4 of Part I).  It might be argued that our present view also contains some arbitrariness.  Why should we define “propositions” as God’s ideas rather than the ideas of someone else?  But there is good reason for this.  For one, God is the only necessarily omniscient being, and presumably also the only being that necessarily has ideas of all realities.  For another, the ground of the possibility of the content of those ideas that are of possibilia is the power of God: it is God’s choice that is necessarily the first branching in the “history” (in quotes as God’s choice might not be in time) of the cosmos, and it is appropriate the propositions be found at that level.

1.3: Not a completely new ontology

The AL model does involve a rich ontology containing God, an ontology strictly richer than that of the ersatzist.  For, all the items in the ersatzist’s menagerie exist on the AL model: there are propositions, i.e., divine ideas, and there are sentences in all possible languages, i.e., divine ideas of sentences in all possible languages.  However, this richness is necessary to do justice to modality, as can be seen from the arguments against the ersatzist views in Part IV.  Very briefly and schematically, an account of modality that involves merely propositions or sentences makes the ground of modality merely “descriptive”: for the Parmenidean problem to be resolved, there needs to be an “executive power” by virtue of which the ersatz worlds are made possible, and this is God.

However rich the AL model’s ontology may be, it is not revisionary in the way that EMR is.  There is evidence for the ontology of the AL model, i.e., for the existence of God, that is prior to the AL model itself.  Indeed, this ontology has historically been widely believed, and the historical success of this ontology makes it plausible that there will be significantly fewer revisions to important areas of our thought such as ethics, induction and probability, whereas EMR’s ontology entails many such revisions.

1.4: Connection with theistic arguments for the existence of God

If traditional theism is true, then God is the “ground of being”, the first cause of the existence of all things outside himself, indeed the first cause of all contingent states of affairs.  Moreover, good reasons can be given for why on the theistic view God is to be taken to be necessarily the first cause of all beings outside himself.  First of all, if one brings God in as a first cause, as an explanation of all things other than himself, then to avoid Schopenhauer’s “taxi cab” objection to the cosmological argument (Schopenhauer charged that the causal principle behind the cosmological argument was dismissed once the existence of God was proved, like a cab that is no longer needed once one is at the destination, and not applied to God himself) one must affirm that God is the explanation of his own existence, perhaps by there being a sound ontological argument, though possibly outside of our grasp, for his existence or by his existence being implicated by his essence.  Moreover if God’s actions are to provide the ultimate explanation of all contingent truths in one world, then Jerome Gellman (2000) has argued persuasively that the same must hold in all worlds and that God must necessarily be omnipotent.  Thus, theism should hold, and many strands of it explicitly do, that God is necessarily the ultimate ground of all contingent being.

But if this is so, then traditional theism comes very close to the proposed Aristotelian-Leibnizian view.  The only additional step that this view takes is that not only is it the case that God must be the first cause of the realization of any possibility, but that its being a possibility should be analyzed in terms of God.  Theoretical simplicity and Ockham’s razor are in favor of taking the two concepts “That which God can be the first cause of” and “That which is possible” which have the same extension and positing, as the Aristotelian-Leibnizian view does, that they are the same concept.  Thus, if there is a God who is the ground of being, it is plausible to suppose him also to be the ground of possibility.

Consequently, all arguments for traditional theism also lend plausibility to the present view, and certainly, there are many such arguments (see, for instance, Swinburne, 1979).  And, conversely, the present view’s theoretical virtues in explicating modality lend plausibility to the view’s truth and thus to traditional theism the central tenets of which the view entails.

Observe, too, how the AL account of possibility not only gives an account of what possibility is but also gives a partial explanation why what is actual is actual: namely, because of God’s creative act.

Of course, similarly, many arguments against traditional theism are also arguments against the present view.  One exception is the argument from evil, which need only be handled only if one wishes to supplement the basic AL model with a claim that the God in whom all possibility is grounded is perfectly good, something that I take to be the case but which is not a part of the AL model itself.  And, aside from the argument from evil, there are few serious objections to theism.  Substantiating the claim that none of the other putative objections to theism is a serious one is, of course, not a completely trivial task, but limitations of space do not permit it to be attempted here.

Section 2: Conclusions

We need possibility and probably also possible worlds.  Without these, the collection of all truths would be seriously impoverished.  Paradoxically, there are facts about the actual world that cannot be expressed without bringing in possibilia.  However, this is going to be less paradoxical when we realize that the ontological ground of possibilia is the actual world, something that must be the case if we are to escape the force of the intuition that actuality and existence are the same whereas one cannot talk truly of what is not.

None of the extant serious accounts of possible worlds are fully satisfactory.  This thesis very briefly sketches a model that takes from Aristotle the notion that potentialities are grounded in actual features of substances and from Leibniz the notion of possible worlds as the ideas of God, assuming the latter notion can be made sense of.  This model overcomes various fatal objections to the other theories, objections ranging from their lack of a solution to the Parmenidean problem to paradoxical conclusions such as that there is no such thing as inductive knowledge.  Furthermore, the model gives a clarification of the nature of propositions.  Since we need a theory of modality, and would like to have propositions and possible worlds, and the present theory is coherent and avoid egregious paradox, this itself is good reason to believe the Aristotelian-Leibnizian model to be true.  As Leibniz said, “il semble que c’est quelque chose de considerable qu’une hypothese paroisse possible, quand toutes les autres ne le paroissent point, et … il est extrement probable qu’une telle hypothese est la veritable.” (Gerhardt (1960–61), vol. III, p. 353).  But, furthermore, the present theory receives additional evidential support from the various extant arguments for theism.

Lewis said that his theory was to be believed until one came along that gave the same benefits for a lower price.  If one is optimistic about making sense of a faculty of intentionality in a non-natural being, this has indeed happened—though not all benefits are shared by the new theory, but only those that were not seen in Part II to be chimerical, like the alleged set-theoretic reduction of propositions.

http://www.georgetown.edu/faculty/ap85/papers/PhilThesis.html#_Toc515941380