Plantinga's ontological argument

Originally posted by googlefudge
It is simply enough to say that it is a positive claim that actually needs to be demonstrated
and can't just be assumed.

Yes - but you are the one making the stronger claim! The theist here is claiming that G's existence is possible - in other words, the likelihood of it is greater than 0%. This is a very weak claim. To deny this claim, you must assert that the likelihood of G's existence is 0%.

Originally posted by SwissGambit
def. [b]God: a being which is "maximally excellent" in every possible world. Maximal Excellence includes such properties as omniscience, omnipotence, and moral perfection. A being which has maximal excellence in every possible world would have "maximal greatness."

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

2. If it is pos ...[text shortened]... accept the argument entirely. For my atheist brethren: which premise(s) would you reject?[/b]

I do not accept the 2nd premise so I saw no need to examine the remainder. I reason that just because something is possible, like evolution, does not mean it actually exists. HalleluYah !!! Praise the Lord! 😏

Originally posted by RJHinds
I do not accept the 2nd premise so I saw no need to examine the remainder. I reason that just because something is possible, like evolution, does not mean it actually exists. HalleluYah !!! Praise the Lord! 😏

Wow, 2 rejections of premise 2 so far. That's 2 more than I thought I would get. 😵

Originally posted by SwissGambit
def. [b]God: a being which is "maximally excellent" in every possible world. Maximal Excellence includes such properties as omniscience, omnipotence, and moral perfection. A being which has maximal excellence in every possible world would have "maximal greatness."

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

2. If it is pos ...[text shortened]... accept the argument entirely. For my atheist brethren: which premise(s) would you reject?[/b]

the premises are logically sound until #3, which is a false assumption. premise #4 is meaningless in context and premise #5 is actually a conclusion so it doesn't apply as a premise.

the only conclusion that can be drawn from the first two hypothetical premises is that a maximally great being exists somewhere which has the undefined characteristics of excellent omniscience, omnipotence and morality.

note these premises have to be taken as what they are; assumptions to support a conclusion. neither premises nor conclusions derived from them are necessarily valid unless they can be shown to be true. in this case, premise #1 cannot be shown to be true. it must remain an assumption for speculative thought.

Originally posted by SwissGambit
def. [b]God: a being which is "maximally excellent" in every possible world. Maximal Excellence includes such properties as omniscience, omnipotence, and moral perfection. A being which has maximal excellence in every possible world would have "maximal greatness."

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

2. If it is pos accept the argument entirely. For my atheist brethren: which premise(s) would you reject?[/b]

The problem with this type of argument is that a "possibility" gets transformed into a "necessity" over a number of steps when the fact remains that it is still only a possibility. The language should reflect this fact in all instances where it is referenced otherwise information gets lost.

For example #2 should read as follows:
"2. If it is possible that a maximally great being exists, then a maximally great being [possibly] exists in some possible world.

There are similar problems throughout.

Originally posted by SwissGambit
Wow, 2 rejections of premise 2 so far. That's 2 more than I thought I would get. 😵

This sounds more like hypothetical stuff to me. So this is the last time I am looking at this thread because it does not interest me.

Originally posted by VoidSpirit
the premises are logically sound until #3, which is a false assumption. premise #4 is meaningless in context and premise #5 is actually a conclusion so it doesn't apply as a premise.

the only conclusion that can be drawn from the first two hypothetical premises is that a maximally great being exists somewhere which has the undefined characteristics of ...[text shortened]... , premise #1 cannot be shown to be true. it must remain an assumption for speculative thought.

We are pretty much in agreement. Note that I did offer some possible definitions of omnipotent [ability to do anything logically possible], omniscient [knows all true propositions], and morally perfect [always prefers the most good state of affairs].

Originally posted by ThinkOfOne
The problem with this type of argument is that a "possibility" gets transformed into a "necessity" over a number of steps when the fact remains that it is still only a possibility. The language should reflect this fact in all instances where it is referenced otherwise information gets lost.

For example #2 should read as follows:
"2. If it is possible ...[text shortened]... t being [possibly] exists in some possible world.

There are similar problems throughout.

So you would reject Premise 2 as it is written?

Originally posted by RJHinds
This sounds more like hypothetical stuff to me. So this is the last time I am looking at this thread because it does not interest me.

No, it's not hypothetical - two people, including you, actually rejected it. 😵

Don't let the door hit you on the way out.

Originally posted by SwissGambit
So you would reject Premise 2 as it is written?

As written, I reject the entire line of thought. The premise is that it is "possible" that a "maximally great being exists". That it is only a "possibility" gets lost in #2. Each subsequent "premise" is built upon this and is tainted.

For example #3 should begin as follows:
3. If a maximally great being [possibly] exists in some possible world...

The conclusion doesn't make any sense whatsoever in that context:
"then it exists in every possible world."

So unless there's something more to it, I don't see anything of value.

Originally posted by ThinkOfOne
As written, I reject the entire line of thought. The premise is that it is "possible" that a "maximally great being exists". That it is only a "possibility" gets lost in #2. Each subsequent "premise" is built upon this and is tainted.

For example #3 should begin as follows:
3. If a maximally great being [possibly] exists in some possible world...

