11 Ontological Arguments, from Anselm to Nagasawa

In this video, Dr. Chad McIntosh outlines, explains, and provides resources for 11 peer-reviewed ontological arguments put forth by various philosophers over the centuries.

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#OntologicalArguments #CapturingChristianity

[nathanaelculver]

*Ontological Arguments*

21 00:42 Anselm's First OA (Proslogion II)
22 01:51 Descarte's OA
23 03:05 Anselm's 2nd OA (Proslogion III)
23b 04:39 Hartshorne on Anselm’s Proslogion III
23c 05:35 Maydole’s Reconstruction
24 06:06 Anselm's _Other_ Other OA
25 07:15 Plantinga's OA
25b 08:05 The Modal OA Simplified
25c 09:40 Key Modal Inference
- - 10:56 *Defenses of the Possibility Premise*
26 11:47 The Phenomenal Defense of Plantinga's Possibility Premise
27 13:52 Godel's Demonstration of the Possibility Premise
28 15:12 Pruss's Improvement on Godel's Demonstration
29 15:54 Maydole's Modal Perfection Argument
30 18:18 Bernstein's Demonstration of the Possibility Premise
31 19:50 Nagasawa's Maximal God Approach to the Possibility Premise

[internetenjoyer]

nothing triggers internet atheists like the ontological argument, i love it

[naparzanieklawiatury]

Why would you even list ontological aguments like that? I don't get the point. What do you think the point of arguments is?
Clearly, if one didn't accept theism beforehand, none of the listed arguments do the work, what's more, I think there's a consensus among philosophers (a very rare thing) about ontological arguments being entirely unconvincing and at most a good exercise in finding equivocations. Or maybe some of you do think that some of these arguments give an atheist a new reason to accept theism?

[susanhoyle]

Thank you so much Cam! I am so glad you decided to break down the arguments into smaller bite sized videos! Thanks for taking our advice! A deeper break down would be really cool!

[texasfight]

Lol, “Ian Malcom” 😂😂 life finds a way, no doubt.

[internetenjoyer]

it is interesting that Plantinga's proof works in B. I'd hazard a guess people don't look into it because at this point most people accept S5 as the most plausible system for dealing with metaphysical and logical possibility; ie any context where we don't want to restrict the scope of possibility and necessarily to a specific set of possible worlds with certain properties (which we want to do if we're dealing with counterfactuals for example). Then again, I can't remember what system the Lewis-Stalnaker work on coutnerfactuals is using to formulate the truth conditions of counterfactuals. Damn, I've forgotten so much i used to know about modal logic. Edit: racking my brains a bit more, im pretty sure Lewis used S5 but used an additional semantics to arrange possible worlds in order of closeness to a given world which the counterfactual is true or false on

[roderictaylor]

In this video Dr. Chad McIntosh asks the question why do philosophers appeal to S5 in these arguments rather than to B, when S5 is stronger than B. S5 has the axiom that if it is possible a proposition is necessarily true, then the proposition is necessarily true. B has the weaker axiom, if it is possible a proposition is necessarily true, then the proposition is true (in B, it doesn't have to follow the proposition is necessarily true).

I believe there are two reasons why philosophers appeal to S5 instead of B.

(1) We get S5 if we add to B the axiom that if it is possible a proposition is possibly true then the proposition is possibly true. We can alternatively state this axiom as saying if a proposition is necessarily true, then it is necessarily true that it is necessarily true. This axiom doesn't seem particularly controversial, certainly far less controversial than what we already accept in B. So why not use it?

(2) Using only B in Plantinga's MOA, we cannot show a MGB exists. We can only show a MEB exists.

Plantinga defined a MEB to be an omniscient omnipotent perfectly good being that has these properties in every world in which it exists. He defined a MGB to be a MEB that necessarily exists.

