sbchan
09-25-2006, 12:14 PM
AT A GLANCE: THE ONTOLOGICAL ARGUMENT
1. Anselm’s Ontological Argument
• The argument is a reductio.
Premise #1: God is a being than which nothing greater can be conceived.
Premise #2: We understand the words, “A being than which nothing greater can be conceived.”
Premise #3: Whatever is understood is in the understanding (mind).
Premise #4: Therefore, a being than which nothing greater can be conceived exists in the understanding (from 2 and 3).
Premise #5: Either a being than which nothing greater can be conceived exists in the understanding but not in reality, or a being than which nothing greater can be conceived exists both in the understanding and in reality.
Premise #6: Assume (to show false by reductio) that a being than which none greater can be conceived exists in the understanding but not in reality.
(a) A being than which nothing greater can be conceived can be thought to exist in reality.
(b) Existing in reality and in the understanding is greater than existing in the understanding alone.
(c) A being than which nothing greater can be conceived (if it exists in the understanding alone) is not a being than which nothing greater can be conceived, for another being greater than it can be conceived—namely, the same being that exists in reality. A contradiction results from the original assumption, allowing us to conclude that it is false.
Conclusion: Therefore, a being than which nothing greater can be conceived (God) exists in the understanding and in reality (from 4, 5, and 6c).
2. Existing in the Understanding
• We can replace talk of “existing in the understanding” with talk of concepts.
• The question becomes, is the concept of a being that lacks existence as great as the concept of a being that also actually exists?
3. The Perfect Island
• Gaunilo: Anselm’s argument if correct, would prove the existence of an island than which none greater can be conceived.
• Possible reply: “the island than which none greater can be conceived” is not a coherent concept.
4. Is Existence a Perfection?
• Kant: existence is not a predicate (quality or property).
• If so, then existence is not a perfection, and so it does not make God greater.
5. The Anselm/Malcolm Argument
• Defines God as (in one sense) a necessary being.
• A being than which none greater can be conceived would have be so great that its nonexistence is inconceivable.
5.1. Necessary Existence a Predicate
• Necessary existence seems to be a predicate.
• If we are told that something exists necessarily, we know something about it (for example, not an ordinary space-time object).
5.2. Some philosophers doubt that anything exists necessarily. It’s difficult to find clear example. Numbers might qualify but some philosophers (Nominalists) argue that mathematics doesn’t require the literal existence of numbers.
5.3. Definitions and Concepts
• Kant: even if “God exists necessarily” is a matter of definition, we can still say that God doesn’t exist by “rejecting the subject.”
• Malcolm: this is like saying, “If God exists (and it’s possible that He doesn’t), then He exists necessarily,” a seeming implicit contradiction
• Reply: if the word “possible” in parentheses is understood in the epistemic sense and the word “necessary” is understood in the metaphysical sense, the appearance of contradiction goes away.
6. To assess the ontological argument fully, we need to explore concepts from modal logic—possibility and necessity.
6.1. Possibility in the Metaphysical Sense
• Something is metaphysically possible if it could be or could have been true.
6.2. Possible Worlds
• Something is possible if it’s true in at least one possible world.
• Something is necessary if it’s true in all possible worlds.
• This entails that if God is by definition a necessary being, then if it’s possible that God exists, God does exist.
• Possible reply: God as Anselm and Malcolm understand God is not a possible being; an omnipotent, omniscient, and omnibenevolent being is a possible being, but not a necessary being.
6.3. Plantinga’s Argument
• Define “maximally excellent being” relative to a given world: a being that possesses all perfections in that world.
• Define “maximally great being” as one that possesses maximal excellence in every world.
Premise #1: It’s possible that a maximally great being exists.
Premise #2: If it’s possible that a maximally great being exists, then such a being actually exists.
Conclusion: Therefore, a maximally great being actually exists.
• Explanation of Premise 2: a maximally great being has maximal excellence and hence exists in every world (is necessary). See Heading 6.2 above.
6.4. Rowe’s Objection
• Plantinga doesn’t say he can prove that a maximally great being is possible.
• However, he thinks it’s reasonable to believe this.
• Rowe objects that it’s not obviously reasonable. It would rule out a possible world where every being is flawed to at least some degree.
WEB RESOURCES
You can read Anselm’s Ontological Argument online at http://www.fordham.edu/halsall/source/anselm.html.
Kant’s argument is available at http://www.fordham.edu/halsall/basis/anselm-critics.html#KANT.
A survey of the Ontological Argument can be found in the Stanford Encyclopedia of Philosophy: http://plato.stanford.edu/entries/ontological-arguments/.
There is also a survey in the Internet Encyclopedia of Philosophy at
http://www.iep.utm.edu/o/ont-arg.htm#H4.
