Instigator / Pro
1485
rating
92
debates
45.65%
won
Topic
#6223

Resolved: The modal ontological argument is sound

Status
Debating

Waiting for the next argument from the instigator.

Round will be automatically forfeited in:

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DD
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Parameters
Publication date
Last updated date
Type
Standard
Number of rounds
4
Time for argument
One week
Max argument characters
10,000
Voting period
One month
Point system
Multiple criterions
Voting system
Open
Contender / Con
1579
rating
34
debates
70.59%
won
Description

INTRO

The modal ontological argument is an intriguing argument for the existence of God. Originally attributed to St. Anselm of Canterbury, Alvin Plantinga turned this argument into a modal argument for God's existence.

1. It is possible that a maximally great being exists.
2. If it is possible that a maximally great being exists, then a maximally great being exists in some possible world.
3. If a maximally great being exists in some possible world, then it exists in every possible world.
4. If a maximally great being exists in every possible world, then it exists in the actual world.
5. If a maximally great being exists in the actual world, then a maximally great being exists.
6. Therefore, a maximally great being exists.

=== Definitions ==

Ontological argument: See above

Sound: An argument is sound if and only if it is valid and all its premises are true. If an argument is sound, then the conclusion follows

-- STRUCTURE --

1. Opening
2. Rebuttals
3. Rebuttals
4. Rebuttals/Close

Rules

1. No forfeits
2. Citations must be provided in the text of the debate
3. No new arguments in the final speeches
4. Observe good sportsmanship and maintain a civil and decorous atmosphere
5. No trolling
6. No "kritiks" of the topic (challenging assumptions in the resolution)
7. For all resolutional terms, individuals should use commonplace understandings that fit within the logical context of the resolution and this debate
8. The BOP is on Pro; Con's BOP lies in proving Pro wrong. Con may make original arguments if he wants to.
9. Rebuttals of new points raised in an adversary's immediately preceding speech may be permissible at the judges' discretion even in the final round (debaters may debate their appropriateness)
11. Violation of any of these rules merits a loss.

Round 1
Pro
#1
Thank you, con, for accepting this debate!

Intro

The ontological argument for God's existence is an intriguing argument that dates back to Anselm of Canterbury. Anselm argued that God is, by definition, the greatest conceivable being because if there was a being that could be deceived that is greater, then that thing would be God. Throughout the centuries many philosophers engaged with this argument. Although it is easily dismissed, it is a solid argument that is worth defending. In recent years, Alvin Plantinga offered his own modal version of the argument [1]: 

1. It is possible that a maximally great being exists.
2. If it is possible that a maximally great being exists, then a maximally great being exists in some possible world.
3. If a maximally great being exists in some possible world, then it exists in every possible world.
4. If a maximally great being exists in every possible world, then it exists in the actual world.
5. If a maximally great being exists in the actual world, then a maximally great being exists.
6. Therefore, a maximally great being exists.

With that, let's begin.

I. Types of Worlds and Beings

In philosophy we distinguish between 3 types of entities [2]: 
  1. A contingent entity - an entity that could exist in some worlds, but does not have to exist others. Examples of this are humans as there is nothing about us that says we must exist (and indeed, until about 300,000 years ago humans did not exist). 
  2. A necessary entity - An entity that must exist in all possible worlds and cannot fail to exist. 
  3. An impossible entity - An entity that cannot exist in any possible world due to the nature of their properties being incompatible. Examples of this are a square circle, married bachelor, and an invisible pink unicorn. 
In modal logic, we also distinguish between possible worlds [3]:
  1. The actual world - The world we live in.
  2. A possible world - A world that could have been but did not actualize (i.e. it is possible to live in a world in which the COVID-19 crisis never occured). 
  3. An impossible world - A world in which could never actualize due to incompatibilities within it's properties (i.e. a world in which married bachelors exist). 
With that, let's analyze the syllogism.

P1) It is possible that a maximally great being exist

When we state that it is possible for a maximally great being to exist, we are saying that there is a hypothetical world that exists in which there is a maximally great being. This maximally great being would possess all great-making properties to the maximum degree. These great making properties includes, but is not necessarily limited to, omnipotence, omniscience, moral perfection, and necessary existence. This premise is reasonable because there is nothing that is logically incoherent about such a being. 

