Anselm’s “1st” ontological argumentAnselm’s “1st” ontological argument

Something than which nothing greater can be thought of cannot exist only as an idea in the mind because, in addition to existing as an idea in the mind, it can also be thought of as existing in reality, that is, objectively, which is greater than existing only as an idea in the mind.

If something than which nothing greater can be thought of exists only as an idea in the mind, then “that than which something greater cannot be thought of” is “that than which something greater can be thought of,” which is impossible because it is self-contradictory.

Something than which nothing greater can be thought of must exist, not only as an idea in the mind, but in reality.

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In other words,In other words,

A God that actually exists is greater than a “God” that exists only as an idea in the mind.

If “God” exists only as an idea in the mind, then “God” is “not-God” (because something that exists only as an idea in the mind is not “something than which nothing greater can be thought of”).

Thus, the claim that God does not actually exist implies a contradiction and is therefore necessarily false.

If the claim that God does not actually exist is necessarily false, then the claim that God actually exists is necessarily true (because the negation of a contradiction is a tautology).

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Anselm’s “2nd” Ontological ArgumentAnselm’s “2nd” Ontological ArgumentIt is possible to think of something that cannot be thought not to exist [that is, a necessary being].A necessary being [something that cannot be thought not to exist] would be greater than something that can be thought not to exist [that is, a contingent being].If something than which nothing greater can be thought of could be thought of as not existing, then something than which nothing greater can be thought of would not be something than which nothing greater can be thought of, which is an outright contradiction and thus absurd.Something than which nothing greater can be thought of has such a high degree of existence, that is, necessary existence, that it cannot be thought of as not existing, that is, its nonexistence is impossible.

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In other words,In other words,

It is possible to think of a necessary being, i.e., a being It is possible to think of a necessary being, i.e., a being whose nonexistence is impossible.whose nonexistence is impossible.

Necessary existence is greater than contingent existence, Necessary existence is greater than contingent existence, and a necessary being is greater than a contingent being.and a necessary being is greater than a contingent being.

If the nonexistence of God is possible, then God must be a If the nonexistence of God is possible, then God must be a contingent being. But then “God” would be “not-God” contingent being. But then “God” would be “not-God” because a contingent being cannot be “something than because a contingent being cannot be “something than which nothing greater can be thought of.”which nothing greater can be thought of.”

Thus, the claim that God’s nonexistence is possible implies a Thus, the claim that God’s nonexistence is possible implies a contradiction and is therefore necessarily false.contradiction and is therefore necessarily false.

If the claim that God’s nonexistence is possible is If the claim that God’s nonexistence is possible is necessarily false, then the claim that God’s nonexistence is necessarily false, then the claim that God’s nonexistence is impossible is necessarily true (because the negation of a impossible is necessarily true (because the negation of a contradiction is a tautology).contradiction is a tautology).

MORE THAN 150 YEARS LATER…

Aquinas’ ProofsAquinas’ Proofs

The five waysThe five ways

Thomas Aquinas (1225-1274) Thomas Aquinas (1225-1274)

Joined Dominican order Joined Dominican order against the wishes of his against the wishes of his family; led peripatetic family; led peripatetic existence thereafter.existence thereafter.

Considered the most Considered the most learned man of his day; learned man of his day; much in demand as much in demand as teacher and lecturer.teacher and lecturer.

Summa TheologicaSumma Theologica never never finished, following finished, following ‘ecstasy’ in Dec. 1273‘ecstasy’ in Dec. 1273

Doctor of the ChurchDoctor of the Church

Aquinas on God’s existenceAquinas on God’s existence

Believed, as against several interesting Believed, as against several interesting objections, that God’s existence can (and needs objections, that God’s existence can (and needs to be) ‘demonstrated’ (‘proved’, in the modern to be) ‘demonstrated’ (‘proved’, in the modern sense).sense).