1. Anselm’s Ontological Argument
• The argument is a reductio.
Premise #1: God is a being than which nothing greater can be conceived.
Premise #2: We understand the words, “A being than which nothing greater can be conceived.”
Premise #3: Whatever is understood is in the understanding (mind).
Premise #4: Therefore, a being than which nothing greater can be conceived exists in the understanding (from 2 and 3).
Premise #5: Either a being than which nothing greater can be conceived exists in the understanding but not in reality, or a being than which nothing greater can be conceived exists both in the understanding and in reality.
Premise #6: Assume (to show false by reductio) that a being than which none greater can be conceived exists in the understanding but not in reality.
(a) A being than which nothing greater can be conceived can be thought to exist in reality.
(b) Existing in reality and in the understanding is greater than existing in the understanding alone.
(c) A being than which nothing greater can be conceived (if it exists in the understanding alone) is not a being than which nothing greater can be conceived, for another being greater than it can be conceived—namely, the same being that exists in reality. A contradiction results from the original assumption, allowing us to conclude that it is false.
Conclusion: Therefore, a being than which nothing greater can be conceived (God) exists in the understanding and in reality (from 4, 5, and 6c).
2. Existing in the Understanding
• We can replace talk of “existing in the understanding” with talk of concepts.
• The question becomes, is the concept of a being that lacks existence as great as the concept of a being that also actually exists?
3. The Perfect Island
• Gaunilo: Anselm’s argument if correct, would prove the existence of an island than which none greater can be conceived.
• Possible reply: “the island than which none greater can be conceived” is not a coherent concept.
4. Is Existence a Perfection?
• Kant: existence is not a predicate (quality or property).
• If so, then existence is not a perfection, and so it does not make God greater.
5. The Anselm/Malcolm Argument
• Defines God as (in one sense) a necessary being.
• A being than which none greater can be conceived would have be so great that its nonexistence is inconceivable.
5.1. Necessary Existence a Predicate
• Necessary existence seems to be a predicate.
• If we are told that something exists necessarily, we know something about it (for example, not an ordinary space-time object).
5.2. Some philosophers doubt that anything exists necessarily. It’s difficult to find clear example. Numbers might qualify but some philosophers (Nominalists) argue that mathematics doesn’t require the literal existence of numbers.
5.3. Definitions and Concepts
• Kant: even if “God exists necessarily” is a matter of definition, we can still say that God doesn’t exist by “rejecting the subject.”
• Malcolm: this is like saying, “If God exists (and it’s possible that He doesn’t), then He exists necessarily,” a seeming implicit contradiction
• Reply: if the word “possible” in parentheses is understood in the epistemic sense and the word “necessary” is understood in the metaphysical sense, the appearance of contradiction goes away.
6. To assess the ontological argument fully, we need to explore concepts from modal logic—possibility and necessity.
6.1. Possibility in the Metaphysical Sense
• Something is metaphysically possible if it could be or could have been true.
6.2. Possible Worlds
• Something is possible if it’s true in at least one possible world.
• Something is necessary if it’s true in all possible worlds.
• This entails that if God is by definition a necessary being, then if it’s possible that God exists, God does exist.
• Possible reply: God as Anselm and Malcolm understand God is not a possible being; an omnipotent, omniscient, and omnibenevolent being is a possible being, but not a necessary being.
6.3. Plantinga’s Argument
• Define “maximally excellent being” relative to a given world: a being that possesses all perfections in that world.
• Define “maximally great being” as one that possesses maximal excellence in every world.
Premise #1: It’s possible that a maximally great being exists.
Premise #2: If it’s possible that a maximally great being exists, then such a being actually exists.
Conclusion: Therefore, a maximally great being actually exists.
• Explanation of Premise 2: a maximally great being has maximal excellence and hence exists in every world (is necessary). See Heading 6.2 above.
6.4. Rowe’s Objection
• Plantinga doesn’t say he can prove that a maximally great being is possible.
• However, he thinks it’s reasonable to believe this.
• Rowe objects that it’s not obviously reasonable. It would rule out a possible world where every being is flawed to at least some degree.
WEB RESOURCES
You can read Anselm’s Ontological Argument online at http://www.fordham.edu/halsall/source/anselm.html.
Kant’s argument is available at http://www.fordham.edu/halsall/basis/anselm-critics.html#KANT.
A survey of the Ontological Argument can be found in the Stanford Encyclopedia of Philosophy: http://plato.stanford.edu/entries/ontological-arguments/.
There is also a survey in the Internet Encyclopedia of Philosophy at
http://www.iep.utm.edu/o/ont-arg.htm#H4.