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Author Topic:   Plantinga's ontological argument
DominionSeraph
Member (Idle past 4745 days)
Posts: 365
From: on High
Joined: 01-26-2005


Message 1 of 20 (234716)
08-19-2005 4:08 AM


From Wikipedia:
1. By definition a maximally great being is one that exists necessarily and necessarily is omniscient, omnipotent and perfectly good. (Premise)
2. Possibly a maximally great being exists. (Premise)
3. Therefore, possibly it is necessarily true that an omniscient, omnipotent and perfectly good being exists (By 1 and 2)
4. Therefore, it is necessarily true that an omniscient, omnipotent and perfectly good being exists. (By 3 and S5)
5. Therefore, an omniscient, omnipotent and perfectly good being exists. (By 4 and since necessarily true propositions are true.)
Doesn't 'possibly' = 'It might be true, and it might be false'? If so, don't we have:
1. By definition a maximally great being is one that exists necessarily and necessarily is omniscient, omnipotent and perfectly good.
2. It might be true, and it might be false that a maximally great being exists.
3. Therefore, it might be true, and it might be false that it is necessarily true that an omniscient, omnipotent and perfectly good being exists.
4. Therefore, it is necessarily true that an omniscient, omnipotent and perfectly good being exists.
5. Therefore, an omniscient, omnipotent and perfectly good being exists.
As 'might be true' is inherent in 'might be false', that can be simplified to:
1. By definition a maximally great being is one that exists necessarily and necessarily is omniscient, omnipotent and perfectly good.
2. It might be false that a maximally great being exists.
3. Therefore, it might be false that it is necessarily true that an omniscient, omnipotent and perfectly good being exists.
4. Therefore, it is necessarily true that an omniscient, omnipotent and perfectly good being exists.
5. Therefore, an omniscient, omnipotent and perfectly good being exists.
Doesn't (2) contradict (1), and (4) contradict (3)?
This message has been edited by DominionSeraph, 08-19-2005 04:58 AM

Replies to this message:
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 Message 5 by General Nazort, posted 08-22-2005 12:43 PM DominionSeraph has not replied
 Message 6 by Chiroptera, posted 08-22-2005 12:49 PM DominionSeraph has replied
 Message 7 by clpMINI, posted 08-22-2005 1:45 PM DominionSeraph has not replied

  
AdminAsgara
Administrator (Idle past 2293 days)
Posts: 2073
From: The Universe
Joined: 10-11-2003


Message 2 of 20 (235095)
08-20-2005 9:01 PM
Reply to: Message 1 by DominionSeraph
08-19-2005 4:08 AM



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DominionSeraph
Member (Idle past 4745 days)
Posts: 365
From: on High
Joined: 01-26-2005


Message 3 of 20 (235363)
08-22-2005 2:43 AM


Only 2 places where it might fit are Faith and Belief (since the argument purports to prove that said 'maximally great being' exists), or perhaps Misc Topics.

  
AdminAsgara
Administrator (Idle past 2293 days)
Posts: 2073
From: The Universe
Joined: 10-11-2003


Message 4 of 20 (235410)
08-22-2005 8:44 AM


Thread moved here from the Proposed New Topics forum.

  
General Nazort
Inactive Member


Message 5 of 20 (235516)
08-22-2005 12:43 PM
Reply to: Message 1 by DominionSeraph
08-19-2005 4:08 AM


I don't understand the transition between (3) and (4) in the original argument...

The LORD gave, and the LORD hath taken away; blessed be the name of the LORD.

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 Message 1 by DominionSeraph, posted 08-19-2005 4:08 AM DominionSeraph has not replied

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Chiroptera
Inactive Member


Message 6 of 20 (235519)
08-22-2005 12:49 PM
Reply to: Message 1 by DominionSeraph
08-19-2005 4:08 AM


