St. Thomas Aquinas Five Ways

St. Thomas Aquinas -- Summa Theologicae

Five ways to prove god exists.

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.

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.

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. But every necessary thing either has its necessity caused by another, or not. Now it is impossible to go on to infinity in necessary things which have their necessity caused by another, as has been already proved in regard to efficient causes. Therefore we cannot but postulate the existence of some being having of itself its own necessity, and not receiving it from another, but rather causing in others their necessity. This all men speak of as God.

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.

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.

Breakdown

The key to fooling people with these arguments is simple: insert a naked assertion in the middle of the argument, hoping the latter parts of the argument will distract the reader from analyzing erroneous presuppositions upon which the other, more logical components rely.

Let's break them down:

The First Way: Argument from Motion

This is basically the first cause argument. Everything in motion must have been put in motion by another force.

1. Our senses prove that some things are in motion.

2. Things move when potential motion becomes actual motion.

3. Only an actual motion can convert a potential motion into an actual motion.

4. Nothing can be at once in both actuality and potentiality in the same respect (i.e., if both actual and potential, it is actual in one respect and potential in another).

5. Therefore nothing can move itself.

6. Therefore each thing in motion is moved by something else.

7. The sequence of motion cannot extend ad infinitum.

8. Therefore it is necessary to arrive at a first mover, put in motion by no other; and this everyone understands to be God.

Argument from Ignorance (anything we don't understand must be attributed to "god."). Special pleading fallacy (making "god" an exception to the rule that all causes themselves need a cause).

The Second Way: Argument from Efficient Causes

1. We perceive a series of efficient causes of things in the world.

2. Nothing exists prior to itself.

3. Therefore nothing is the efficient cause of itself.

2 and 3 are naked assertions; they may be correct, but there is no proof. You cannot prove something doesn't exist. This is a logical, semantical trap that many theists use - a variety of the Shifting the Burden of Proof fallacy.

4. If a previous efficient cause does not exist, neither does the thing that results.

5. Therefore if the first thing in a series does not exist, nothing in the series exists.

6. The series of efficient causes cannot extend ad infinitum into the past, for then there would be no things existing now.

Another naked assertion, just like in the first argument - an arbitrary pseudo-factual claim is made that something "cannot extend ad infinitum" without any evidence, and again, it's impossible to prove.

7. Therefore it is necessary to admit a first efficient cause, to which everyone gives the name of God.

This is exactly the same as #1. It's another "First cause argument".

The Third Way: Argument from Possibility and Necessity (Reductio argument)

1. We find in nature things that are possible to be and not to be, that come into being and go out of being i.e., contingent beings.

2. Assume that every being is a contingent being.

3. For each contingent being, there is a time it does not exist.

4. Therefore it is impossible for these always to exist.

5. Therefore there could have been a time when no things existed.

Naked assertion. Impossible to prove; shifting the burden of proof.

6. Therefore at that time there would have been nothing to bring the currently existing contingent beings into existence.

Naked assertion. Impossible to prove; shifting the burden of proof.

7. Therefore, nothing would be in existence now.

Naked assertion. Impossible to prove; shifting the burden of proof.

8. We have reached an absurd result from assuming that every being is a contingent being.

Naked assertion. Impossible to prove; shifting the burden of proof.

9. Therefore not every being is a contingent being.

... you get the idea...

10. Therefore some being exists of its own necessity, and does not receive its existence from another being, but rather causes them. This all men speak of as God.

Argument from Ignorance. We don't understand the nature of existence, therefore there must be some cosmic overlord who magically makes it all work.

There is a special pleading, an exception to the rules in each of the first three arguments: Acquinas simply says, "God did it" and declares that's where his logic ends. But the question remains, who moved/created/made exist god?

The Fourth Way: Argument from Gradation of Being

This is called The Transcendental Argument (or Ontological Argument). It is based around naked assertions and using semantics.

1. There is a gradation to be found in things: some are better or worse than others.

Naked assertion; subjective.

2. Predications of degree require reference to the “uttermost” case (e.g., a thing is said to be hotter according as it more nearly resembles that which is hottest).

3. The maximum in any genus is the cause of all in that genus.

Naked assertion, and in this case, easily provable to be wrong. It's doubtful the ugliest person in the world gave birth to the second ugliest person in the world. When you strike a match, it isn't ignited by the core of the sun.

4. 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.

Argument from Ignorance - a key component to each and every one of Acquinas' claims.

The Fifth Way: Argument from Design

yawn

The only thing ad infinitum in these arguments is the faulty reasoning and naked assertions..

1. We see that natural bodies work toward some goal, and do not do so by chance.

BAM. Naked Assertion/Unstated Major Premise.

The oldest, lamest theist argument ever: "nothing happened by chance". That's not what scientists are saying. Evolution happened by natural selection, which is a process which favors better-developed creatures. It is anything but random.

2. Most natural things lack knowledge.

Naked assertion.

3. But as an arrow reaches its target because it is directed by an archer, what lacks intelligence achieves goals by being directed by something intelligence.

Naked assertion. Is there a "rainbow factory?"

This leads us into the circular argument, begging the question of who created who, and so on.

4. Therefore some intelligent being exists by whom all natural things are directed to their end; and this being we call God.

Argument from Ignorance. Special pleading. "God did it!" Oh wait? Who created god? Because by your definition something more complex and powerful must have been involved.. but then you go "stop, that's it!"