Jason Dulle

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Can God's Existence be Logically Necessary?
« on: November 10, 2009, 02:48:32 am »
 

As I understand it, the ontological argument attempts to prove that God’s existence is logically necessary, not just factually necessary.  But how could this be?  If there is no logical contradiction entailed by a denial of God’s existence, why think His existence is just as logically necessary as are the laws of logic (the denial of which does entail a logical contradiction)?

 

Someone on this forum once offered some thoughts that I think might apply to the question at hand, but I wanted to submit them to the RF community to see if you think they are sound (or know of additional/better responses).  The commenter (I don’t remember the name) argued that while incorrigibility may be a sufficient condition for determining logically necessary truths, it is not a necessary condition.  He (I’m assuming he was a he) noted that there are necessary truths that are unknown to most people, such as advanced mathematical truths.  Additionally, there are necessary truths that are corrigible, such as the necessary truth that Hesperus is identical to Phosphorus.  There are even incorrigible contingent truths, such as knowledge of our own existence. Incorrigibility, then, is not sufficient to judge whether a truth is necessary.  As such, incorrigibility is not sufficient to judge whether God’s existence is a logically necessary truth.

 

Maybe Descartes was right in seeing a difference between a self-evident truth that was immediately self-evident, and one that is discovered to be self-evident upon further reflection.

 

 


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Can God's Existence be Logically Necessary?
« Reply #1 on: November 10, 2009, 02:27:33 pm »
jasondulle wrote:  

As I understand it, the ontological argument attempts to prove that God’s existence is logically necessary, not just factually necessary.  But how could this be?  If there is no logical contradiction entailed by a denial of God’s existence, why think His existence is just as logically necessary as are the laws of logic (the denial of which does entail a logical contradiction)?

 


 

 


Well, some people have claimed that the non-existence of God is logically impossible. Chapter 3 of the Proslogion argues "That God cannot be thought no to exist".

As to the interesting point about necessary/incorrigible truths and combinations thereof, the example of an incorrigible contingent truth you came up with was one's knowledge of one's own existence. The reason why one's own existence is not neccesary is because it depends upon factors outside of oneself, and because one's own existence is not entailed by one's essence anyway. Yet the reverse of these is true for God if the argument suceeds. So if (the argument for) God's existence appears incorrigible, he will neccesarily exist (ie. because God only depends on his essence for his existence, which appears to entail it). Therefore here, incorrigibility would entail neccessary truth.

And I agree viz. Descartes.

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Jason Dulle

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Can God's Existence be Logically Necessary?
« Reply #2 on: November 10, 2009, 07:16:45 pm »
The question isn't whether the OA succeeds, but how we could consider God's existence to be logically necessary if there is no logical contradiction in denying His existence.  The points I raised about incorrigibility were to possibly show that it is wrongheaded to think that a necessary property of logically necessary truths is the incorrigibility.  And if incorrigibility is not a necessary property of logically necessary truths, then God's existence could be considered logically necessary just as the OA claims.


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Can God's Existence be Logically Necessary?
« Reply #3 on: November 11, 2009, 04:33:04 pm »
jasondulle wrote: The question isn't whether the OA succeeds, but how we could consider God's existence to be logically necessary if there is no logical contradiction in denying His existence.  The points I raised about incorrigibility were to possibly show that it is wrongheaded to think that a necessary property of logically necessary truths is the incorrigibility.  And if incorrigibility is not a necessary property of logically necessary truths, then God's existence could be considered logically necessary just as the OA claims.


Fine, but surely we need to examine Anselm's claim that denying God's existence is a logical contradiction (see the reference I supplied earlier).

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Jason Dulle

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Can God's Existence be Logically Necessary?
« Reply #4 on: November 11, 2009, 06:27:18 pm »
That is the claim I am examining.  The OA attempts to prove that God's existence is logically necessary.  What I am seeking to know is how it can be thought of as logically necessary, if there is no logical contradiction in denying it.  Usually when we think of a logically necessary truth we are thinkging of truths that cannot be denied without encountering a logical self-contradiction.  

