There are many versions of it, some intensely complicated. The OPs version is Anselmian, and those arguments typically run:
(1) If God exists then God necessarily exists. (G -> nG) [Partial Definition of God]
(2) If its logically possible that God exists then God exists (pG -> G) [From (1)]
(3) It is logically possible that God exists. (pG) [Premise]
(C) God exists (G) [From 1-3]. — PossibleAaran
Imagine a being, such that it cannot fail to exist.
Therefore, it exists. — SophistiCat
You see I don't think so. None of the premises of the argument say 'imagine a being such that it cannot fail to exist'. — PossibleAaran
But necessary existence is a property, and is immune to the criticism which Kant makes. — PossibleAaran
Perhaps we could argue that the world is the necessary thing, as it seems tautological to say that the world exists in every possible world. — Michael
I don't know. I read that passage you linked to from the Summa, and I really don't think Aquinas does succeed in refuting Objection 1. And I think subsequent history has borne out the argument that the existence of God cannot be 'demonstrated scientifically'. — Wayfarer
The point I was making was more specific - it was about the sense in which something like ‘the ontological argument’ can be regarded as persuasive. After all, none of those particular philosophers would concur that it is (granting that the first two were historically prior to it.) What I’m saying is, in order to regard it as conclusive, or to understand the terms of the argument in such a way that it seems to be, already indicates a pre-disposition to believing it; I think, perhaps, it is that very pre-disposition that is really meant by the term ‘belief’. (But I do quite agree that it’s a very delicate question.) — Wayfarer
I think it is fair to argue that the existence of scientific laws suggests an Author, but that whether that is so, must be a matter forever beyond scientific demonstration or (I suppose you could say) mundane certainty. That's why I said before, I think it's important to always have a sense of the unknown-ness of whatever is claimed to be ultimate or absolute; so, to say that God can be demonstrated or known scientifically seems hubristic to me. — Wayfarer
So the ontological argument doesn't defend its assumption that the necessary thing (assuming there is one) has those other properties posited of God. — Michael
(2) If it's logically possible that a necessary thing exists then a necessary thing exists — Michael
Although saying that, I find 2 troublesome. To be logically possible is to exist in a possible world and to be necessary is to exist in every possible world, and so the second premise states that if a thing which exists in every possible world exists in a possible world then a thing which exists in every possible world exists. It defines a necessary thing into existence. — Michael
First he asks us to accept that a Super-Duper Being is at least within the realm of the possible (not his exact words, of course, but that doesn't matter, since he doesn't explain what the words mean in this premise). Hopefully, a charitable and careless reader will not ask what a Super-Duper Being is and will grant this premise for the sake of an argument. — SophistiCat
Of course, stated this way, no one who does not independently believe the conclusion would go along with such an argument (and those who do ought not go along with it either). — SophistiCat
If a necessary being exists in one possible world (it need not be the actual one. Suppose it isn't) — PossibleAaran
How can a necessary thing exist in one possible world but not the actual world?
I can't quite put my finger on the actual logical misstep. There's something wrong about talking about the logical possibility of the logical necessary. I wonder if such talk requires something like Tarski's hierarchy of language, or different sets of possible worlds, and the argument above conflates the members of the hierarchy/conflates the sets.
It just isn't right to say that there must be a necessary thing because a necessary thing is defined as something that exists in every possible world (and so the actual world).
As I said, the only thing that could perhaps be said to exist in every possible world is "the world", which is just an abstract container. — Michael
Rather, if the concept of necessary existence is coherent, there must be a necessarily existent thing, since coherence entails logical possibility. — PossibleAaran
Sure, I can use possible world lingo to make it seem less obscure. "Imagine a being which exists in not just one possible world, but every possible world". I then picture all of these different spheres and the necessary thing is in not just one, but all of them.
