Pages

Saturday, April 13, 2013

Thomas Aquinas Second Way of Proving God’s Existence



Aquinas’ Second Way of Proving God’s Existence

There is an order of causes and effects in the world.

Causes are always prior to their effects in time.

If something caused itself, it would have to precede itself in time, which is impossible.

So it is impossible for something to be its own cause.

In a series of causes, the first cause brings about the intermediate causes, which bring about the current or final member.

If the series goes on forever (into the past), then there will be no first cause.

If the first cause is eliminated, then there can be no intermediate or current members in the series.

But there are intermediate and current members of the series.

So there must have been a first cause.  (A series that recedes infinitely into the past is impossible.)

We call this first cause “God.”




Aquinas’ Third Way of Proving God’s Existence


Everything is either contingent or necessary.

Since things in nature are generated and then decay, they are contingent beings.
That is, it is possible for them to exist or fail to exist, and their existence is dependent upon things other than themselves.

3.  If something is contingent, then there must have been a time when it failed to exist.

4.  If everything is contingent, then there must have been a time when nothing existed.

5.  Everything that comes into existence must have been caused to exist by some other thing that already exists.

6.  If nothing existed at one time, nothing could have ever come into existence.

7.  That is, if everything was contingent, then nothing would exist now.

8.  But something does exist now:  all of the things we see around us.

9.  Therefore, everything that exists cannot be contingent.

10.  That is, some necessary being(s) must exist.

11.  There cannot be an infinitely receding series of necessary beings.  See the Second Way.
A.  If the series of all things recedes infinitely, then there would be no first cause.
B.  If there is no first cause, then there would be no subsequent effects.
C.  There are subsequent effects (as is obvious around us).

D.  Therefore, there must have been a first cause.

12.  So there must be  some necessary being that derives its necessity from itself, not from another necessary being.

13.  That necessary thing is God.

The Fallacy of Composition is the mistake of thinking that if the parts of a whole all possess a property, then the whole collection of them must possess the property too.
In some cases, the inference appears to be valid:  if all of the parts of a car are red, then the whole car will be red.  Or if every part of a chair is made of wood, then the whole chair is made of wood.

But the properties of the parts might or might not transfer to the whole.  If every part of a car weighs less than 100 lbs, it does not follow that the whole car weighs less than 100 lbs.

And Aquinas' mistake regarding the time when contingent things did not exist can be seen in this example:

1.  There was a time when every person in the room was born.
2.    Therefore, there was a single, concurrent time when every person in the room was born.

No comments:

Post a Comment