Working in B, we start with, "It is possible a MGB exists." This means "It is possible a MEB that necessarily exists, exists." It follows that "It is possible it is necessarily true a MEB exists." From this, working in B alone, it only follows "A MEB exists." Working only in B, we cannot conclude this MEB necessarily exists. We cannot conclude a MGB exists.

We can illustrate this using a possible worlds model:


In this possible worlds model, each world is accessible from itself ( the accessibility relation is reflexive), A and B are accessible from each other, and A and C are accessible from each other (the relation is symmetric). But C is not accessible from B and B is not accessible from C (the relation is not transitive). A MEB exists in worlds A and B, but not in world C. A is the actual world.

This model has an accessibility relation that is reflexive, symmetric, but not transitive. It is a model appropriate for B, but not for S5.

Since the MEB exists in every world accessible from B, in B it is necessarily true this MEB exists, and so within B this MEB is a MGB.

Since B is accessible from the actual world A, it is possible a MGB exists. But since this MEB is not in all worlds accessible from the actual world, it is possible this MEB. does not exist. Within the actual world, the MEB is not a MGB.

This proves that, working within B, it can be possible a MGB exists, and yet it may be the case that in the actual world only a MEB exists.

[paulkelly]

Hey Cameron! Can you please, please invite Robert Maydole on to discuss his defense of Anselm's argument and his modal perfection argument??

[roderictaylor]

Premise 2 of the phenomenal defense is indefensible.

“It is reasonable for me to believe that if it is impossible that God exists, it would probably appear to me that it is impossible God exists upon further reflection.”

Suppose it were the case that no being having the attributes of a MGB existed in reality (though no one necessarily knew it), and as a result of the way we've defined a MGB and our choice to work in S5, it was impossible a MGB existed (again, no one necessarily knew it). Why does it follow that it would then appear to you upon further reflection it was impossible a MGB existed?

The MOA tells us that if no MGB exists, then it will be impossible a MGB exists purely because no MGB exists, because we have defined a MGB to be a necessary being, because we have chosen to work in S5, and for no other reason. There is nothing in the MOA to suggest that if no MGB exists, the idea of a MGB will somehow become internally incoherent in some sense that would make it appear impossible a MGB exists to someone on further reflection.

Like so many other attempts to defend the MOA, the phenomenal defense confuses metaphysical and epistemic possibility. The MOA tells us if no MGB exists, it will be metaphysically impossible a MGB exists. It does not tell us it will be epistemically impossible a MGB exists, in the sense that it will appear to someone to be impossible a MGB exists upon reflection.


I did a video series on the MOA I invite you to take a look at.

[TimCrinion]

It seems like godel defines a positive property as one which is compatible with necessary existence.

[Bcklm]

One big reason I stopped being religious was because this was the peak of trying to prove the nonsense.

[veganworldorder]

How do christians explain that Jesus once got mad at a fig tree and destroyed it out of anger ? Sounds like a not really holy way to act. The supposed son of God should do better Imho

[roderictaylor]

Nagasawa’s Maximal God Approach

This argument is an interesting variation. Plantinga’s argument defines a MGB and assumes an axiom system such that premise 2,

“if there is a possible world in which a maximally great being exists, then a real maximally great being exists in all possible worlds”

is true by definition. It must be the case that if a MGB exists in a possible world then it exists in every possible world, because a being that didn’t exist in every possible world would not fulfill the definition of a MGB.

But then we have trouble supporting the first premise, “there is a possible world in which a MGB exists.” To verify that premise, we must show that there is a possible world with a being that satisfies the definition of a MGB within that possible world. But since that definition of a MGB requires it exist in all possible worlds, to show the proposed being in a possible world really is a MGB, we must show it exists in all possible worlds including the actual world. So to verify a MGB exists in a possible world, we must show a MGB exists.



Nagasawa’s argument turns this around. Now it is premise 1 that is true by definition. By definition, there is a being in some world that is the MGB. Ok.