If god existed only in our imaginations, he wouldn't be the greatest thing that we can think of, because God in reality would be better. — Harjas
Kant is disagreeing with this premise (bold) — bloodninja
All of this is quite uncharitable to Plantinga. — PossibleAaran
He does define his 'super-duper being' very carefully. He defines a maximally great being as one which is maximally excellent in every possible world, and maximal excellence is defined as entailing omnipotence, omniscience and moral perfection. To wit, the first two premises of his argument from the Nature of Necessity, page 214 — PossibleAaran
I think there's a fundamental problem with saying that a logical necessity is logically possible. I can't quite put my finger on what that problem is, though, but as I said before, my instinct is that it's related in kind to Tarski's hierarchy of language. — Michael
But then, suppose I don't have this bias. Suppose that I am not such that, when I see that a premise entails that God exists, I will not accept that premise. — PossibleAaran
You also say that it is illegitimate to predicate necessary existence. Why? You say that Michael's argument shows why. But which argument of Michael's do you mean? — PossibleAaran
Do you mean the argument that we can tack 'necessary existence' onto any concept and then create an argument for its existence, regardless of what the concept is? — PossibleAaran
The point is just that Aquinas (and the traditional Catholic church) claimed that [the existence of God could be demonstrated scientifically]. They rejected fideism. — Andrew M
Ockham rejected all contemporary arguments for God's existence including Aquinas' Five Ways (he was a fideist). — Andrew M
Having properties implies existence. — SophistiCat
"Knowledge," says Clement, "is more than faith." "Faith is a summary knowledge of urgent truths, suitable for people who are in a hurry; but knowledge is scientific faith." "If the Gnostic (the philosophical Christian) had to choose between the knowledge of God and eternal salvation, and it were possible to separate two things so inseparably connected, he would choose without the slightest hesitation the knowledge of God." On the wings of this "knowledge" the soul rises above all earthly passions and desires, filled with a calm disinterested love of God. In this state a man can distinguish truth from falsehood, pure gold from base metal, in matters of belief; he can see the connexion of the various dogmas, and their harmony with reason; and in reading Scripture he can penetrate beneath the literal to the spiritual meaning. But when Clement speaks of reason or knowledge, he does not mean merely intellectual training. "He who would enter the shrine must be pure," he says, "and purity is to think holy things." And again, "The more a man loves, the more deeply does he penetrate into God." Purity and love, to which he adds diligent study of the Scriptures, are all that is necessary to the highest life, though mental cultivation may be and ought to be a great help.
I don't think you're picturing every possible world. Surely you can imagine that one of these spheres doesn't share this thing in common? I certainly can. — Michael
I can imagine a possible world without a God, and so God can't be necessary. It's ridiculous to think that you can just define him to be, just as it would be ridiculous for me to define the Flying Spaghetti Monster as being necessary. This is the problem with treating "existence" as a property. — Michael
the premise that he asks us to accept is much stronger than the conclusion of the argument. Thus, even those who already believe the conclusion independently may not accept his starting premise. — SophistiCat
I hope I explained why this is not the reason that neither I nor anyone who understands the argument that Plantinga is making - not in retrospect, but right as it is unfolding - would be likely to accept it. — SophistiCat
It is what StreetlightX and @Michael (and, no doubt, others who have criticized Anselm's argument) have said about predicating existence (necessary existence, as has been discussed, has even more severe problems). Having properties implies existence. So when we predicate a property of something, the qualification "provided that the thing exists" is already implied. When we define a unicorn as "a horse with a single horn," the same definition could be equivalently restated as "a being, such that if it exists, it exists as a horse with a single horn." The actual predicate here is still "being a horse with a single horn," nothing more. So when we "predicate" existence of a being, that is equivalent to saying "a being, such that if it exists, it exists" - which is just a tautology that applies to any hypothetical being. — SophistiCat
That, too. Plantinga's argument is, if anything, even easier to parody than the original. Those attributes of Super-Dupeness Maximal Greatness do no work in the argument - they ride free and thus can be replaced with anything whatsoever. — SophistiCat
The starting premise is that it is logically possible that a maximally great being exists. If someone believes that a maximally great being does exist, then they surely also believe that it is logically possible. Now consider someone who doesn't already believe the conclusion. Such a person might believe that the concept of a maximally great being is coherent. I think many people who deny the existence of God do believe that the concept is at least coherent. But then, it could be pointed out to them that this premise, which they believe, entails that a maximally great being exists. Why wouldn't that be an effective argument? — PossibleAaran
But are there only two options here - fideism, acceptance on faith, or 'scientific demonstration?'