Con might argue that the possibility of an MGB is not self-evidence and requires proof; however, in modal logic, something is considered possible when their properties do not contradict each other. 

P2 - P6) From possibility to necessity 

P2-6 is accepted universally among philosophers as a logical continuum of modal logic. If an MGB is possible in at least one world, then we g et from possible necessary to necessary from an axiomatic modal logic S5: P3 is a statement of axiom S5 modal logic: S5: If possibly necessarily P, then necessarily P. 

P2) If it is possible that a maximally great being exists, then a maximally great being exists in some possible world.

This premise follows directly from the definition of possibility in modal logic. If something is possible, there exists at least one possible world in which it is true. Thus, if a maximally great being is possible then it exists in at least one possible world. This step is uncontroversial, as it reflects the standard interpretation of modal possibility.

P3) If a maximally great being exists in some possible world, then it exists in every possible world.

P3 is a statement of axiom S5 modal logic: S5: If possibly necessarily P, then necessarily P. 

P4–6): From every possible world to the actual world.

Premise 4 follows logically: if an MGB exists in every possible world, it must exist in the actual world, as the actual world is one of the possible worlds including our own. 

II. Common Objections

I will now engage in some common objections. 

A. The stone paradox

The stone paradox is an argument that challenges the possibility of omnipotence. The argument states "Can God create a stone to heavy that even he cannot lift it?". This objection unfortunately fails because it misrepresents what we mean by omnipotence. Omnipotence means having the maximum power to actualize any logically possible state of affairs. Not being able to do the impossible is not a limitation on omnipotence nor is it a limitation on God. 

B. Maximally great islands 

Some have attempted to parody this argument by pointing to the possibility of a maximally great island. The attempts to parody this argument typically fail for one of two reasons: 1) the entity is impossible and cannot exist in any possible worlds; and 2) it lacks the definition of necessary. Dr. Craig notes [5]:

“When you look at these parodies of the argument they turn out to involve things that are logically incoherent. For example, there is no such thing as the greatest possible island. You could always have more palm trees and more dancing girls on the island. And besides what makes an island great is person relative. Do you prefer an island that is a desert island remote from civilization? Or do you prefer an island that is packed with the finest resort hotels? It’s person relative. So there isn’t any such things as objective great-making properties of islands” 
C. Free-will vs. All-knowing

Some have attempted to show that it is impossible for God to be both free and possess all knowledge. If God knows at time t that He will perform action A at t+1, He cannot choose otherwise, negating free will. This objection fails because omniscience and free will are compatible under several coherent frameworks. First, compatibilism holds that free will holds that God’s actions are free if they align with His perfect nature, even if known in advance. God’s foreknowledge of His choice is merely a reflection of his self-determined will and is not externally constricted. Alternatively, under a Molinist model of knowledge, God’s knowledge of His actions is contingent on His free choices, preserving both properties. Since no logical contradiction has been shown between omniscience and free will, the coherence of an MGB remains intact, supporting Premise 1 that such a being is possible. [6] Moreover, Rambam in Hilchot Teshuva writes that the knowledge of God is vastly different than the way that humans perceive knowledge:

The Holy One, blessed be He, does not know with a knowledge that is external from Him as do men, whose knowledge and selves are two [different entities]. Rather, He, may His name be praised, and His knowledge are one. 

Accordingly, we do not have the potential to conceive how The Holy One, blessed be He, knows all the creations and their deeds. However, this is known without any doubt: That man's actions are in his [own] hands and The Holy One, blessed be He, does not lead him [in a particular direction] or decree that he do anything.
This matter is known, not only as a tradition of faith, but also, through clear proofs from the words of wisdom.

Consequently, the prophets taught that a person is judged for his deeds, according to his deeds - whether good or bad. This is a fundamental principle on which is dependent all the words of prophecy.

Conclusion

The resolution is affirmed. I turn this debate over to Con. I look forward to an excellent debate 

Con
#2
Thanks for this debate opportunity Pro, I'm excited for a fun debate. I'm going to deconstruct the argument through replying to Pro's original arguments, that was I don't misinterpret a specific premise or anything like that.

