It is not easy to prove the existence of God by reason alone. Nonetheless, it is
possible. And among all of the various “proofs” for God’s existence, perhaps none are more famous
than the “Five Ways” of the thirteenth-century philosopher and theologian, Saint Thomas Aquinas.
In this second video, we continue our three-part examination of the “Second Way”
in which Aquinas demonstrates the existence of God: the way of efficient causality.
In our previous (the first) video on Aquinas’s Second Way, we introduced this famous argument
for God’s existence. And we noted three of the proof’s big-picture themes and characteristics:
First, we noted that the argument BEGINS with something accessible to all normal
people in all ordinary circumstances: human sensation of the world around
us. Aquinas begins his Second Way with ordinary human experience.
Second, we noted that the argument CONCLUDES, unsurprisingly,
that God exists. And when we compared the beginning of the argument with its conclusion,
we observed that the Second Way reasons FROM what is most immediately knowable (sensible reality)
TO what is not immediately knowable (God, divine reality).
Third, we noted how Aquinas’s CONNECTS the starting point of
the Second Way to the conclusion of his argument: he explains that this
is a proof of God’s existence “from the nature of the efficient cause.”
And it is to the nature of efficient causality that we now turn our attention.
In order to understand “efficient causality,” it
is helpful to reflect briefly on causality in general.
Everyone possesses at least a vague or a general notion of what a “cause” is.
And if we were asked to provide a definition of “cause,” we would probably say something like:
“a cause is something that does something to something else.”
And this is quite true. We can define a cause PRECISELY
as “that from which something else proceeds with a dependence in being.”
Although there are many different types of causes,
generally speaking, a “cause” is a positive principle (or reality)
that exerts some influence on a thing that is coming into existence in some way.
And Aquinas famously identifies FOUR specific and fundamental types of causes: formal causality,
material causality, efficient causality, and final causality. All four of these types of
causes are important for a precise and accurate knowledge of created reality.
Aquinas’s Second Way, however, proceeds “from the nature” of EFFICIENT CAUSALITY. Therefore,
in this video, we will investigate this very specific type of causality.
If the general definition of a “cause” is “that from which something else proceeds with
a dependence in being,” a specific definition of an “efficient cause” could run like this:
An efficient cause is THAT WHICH BRINGS SOMETHING INTO BEING or IN SOME WAY ALTERS
A BEING THAT ALREADY EXISTS. Therefore, an efficient cause is a profoundly ACTIVE cause.
Let us consider an example: envision a sculptor chiseling a bust of Aristotle
out of a block of marble. Before the sculptor began his work, the bust of Aristotle did not
exist. The only thing that existed was the block of marble. It is only through the
work of the sculptor on the marble block that the bust of Aristotle comes into existence.
In this scenario, the sculptor is the EFFICIENT CAUSE of the bust of Aristotle: the sculptor is
the “agent” that ACTS upon the marble—that brings the marble resemblance of Aristotle into being.
If we reflect further on this example of efficient causality, we also realize
that the bust of Aristotle was incapable of bringing itself into existence. In other words,
the bust of Aristotle is an EFFECT of the sculptor (who is the EFFICIENT CAUSE).
The bust could not make ITSELF the bust that it is. Of course,
a marble bust isn’t alive. It can’t move. But even if it could move, it wouldn’t be able to make
itself. Absolute self-causation is impossible. Not even God could have “created” himself.
In order for a something to bring itself into its own existence, it would have to be and not
be at the same time and in the same respect. It would simultaneously have to exist as such
(in order to be a cause) and not exist as such (in order to be caused), and this is impossible.
Therefore, any time there is an efficient cause (for example, our sculptor working on marble),
there is a corresponding effect (in this case, the marble bust of Aristotle). The
sculptor is only an actual efficient cause of the bust if he actually makes (or made)
the bust. And an efficient cause is really distinct from its effect.
So far, we have considered an efficient cause in relation to its effect.
Let us now REVERSE this order, and consider an EFFECT in relation to its CAUSE.
Imagine that you walk into a room and see a fully completed bust of Aristotle
sitting on a table. What do we encounter in this scenario? We encounter the EFFECT (the
bust) of the EFFICIENT CAUSE (the sculptor). And even if the sculptor is no longer present
or working on the bust, we still know that the bust’s sculptor exists (or did exist).
In other words, we recognize that the bust of Aristotle did not make itself.
Something or someone else made it. And this conclusion is not a
mere conjecture. We know this with absolute certitude. Even if we don’t employ the term,
we realize that the bust of Aristotle is an effect of an EFFICIENT CAUSE.
Every EFFICIENT CAUSE produces an EFFECT. Thus, every effect (as such) receives
its being and existence from an efficient cause. Every effect (as such, necessarily)
has an efficient cause. And, therefore, anytime we encounter something that is an effect, we can
conclude with absolute certitude that it has an efficient cause—that its efficient cause exists.
To conclude this video, let us summarize what we have covered so far: In the FIRST video, we
observed that Aquinas BEGINS his Second Way with reference to what humans can sense and experience
in their everyday lives, and that he ENDS his argument with the conclusion that God exists.
In this video, the SECOND video, we followed an overview of the PRINCIPLE that Aquinas
follows from the beginning of his argument to its demonstrative conclusion: EFFICIENT CAUSALITY.
In our NEXT video—the third, and final video on Aquinas’s Second Way—we will apply what we
have considered so far to the concrete steps of this argument for the existence of God—an
argument that proves God’s existence from the nature of efficient causality.
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