By this he meant 2 things:By this he meant 2 things:1. That God exists is not ‘self-evident’ or 1. That God exists is not ‘self-evident’ or

axiomatic or a matter of definitionaxiomatic or a matter of definition2. That God exists is something which we 2. That God exists is something which we

can be completely sure of, as a matter of reason can be completely sure of, as a matter of reason (and not simply of faith)(and not simply of faith)

Is the existence of God Is the existence of God self-evident?self-evident?

““self-evident” = that which requires no self-evident” = that which requires no proof in order to be known.proof in order to be known.

3 objections: the existence of God is self-3 objections: the existence of God is self-evident because:evident because:

I. Knowledge of God is innateI. Knowledge of God is innate

II. The concept includes existenceII. The concept includes existence

III. God is truth, & no one can III. God is truth, & no one can consistently deny the existence of truth.consistently deny the existence of truth.

Answers to the objectionsAnswers to the objections Objection 1: we know only in a vague way (“God is Objection 1: we know only in a vague way (“God is

man’s beatitude”) that God exists, and this is quite man’s beatitude”) that God exists, and this is quite different from knowing absolutely that He exists.different from knowing absolutely that He exists.

Obj.2: distinction between mental and real existence Obj.2: distinction between mental and real existence maintained even in the case of “that than which no maintained even in the case of “that than which no greater can be thought”greater can be thought”

Obj.3: “The existence of truth in general is self-evident Obj.3: “The existence of truth in general is self-evident but the existence of a Primal Truth is not self-evident to but the existence of a Primal Truth is not self-evident to us.”us.”

General rejoinder: what is self-evident cannot be denied, General rejoinder: what is self-evident cannot be denied, but “God is” can be denied.but “God is” can be denied.

Therefore, “God is” is not self-evident (that is, his existence Therefore, “God is” is not self-evident (that is, his existence requires proof)requires proof)

Objections to the idea that God’s Objections to the idea that God’s existence can be provenexistence can be proven

Objection 1: God’s existence is a matter of faith, not Objection 1: God’s existence is a matter of faith, not demonstration (reason)demonstration (reason)

Obj. 2: God, by definition, exceeds our understanding, Obj. 2: God, by definition, exceeds our understanding, therefore we can’t even know therefore we can’t even know whatwhat it is we’re trying to it is we’re trying to prove the existence of (“the essence is the middle term prove the existence of (“the essence is the middle term of demonstration”)of demonstration”)

Obj.3: We can’t know God directly, only by his effects; Obj.3: We can’t know God directly, only by his effects; but His effects (as finite objects or events) can’t tell us but His effects (as finite objects or events) can’t tell us anything about His nature (which is, by dfn., infinite). anything about His nature (which is, by dfn., infinite). Therefore, we can’t prove anything about Him.Therefore, we can’t prove anything about Him.

Replies to the objectionsReplies to the objections

Objection 1: Anything which can be known by Objection 1: Anything which can be known by “natural reason” is not an article of faith -- something is “natural reason” is not an article of faith -- something is an article of faith an article of faith only ifonly if it cannot be known by other it cannot be known by other meansmeans

Obj.2: We don’t need to know what it is that we’re Obj.2: We don’t need to know what it is that we’re proving the existence of (that is, it’s essence), only proving the existence of (that is, it’s essence), only thatthat it it existsexists

Obj.3: As in 2, we’re only trying to prove that He exists Obj.3: As in 2, we’re only trying to prove that He exists and not anything about His nature. Every effect and not anything about His nature. Every effect indicates, at the very least, the existence of its cause.indicates, at the very least, the existence of its cause.

General rejoinder: 2 ways of proving things: General rejoinder: 2 ways of proving things: a prioria priori and and a a posterioriposteriori; God’s existence can only be proven in the ; God’s existence can only be proven in the latter waylatter way

Character of Aquinas’ proofsCharacter of Aquinas’ proofs

Aquinas distinguishes Aquinas distinguishes a prioria priori (from cause (from cause to effect; from the nature of something to to effect; from the nature of something to its consequences) from its consequences) from a posterioria posteriori (from (from effect to cause; from observable effect to cause; from observable consequences to the nature of what consequences to the nature of what causes those) proofs -- the first are causes those) proofs -- the first are deductive proofs, what are the second deductive proofs, what are the second kind? Are they proofs at all? (recall our kind? Are they proofs at all? (recall our previous discussion of “proof”?)previous discussion of “proof”?)