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Randy Everist

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Can God's Existence be Logically Necessary?
« Reply #5 on: November 12, 2009, 10:44:56 am »

jasondulle wrote: That is the claim I am examining.  The OA attempts to prove that God's existence is logically necessary.  What I am seeking to know is how it can be thought of as logically necessary, if there is no logical contradiction in denying it.  Usually when we think of a logically necessary truth we are thinkging of truths that cannot be denied without encountering a logical self-contradiction.  

If the OA succeeds, I submit there is in fact a logical contradiction. For a contradiction is something that purports "a" and "not-a" at the same time and in the same sense.

This fact was illustrated to me when I was debating someone concerning the OA. He offered an alternate argument, one that went like this:

1'. It is possible that a maximally great being does not exist.
2'. If it is possible that it does not exist, then it does not exist in some possible world (thus contradicting the premise that it exists in all possible worlds).

I considered this before realizing that if the OA is taken as true, then the conclusion is such that it renders (1') false. After all, something is necessary if it is not possible that not-p; and something is possible if it is not necessarily not-p. So if God's existence is necessary (as the conclusion purports) then we should have no problem in denying (1') as impossible. So I think the success of the OA can be central, for if it is true then it is not possible for God not to exist; ie, His existence is logically necessary.
"Every great man was thought to be insane before he changed the world. Some never changed the world. They were just insane."

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Jason Dulle

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Can God's Existence be Logically Necessary?
« Reply #6 on: November 12, 2009, 01:38:24 pm »
I'm beginning to think my question was not worded clearly enough because the responses you have provided (of which I appreciate) are not getting to the heart of my question.  So let me attempt to clarify.

I am not asking whether God's existence is logically necessary.  If the OA is successful, then it follows that God's existence is logically necessary.  But some people think there must be something wrong with the OA (even if they can't put their finger on it) because they presuppose that for a truth to be logically necessary its truth must be self-evident, and/or its denial must entail a logical contradiction.  

For example, for someone to deny logic requires that he use logic, and thus it is self-evident that logic is, well, logically necessary.  But God's existence does not appear to be self-evident in this way (if it was self-evident, we wouldn't need the OA to prove it), and there is no logical contradiction in denying God's existence.  So anyone who thinks logically necessary truths must be self-evident and/or their denial must entail a logical contradiction tend to doubt the validity of the OA.  

It seems to me that to answr this objection, one would have to demonstrate that it is not required of logically necessary truths that they be (1) self-evident or (2) that their denial entail a logical contradiction.  Would anyone agree with this assessment?  If so, how would you go about demonstrating this?  Would the examples provided in my initial post suffice?

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Can God's Existence be Logically Necessary?
« Reply #7 on: November 12, 2009, 01:55:30 pm »
Sorry to butt in, but I too reject the assertion that God's non-existence is not logically contradictory. Anselm's argument in Proslogion 2 and 3 is reductio ad absurdum, and aims to show that God's non-existence in re is logically incompatible with his existence in intellectu. Therefore, if correct, this does show your assumption to be false, since God is necessarily possible, if he is possible. As to your point that if Anselm is right that God's non-existence is logically impossible, he answers this in Proslogion 4 by pointing out that the only way to think this is if one is indeed insipiens! (not that I'm accusing anyone!)

I hope this answers your objection, although for Plantinga's argument, it may be more valid, although RandyE may have answered this.


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Randy Everist

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Can God's Existence be Logically Necessary?
« Reply #8 on: November 12, 2009, 01:59:42 pm »

jasondulle wrote: If the OA is successful, then it follows that God's existence is logically necessary.  But some people think there must be something wrong with the OA (even if they can't put their finger on it) because they presuppose that for a truth to be logically necessary its truth must be self-evident, and/or its denial must entail a logical contradiction.  

For example, for someone to deny logic requires that he use logic, and thus it is self-evident that logic is, well, logically necessary.  But God's existence does not appear to be self-evident in this way (if it was self-evident, we wouldn't need the OA to prove it), and there is no logical contradiction in denying God's existence.  So anyone who thinks logically necessary truths must be self-evident and/or their denial must entail a logical contradiction tend to doubt the validity of the OA.