But now premise 2 is no longer true by definition and must be supported. We have not defined a MGB to be a necessary being. Of course, if it is true that a necessary omniscient omnipotent omnibenevolent being exists in reality, it seems fair to assume that would be the MGB we know exists in a possible world. But why should we assume that is the case? That was supposed to be the conclusion of the argument.


Imagine a dialogue.

“I have defined my terms in such a way that premise 1 of my argument is true by definition. And now I offer premise 2: If premise 1 is true then God exists.”

“Wait. Premise 1 is true because of the way we’ve defined our terms? It is purely analytic? So why should we assume that if a premise that is defined in such a way that it must be true actually is true, then it follows God exists?”

“It’s up to you to show that it doesn’t!”

Defining our terms in such a way that a premise is true by definition, and then assuming if that premise is true, then God exists, is no different than assuming God exists.

In case it’s of interested, I’ve made a video that explains Plantinga’s MOA in detail, and explains why, even if is sound, it cannot be persuasive.

[HyperFocusMarshmallow]

Ontological arguments: one of the reasons people laugh at theistic philosopher types. Can it be modalized? Yes of course! 🤣

[Fuzzawakka]

These arguements are so powerful that Jesus went around preaching them. That's how he convinced people he was God. Oh wait....no.

[Jockito]

How can anyone know that a MGB is metaphysically possible without first knowing every logical and metaphysical entailment of such a being?

[TheMirabillis]

1. Omniscience clashes with Freedom.

There was never a place in God’s mind where He did not know what He would do. He could never do other than what He always knew He would do. He had to create this World and could not refrain from creating it. He had to create the exact people who exists within this World and could not refrain from creating them.

Thus, God’s Omniscience rules over God and both God and man are fated to do what they do based on God’s knowledge ( and it is irrelevant whether you think God was Timeless or not because that does not change Omniscience ).

God is not Free if He is Omniscient. God is not Omniscient if He is Free.

2. Omnibenevolence clashes with Hell, Lake of Fire, Annihilationism, and creating people whom God knew would never benefit from existence.

If God is Morally Perfect and Good, then He cannot create and bring into existence people whom He knew would never benefit from existence. God creating people whom He knew would suffer in this life and also after they die by being thrown into a Lake of Fire or being subjected to an horrific experience of being annihilated is an expression of cruelty and immorality.

God is Cruel and Immoral because of Hell, Lake of Fire, Annihilationism, and creating people whom He knew would never benefit from existing.

Thus, there cannot be a Greatest Conceivable Being nor a Maximally Great Being.

Done and Dusted. Ontological Arguments fail !!

[zacharybohn]

I've been trying to understand this argument, but I feel either I don't understand, or the argument is incredibly weak.

To my understanding, the argument is basically (please correct any of my misunderstandings):
1. MGB possibly exists.
2. If a MGB possibly exists, then it is contingent.
3. A MGB that is necessary is greater than a MGB that is contingent.
4. Therefore, a MGB must be necessary. (from 2, 3)
5. If a MGB is necessary, then it exists.

However, as far as I can see, this only gets us to deducing that a MGB is necessary to reality in definition only. Defining something as necessary to reality, doesn't mean it exists. (This would be me disagreeing with the premise 5 I gave.)

[TimCrinion]

When I was at school I made my own version where I defined God as "unstoppable". Then, if he doesn't exist, he has been stopped. So you weren't actually thinking of an unstoppable being.

[hashiromer]

In my opinion, the main problem with all deductive arguments in philosophy of religion both for as well against existence of God is that they are anchored upon terminology which is usually vague and cannot be formalized, such as "ultimate, greatest, better, ..etc. Mathematics is another discipline which solely relies upon deductive arguments but there is consensus about validity of proofs in mathematics because there is little room for different interpretations of terms used in the proof.


I think all disagreements about efficacy of (sound) deductive arguments boil down to having different definitions of terminology. This is particularly evident in many responses to the problems of evil where omni-benevolence implies different state of affairs due to disagreements about its definition.