Tuesday, August 10, 2010

Plantinga's Possible World's Argument

 





This is based upon and largerly taken from the website of a professor of Philosphy nemed Forest Baird. Unfortunatley his stie is no longer up.

P1 A thing has maximal greatness if and only if it has maximal excellence in every possible world.

P2 Whatever has maximal excellence is omniscient, omnipotent and morally perfect.

P3 There is a possible world in which the property of possessing maximal greatness is exemplified.

P4 The property of possessing maximal greatness is exemplified in every possible world.

P5 If maximal greatness is exemplified in every world, then it is exemplified in this world.




Baird:

Quote:


Plantinga is a leading figure in what is called "analytic philosophy." This type of philosophy represents not so much a particular content as a method of dealing with philosophical problems. The method uses rigorous logical analysis of propositions using a number of rather technical logical concepts.

Like others who use this method, Plantinga's work is difficult to understand without some background in logic. Plantinga uses a system of modal logic that is on the cutting edge and still the topic of much debate. He relies heavily on certain theorems about modal operators that are not universally accepted. Many articles that critique his work are written almost entirely in symbolic logic and so are not accessible to most students.(24) But by first examining some key concepts Plantinga uses, we should be able to make sense of his version of the argument.


A. Concepts


1) Possible Worlds.


Baird

Quote


"Plantinga begins his discussion of the ontological argument by borrowing seventeenth century philosopher Leibniz' idea of "possible worlds." A possible world is a possible state of affairs. So, for example, there is a possible world in which I am able to execute dazzling slam dunks and a possible world in which I am lucky to make a basket at all. The second of these, but certainly not the first, is actual or "obtains." But both of these worlds are possible. While the first does not obtain, there is nothing that is logically impossible about it. On the other hand, a world in which I play basketball with a round square is not possible. Such a world not only does not obtain, it could not obtain."(25)

"Turning to the ontological argument, Plantinga rewrites the argument in terms of possible worlds. Instead of using a premise which says that God's existence is possible, Plantinga says that God exists in a possible world. If God's existence is possible, then there must be a possible world in which God exists. Of course that possible world might not be this world--just as the possible world in which I can slam dunk is not this world. But if God's existence is at least logically possible (i.e., the concept of God's existence is not a concept like "round square"), then there is a possible world in which God exists."




2) Possible Beings.


Baird
"Immediately after stating that there is a possible world in which God exists, Plantinga makes a revision of this statement. To say "There is a possible world in which God exists" is to talk about God as a possible being. Both Malcolm and Hartshorne had assumed that this makes sense: that one can talk about God as a possible being and discuss the qualities of this possible being. Plantinga questioned this assumption."


B. Properties rather than beings.



"But, Plantinga argues, it does not make sense to speak of merely possible beings, beings that don't in fact exist. We can't say that "X does not exist" leads to the statement "there is an X such that X does not exist." This would be like saying "there is a thing that does not exist." If it does not exist we can't say "there is a thing...." Or, we can't say "there is a thing such that this thing does not exist." Plantinga suggests that we should be talking about properties. Rather than talking about wheather a particular being exists, we should talk about the exemplification of certain properties. Is there an instance of this property in a possible world. Baird says:"

"Consider the case of the property of being able to execute dazzling slam dunks. In one possible world (the actual world) that property is exemplified by Michael Jordan (and others). In another possible world (the one of my imagination) that property is exemplified by Forrest Baird. In yet another possible world that property is exemplified by some unidentified being. But in all three cases we are talking about the property of being able to execute dazzling dunk shots. We can ask whether or not that property is exemplified in a particular possible world without talking about the being that exemplifies it."

"By revising the argument in terms of properties, Plantinga makes the argument immune to Kant's criticisms about existence not being a predicate. The argument is no longer talking about a thing that may or may not have certain predicates--including existence. It is now an argument about certain predicates and whether or not there is an instance of them. Plantinga even disagrees with Malcolm and Hartshorne about necessary existence. Plantinga holds that not only is existence not a predicate, neither is necessary existence": As Plantinga Says:"

"...A being has no properties at all and [therefore] no excellent-making properties in a world in which it does not exist. So existence and necessary existence are not themselves perfections, but necessary conditions of perfection."(28) "A being must first exist to have any perfections, so existence, of any type, cannot be one of the perfections a being has."(29)


C. Maximal Greatness.



"Rather than thinking of God in terms of a being, "that which none greater than can be concieved," Plantinga thinks in terms of the property of "maximal greatness" or the property of unsurpassible greatness; none other could possess such a quality for there can only be one such manifestation of this property. If two beings were each "the greatest possible being" wich would be greater than the other?"


