Proteomics studies of PC

There are two basic kinds of arguments claiming rational certainty about God’s existence.

The first is a posteriori, arguing from effect to cause, and the other is a priori, arguing from the idea of God.

The Arguments from Effect to Cause

There are two main forms of this argument: the one begins with ideas and argues to God and the other begins with contingent facts. This first form of the argument is represented by

Augustine (354–430) and Descartes (1596–1650).

Augustine’s argument from truth. St. Augustine’s form of this argument may be summarized as follows:

(1) There are some necessary and unchangeable truths (ideas) such as 7 + 3 = 10.

(2) But a finite mind, such as mine, is not unchangeable.

(3) An unchangeable truth cannot be based in a changeable, finite mind.

(4) Therefore, there must be an infinite, unchangeable Mind (that is, God) which is the basis for all unchangeable truths.

There are two basic criticisms of this argument. First, some question whether or not any necessary truths about reality exist. Mathematic “truths,” they say, are merely definitional and stipulative—they are not informative about reality. The second criticism asks why an immutable idea cannot arise in a finite mind. Why cannot one think about an immutable or necessary truth unless one is an immutable or necessary being?

Descartes’ s argument from the perfect idea. A later correlative to Augustine’s a posteriori argument from “immutable truth” is Descartes’s argument from the “perfect idea.” His reasoning proceeds this way:

(1) I have imperfect ideas (for example, I doubt).

(2) But one cannot know the imperfect unless he knows the perfect.

(3) However, an imperfect mind cannot be the source of a perfect idea.

(4) Therefore, there must be a perfect Mind which is the source of my idea of perfection.

Objections to Descartes’s argument follow similar lines as those of Augustine’s. First, some ask why an imperfect mind cannot imagine the idea of perfection. Second, why must doubt be called “imperfect”? Perhaps doubt is an accurate (or, perfect) representation of the actual state of affairs. The third criticism is that both Augustine and Descartes assume, without proof, that ideas need causes. This invokes the principle of causality without logical justification.

Aquinas’s argument from contingents to God. Another major fonn of the a posteriori proof for God was presented by Thomas Aquinas (1224–1274). The heart of his reasoning is as follows:

(1) Every effect, by its very nature, needs a cause.

(2) Every contingent being is an effect.

(3) Hence, every contingent being is caused.

(4) Therefore, it follows that the cause of every contingent being is not contingent, but Necessary (that is. God).

The opponents of this proof for God cannot object to the first premise because it is true by definition, that is, an effect by its very nature is something which is caused. It is saying no more than every person with a navel had a mother. The problem comes with proving that the world has a “navel” (i.e., that it is an effect). There are two main objections. First, some ask, must every contingent thing be caused? Why cannot a contingent being simply exist uncaused? Second, even if every individual, contingent being is caused, why must the whole composition of contingent beings be caused? Perhaps the parts are caused but the whole universe is uncaused. Such critics claim that to say otherwise is to be guilty of the fallacy of composition. It is like arguing that a whole mosaic must be the same shape as each piece of tile or glass. Third, some ask why the cause of a contingent being cannot be another contingent being. Why must it be a Necessary Being?

Arguments from the Idea of God

The second major attempt to prove God’s existence comes from St. Anselm (1033–1109).

Since Kant’s day this argument has been known as the Ontological Argument. There are at least two forms of the argument.

Argument from the idea of the most perfect Being conceivable. In meditating upon God, Anselm concluded that God by definition must be the most perfect Being possible or conceivable. For if one could conceive of anything more perfect, then that would be God.

His argument unfolds this way:

(1) God is by definition the most perfect Being conceivable.

(2) The most perfect Being conceivable cannot lack anything.

(3) But if God did not exist. He would lack existence.

(4) Therefore, God must exist.

This argument has come under two basic criticisms. First, Gaunilo, a monk in Anselm’s day, contended that the fact that he could conceive of a perfect island did not mean such an island actually existed. Anselm insisted in response that an island by definition need not be absolutely perfect in the same sense that God by definition must be absolutely perfect.

Therefore a “perfect” island might exist in the mind but not in reality, but God, to be perfect, must exist in reality.

The second criticism is held more widely to be decisive. Immanuel Kant insisted that Anselm wrongly assumed that existence is a property of perfection. On the contrary, said Kant, existence is not a predicate or attribute of a concept. Anselm assumed that the concept must be instantiated, that is, that an example of it had to be found in experience or reality. But since existence is not a property of perfection, then positing God’s

non-existence takes nothing away from the absolute perfection of the idea in one’s mind. In short, it is possible that God does not exist. And if this is so, then it is not rationally

necessary that God exists. No one, therefore, can use this argument to claim that God exists for certain.

Argument from the idea of a Necessary Being. The second form of Anselm’s argument is more difficult to criticize. It has also been held by philosophers such as Descartes, Spinoza, and Charles Hartshome. We may summarize Hartshome’s argument as follows:

(1) The existence of a Necessary Being must be either (a) an impossible existence, (b) a possible but not necessary existence, or (c) a necessary existence.

(2) It cannot be impossible, since it is not a contradication in terms to affirm “a Necessary Being necessarily exists.”

(3) It is a contradiction to affirm that a Necessary Being (one that cannot not exist) is a possible Being (i.e., one that can not exist).

(4) Therefore, a Necessary Being necessarily does exist. This argument seems to avoid all the criticisms of the first, since: (1) only a Necessary Being (not a perfect island, or the like) necessarily exists, and (2) existence is not being used as a property. In fact, the argument is not based on the concept of God as an absolutely perfect Being but as a Necessary Being.

Two other criticisms have been leveled at this form of the ontological argument. The first insists that necessary existence is “smuggled” into the argument under the concept of God. Just because a triangle must be conceived as having three sides does not mean that a triangle actually exists. Likewise, it is argued, simply because God must be conceived as necessarily existing does not mean that He actually exists. Some feel this objection misses the target, because triangles and all other things—except God—need not be conceived as actually existing. But if God is necessarily existent, they insist, then He must necessarily exist. A Necessary Being by His very nature cannot not exist.

A second criticism has been offered by some, namely, that it is logically possible that God does not exist. One can argue that granted, if a Necessary Being does indeed exist, then it cannot have a possible (i.e., contingent) kind of existence. But it is always logically

possible that no Necessary Being exists.

Third, some have insisted either that the very concept of a Necessary Being is

inconsistent or contradictory. Some even say it is impossible (this will be discussed below

under attempted disproofs for God). But such critics claim that one need not claim that the concept is impossible to invalidate the ontological argument. They say that even if it is possible that the concept of a Necessary Being is contradictory, then it is possible that such a being does not exist. If it is possible that the concept is contradictory, then it is not

necessary that it is non-contradictory. And since no theist has offered a widely held and convincing argument to prove that the concept of a Necessary Being is necessarily non-contradictory, then no absolutely certain conclusion follows from the ontological argument;

it is always possible that the very concept of God is contradictory. In short, if it is rationally possible that the very idea of a Necessary Being is contradictory, then the existence of such a God is not rationally necessary.