I appreciate what you're trying to ask, but I would submit that though the first part is true (that God's existence is not immediately self-evident), the OA provides us reason to think that denying his existence is indeed a logical contradiction. For one's objection to the argument is that the conclusion does not entail God's necessary existence because denying his existence wouldn't be a logical contradiction; but this is false. If His existence is necessary, then it means it is not possible that God does not exist. Of course, this is apparently NOT what you are asking, and rather asking if the criteria given are good tests of whether or not something is a necessary truth.

It seems to me the criteria may itself not live up to its own standard. For instance, it doesn't seem self-evident to me that all necessary truths must be self evident (especially given your objections stated in the op[?]). There also seems to be no logical contradiction in saying that the truth that "all necessary truths must be either a) self-evident or b) result in a contradiction if denial occurs" is not true. If that is the case, then the aforementioned truth is not a necessary one. If that is the case, then that truth is contingent. But then we must ask, contingent on what? Those necessary truths conforming to that standard? If that is the case, then it is not necessarily true that God's existence could not be a necessary truth (though I do think the OA establishes that it fits one of the criteria anyway).

Your objections do seem to be sufficient, in any case. These are just my thoughts.

"Every great man was thought to be insane before he changed the world. Some never changed the world. They were just insane."

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Jason Dulle

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Can God's Existence be Logically Necessary?
« Reply #9 on: November 12, 2009, 06:47:08 pm »

Scotus17 wrote: Sorry to butt in, but I too reject the assertion that God's non-existence is not logically contradictory. Anselm's argument in Proslogion 2 and 3 is reductio ad absurdum, and aims to show that God's non-existence in re is logically incompatible with his existence in intellectu. Therefore, if correct, this does show your assumption to be false, since God is necessarily possible, if he is possible. As to your point that if Anselm is right that God's non-existence is logically impossible, he answers this in Proslogion 4 by pointing out that the only way to think this is if one is indeed insipiens! (not that I'm accusing anyone!)

I've just barely started studying the OA a few months ago, so I am no expert, but it appears to me that most people (including Plantinga, Peter Williams, and I believe WLC as well) agree that Anselm's and Descartes' formulation of the argument was fallacious (for various reasons, not the least of which is Anselm's equivocation between the idea of the greatest conceivable being and a real greatest conceivable being).  The versions Craig and Plantinga put forth do not involve the reductio ad absurdum (RAA) approach that Anselm used.  If a successful version of the OA does not entail a RAA, then we can't say the OA shows that a denial of God's existence is logically contradictory.  

But even if all that I just said is rubbish, I think your comment misses the point.  People who object to the OA are saying that on its face, God's existence cannot be logically necessary because that proposition itself is not self-evident, and denying it does not entail a logical contradiction.  After all, if you need to formulate an argument in order to prove that God's existence is logically necessary, then its clear that such a proposition is not self-evident, at least not immediately self-evident (like Descartes said).  They are not saying that God's existence doesn't appear to be logically necessary after one has read and believed the OA.  They are saying God's existence does not appear to be logically necessary prior to reading the OA, and that's why they have a difficult time accepting the validity of the OA: becuase it would require that they believe God's existence is logically necessary, even though God's existence does not meet either of their requirements for a logically necessary being: (1) self-evident; (2) its denial entails a logical contradiction.


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Randy Everist

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Can God's Existence be Logically Necessary?
« Reply #10 on: November 13, 2009, 07:34:11 am »

jasondulle wrote: They are saying God's existence does not appear to be logically necessary prior to reading the OA, and that's why they have a difficult time accepting the validity of the OA: becuase it would require that they believe God's existence is logically necessary, even though God's existence does not meet either of their requirements for a logically necessary being: (1) self-evident; (2) its denial entails a logical contradiction.

If I may, I think I can shed some light here (at least for me). It seems, under this method of reasoning, that they are really saying that (2) is entailed by (1), and not separate from it. For instance, they are saying that, without any other evidence, its denial does not entail a logical contradiction. But why should that be so? Only if we should also expect it to be self-evident. But demanding that all necessary truths should be self-evident and its denial entails a logical contradiction is not a necessary truth in and of itself (for the self-same reasons) and thus does not apply.

Knowing if something entails a logical contradiction can also be related to background knowledge. Typically, this is done through a definition. One who didn't know what a "square" or "circle" was would not immediately know they were logically contradictory when combined. The point is that, if the OA succeeds, we have the background knowledge sufficient to say God's existence is necessary; and then the onus is on the affirming party to provide a reason why God's existence is possible (and conversely on one to say it is impossible).