But Plantinga doesn't talk about a being with this property. Rather, he asks, is the properly exemplified in any possible world? Maximal greatness, or Maximal excellence would consist of omniscience, omnipotence and moral perfection, so the question is, is this quality exemplified in any possible world? But this still doesn't mean that this quality is exemplified in our world. In some other possible world the maximal greatness might be petty in our world. But Plantinga argues: "...The greatness of a being in world W [any given possible world] depends not merely upon the qualities it has in W; what it is like in other worlds is also relevant." (in Baird) (32) So greatness is relative from one world to another. But to have the property of maximal greatness a being would have to be the greatest in all possible worlds.


D. The Point of the Argument.


1) Plantinga's Modal Version of the Argument.



P1 A thing has maximal greatness if and only if it has maximal excellence in every possible world.
P2 Whatever has maximal excellence is omniscient, omnipotent and morally perfect.
P3 There is a possible world in which the property of possessing maximal greatness is exemplified.
P4 The property of possessing maximal greatness is exemplified in every possible world.
P5 If maximal greatness is exemplified in every world, then it is exemplified in this world.


Barid says:


"This argument is valid in its logical structure, but is it sound and persuasive? As mentioned above, to be sound means that the premises must be true and to be persuasive means that most persons would accept the truth of the premises. P1 and P2 are both given as definitions of terms. Plantinga stipulates them as the definitions of the terms he is using.(34) They are, quite literally, true by definition. P4 follows from P1 and P3. Given P1 and P3 there must be some individual (let's call that individual "x") that exists and has maximal excellence in every possible world. No matter what possible world we choose to examine, x would have to have maximal greatness in that world since x possesses maximal excellence in every world. P5 makes the rather obvious point that since our actual world is also a possible world, whatever is true of all possible worlds must be true of this possible world. So P1, P2, P4, and P5 are all true: P1 and P2 by definition and P4 and P5 by logical inference. That leaves only P3".


Plantinga's conclusion:

"What shall we say of this argument? It is certainly valid; given its premises, the conclusion follows. The only question of interest, it seems to me, is whether its main premise--that maximal greatness is possibly instantiated--is true. I think it is true; hence I think this version of the ontological argument is sound." [In Baird](35)


2. The Possibility of God's Existence.


But can he really prove P3? That might require making a whole other proof for a skeptic.However, God's existence is certainly possible in some possible world. Like Hartshorne he argues that if God is possible than he is necessary, or there is no sense in speaking of a merely possible necessary being. If God exists than God's existence cannot be a contingent fact. To question this would be like questioning whether tables are things to put things on. That is what God is, necessary being, and if God is not actually necessary than he is impossible but cannot be merely possible. God is not like other beings who may or may not exist. If my Parents had met different people and been married to them rather than each other I would not be me, but they might or might not have had any children at all.This might have happened, therefore, I might or might not have come to be. My existence is contingent. But God is not like this, he either must exist or else it is impossible that he could exist, but there is no "might or might not" in the equation.

If God might exist in some possible world he must exist in all possible worlds.

E. Objections.


1) Tooley, revese possible world thinking.


Michael Tooley try's to reverse Plantinga's argument by saying that a statement that is not self contradictory is true in some possible world. So to to say "there is no maximally great being"is true in some possible world. The statement "there may be a unicorn" must be true in some possible world because it could be true. But reversing Plantinga's logic, the talk about a maximally great being must apply to all possible worlds and so there cannot be a maximally great being! [this is in Dr. Baird's notes]


Answer: Mark Stasser comes to the resue in arguing that Plantinga could say that "there is an X" could be true in some possible world unless it is contradictory. If X is the maximally great being. In that case X would have to be true in all possible worlds since a maximally great being could not be merely possible. Both Tooley and Plantinga have concepts that are not self contradictory. Strasser argues that the contradiction test alone is not sufficient to determine the case.

