It is impossible to give here an exhaustive treatment of the arguments for the existence of God, even the one's I will present, and the many ways of responding to them. What follows is a cursory overview of some of the more famous arguments, intended to provide a basis for classrom discussion.
Pascal’s
Wager
Pascal
gives a pragmatic rather than evidential reason to believe that
God exists. He does not gives reasons for the truth of the claim. Rather, he gives a motive for believing it.
The argument goes like this:
It is better to believe than not. If you don’t believe and God does not exist, you come out even. But if he does, you lose everything. If you do believe and he doesn’t exist, you come out even. But if he does, you gain everything. So bet on God if you know what’s good for you.
The Ontological
argument from St. Anselm (1033-1109)
Anselm of Canterbury provides an a priori argument... God’s
existence is proven by Anselm a priori (apart from experience), by the meaning of
the term.
Proslogion Ch. 2
So Lord — you who reward faith with understanding — let me understand, insofar as you see fit, whether you are as we believe and whether you are what we believe you to be. We believe you to be something than which nothing greater can be conceived. The question, then, is whether something with this nature exists, since “the fool has said in his heart that there is not God” [Ps. 14:1, 53:1]. But, surely, when the fool hears the words “something than which nothing greater can be conceived,” he understands what he hears, and what he understands exists in his understanding — even if he doesn’t think that it exists. For it is one thing for an object to exist in someone’s understanding, and another for him to think that it exists. When a painter plans out a painting, he has it in his understanding, but — yet having produced it — he doesn’t yet think that it exists. After he has painted it, he has the painting in his understanding, and — having produced it — he thinks that it exists. This should convince even the fool that something than which nothing greater can be conceived exists, if only in the understanding — since the fool understands the phrase “that than which nothing greater can be conceived” when he hears it, and whatever a person understands exists in his understanding. And surely that than which a greater cannot be conceived cannot exist just in the understanding. If it were to exist just in the understanding, we could conceive it to exist in reality too, in which case it would be greater. Therefore, if that than which a greater cannot be conceived exists just in the understanding, the very thing than which a greater cannot be conceived is something than which a greater can be conceived. But surely this cannot be. Without doubt, then, something than which a greater can’t be conceived does exist — both in the understanding and in reality.
Let's look at the argument...
1. By ‘God’ we mean that than which none greater can be conceived.
2. God exists in the mind and reality or in the mind alone.
3. It is greater to exist in the mind and reality than in the mind alone.
4. If God exists in the mind alone, then something that is greater than God can be conceived.
5. But this is impossible, for by ‘God’ we mean…
6. Therefore, God exists in the mind and in reality.
St. Thomas
on the existence of God (Summa 1.2.3)
At Summa Theologica 1.2.3, Aquinas gives five proofs for the existence of God.
We’ll run
through all five. Each begins with a feature of the world that we can observe. Aquinas then proves that God is required to explain it.
Important: He does not claim to prove the whole of our undertanding of what God is with each proof. Rather, with each he argues for a 'slice' of what we mean by 'God,' enough to refute atheism. Taken together, we can lean alot about what God is. We'll take up this topic when we move to God's nature.
Objections
Aquinas
begins, as always, by articulating objections. We considered the first of these
last time. The proofs he gives largely address the second, so we’ll cover it
indirectly today…
Objection 1: It seems that God does not exist; because if one of two contraries be infinite, the other would be altogether destroyed. But the word God means that He is infinite goodness. If, therefore, God existed, there would be no evil discoverable; but there is evil in the world. Therefore God does not exist.
Obj. 2: Further, it is superfluous to suppose that what can be accounted for by a few principles has been produced by many. But it seems that everything we see in the world can be accounted for by other principles, supposing God did not exist. For all natural things can be reduced to one principle which is nature; and all voluntary things can be reduced to one principle which is human reason, or will. Therefore there is no need to suppose God’s existence.
The idea
here is that natural (and voluntary) things can be explained without God.