Here is a link to the original article.
DominionSeraph, the form of the argument is correct. What is being used here is a certain axiom from modal logic: If it is possible for something to be necessarily true, then that something is true. As far as I can see, the logical form of Platinga's argument is valid.
Of course, it depends on you accepting this axiom from modal logic. It sounds kind of fishy to me. I can't argue with the description to which I linked, and it appears it is commonly accepted, but I remain skeptical. But it may be that I'm not used to modal logic, being trained in mathematics.
However, there appears to be a more serious problem, and that is the first premise. Platinga is including "necessarily exists" in his definition of "maximally great being". That doesn't seem right to me. I should think that one should list the characteristics that define "maximally great" and then check that "necessarily exists" is a consequence of the definition.
If I'm just allowed to include "necessarily exists" in the definition, then I can prove the existence of anything using Platinga's argument.
By definition an invisible pink unicorn is a being that necessarily exists and is invisible, pink, and a unicorn.
By definition, Harvey is a space alien that necessarily exists and lives in your basement.
And so forth.
I don't see how "necessarily exists" is a consequence of "omniscient, omnipotent, and perfectly good". In fact, I don't think this definition is even logically consistent; it is already accepted even by Christians that omnipotent does not mean "can do anything" (many people on this very bulletin board have already stated that God cannot act against his nature, for example), but then it's not clear that omnipotent even has a meaning. Once a being has some limitation, it may be possible to have a being that is also limited, but has a little more power -- sort of like "the largest real number less than 1" -- if omnipotent does not mean can do anything, then there may not be a "maximally powerful being".
Also, "perfectly good" is ill-defined -- unless one can demostrate the existence of a non-arbitrary standard of good/bad, then there is nothing to which to compare God, and so one cannot say that he is perfectly good.
I think I must be missing something here, because to me this argument is so sophmoric that I cannot believe that it is actually being discussed as if it has something to say.
This message has been edited by Chiroptera, 22-Aug-2005 05:50 PM

This message is a reply to:
 Message 1 by DominionSeraph, posted 08-19-2005 4:08 AM DominionSeraph has replied

Replies to this message:
 Message 11 by DominionSeraph, posted 08-22-2005 5:58 PM Chiroptera has replied

  
clpMINI
Member (Idle past 5155 days)
Posts: 116
From: Richmond, VA, USA
Joined: 03-22-2005


Message 7 of 20 (235551)
08-22-2005 1:45 PM
Reply to: Message 1 by DominionSeraph
08-19-2005 4:08 AM


My issue with this argument...
If a maximally great being is omnipotent, omniscient, and perfectly good, then why is there suffering?
If you are all powerful, all knowing, and all good, you logically wouldn't let there be suffering.
1.Since you know all that is possible to be known, you realize that a piano was about to fall on my head;
2.Since you are as good as can be, you don't want to see my head bashed in by a falling piano; and
3.Since you are so powerful, you have the ability to keep the piano from falling on my head.
However, pianoes fall on people all the time. Suffering exists, evil exists. Therefore, a "maximally great being (who) is omnipotent, omniscient, and perfectly good" apparently does not.
-clp

Men have nipples. Adam was the first man, created by God in His image. Why does God have nipples?

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Chiroptera
Inactive Member


Message 8 of 20 (235554)
08-22-2005 1:49 PM
Reply to: Message 5 by General Nazort
08-22-2005 12:43 PM


Hello, General Nazort.
The transition between (3) and (4) relies on a certain axiom used in some systems of modal logic: if it is possible that a statement is necessarily true, then the statement is true. Here is a description of that axiom.
So, (3) states: It is possible that it is necessarily true that an omniscient, omnipotent, perfectly good being exists.
Therefore, our special axiom (possible that it is necessarily true = true) allows us to conclude: It is true that an omniscient, omnipotent, perfectly good being exists.

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ramoss
Member (Idle past 602 days)
Posts: 3228
Joined: 08-11-2004


Message 9 of 20 (235613)
08-22-2005 3:39 PM
Reply to: Message 8 by Chiroptera
08-22-2005 1:49 PM


Of course, that is the crux.. The premsis is making some assumptions that are 'begging the question'. It is trying to define 'GOD' into existance.. however, reality has very little to do with philosphical word games.

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Chiroptera
Inactive Member


Message 10 of 20 (235623)
08-22-2005 4:00 PM
Reply to: Message 9 by ramoss
08-22-2005 3:39 PM


Hi, ramoss.
It might be deeper than that, though. It certainly looks like a silly argument to me (for the reasons I mention), yet it made it into a Wikipedia article, and while that is no guarantee of legitimacy I am led to believe that Platinga's argument is being taken seriously by people far more knowledgeable than me.