T ...[text shortened]... e world."

So unless there's something more to it, I don't see anything of value.

Wow, 3 and counting!

I don't see why Premise 2 needs any added words or modification. As stated earlier, it seems obvious that if god's existence is possible, then he must exist in at least one member of the set of possible worlds.

I think the 'possibility' bit does not morph into something more until we hit Premise 3.

Originally posted by SwissGambit
Tell me more about why you reject premise 1.

I think much of the argument is based on wordplay with the definition and premise 1. The definition suggests that the entity must be possible in all possible worlds and be maximally great in all possible worlds, then the later steps try to make it look like the argument is cumulative starting with single words then using the definition to expand it.

I would therefore reject premise 1. because each possible world is different and therefore the maximally great possible being in each world should be different so it should not be possible to have a being that is maximally great in every possible world. More importantly it should not be possible to have any being that could exist in every possible world. For any attribute of a being, there may be a possible world in which that attribute is not possible. For example suppose a being is red. Maybe there is a possible world that does not have the colour red. Once you specify more attributes it becomes even less possible.

[edit]
To take your definition of omniscient [knows all true propositions], presumably there are is a different set of true propositions in different possible worlds. Therefore a being that knows all true propositions in one possible world would not know them in another possible world and the defined maximally great being could not exist.

Originally posted by SwissGambit
Are you a non-determinist because of Quantum Mechanics?

Yes.

Originally posted by SwissGambit
def. [b]God: a being which is "maximally excellent" in every possible world. Maximal Excellence includes such properties as omniscience, omnipotence, and moral perfection. A being which has maximal excellence in every possible world would have "maximal greatness."

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

2. If it is pos accept the argument entirely. For my atheist brethren: which premise(s) would you reject?[/b]

I reject 2 and 3.

2 implies hat because something is possible then it must be so; this is subject to the multiverse theory being actualised and negates 1 which uses "possible" as being "possible" within the realm of our existant universe.

I reject 3 because I don't see why it follows that even if 2 is true, that that "true" should be "true" for all universes. Furthermore, if 2 and 3 were true there would be an infinite number of maximally great beings.

Originally posted by SwissGambit
def. [b]God: a being which is "maximally excellent" in every possible world. Maximal Excellence includes such properties as omniscience, omnipotence, and moral perfection. A being which has maximal excellence in every possible world would have "maximal greatness."

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

2. If it is pos accept the argument entirely. For my atheist brethren: which premise(s) would you reject?[/b]

If we hold to S5 modal logic, then I think Premise 3 just follows trivially from P's own definitions of his world-indexed properties and thus cannot be reasonably rejected. For instance, P states "The property has maximal greatness entails the property has maximal excellence in every possible world". Based on P's formulation, I think it should follow that 'maximal greatness' is a property that is either instantiated in every possible world or not instantiated at all. So, I would not reject Premise 3 (though, I think it could be rejected on the grounds that S5 is not the right system here, in virtue of P's use of world-indexed properties).

Premise 1, though, needs to be rejected. The problem again goes back to P's use of world-indexed properties. Premise 1 seems innocuous enough because it is very natural for us to infer from non-contradiction to mere possibility and thus to possible worlds. For instance, if a property does not itself entail contradiction, then it is ordinary to conclude that there is some possibility that this property is instantiated; and to the extent that 'maximal greatness' does not itself entail contradiction, it is natural to infer that there is some possibility that maximal greatness is instantiated (and it is this which is supposed to constitute the justification for Premise 1). This pattern of inference from internal consistency to an associated possibility or a possible world is fine, if the possible worlds are independent of each other. However, within P's system of world-indexing here, the possible worlds are not independent of each other because, for example, properties in some possible world entails properties in others. The upshot is that the pattern of inference from non-contradiction to possibility or a possible world is no longer innocuous, since the possible world associated with some non-contradiction may in fact be inconsistent with the possible world associated with some different non-contradiction. We have no good reason here to accept Premise 1.

At the very least, we can say this: if the only proposed justification for accepting Premise 1 is that we ought to infer from non-contradiction of a property to the possibility that the property is instantiated; then that is wholly inadequate in this particular case. We can see that it is inadequate by considering another term defined by P as 'no-maximality', which is basically the counter-concept of maximal greatness (the one is exemplified where the other is not and vice versa). We could then construct a similar argument as follows:

1*. It is possible that no maximally great being exists.
2*. If it is possible that no maximally great being exists, then no-maximality is exemplified in some possible world.
3*. If no-maximality is exemplified in some possible world, then it is exemplified in every possible world.
4*. If no-maximality is exemplified in every possible world, then it is exemplified in the actual world.
5*. Therefore, it is not the case that a maximally great being exists.

Now, if the justification that it is natural to infer from non-contradiction to possibility were good enough for Premise 1, it should also be good enough for Premise 1*. But, this leads one to taking on possible worlds that are, in fact, incompatible with each other. The sensible conclusion here is that there is clearly something wrong with this pattern of inference for this case that features world-indexed properties (at least when conjoined with the S5 system).

If you want a short, but good in my opinion, refutation of P's ontological argument, you can check out the section in Mackie's The Miracle of Theism that deals specifically with P's argument. Mackie thrashes P's argument.