The first
way: The argument from motion/change
The first and more manifest way is the argument from motion. It is certain, and evident to our senses, that in the world some things are in motion. Now whatever is in motion is put in motion by another, for nothing can be in motion except it is in potentiality to that towards which it is in motion; whereas a thing moves inasmuch as it is in act. For motion is nothing else than the reduction of something from potentiality to actuality. But nothing can be reduced from potentiality to actuality, except by something in a state of actuality. Thus that which is actually hot, as fire, makes wood, which is potentially hot, to be actually hot, and thereby moves and changes it. Now it is not possible that the same thing should be at once in actuality and potentiality in the same respect, but only in different respects. For what is actually hot cannot simultaneously be potentially hot; but it is simultaneously potentially cold. It is therefore impossible that in the same respect and in the same way a thing should be both mover and moved, i.e. that it should move itself. Therefore, whatever is in motion must be put in motion by another. If that by which it is put in motion be itself put in motion, then this also must needs be put in motion by another, and that by another again. But this cannot go on to infinity, because then there would be no first mover, and, consequently, no other mover; seeing that subsequent movers move only inasmuch as they are put in motion by the first mover; as the staff moves only because it is put in motion by the hand. Therefore it is necessary to arrive at a first mover, put in motion by no other; and this everyone understands to be God.
Let's look at the argument...
1. Some things are in motion (changing). (an observation)
2. Whatever is in motion is moved by another.
2a. Whatever is in motion is moved by something.
2b. Whatever is moved by something is moved by itself or another.
2c. Nothing can be moved by itself.
3. A series of moved movers cannot proceed to infinity.
3a. Every moved mover derives its motion from another.
3b, Without a first unmoved mover, there would be no motion to be derived.
4. Therefore, there is a first unmoved mover.
A chain of moved
movers cannot go back indefinitely. Why not?
A train car moves up a hill… “What’s moving that car up the hill?” “A second car.” “What’s moving the second car?” “A third.” What’s moving the third? “It’s just cars all the way back.”
Is this a
“real” explanation? Things don’t happen for no reason. Without an engine
(without a first mover of some kind) the movement of the cars is unexplained.
Important: The argument here is not for a temporal first cause but ontological dependence on a first cause. There must be an animating force of all the changes in the iniverse.
The
argument from efficient causality
The second way is from the nature of the efficient cause. In the world of sense we find there is an order of efficient causes. There is no case known (neither is it, indeed, possible) in which a thing is found to be the efficient cause of itself; for so it would be prior to itself, which is impossible. Now in efficient causes it is not possible to go on to infinity, because in all efficient causes following in order, the first is the cause of the intermediate cause, and the intermediate is the cause of the ultimate cause, whether the intermediate cause be several, or only one. Now to take away the cause is to take away the effect. Therefore, if there be no first cause among efficient causes, there will be no ultimate, nor any intermediate cause. But if in efficient causes it is possible to go on to infinity, there will be no first efficient cause, neither will there be an ultimate effect, nor any intermediate efficient causes; all of which is plainly false. Therefore it is necessary to admit a first efficient cause, to which everyone gives the name of God.
Let's look at the argument. Some of the same principles apply as before...
1. There is a series of efficient causes.
2. Nothing is the efficient cause of itself.
3. A series of efficient causes cannot proceed to infinity.
3a. Without a first, self existing, efficient cause, there would be no efficient causes.
4. Therefore, there is a first, self-existing, efficient cause.
The argument from contingency
The third way is from consingent things. A contingent thing is something that does not have to be. A necessary thing is something that cannot not be.
The third way is taken from possibility and necessity, and runs thus. We find in nature things that are possible to be and not to be, since they are found to be generated, and to corrupt, and consequently, they are possible to be and not to be. But it is impossible for these always to exist, for that which is possible not to be at some time is not. Therefore, if everything is possible not to be, then at one time there could have been nothing in existence. Now if this were true, even now there would be nothing in existence, because that which does not exist only begins to exist by something already existing. Therefore, if at one time nothing was in existence, it would have been impossible for anything to have begun to exist; and thus even now nothing would be in existence---which is absurd. Therefore, not all beings are merely possible, but there must exist something the existence of which is necessary.