Here is Strasser's test for determining the possible existence in all possible worlds:


1. A is not internally inconsistent, and,
2. A does not entail that A1 exist in all possible worlds, or,
3. if A's existence does entail the necessary existence of A1, then we must establish independently that A1 exists in all possible worlds.(45)

But I suggest that the answer is much simpler than turning some test. The reversal of an ontological argument, which many have attempted, goes back to he work of J.N. Findly in his classic argument with Hartshorne. Hartshorne convened Findlay that the argument of reversal always leads to a ready inversion, so the OA is on again. I suggest that the principle of ontology always works toward reversing its opposite but doesn't work work the other way around. In other words, anytime the OA is reversed it leads back to inversion. But if one reverses Findley or Tooley it does not. This is illustrated as follows:

If we say "There is no maximally great being" in some possible world, this is not ture obviously if it is true that there can be such a being in some possible world, because if there is than there must be one in all possible words, since that is what Maximal greatness is; necessary being. IF it is possible for God to exist than God must exist! In other words, "there is no maximally great being" is never a true statement. Tooley's argument is not sound. It would be correct to say, "we don't' know that God actually exists, perhaps God is impossible." But if God is not impossible (because not self contradictory) than it makes no sense to apply the possible world's theory to God's existence in some possible world since for God to be possible is to be necessary in all worlds. NO one could say then that "there is no maximal being in some possible world" because that would be like trying to confine God's necessary existence to some possible world. Trying to imposes God's non-existence upon all possible world's through the possibility of it on some possible world is like trying to confine God's existence to just one possible world, it does not make sense.



2) Existence is not a predicate.


This is one of the traditional objections that was assumed to have killed off the original OA when Kant siad that existing is not a quality of perfection that can define it's being. So the phrase "that which nothing greater than can be concieved" is not telling us that God actually exists because we do not know that existing is gratness is predicated upon existing. This is discussed on the previous page (unless I decided not to and forogt). But possibility is a predicate of existence. The possible worlds senerio may get around this argument becasue in this case greatness is not predicated upon existence but upon the possibility of existence, and for that it may well be. Why? Because we have added something to the concept. We are being told something different in this case about the situation. We are being told that not only is this quality one of greatness, but it is one of possible greatness, as oppossed to impossible greatness.


11 comments:

Brap Gronk said...

"P4 follows from P1 and P3."

I'm not seeing how P4 can be considered true without begging the question. P4 is: "The property of possessing maximal greatness is exemplified in every possible world."

Possessing maximal greatness implies having maximal excellence, which implies omniscience, omnipotence and moral perfection. I can certainly think of a possible world without an omniscient being or thing. In fact, I'm not aware of an omniscient being in this world.

It looks to me like one has to accept the existence of an omniscient being in order to accept P4, which is part of an argument that is trying to prove the existence of an omniscient being.

Metacrock said...

No I already explained that Maximal greatness is the alternative to the omnis. The phrase "all knowing" is meaningless because it's ambiguous as to what is knowable...are possibilities that never came to pass knowable? Is the uncertainty principle knowable?

Moral perfection is not an impossibility or a self contradictory attribute.


I can certainly think of a possible world without an omniscient being or thing. In fact, I'm not aware of an omniscient being in this world.

but here you are begging the question. Because you are assuming that God is just adding a fact to the universe. God is not one single being or thing, but the basis of all things.

Moreover, the point is you can't have something like the J/C God and say it's confined to one possible world. If go exists necessarily then God must exist in all possible worlds.



It looks to me like one has to accept the existence of an omniscient being in order to accept P4, which is part of an argument that is trying to prove the existence of an omniscient being.

NO it's more like you don't get what it's saying. God is not just a thing in the universe. If God exist in world God must exist in all word for if God does exist in one possible world that means that possible world is contingent upon the basis of all things. That would mean therefore that all things are so contingent, that there must be a basis of all possible things.

If God does not exist then there is basis of all things. But how could there not be a basis for all things because being itself must be the basis or else whatever it is that's the first thing and gives rise to all else is the basis. To say there is no basis is like dying there is no up.

Metacrock said...

we could start with a previous proposition saying "Either God exists or not, if so then God must exist necessarily, and if not then God's existence must be impossible."

but should should go without saying, especially after the discussion about the modal argument. This argument is basically the modal argument from another view point:

P1 A thing has maximal greatness if and only if it has maximal excellence in every possible world.

P2 Whatever has maximal excellence is omniscient, omnipotent and morally perfect.

P3 There is a possible world in which the property of possessing maximal greatness is exemplified.

P4 The property of possessing maximal greatness is exemplified in every possible world.

P5 If maximal greatness is exemplified in every world, then it is exemplified in this world.

p1 is true without regard to weather or not God exists. WE do not have assume there's a God for p1 to be true. If there is no exemplification of it is still true none the less that if MG exists it must do so in every world. How could something be MG and not be in every world?

that means p4 is also true becasue it come out of p1.

Brap Gronk said...

"p1 is true without regard to weather or not God exists. WE do not have assume there's a God for p1 to be true."

Agreed.

