Parents may not be allowed to have favorite kids, but philosophers are definitely allowed to have
favorite arguments. So, which—if any—of the famous five ways at the beginning of
Aquinas’s Summa Theologiae was his favorite argument for proving that there’s a god?
He never really tells us, but I think there are some pretty good reasons to
say that his favorite argument for God’s existence was the first way.
One of those reasons has to do with the way that St. Thomas describes the first way when
he introduces it. He calls it “manifestior,” a Latin word that means “clearer,” “more obvious,”
“more evident”, or—and this is probably my favorite translation—“more palpable.”
And it’s clear from the context that he thinks it’s more obvious, more evident,
more palpable than the other four ways. So at the very least we can
say that the first way holds a special place in Aquinas’s mind, if not also in his heart.
But what does it mean to say that the first way is the more obvious, or more evident,
or more palpable way of proving that there’s a god? It can’t mean that the first way is more
certain. After all, the five ways are all supposed to be proofs that there’s a god,
and Aquinas thinks that a proof is an argument that leaves no room for doubt or error.
So clarity or evidence can’t be about how sure we are that the premises and conclusion are true. To
see what it is about, we need to take a closer look at the actual argument of the first way.
In the introductory video to this series on the five ways,
we saw that all five ways have the same core structure: “__________ (blank) is what we call
‘a god’; but some being is a __________ (blank); therefore, some being is what we call ‘a god’.”
When we fill in the blank, the first premise gives us a working definition of the word ‘god’, while
the second premise tells us that there’s something in the world corresponding to that definition.
What does Aquinas use to fill in the blank of the argument of the first way? The answer is:
“a first mover that is in no way moved.” So, the core argument of the first way goes like this:
“a first mover that is in no way moved is what we call ‘a god’; but some being is a first mover
that is in no way moved; therefore, some being is what we call ‘a god.’”
Clear, right? Obvious? Evident? Palpable? Even if you’re steeped in philosophy,
those seem like the bad descriptions of that argument—because it’s not at all obvious,
or evident, or palpable what “a first mover that is in no way moved” either means, or is.
But that doesn’t mean we can’t make St. Thomas’s meaning clear.
What he means by “a mover” is something that causes a change.
So, for example, when fire causes wood to burn, it’s a mover.
When light causes a stained-glass window to shine with brilliant colors, it’s a mover. And
if a Dominican causes his audience to fall asleep with his boring philosophy lecture, he’s a mover.
Now, some movers are also moved—in other words,
some things that cause change are also caused to change. When the fire causes the wood to burn and
the burning wood warms cold people nearby, the burning wood is both mover and moved.
When light causes the stained-glass window to shine and the shining stained-glass
window paints the opposite wall with color, the stained-glass window is both mover and moved.
And if a Dominican causes his audience to fall asleep with his boring philosophy lecture,
and falling sleep causes an audience member to be late for his next class,
falling asleep is both mover and moved.
So, when Aquinas defines ‘a god’ as “a first mover that is in no way moved” what he means
is that a god is something that causes change but is itself in no way caused to change.
Why should we think that there actually is such a thing? Aquinas’s argument is simple. It goes
like this: if something is moved by something else, then there must be an unmoved mover;
but something is moved by something else; therefore, there must be an unmoved mover.
Now, if you’re wondering why, exactly, should we grant Aquinas the premise that if something
is moved by something else, then there has to be an unmoved mover, you’re worried about
exactly the right thing. This is the premise in the first way that most people object to.
But that’s the topic of the next video.
For now, I want to focus on the other premise that something is moved by something else.
That premise seems . . . obvious. Maybe even . . . evident. Perhaps
almost . . . palpable. Wood is changed by fire.
Stained glass is changed by light. Audience members are changed by boring philosophy lectures.
But Aquinas thinks that even something as evident as this can still be proved.
The proof goes like this: everything that is changed is changed by something else;
but something is changed; therefore, something is changed by something else.
And this is where we hit rock-bottom. This is the firm foundation we cannot doubt. For Aquinas
thinks that anyone who really understands what it is to change and to be changed will
understand that something must be changed by something else. Nothing really changes
itself. At most, one part of something will change another part of something.
And that brings us to the final premise: something changes. Here,
at last, we have reached what is manifestior—what is clearer, more obvious, and more evident than
anything else. Here, at last, we have reached something genuinely palpable.
The reality of change is something we see with our eyes, hear with our ears, and touch with our
hands. It’s not that this premise is more certain than its companion. We can be just
as sure that everything changed is changed by something else as we are that something changes.
But there’s a difference: we can both think and feel the truth that something changes.
We can only think the truth that everything that changes is changed by something else.
As embodied beings, the truth that something changes is closer to us,
nearer to us, and dearer to us, because it’s part and parcel of our embodied experience.
And that’s the starting point for the first way, the unique foundation on which it’s built:
something changes; but everything that changes is changed by something else;
so something is changed by something else;
but if something is changed by something else; then there must
be an unmoved mover—an unchanged cause of change; so there must be an unmoved mover;
and an unmoved mover is what we call ‘a god’; so something is a god.
You can decide for yourself whether that’s your favorite of the five ways.
But there’s one thing that’s not up for discussion: its starting-point is clearly,
obviously, and evidently the most palpable.
For readings, podcasts, and more videos like this go to Aquinas101.com. While you're there,
be sure to sign up for one of our free video courses on Aquinas. And
don’t forget to like and share with your friends, because it matters what you think!