You start off by defining your terms. I agree with pretty much everything said there so I'll skip it for now. Moving on to Premise 1:

When we state that it is possible for a maximally great being to exist, we are saying that there is a hypothetical world that exists in which there is a maximally great being.
I wouldn't dispute this premise. I'd say it's hypothetically possible for God to exist, but until some other form of proof materializes, he only exists in hypothetical worlds, which essentially means he doesn't exist. Any world you can imagine that contains God does not actually contain God because the imagined being is not real, and thus is not God. It's a caricature of God, not really him.

Con might argue that the possibility of an MGB is not self-evidence and requires proof; however, in modal logic, something is considered possible when their properties do not contradict each other. 
I wouldn't argue that. I'd say there are no absolute contradictions in the nature of god, and though I believe there to be soft-contradictions that make him more unlikely, that's another debate.

Premise 2:

This premise follows directly from the definition of possibility in modal logic. If something is possible, there exists at least one possible world in which it is true. Thus, if a maximally great being is possible then it exists in at least one possible world. This step is uncontroversial, as it reflects the standard interpretation of modal possibility.
This is a premise I have a problem with, but that may be just because I don't understand your wording of it completely. Currently in this syllogism, we've only established that God exists in the world of thought, or hypothetical worlds. However this means that God isn't actually real, and it's actually God. You've established that God must exist in the real world in order to be God, but that implies that a "God" existing in thought simply isn't God rather than necessitating God's existence. 

Also, this premise rests on the assumption that the universe is infinite. If you have an infinite amount of monkeys on typewriters or an infinite amount of time, then yes, they will eventually produce the works of Shakespeare. However you haven't proven that the universe is infinite in either time or space. In a set of infinite numbers, the number 12 is a necessary being, but in a set of the numbers 1-5 it is an impossible being. Likewise with the universe, the possibility of God doesn't directly translate to his existence in any possible worlds.

I do still feel like I'm missing something though, so if you could explain to me how you got from "may exist in any worlds" to "must exist in some world" that would be appreciated.

Premise 3: 

P3 is a statement of axiom S5 modal logic: S5: If possibly necessarily P, then necessarily P. 
I won't dispute this sentence in itself, but a lot of proponents of the ontological argument misunderstand it. I'd like to clarify that my perception of God, the God that exists in my imagination isn't actually God as per your definition. If a MGB exists in any world, it must exist in all worlds, but simply imagining God doesn't qualify as summoning a MGB into existence.

Premises 4-6:

Premise 4 follows logically: if an MGB exists in every possible world, it must exist in the actual world, as the actual world is one of the possible worlds including our own. 
Once again, logically indisputable. Not going to try going after this one.

Moving on to your common objections...

The stone paradox is an argument that challenges the possibility of omnipotence. The argument states "Can God create a stone to heavy that even he cannot lift it?". This objection unfortunately fails because it misrepresents what we mean by omnipotence. Omnipotence means having the maximum power to actualize any logically possible state of affairs. Not being able to do the impossible is not a limitation on omnipotence nor is it a limitation on God. 
This is less of an objection to the Ontological argument and more of just a straight up argument for atheism. I've never liked this one, and I won't use it in this debate. I completely agree, God is also bound by the laws of logic. Omnipotence is simply all powerful... within logic.

Some have attempted to parody this argument by pointing to the possibility of a maximally great island. The attempts to parody this argument typically fail for one of two reasons: 1) the entity is impossible and cannot exist in any possible worlds; and 2) it lacks the definition of necessary. Dr. Craig notes [5]:

“When you look at these parodies of the argument they turn out to involve things that are logically incoherent. For example, there is no such thing as the greatest possible island. You could always have more palm trees and more dancing girls on the island. And besides what makes an island great is person relative. Do you prefer an island that is a desert island remote from civilization? Or do you prefer an island that is packed with the finest resort hotels? It’s person relative. So there isn’t any such things as objective great-making properties of islands” 
I was planning to use this counterpoint, so good job predicting your opponent. Since you've already gotten us started, I'll move into my classic response to Craig. The problem he makes here is he holds the island and God to different standards. When it comes to the island, William Lane Craig says "Oh, well Morality is subjective and the best island differs from person to person", but somehow when it comes to God he believes that goodness is objective. If Morality and inherent "good" qualities are subjective, then omnipotence is subjective, omnipresence is subjective, and most importantly existence in every possible world is subjective, thus collapsing the whole argument on it's head.