"If there is no exemplification of it is still true none the less that if MG exists it must do so in every world."

Agreed. I especially like the first seven words of that sentence.

"How could something be MG and not be in every world?"

It can't.

"that means p4 is also true becasue it come out of p1."

Don't you need some exemplification of omniscience, omnipotence, and moral perfection to claim p4 is true? The definition of "exemplify" I am using is "to show or illustrate by example." If I need to think of exemplification differently, please let me know.

Metacrock said...

I think the point is that terms like "omnipotence" are not meaningful so why use them? Why allow a meaningless word to be the standard?

The question, do we have to show an example of whatever quality we suppose God has, thus demonstrating that such quality must be in every possible world?

The arguments turns upon the idea that God is conceived as possible in this possible world, then God must exist in all because otherwise he would not be possible in this one (that's the thing about God can't be merely possible since he's necessary) that is the rationale for the argument, not necessarily any particular attribute.

But if you want an attribute and that's your "price" so to speak for considering the argument, rather the omnis I use:

eternal necessary being.

but then invovles employing another argument to prove this argument.

Brap Gronk said...

"I think the point is that terms like "omnipotence" are not meaningful so why use them? Why allow a meaningless word to be the standard?"

I think that's a question for Plantinga to answer, since he uses the terms "omniscient" and "omnipotent" in P2.


"The question, do we have to show an example of whatever quality we suppose God has, thus demonstrating that such quality must be in every possible world?"

If you want to provide a convincing argument that P4 is true, then yes, showing an example of maximal greatness, which can be done by showing an example of maximal excellence (P1), which can be done by showing an example of omniscience, omnipotence, or moral perfection (P2), seems like a reasonable request.


"The arguments turns upon the idea that God is conceived as possible in this possible world, then God must exist in all because otherwise he would not be possible in this one (that's the thing about God can't be merely possible since he's necessary) that is the rationale for the argument, not necessarily any particular attribute."

Again, doesn't P4 imply the attributes listed in P2 are being exemplified in this world?


"But if you want an attribute and that's your "price" so to speak for considering the argument, rather the omnis I use:

eternal necessary being.

but then invovles employing another argument to prove this argument."

Exactly my point. The truthiness of P4 is not a given by any means and requires other arguments to support it. Those who accept P4 as true don't need the possible worlds argument to convince them of God's existence, because they're already convinced.

Metacrock said...

"I think the point is that terms like "omnipotence" are not meaningful so why use them? Why allow a meaningless word to be the standard?"

I think that's a question for Plantinga to answer, since he uses the terms "omniscient" and "omnipotent" in P2.


why that dirty so and so! wel when I'm king we are not going to do that anymore!


"The question, do we have to show an example of whatever quality we suppose God has, thus demonstrating that such quality must be in every possible world?"

If you want to provide a convincing argument that P4 is true, then yes, showing an example of maximal greatness, which can be done by showing an example of maximal excellence (P1), which can be done by showing an example of omniscience, omnipotence, or moral perfection (P2), seems like a reasonable request.


why have to do that when the point of the argument is not "Hey looki there's some empirical aspect of God we can point to" but rather that if God is possible at all he can't be just possible but must be necessary, if necessary than must be in all worlds, thus in this world.


"The arguments turns upon the idea that God is conceived as possible in this possible world, then God must exist in all because otherwise he would not be possible in this one (that's the thing about God can't be merely possible since he's necessary) that is the rationale for the argument, not necessarily any particular attribute."

Again, doesn't P4 imply the attributes listed in P2 are being exemplified in this world?

well for the sake of defending P's argument, though I would word it differently, I don't see why we have to show that (not that we can't) because that's not the point of the argument.


"But if you want an attribute and that's your "price" so to speak for considering the argument, rather the omnis I use:

eternal necessary being.

but then invovles employing another argument to prove this argument."

Not necessarily, just a teak. ie: omnipresence is guaranteed through eternal necessary being (if you understand eternal as also Infinite)

we can understand omnipotent as excluding nonsense such as "make square circles"

we can understand omniscience as confined to the knowable so it doesn't' mean negating uncertainty.

If that's the case then the same argument P makes is still based no upon demonstrating the attributes but upon the transmutation from possibility to necessity.




Exactly my point. The truthiness of P4 is not a given by any means and requires other arguments to support it.

except it doesn't because you made an illegal move. there's no reason to move from what the arguments turns upon to demanding this empirical show of things that should have to be demonstrated because they are beyond human understanding and becasue that's not what the argument turns upon.



