[I continue (Part 1 and Part 2) my assessment of the ontological argument by looking at modal versions of it and finally a conclusion.]
These modes of being (necessity and contingency) have led to a resurgence of the ontological argument by modern philosophers. Norman Malcolm (1911- ) has attempted to make the persuasive force for the ontological argument more transparent by recasting the argument in contemporary modal logic. Malcolm summarizes his proof as follows:
If God, a being greater than which cannot be conceived, does not exist then He cannot come into existence. For if He did He would either have been caused to come into existence or have happened to come into existence, and in either case He would be a limited being, which by our conception of Him He is not. Since He cannot come into existence, if He does not exist His existence is impossible. If He does exist He cannot have come into existence (for the reasons given), nor can He cease to exist, for nothing could cause Him to cease to exist nor could it just happen that He ceased to exist. So if God exists His existence is necessary. Thus God’s existence is either impossible or necessary. It can be the former only if the concept of such a being is self-contradictory or in some way logically absurd. Assuming that this is not so, it follows that He necessarily exists.[1]
On Malcolm’s view, the existence of an unlimited being is either logically necessary or logically impossible. Since the idea of God is logically coherent and possible, God’s existence is logically necessary. Malcolm’s argument can be shown in logical form as:
- The existence of a necessary being must be either
- Impossible; or
- Possible; or
- Necessary.
- But the existence of a necessary being is not impossible. (The concept of a necessary being is not contradictory or incoherent.)
- And the existence of a necessary being cannot be merely possible. (A necessary being cannot be merely possibly necessary.)
- Therefore, the existence of a necessary being must be necessary.[2]
Although Malcolm’s version is immune to criticisms directed at the claim that necessary existence is a perfection, there are other problems with it. Alvin Plantinga claims that Malcolm’s reconstruction does not succeed because of equivocation of the word necessity. There are two different ways of being necessary. One is logical and that is entailed in Malcolm’s argument. The other way of being necessary is metaphysical necessity, which is not obvious from the argument, although asserted (premise four). Another logical possibility (not addressed by Malcolm) is that nothing could exist. Norman Geisler (in his assessment of Malcolm’s reconstruction) claims that once Malcolm affirms that something does exist, he has moved from an a priori argument to an a posteriori one (specifically the cosmological argument).
Plantinga, after studying the ontological argument for years, conceded that it looks “like a verbal sleight of hand or piece of word magic.”[3] This led Plantinga to develop his own modal version of the ontological argument, which he (among many others) considers valid. This version does not require that necessary existence is a property as Anselm’s second argument, but instead works with possible worlds. The logical form follows:
- There is a possible world in which maximal greatness is instantiated.
- Necessarily, a being is maximally great only if it has maximal excellence in every world.
- Necessarily, a being has maximal greatness in every world only if it has omniscience, omnipotence, and moral perfection in every world.
- Maximal greatness is possibly exemplified.
- So there is a possible being x and a world W’ such that x is exemplified in W’ and x entails “has maximal greatness in W’.”
- But if x has maximal greatness in W’, then x has maximal greatness in all possible worlds.
- If W’ had been actual, it would have been impossible for x not to have been exemplified.
- What is impossible is invariant across possible worlds.
- Therefore, there exists a being which has maximal greatness in every possible world.
- Therefore, there exists a being which has maximal greatness in the actual world.[4]
The evaluation of this line of reasoning by many philosophers is that it is a tight, compelling argument. For others, it is suggested that premise six is based upon a controversial modal principle AxS5: If A is possible, then it is necessarily true that A is possible. But this is not evident as premise six would need to be reworded to the following to be based upon AxS5:
6′. But if x has maximal greatness in W’ (i.e. possible), then necessarily ‘x has maximal greatness in all possible worlds’ is possible.
Instead, Plantinga builds his case upon the notion of maximally great, which is entailed in every possible world.[5] Plantinga explains this premise further, “By the principle that what is necessary or impossible does not vary from world to world, this property cannot be instantiated in some worlds but not in others. Either it is instantiated in every world or it is not instantiated at all.”[6] Still others have claimed the concept of a maximally great being is incoherent. This charge is based upon the assertion that two of the great-making characteristics of the classic conception of God are incompatible (e.g. omniscience and omnipotence). It would be difficult to delve into this indictment in any way to do it justice, but might suggest (to the interested reader) investigation of the coherence of theism outside this paper.[7] It suffices for our sake to claim that these attributes can be logically instantiated in the same being.
Another attack on this argument is that it is circular or question begging. This argumentative fallacy is when one implicitly uses the conclusion as a premise, such as the following:
- The Bible is true because God wrote it.