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DominionSeraph
Member (Idle past 4745 days)
Posts: 365
From: on High
Joined: 01-26-2005


Message 11 of 20 (235657)
08-22-2005 5:58 PM
Reply to: Message 6 by Chiroptera
08-22-2005 12:49 PM


Chiroptera writes:
If it is possible for something to be necessarily true, then that something is true.
Of course, it depends on you accepting this axiom from modal logic. It sounds kind of fishy to me.
Sounds kinda contradictory to me, since the premise allows for it to be false.
1. (It is true that) it might be false that X is necessarily true.
2. Therefore, it is false that it might be false that X is necessarily true.
Premise says it's true; conclusion says it's false.

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 Message 6 by Chiroptera, posted 08-22-2005 12:49 PM Chiroptera has replied

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 Message 13 by Chiroptera, posted 08-22-2005 9:16 PM DominionSeraph has replied

  
Chiroptera
Inactive Member


Message 12 of 20 (235711)
08-22-2005 8:09 PM
Reply to: Message 11 by DominionSeraph
08-22-2005 5:58 PM


I can't claim to understand modal logic completely, my understanding is this is a perfectly valid axiom in modal logic -- that is, it is not contradictory. You are free to accept it if you wish.
On the other hand, it is an axiom, and so you are free to not accept it if you wish.
When axioms are accepted, it is because they are "self-evident" but cannot be proven from the other axioms. I can see how this axiom can be self-evident to someone. The argument in the Wikipedia article to which I linked makes sense. However, I cannot claim that it is self-evident to me -- as I hinted, the argument in the article doesn't quite convince me.
At any rate, in my opinion, even if we accept this axiom, Platinga's argument has more serious problems.

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Chiroptera
Inactive Member


Message 13 of 20 (235737)
08-22-2005 9:16 PM
Reply to: Message 11 by DominionSeraph
08-22-2005 5:58 PM


a thought
DominionSeraph, it just occurred to me why you don't like the axiom that is being used in Platinga's argument. I think you may be trying to read it as if it were a plain English sentence. Well, it is actually a statement in logic, where the words have a rather precise meaning.
If this is your problem, then maybe these articles on modal logic and possible worlds (not to be confused with the Many Worlds interpretation of quantum mechanics) will help you understand.

This message is a reply to:
 Message 11 by DominionSeraph, posted 08-22-2005 5:58 PM DominionSeraph has replied

Replies to this message:
 Message 15 by DominionSeraph, posted 08-23-2005 12:58 AM Chiroptera has replied

  
ramoss
Member (Idle past 602 days)
Posts: 3228
Joined: 08-11-2004


Message 14 of 20 (235758)
08-22-2005 9:55 PM
Reply to: Message 10 by Chiroptera
08-22-2005 4:00 PM


I think it is taken seriously by people who NEED to believe. However, logic is only as good as an assumption, and it seems to me many of the assumptions just don't hold up.
It seems to me the assumptions are designed to come to the conclusion.

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DominionSeraph
Member (Idle past 4745 days)
Posts: 365
From: on High
Joined: 01-26-2005


Message 15 of 20 (235807)
08-23-2005 12:58 AM
Reply to: Message 13 by Chiroptera
08-22-2005 9:16 PM


Re: a thought
Thanks. However, if it is true in one world that X is true in all worlds, it is true in all worlds that X is true in all worlds. So, whenever you're dealing with a 'necessarily', there's really no point in using 'possibly'. So, what we'd end up with is:
1. By definition a maximally great being is one that exists necessarily and necessarily is omniscient, omnipotent and perfectly good. (Premise)
2. Necessarily a maximally great being exists. (Premise)
3. Therefore, necessarily it is necessarily true that an omniscient, omnipotent and perfectly good being exists (By 1 and 2)
So, it's a circular argument, as 'possibly necessary' = 'necessarily necessary. He's starting with the assumption that this being exists in all possible worlds, and concludes that this being exists in all possible worlds. There's just an additional layer of, "It is true in all worlds," and a detour through, "It is true in at least one world," to mask it.
This message has been edited by DominionSeraph, 08-23-2005 01:01 AM

This message is a reply to:
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