Proof 1: argument Proof 1: argument from motionfrom motion

““motion” Aquinas understands to be a paradigm motion” Aquinas understands to be a paradigm case of change; the argument here is better case of change; the argument here is better thought of as the argument from changethought of as the argument from change

Change = going from potential to actualChange = going from potential to actual Every such ‘move’ requires something which is Every such ‘move’ requires something which is

itself actual to begin withitself actual to begin with A chain of such ‘moves’ cannot be infinitely longA chain of such ‘moves’ cannot be infinitely long Therefore, there must be a ‘first mover’ (a first Therefore, there must be a ‘first mover’ (a first

initiator of change), which is not itself moved; this initiator of change), which is not itself moved; this first mover is God.first mover is God.

Proof 2: argument from Proof 2: argument from efficient causeefficient cause

Aquinas, following Aristotle, recognizes four Aquinas, following Aristotle, recognizes four kinds of ‘causes’ (4 kinds of ‘why’): formal, kinds of ‘causes’ (4 kinds of ‘why’): formal, material, final, and material, final, and efficient causesefficient causes

Nothing is the efficient cause of itself; therefore, Nothing is the efficient cause of itself; therefore, for every effect there must exist some efficient for every effect there must exist some efficient cause distinct from the effectcause distinct from the effect

Such a chain of causes cannot go on to infinity; Such a chain of causes cannot go on to infinity; therefore there is a first cause (and that is God)therefore there is a first cause (and that is God)

Proof 3: argument from Proof 3: argument from possibilitypossibility

Everything which exists, exists only contingently Everything which exists, exists only contingently (that is, it is possible that it could not exist)(that is, it is possible that it could not exist)

Any contingent being must have, at some time, Any contingent being must have, at some time, not existed (if it is possible that it not exist at this not existed (if it is possible that it not exist at this time, then necessarily it did not exist at some time, then necessarily it did not exist at some time) time)

The world, taken as a whole & as contingent, The world, taken as a whole & as contingent, must have at some time therefore not existedmust have at some time therefore not existed

But what once did not exist must come to exist in But what once did not exist must come to exist in virtue of something which itself must exist.virtue of something which itself must exist.

That necessary being is God.That necessary being is God.

Proof 4: argument from Proof 4: argument from gradationgradation

Every quality or attribute which can be thought Every quality or attribute which can be thought of in terms of degree, is referenced to some of in terms of degree, is referenced to some standard (more or less good to some standard standard (more or less good to some standard of goodness, more or less red to some standard of goodness, more or less red to some standard of redness, etc.)of redness, etc.)

Since being admits of degrees (as does Since being admits of degrees (as does goodness & every other sort of perfection), there goodness & every other sort of perfection), there must be something which is the standard for that must be something which is the standard for that attribute (a formal cause of that attribute)attribute (a formal cause of that attribute)

That standard is GodThat standard is God

Proof 5: argument Proof 5: argument from design from design

Natural kinds and events are only understood Natural kinds and events are only understood properly as having an end state or aim properly as having an end state or aim

Such non-intelligent things can act towards such Such non-intelligent things can act towards such ends only by being directed by something which is ends only by being directed by something which is intelligent (something which could have motives intelligent (something which could have motives or purposes)or purposes)

Therefore there is an intelligent being which Therefore there is an intelligent being which directs natural kinds and events; and that being is directs natural kinds and events; and that being is God.God.

Character of Aquinas’ GodCharacter of Aquinas’ God

What is the nature of the God which is What is the nature of the God which is revealed by “the five ways”?revealed by “the five ways”?

the initiator of all motion (change)the initiator of all motion (change)

the ultimate cause of all thingsthe ultimate cause of all things

a necessary beinga necessary being

the standard against which all things the standard against which all things are measuredare measured

a surpassingly complex intelligencea surpassingly complex intelligence