Finally, philosophers of all stripes recognize that in order for a truth to be necessary, the criteria is simply that it is not possible that not-p. So, in order for God's existence to be necessary it only must be not possible that God does not exist. Necessity does not require that, sans any arguments (self-evidence), it is not possible that not-p. For all "necessary" really means is that it must be, and regardless of how we arrive at that conclusion, as long as it is justified (and true), it is necessary.
"Every great man was thought to be insane before he changed the world. Some never changed the world. They were just insane."

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Jason Dulle

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Can God's Existence be Logically Necessary?
« Reply #11 on: November 13, 2009, 12:58:02 pm »

RandyE wrote: It seems to me the criteria may itself not live up to its own standard. For instance, it doesn't seem self-evident to me that all necessary truths must be self evident.... There also seems to be no logical contradiction in saying that the truth that "all necessary truths must be either a) self-evident or b) result in a contradiction if denial occurs" is not true. If that is the case, then the aforementioned truth is not a necessary one. If that is the case, then that truth is contingent. But then we must ask, contingent on what? Those necessary truths conforming to that standard? If that is the case, then it is not necessarily true that God's existence could not be a necessary truth (though I do think the OA establishes that it fits one of the criteria anyway).

Good point!  I am wondering, however, if someone might respond to this by saying it is a red herring, because they never claimed that their two criteria for identifying necessary truths are themselves necessary truths. They could fully agree that they are contingent truths.  So then it boils down to examining whether there are good grounds for thinking those contingent criteria are valid. And it seems you agree with me that they are not.  Thus, it would follow that the OA does demonstrate that God’s existence is logically necessary.

I like what you had to say in post #11 about background knowledge. I think you are right.  We should not judge whether a truth is necessary based on some criteria that we take to the evidence, but rather our criteria should be informed by genuine instances of necessary truths. Since the OA demonstrates that God’s existence is logically necessary, a rational person should conclude that necessary truths need not be immediately self-evident or entail a logical contradiction when denied, since they have discovered a necessary truth that is not immediately self-evident.

I think your last paragraph is extremely helpful.  Indeed, what makes something necessary is that not-p is impossible, not that not-p is immediately self-evident. Just like mathematical truths may not be self-evident, once the terms are understood and the reasoning discovered, we see that they are self-evidently (though not immediately) and necessarily true.



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Can God's Existence be Logically Necessary?
« Reply #12 on: November 13, 2009, 01:15:46 pm »
Agreed, although I don't think we should dismiss Anselm's approach so easily (I actually prefer it to Plantinga's), since Charlesworth shows that "existence is not a predicate" is unreasonable. But that is another discussion.  

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Jason Dulle

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« Reply #13 on: November 13, 2009, 01:22:44 pm »

Scotus17 wrote: Agreed, although I don't think we should dismiss Anselm's approach so easily (I actually prefer it to Plantinga's), since Charlesworth shows that "existence is not a predicate" is unreasonable. But that is another discussion.

The problem I've seen leveled most at Anselm's approach is the one I mentioned in my earlier comments: equivocating between the concept of a being of which none greater can be conceived, and an actual being of which none greater can be conceived.  So even if we agreed that existence is a predicate, Anselm's version of the OA would still flounder.


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Can God's Existence be Logically Necessary?
« Reply #14 on: November 13, 2009, 02:00:41 pm »
Well, I don't precisely understand your objection.

But it seems reasonable to me to conceive of something of existing in the mind (or one can read, in possibility for in intellectu,) as one manner of the existence of something, and of something existing in re as another. A chair in possibility is not different from one in reality in terms of essence. Indeed, Kant's analysis of "existence is not a predicate" shows that a thing existing conceptually (or in possibility) differs in no predicate from something existing in reality. Therefore to claim these are different things entirely seems silly.

My claim is not that existence is a predicate, but a meta-predicate (ie. the ability to be predicated in a particular manner). So Anslem contends that things with the same predicates can exist in different ways. That, I think, is not conflation, since it shows that something's essence is conceptually separate from the question of it's manner of existence (but in the case of God, and other necessarily existent things, not actually separate.