- The Bible says that God exists.
- Therefore, God exists.
This is obviously faulty logic because one smuggles in the proposition that God exists in the first premise. In regards to Plantinga’s modal version of the ontological argument, the circular charge is that one who comes to the conclusion that God exists, already assumes God exists from a previous premise. However, upon inspection of the argument, it is difficult to grasp how one infers the conclusion when accepting one of the main premises. One could deny one of the premises (such as premise three) because of the view that it is incoherent, but it seems difficult to presume that one accepts these premises because they accept the conclusion [that God exists] a priori.
From our historical tour of the ontological argument, it is evident that at least two forms of the argument are valid. Anselm’s “proof from prayer” in chapter two of Proslogion was argued against by Gaunilo and successfully rebutted by Anselm. Although others still rejected his argument, it was not until Kant stipulated that “existence is not a perfection” that the argument was considered defeated. As we saw, however, Kant did not address Anselm’s second argument in chapter three in which “necessary existence is a perfection”. Contingent, necessary and impossible existence was investigated to help understand their distinctions, which led to Malcolm’s modal version. Malcolm seems to equivocate on the word necessary, not distinguishing between logical necessity and metaphysical necessity. Lastly, Plantinga’s model uses modal logical to stipulate that a being of maximally greatness exists in all possible worlds. Some charges against Plantinga’s argument were addressed and found lacking.
One could be tempted to finish this historical apologetic on a triumphant note by exclaiming the ontological argument is valid, but another question to ask is if the argument is compelling or cogent. Although the arguments do seem valid, is someone likely to begin as an atheist and upon hearing the argument be compelled to switch to theism? Even Plantinga suggest that this is not the case, and concludes that at least the argument can show that it is rational to accept the conclusion and “perhaps that is all that can be expected of any such argument.”[8] If this is the best we can expect from the argument, then a better purpose for it would be in a cumulative case for God’s existence. By establishing God’s existence with other a posteriori arguments, one could add the ontological argument to allow more attributes of God to be evident, such as omnipotence, omniscience and moral perfection.
[1] Norman Malcolm in “Malcolm’s Statement of Anselm’s Ontological Arguments” in The Ontological Argument ed. Alvin Plantinga (Garden City, New York: Anchor Books, 1965), 146.
[2] Outline of argument taken from lecture notes from Garry DeWeese for theistic arguments in summer 2005, Biola University.
[3] Alvin Plantinga in ‘The Ontological Argument’ in Philosophy of Religion ed. William Lane Craig (New Brunswick, New Jersey: Rutgers University Press, 2002), 180.
[4] Outline of argument taken from lecture notes from Garry DeWeese for theistic arguments in summer 2005, Biola University.
[5] This argument was modified from “Internet Encyclopedia of Philosophy” available from www.iep.utm.edu/o/ont-arg.htm; accessed Feb 11, 2005.
[6] Alvin Plantinga in ‘The Ontological Argument’ in Philosophy of Religion, 184.
[7] William Lane Craig addresses this very topic in Part III of Philosophy of Religion ed. William Lane Craig (New Brunswick, New Jersey: Rutgers University Press, 2002), 201-300.
[8] Alvin Plantinga in ‘The Ontological Argument’ in Philosophy of Religion, 188.
Fire and Mirth says
I still don’t understand the flaw in Malcolm’s version. Can you explain the flaw another way?
Steven Dunn gives this structure (http://www.christianapologeticsalliance.com/2014/09/08/five-ontological-arguments/):
1. If God does not exist, his existence is logically impossible.
2. If God exists, his existence is logically necessary.
3. Hence God’s existence is either logically impossible or logically necessary.
4. If God’s existence is logically impossible, the concept of God is contradictory.
5. The concept of God is not contradictory.
6. Therefore, God’s existence is logically necessary.
Does the flaw in Malcolm’s version hang on #5, that 5 veers from being an ontological argument (Malcolm: “It can be the former only if the concept of such a being is self-contradictory or in some way logically absurd.”)?
Even if Malcolm’s version fails as an ontological argument, does it fail as a good argument?
John Moore says
“The existence of a necessary being cannot be merely possible.” The concept of “possible” includes “might not exist,” so it’s absurd to speak of God as being possible. Either He exists or He does not.
Therefore, Plantinga’s very first premise (“There is a possible world in which maximal greatness is instantiated.”) renders his whole argument absurd.
That’s how it’s circlar, because Plantinga can’t really be saying God is possible. He must be assuming God exists.