To All: Detailed pickings of Aquinas' First Way #3: Two Different Causal Series

NOTE: THIS IS LESS OF A DEBATE THREAD AND MORE OF AN EXPLANATORY THREAD, FOR EASY LATER REFERENCE. THE AIM OF THIS THREAD IS TO GIVE READERS PROPER UNDERSTANDING OF THE ARGUMENT, NOT NECESSARILY TO DEBATE ITS TRUTH VALUE.

Accidentally Ordered Causal Series

The latin name for this is per accidens. In this type of causal series, A is causing B which is causing C. But after A causes B, then B has its own power to cause C. Each member of the series does its own work.

An example would be a hen laying an egg, which then hatches and grows up into an adult hen which lays another egg. Each hen has its own power to generate a new egg. This type of causal series could, in principle, go back forever into the past. NOTE: For this reason among others, Aquinas rejected the Kalam cosmological argument's attempt to argue that there must be a beginning to everything.

Aquinas explains in the Summa Theologica:

...it is not impossible to proceed to infinity "accidentally" as regards efficient causes...as an artificer acts by means of many hammers accidentally, because one after the other may be broken.

You might think of this as a "horizontal" causal series, extending back into the past.

Essentially Ordered Causal Series

The latin name for this is per se. In this type of causal chain, A is causing C by way of intermediate B. B only has the power to pass the causal power along from A to C. It can't generate C by itself. The only one doing any work here is A.

An example might be a series of mirrors bouncing a laser light. The end effect (say, the laser spot on the wall) is C, the mirrors are all Bs, and the only one doing any work is A. The mirrors cannot generate their own laser light; they can only pass it along from previous mirrors and ultimately from the actual laser itself.

What is important to note is that with this series, if the chain of Bs were an infinitely long chain, then there would in effect be no A and hence nothing would be happening to C. So if something is happening to C, then no matter how many Bs there are, there must be an A somewhere down the chain.

Aquinas explains in the Summa Theologica:

...it is impossible to proceed to infinity "per se"--thus, there cannot be an infinite number of causes that are "per se" required for a certain effect; for instance, that a stone be moved by a stick, the stick by the hand, and so on...

You might think of this as a "vertical" causal series, because it is happening in the present.

This Concludes #3

All of Aquinas' Five Ways involve an essentially ordered series, and are thus "vertical", not "horizontal." Whether the universe began to exist or not is irrelevant. His Ways all involve a first cause as in "first in order of importance", or holding up the whole stack. Not first in the past, like the Kalam Cosmological argument attempts to argue.

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