Let's look at the argument...
1. There are contingent things (that exist but don’t have to exist)
2. Contingent things depend on something else for their existence.
3. If everything were contingent, then the set of all things would likewise be contingent.
4. If the set of all things were contingent, it would depend for its existence on something else.
5. But there would be nothing else on which it might depend for its existence.
6. And, so, there would be nothing in existence at all.
7. It follows that not everything is contingent; at least one thing is necessary.
A principle: An explanation cannot be among the things it explains.
The fourth
way
The fourth
way is the one I have the most trouble with…
The fourth way is taken from the gradation to be found in things. Among beings there are some more and some less good, true, noble and the like. But more and less are predicated of different things, according as they resemble in their different ways something which is the maximum, as a thing is said to be hotter according as it more nearly resembles that which is hottest; so that there is something which is truest, something best, something noblest and, consequently, something which is uttermost being; for those things that are greatest in truth are greatest in being, as it is written in Metaph. ii. Now the maximum in any genus is the cause of all in that genus; as fire, which is the maximum heat, is the cause of all hot things. Therefore there must also be something which is to all beings the cause of their being, goodness, and every other perfection; and this we call God.
I will summarize
this way…
There are in things gradations of being, goodness, truth etc., on a scale. There has to be something responsible for the being, the goodness etc. of these things that does not itself fall on the scale (or it too would be among the things whose being etc. requires explanation). It has to be unlimited with respect to being—a transcendent cause of the being of the other things.
The fifth
way
The fifth way is taken from the governance of the world. We see that things which lack intelligence, such as natural bodies, act for an end, and this is evident from their acting always, or nearly always, in the same way, so as to obtain the best result. Hence it is plain that not fortuitously, but designedly, do they achieve their end. Now whatever lacks intelligence cannot move towards an end, unless it be directed by some being endowed with knowledge and intelligence; as the arrow is shot to its mark by the archer. Therefore some intelligent being exists by whom all natural things are directed to their end; and this being we call God.
Let's look at the argument...
1. Things which lack intelligence act with purpose.
2. Not by chance but by design they achieve their end.
3. Whatever lacks intelligence cannot act for an end unless it is given its end by something intelligent.
4. Therefore, there is an intelligent being that directs natural things to their ends.
Paley’s
watch
William Paley provides a similar argument. His is an argument from the beset explanation…
Consider a watch that is discovered…
1. There is a good deal of purposiveness in the watch.
2. This is the result of chance or it is the result of design.
3. It is not the result of chance. (Given chance, this would be highly unexpected.)
4. Therefore, it is the result of design.
5. Therefore, there is a designer of the watch.
Consider, now, the universe…
1. There is a good deal of purposiveness in the universe.
2. This is the result of chance or it is the result of design.
3. It’s not the result of chance. (Given chance, this would be highly unexpected.)
4. It’s the result of design.
5. There’s a designer of the universe.
Premises
(2) and (3) are the contentious one.
Regarding
(2), some say that there’s a third option: Natural selection is not wholly a
matter of chance and it seems to explain some of the apparent design.
But
(consider) natural selection presupposes design:
Nature had
to be ordered such that life would arise and the fit survive etc.
In any
case, there is plenty of purposiveness in the universe outside of the domain of
biology: The laws of nature are incredibly fine-tuned. They didn’t have to be
that way. The odds against it were astronomical. If this needs an explanation, a
designer seems needed.
Regarding (3), some propose a multi-verse hypothesis. The idea here is that our universe is one of an incredible number of universes generated by a mother universe. Eventually one like ours would be generated... and the fact that we’re here asking these questions, indicates that we’re in one of those very rare instances of a rightly tuned universe.
Here's a good presentation fo the argument (no endorsement implied)...
