But I digress. Back to the argument from causality. I've talked a lot about the argument from motion or change, aka, the First Way. You guys are probably pretty familiar with it by now: 1) things are changing; 2) if something is changing then it's being changed by something else; 3) but that means that the something doing the changing itself is changing or not; 4) but since all per se or instrumental causal chains are being powered by some "first" thing, then by nature such causal chains can't infinitely regress; and 5) therefore we must conclude that there is something that is changing everything else that is itself absolutely and completely unchanging (which, upon further analysis, we understand to be actus purus or pure act).
We've talked a lot about how people misunderstand the argument, especially around the two types of causal chains (temporal, accidental chains that go back in time vs. atemporal, instrumental chains in which the events are simultaneously related). But I'm afraid that there's a bit of confusion when we try to apply that reasoning to the Second Way, and I wanted to offer a clarification there that people might find useful--a clarification which in turn should help people understand the First Way better.
So the Second Way is the argument from efficient causality. For those interested, here's Aquinas' explanation of the argument:
- 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. (ST Ia.3.2)
But that's just not true. On the older view, causes can either be necessary or not. Both types of causes are real causes. So if I choose X rather than Y, I really am the efficient cause X even though the choice is itself non-necessary. In other words, we shouldn't understand "cause" in a Newtonian, mechanistic sense, in which X necessarily brings about Y. That may be true with some causes, but not all. The other major problem here, though (and I think this is deeper), is that we have the Kalam Cosmological Argument in the back of our mind. We here "efficient cause" and we tend to think "bring into being." But we have to be really careful here, because "bringing into being" can easily be misinterpreted along the KCA's first premise ("that which comes into existence must have a cause"), but that then quickly devolves into a discussion about temporal, accidental causal chains! The trick here is to recognize that, in the KCA's premise, "comes into existence" is limited to only one type of what we loosely call "change": the KCA is concerned with "generation" (that is, something did not exist, and now it does: e.g., a baby didn't exist and after conception it does; a universe didn't exist and after creation it does, etc.). But in Aquinas' terminology, lots of things can "come into existence," most importantly being the actualization (= "coming into existence") of any potency. If you're familiar with the First Way's argument from change/motion, that should be immediately obvious.
The upshot is that the First and Second ways are actually making the same general argument from the same observed phenomena but thinking looking at slightly different aspects of the same. In the argument from motion, the actualization of potency is analyzed in terms that help us see that if something is changing, there has to be something unchanged and unchanging to all that changing. But in the argument from efficient causality, the actualization of that same potency is analyzed in terms that help us see that if something is efficiently caused (changing in this analysis), then it is ultimately being caused by something that is itself not being caused. The First Way, then, leads us to an Unmoved Mover. The Second Way, though, leads us to an Uncaused Causer.
That, I think, is important to understand so that we don't accidentally fall into KCA style thinking. If we do that, then things like a truly undetermined free choice might lead us to think that the second way fails. After all, if some things don't really have causes, then it just isn't true that any given effect has a cause! Ah, how easily we fall back on Newtonianism . . . no, Aquinas is much, much more dynamic than that. When it comes to free choice (or quantum fluctuations or whatever you want), the cause in question isn't the bringing about of X as opposed Y (as if that needed cause--it doesn't!!!), but rather the fact that X is being actualized at all. What is doing that? I am. But what is causing me to bring about X? What is causing me to choose? To be clear, we aren't asking what is causing me to choose X rather than Y. We're asking what's the efficient cause of my choosing period. And what's the efficient cause of that? And so on. Eventually, you get to a cause that is absolutely uncaused in any sense whatsoever: an Uncaused Causer. Yes, in another analysis (the First Way) the exact same series of causes leads to see the fundamental cause is Unmoved or Unchanging. And in still another analysis (the Third Way), we see the exact same series of causes leads us to see that the fundamental cause is necessary and in no way contingent. So the arguments are similar, but just taken from a little bit of a different perspective.
I hope, then, that helps clarify things. I just too much accidental equating of the Second Way with the KCA, and I hope to see that error reduced just a little bit.
Sorry for the length, as always. If someone can shorten and clarify, feel free.