Those who accept P4 as true don't need the possible worlds argument to convince them of God's existence, because they're already convinced.


that's true, all God arguments are just talking points to give the skeptic an inroad. But skeptics don't want inroads.

both belief and unbelief are world views and that mean paradigm. that means you don't shed them until your paradigm breaks down.

But I don't give arguments to prove God exists but to prove that belief is rationally warranted.

Metacrock said...

"I think the point is that terms like "omnipotence" are not meaningful so why use them? Why allow a meaningless word to be the standard?"

I think that's a question for Plantinga to answer, since he uses the terms "omniscient" and "omnipotent" in P2.


why that dirty so and so! wel when I'm king we are not going to do that anymore!


"The question, do we have to show an example of whatever quality we suppose God has, thus demonstrating that such quality must be in every possible world?"

If you want to provide a convincing argument that P4 is true, then yes, showing an example of maximal greatness, which can be done by showing an example of maximal excellence (P1), which can be done by showing an example of omniscience, omnipotence, or moral perfection (P2), seems like a reasonable request.


why have to do that when the point of the argument is not "Hey looki there's some empirical aspect of God we can point to" but rather that if God is possible at all he can't be just possible but must be necessary, if necessary than must be in all worlds, thus in this world.


"The arguments turns upon the idea that God is conceived as possible in this possible world, then God must exist in all because otherwise he would not be possible in this one (that's the thing about God can't be merely possible since he's necessary) that is the rationale for the argument, not necessarily any particular attribute."

Again, doesn't P4 imply the attributes listed in P2 are being exemplified in this world?

well for the sake of defending P's argument, though I would word it differently, I don't see why we have to show that (not that we can't) because that's not the point of the argument.


"But if you want an attribute and that's your "price" so to speak for considering the argument, rather the omnis I use:

eternal necessary being.

but then invovles employing another argument to prove this argument."

Not necessarily, just a teak. ie: omnipresence is guaranteed through eternal necessary being (if you understand eternal as also Infinite)

we can understand omnipotent as excluding nonsense such as "make square circles"

we can understand omniscience as confined to the knowable so it doesn't' mean negating uncertainty.

If that's the case then the same argument P makes is still based no upon demonstrating the attributes but upon the transmutation from possibility to necessity.




Exactly my point. The truthiness of P4 is not a given by any means and requires other arguments to support it.

except it doesn't because you made an illegal move. there's no reason to move from what the arguments turns upon to demanding this empirical show of things that should have to be demonstrated because they are beyond human understanding and becasue that's not what the argument turns upon.



Those who accept P4 as true don't need the possible worlds argument to convince them of God's existence, because they're already convinced.


that's true, all God arguments are just talking points to give the skeptic an inroad. But skeptics don't want inroads.

both belief and unbelief are world views and that mean paradigm. that means you don't shed them until your paradigm breaks down.

But I don't give arguments to prove God exists but to prove that belief is rationally warranted.

Brap Gronk said...

Meta,

Since you mentioned rationally warranted belief in your most recent comment, I have a question for you. Let’s assume someone is unaware of the case you present for belief being rationally warranted. Let’s also assume the seven points below are true for this person. Would you agree that non-belief is rationally warranted for that person, given the following seven points, or any subset of these points?

1. I have never seen God.
2. I have never heard God.
3. I don’t know anyone who has ever seen God, or claimed to have seen God.
4. I don’t know anyone who has ever heard God, or claimed to have heard God.
5. I am not aware of any evidence of God’s interaction with our world. Natural laws can explain how things work and why things happen, as far as I know.
6. Humans have wondered about the origins of the earth, the sun, the stars, and themselves for a long time. Many creation myths were developed in ancient times in an attempt to explain these origins, and these creation myths are easily proven to be untrue given the current state of scientific knowledge. The account of creation in the book of Genesis appears to be another easily disproven creation myth.
7. I have read “The Demon-Haunted World” by Carl Sagan, and I can’t think of anything in that book I disagree with.
==========

Metacrock said...

Brap, the full answer I have in mind would make a good essay for the blog. I'll try to post that on Wednesday.

Thumbnail answer: Any given argument might be rationally warranted, depending upon how it's argued. Rational warrant is like "logical permission to believe something" not actual proof.

A person is logically justified in not believing something if they truly have no reason to believe it.

However, there's a point at which one can go beyond the line of credulity. For example the reasons you gave for no believing would only be understandable for someone who never actually read a book and knows nothing about modern thought at all.

More on that latter.

Metacrock said...

I didn't mean that last comment as an insult to you. I assume your reasons are more complex that the list implies.