Since objective morality must exist for a maximally great being to exist and the ontological argument to work, the the same argument can realistically be applied to the best island or the best cigarette pack and work the same.

Conclusion

The fundamental problem with ontological argument is not in the possibility of a MGB, but merely in its circular nature. Allow me to demonstrate by rewriting the argument slightly:

P1: God may exist 
P2: If God exists, then by virtue of being God he must exist
FC: God must exist

The whole syllogism is essentially saying "If God exists, then God must exist" which is tautologically true, and gets us nowhere. Some versions of the argument (like the original by St. Anselm) rely on the premise that God exists in the theoretical world of though, but to reiterate again, that is not really God. By only existing in theory, he is not God simply because he is not real and God must be real.
Round 2
Pro
#3
Thank you, Moozer325, for your engaging reply!

Intro

Moozer325 has shown a significant misunderstanding of 5s modal logic as well as possible world semantics. I want to begin by re-iterating the MOA:

1. It is possible that a maximally great being exists.
2. If it is possible that a maximally great being exists, then a maximally great being exists in some possible world.
3. If a maximally great being exists in some possible world, then it exists in every possible world.
4. If a maximally great being exists in every possible world, then it exists in the actual world.
5. If a maximally great being exists in the actual world, then a maximally great being exists.
6. Therefore, a maximally great being exists.

Con made some very critical mistakes in their reply and made some big concessions. I will show that by conceding P1 my opponent has essentially conceded the entire argument. With that, let's begin.

1. It is possible that a maximally great being exists.

Con unfortunately shows a significant misunderstanding of modal logic. First, my opponent concedes that an MGB is logically coherent. This is a big concession as this is the only premise my opponent can possibly challenge without conceding the entire argument. The MOA stands or falls on this premise. 

Con's fatal flaw is that they misunderstand possible worlds and treats them as an imaginative scenario or mental constructs. Rather, these are rigorous philosophical models about a potential state of affairs. Thus we P1 can be rewritten as: There exists a logical state where a MGB (a being that is omnipotent, omnipresent, morally perfect, and necessary being) exists. The key of 5S modal logic is that if this being is logically coherent then it must exist in every possible state of affairs, including our own. 

This isn't wishful thinking or imaging God into existence. It is a valid inference based on the rules of modal logic.By confusing hypothetical worlds with figments of imagination my opponent makes a very serious category error. 

Let’s draw an analogy: possible worlds are like valid sequences in chess. Imagine we were playing a game and I could play checkmate on the next move and win the game. This is a 'possible' world because it is a logically consistent and follows the rules of chess. In the game are two possible scenarios for my next move: 1) I find the move and win the game; or 2) I don't find the move and the game continues (I could later win the game in a different manner or even lose the game because of that single critical flaw). 

Similarly, a possible world n modal logic is this type of analysis. What types of worlds are logically coherent and could materialize given the rules of modal logic. If an MGB is logically coherent, then like the chess game there is only one possible scenario: The MGB materializes and is real in the actual world. 

Con's attempt to dismiss possible worlds as just caricatures collapses their entire arguments. If possible worlds were just imaginations and mere caricatures then modal logic would be invalid. Indeed, possible worlds is the cornerstone of modal logic!  [1] 

2. If it is possible that a maximally great being exists, then a maximally great being exists in some possible world.

I want to clarify this premise as my opponent badly misunderstands modal logic. We did not establish that God exists in a world of thought, rather what we established is that a MGB is a logically coherent entity, meaning that there are no internal contradictions within this concept, and that could exist in a potential state of affairs. Let's continue with the chess analogy 

In our game it is possible that I can checkmate you on the next move. This means that there is at least one valid sequence of moves, consistent with the rules of the game, where checkmate happens. In modal logic this is what is called a possible world - a logically coherent scenario. Now on the flip side there also exists a scenario where I do not find the move and the game continues. In both scenarios I'm not talking about imaginary chess positions or caricatures, I am talking about a logically valid state of the game based on the rules of chess. 

In neither scenario do we need an infinite universe nor do we need an infinite number of monkeys typing on keyboards! 