Aside from faith (doxa or pistis) and science (scientia), I think there is another mode of knowing - sapience or sapientia. The reason being, that investigating the reality of spiritual matters, is undertaken in the context of a relationship with a Person, not, like scientific matters, measurements made of an object of perception. It is a different kind of 'knowing' - more like sapience, or gnosis, or noesis, or one of those kinds of terms that denotes a different cognitive 'style' to that of science as now conceived. But is also not strictly speaking simply a matter of belief. — Wayfarer
He was also a voluntarist i.e. believed God to be forever beyond logic, and a nominalist. Some would argue that this is where the decline into materialism began. (See What's wrong with Ockham?) — Wayfarer
I found this quote interesting: 'Louis Dupré, for instance, has complained that “nominalist theology effectively removed God from creation…. The divine became relegated to a supernatural sphere separate from nature… thus making God largely inaccessible to reason.”' — Andrew M
I think it accurately describes the transition from Aquinas' more holistic Aristotelian perspective to a more dualistic understanding of the world. — Andrew M
in the normal sense, a relationship with a person presupposes that the person exists and is demonstratively known to exist. — Andrew M
Modality is a way of thinking, talking, reasoning about the world. Modality can be a property of a proposition, but It makes no sense to talk about modal properties of a thing. Modality is a way of talking about things. So a "necessary being" is just a shorthand for saying that it is necessarily the case that such and such exists. — SophistiCat
Degrees of Reality
In contrast to contemporary philosophers, most 17th century philosophers held that reality comes in degrees—that some things that exist are more or less real than other things that exist. At least part of what dictates a being’s reality, according to these philosophers, is the extent to which its existence is dependent on other things: the less dependent a thing is on other things for its existence, the more real it is. Given that there are only substances and modes, and that modes depend on substances for their existence, it follows that substances are the most real constituents of reality.
This is from Clement of Alexandria, around first-second century AD, when the idea of there being a 'higher knowledge', here presented as a 'scientific faith', was still in circulation; suffice to say it is from a different historical period, and reflects a completely different understanding, of what 'scientific knowledge' comprises than what is understood today, being more typical of what used to be called 'scientia sacra'. Nevertheless, I think this idea of there being a higher order of knowledge has dropped out of contemporary epistemology. — Wayfarer
1.God is the greatest thing we can think of.
2. Things can exist only in our imaginations or they can also exist in reality.
3. Things that exist in reality are always better than the things that only exist in our imaginations.
4. If god existed only in our imaginations, he wouldn't be the greatest thing that we can think of, because
5. God in reality would be better.
Conclusion: Therefore, God must exist in reality! — Harjas
So, no, I don’t agree that they’re matters of ‘feeling or conviction’ only, but they’re also not matters for the natural sciences. That is why they’re referred to as ‘higher knowledge’ in the various traditions. And what I’m saying is that, this sense of there even being such a thing has generally dropped out of philosophical discourse, but that is it at least preserved in some aspects of the Thomist tradition. — Wayfarer
The problem is you can't explain in what sense they are knowledge. — Janus
I have not said they are merely "matters of conviction or feeling only" I have acknowledged that they are matters of higher, or better heightened, feeling or conviction. — Janus
Not for want of trying. — Wayfarer
In which case, there is no reason why they can't provide a basis for qualitative judgements concerning metaphysical and epistemological questions, such as the topic of this thread. — Wayfarer
(1) God exists as a matter of necessity,
or
(2) It is at least logically coherent to think of God as a necessary being.
You say that (1) obviously entails the desired conclusion, but as you point out, it is worthless because (1) just is the conclusion. So we have to understand the premise as (2). I am not sure what would be wrong with (2). You have said it is too weak, but I'm not sure why. — PossibleAaran
(2*) The concept of a being that necessarily exists is logically coherent.
(4) Therefore, it is logically possible that there is a being that necessarily exists.
(5) Therefore, there is a being that necessarily exists.
The inference from (4) to (5) is just collapsing the modal operators in accord with S5. The inference from (2*) to (4) assumes that if a concept is logically coherent, it is logically possible that it is instantiated. — PossibleAaran
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