3. If a maximally great being exists in some possible world, then it exists in every possible world.

Con concedes the main point of 5S modal logic: If possibly necessarily P, then necessarily P; however, my opponent still doesn't fully understand how God is being used. We are not imagining or summoning a God into existence. We are exploring the modal logical implication if we state that an MGB is logically coherent, which my opponent agrees with.

4. If a maximally great being exists in every possible world, then it exists in the actual world.
5. If a maximally great being exists in the actual world, then a maximally great being exists.
6. Therefore, a maximally great being exists.

Con concedes these premises. 

Common Objections 

A. The stone paradox

Con and I are in agreement. 

B. Maximally great islands 

Con claims Craig is applying different standards to God as opposed to a maximally great island. The problem lies in a gross misunderstanding of the two concepts. Craig does not hold God and an island to two different standards, rather he is showing the incoherence of a maximally great island. A maximally great island, and a maximally great cigarette pack, are incoherent entities that cannot exist in any possible state of affairs. If we really want to see why this is the case let's re-write the MOA:

1. It is possible that a maximally great island exists.
2. If it is possible that a maximally great island exists, then a maximally great island exists in some possible world.
3. If a maximally great island exists in some possible world, then it exists in every possible world.
4. If a maximally great island exists in every possible world, then it exists in the actual world.
5. If a maximally great island exists in the actual world, then a maximally great island exists.
6. Therefore, a maximally great island exists.

Islands and cigarette packs are both contingent entities and thus cannot be necessary and cannot be maximally great. Craig does not apply two different standards, rather he shows why applying concepts of maximal greatness to contingent entities are invalid. This argument fails because P1 is false. An MGI is in incoherent entity. Unlike a MGB, an MGI or a maximally great cigarette pack is logically incoherent. 

If my opponent wants to use a maximally great island or maximally great cigarette pack as an argument then I challenge them to actually define what a maximally great island or a maximally great cigarette pack even means. Until they do that then these concepts are incoherent. 

C. MOA is circular

My opponent attempts to show that this argument is circular by rephrasing this as:

P1: God may exist 
P2: If God exists, then by virtue of being God he must exist
FC: God must exist

If this was the argument then it would indeed be circular; however, this is not the case. The MOA does not assume God's existence, but deduces it from the possibility of an MGB. My opponent has already conceded that it is possible. Unlike con's caricature of this argument, there is no assumption here but a mere logical inference. And once again, God is not being merely thought into existence. My opponent, once again, shows a poor misunderstanding of possible world semantics. 

Sources
1. For more information on how possible worlds are treated in modal logic see https://plato.stanford.edu/entries/logic-modal/#PosWorSem
Con
#4

Con's fatal flaw is that they misunderstand possible worlds and treats them as an imaginative scenario or mental constructs.
Let me try and clarify what I mean here by "possible". I mean that God strictly "may" be possible. I never said that God must exist in some world, I only said that he "may". If God exists in one world, then yeah, he must exist in all worlds. But God could also exist in no worlds. God's possibility doesn't necessitate him living in at least one world (and then by extension all worlds). 

Rather, these are rigorous philosophical models about a potential state of affairs.
Okay, so I think the disconnect here is just because you're misusing "possible". By possible, I mean that something could exist, or it could not. That doesn't necessitate the possible thing existing. If God being "possible" necessitates him being real then he is no longer possible, because something that is possible cannot be 100% real, there must be a chance that it isn't real. God is either possibly real or real, there is no in-between. This is not how you used "possible". You used it to mean that God must exist in some world. I do not concede the point that God must exist in some world. I do concede the point that God may exist in some world. I do concede that if he is real in one world then he must be real in all worlds. 

There exists a logical state where a MGB (a being that is omnipotent, omnipresent, morally perfect, and necessary being) exists.
Okay, so you're just using a really weird philosophical definition of the word possible. I do not concede this point, and now I can see that I really was denying P1.

The key of 5S modal logic is that if this being is logically coherent then it must exist in every possible state of affairs, including our own. 
This is the part you didn't explain very well, and I still don't quite understand. God is logically coherent, but that doesn't necessitate his existence. The Padres winning the world series is logically coherent but as a long suffering fan, I can tell you that it hasn't happened. 

To define my terms even more, I'd say God is possible under my definition. It is logically coherent for God to exist or to not exist. However God is not "possible" if that means he must exist in some world.

Let’s draw an analogy: possible worlds are like valid sequences in chess. Imagine we were playing a game and I could play checkmate on the next move and win the game. This is a 'possible' world because it is a logically consistent and follows the rules of chess. In the game are two possible scenarios for my next move: 1) I find the move and win the game; or 2) I don't find the move and the game continues (I could later win the game in a different manner or even lose the game because of that single critical flaw). 
Okay, I'm following your analogy so far, but I'd like to clarify that neither of those possible worlds really exists. By the end, one of them will exist, but currently I have not made a move, and thus the condition for both of those worlds to exist has not been met. These worlds are also in direct contradiction to each other, so they cannot both exist in the future. There cannot be a world where I have my cake and ate it too.

Similarly, a possible world n modal logic is this type of analysis. What types of worlds are logically coherent and could materialize given the rules of modal logic. If an MGB is logically coherent, then like the chess game there is only one possible scenario: The MGB materializes and is real in the actual world. 
But in the chess game there is a choice, so why not with the MGB?

I want to clarify this premise as my opponent badly misunderstands modal logic. We did not establish that God exists in a world of thought, rather what we established is that a MGB is a logically coherent entity, meaning that there are no internal contradictions within this concept, and that could exist in a potential state of affairs.
Yes, there are no contradictions in the nature of God thus he may exist, or may not. By accepting this premise (which you did), you collapse your whole argument by accepting that God may not be real. However if you really mean that God must exist in some world and that's how you define "possible", then you have yet to back it up and support it. I haven't yet seen how God must exist in some world. The key word in this quote is could.

In our game it is possible that I can checkmate you on the next move. This means that there is at least one valid sequence of moves, consistent with the rules of the game, where checkmate happens. In modal logic this is what is called a possible world - a logically coherent scenario.
But just to reiterate, possible worlds are not real worlds, correct? God existing in a possible world does not make him real as a possible world is not real. If all possible worlds exist in the real world, then the real world contains a cake being had and eaten too, which is a logical impossibility.

Now on the flip side there also exists a scenario where I do not find the move and the game continues. In both scenarios I'm not talking about imaginary chess positions or caricatures, I am talking about a logically valid state of the game based on the rules of chess. In neither scenario do we need an infinite universe nor do we need an infinite number of monkeys typing on keyboards! 
Right, but only one of the worlds materialized. Because there is a possibility in God, then that necessitates a choice. The choice is between God existing and not existing. We have no way of knowing which is the real one, which world actually materialized and which one we live in. 

So to close out this argument, possibility ≠ necessity. If God is possible, then he it is necessary that he may not be real, just as it is necessary that he may be real. It is not necessary for him to be actually real, or actually not real.

Islands and cigarette packs are both contingent entities and thus cannot be necessary and cannot be maximally great. Craig does not apply two different standards, rather he shows why applying concepts of maximal greatness to contingent entities are invalid. This argument fails because P1 is false. An MGI is in incoherent entity. Unlike a MGB, an MGI or a maximally great cigarette pack is logically incoherent. 
But why can God be all great and an island cannot? Saying that God is necessary and islands are contingent doesn't make it so.
 
The MOA does not assume God's existence, but deduces it from the possibility of an MGB. My opponent has already conceded that it is possible.
I never conceded that God must exist in some world, which seems to be how you define the word "possible". I conceded that God may exist in any number of worlds, including zero worlds.

Conclusion

You either mean two things by "possible", and I still can't tell which one is really what you're using. You either mean that God could exist or not (the traditional universe), or that God must exist in some universe. If it's the first one, you've conceded the argument by admitting that it's possible that God may not exist. If it's the second one, I never conceded the point, and you now need to prove that God must exist in at least one world. 

Possible worlds are not worlds based on the definition. If something is possible, then there is a chance it is not real. If there is a chance that a world will not end up being real, then it's not a real world yet, and thus if God exists in that world, then God is not real in that world. To satisfy your BOP you now have to prove that God must exist in a world that is a real world, not a possible world.
Round 3
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Round 4
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