(intro music)
Hello, I'm Dr. Timothy Yenter,
assistant professor of philosophy
at the University of Mississippi.
I'll be talking about the[br]cosmological argument.
We just looked at a version[br]of the cosmological argument
that has the following form.
One: whatever begins to[br]exist must have a cause.
Two: the universe began to exist.
Three: therefore, the universe[br]must have a cause.
Considering the first[br]premise led us to ask
"Why might this be true?"
Is it a metaphysical principle,
that is, a principle[br]that applies necessarily
and is not dependent on the particular[br]laws of our universe?
Here's one reason for thinking
that the first premise is[br]a metaphysical principle:
it is just an instance of a[br]more fundamental principle.
This more fundamental principle
is that you can't get[br]something out of nothing.
Sometimes it's stated[br]in the fancy Latin way,
"ex nihilo nihil fit,"
which just means "out of[br]nothing, nothing comes."
This seems like such a[br]bedrock principle of reasoning
that many have claimed it[br]is a metaphysical principle.
It simply must be true.
This bedrock principle[br]could serve as the basis
for the second kind of[br]cosmological argument,
the modal version.
Now, "modal" is just a[br]fancy, technical word
for "anything involving what[br]is possible or necessary."
So, some things are necessary.
Other things aren't[br]necessary, but they exist.
They exist, but they don't have to exist.
These things that don't have[br]to exist, but they might,
are called "contingent things."
So we can divide everything[br]that does or could exist
into necessary things[br]and contingent things.
Using these basic ideas, we can construct
a second version of the[br]cosmological argument
which we'll call the modal version.
It works like this.
One: every contingent thing[br]that exists has a cause.
Two: no contingent thing[br]can cause itself to exist.
Three: so every contingent thing[br]must be caused by something else.
Four: the series of contingent causes[br]and effects is itself contingent.
Five: the series of contingent causes[br]must be caused by something else.
Six: the thing that causes the[br]series of contingent causes
must be a necessary being.
Seven: this necessary being is God.
We've discussed reasons for[br]believing the first premise.
To deny it would be to say
that something could come out of nothing,
which seems absurd.
What happens if we deny[br]the second premise?
If contingent things can[br]cause themselves to exist,
wouldn't that mean that the[br]thing existed before it existed?
If causes happen before their[br]effects, then it seems so.
But that's obviously bad.
No matter how hard you try,[br]you can't bring yourself
into existence, because[br]you don't exist yet.
Well, from the first two[br]premises, the third one follows.
Now the fourth one is a bit tricky.
Why believe this?
Well, imagine something in the[br]universe, like a baby crying.
It has a cause, right?
Now imagine that cause.
Maybe his baby brother[br]hit him on the head.
Now that has a further cause,
and then there's a[br]further cause, and so on.
Each contingent thing or event[br]in the universe has a cause.
You could imagine each of these going back
in a line, perhaps forever.
Now take a step back[br]and look at that line.
Is the line, that series of causes,
is it contingent or necessary?
Well, if it were necessary,[br]then this particular arrangement
of the world, with everything[br]happening as it does,
each of these particular elements
of the universe must be necessary too,
because this whole series[br]of events is necessary.
But this isn't how we[br]usually think of the universe.
I think the baby crying isn't necessary.
There's another way things could have gone
without the baby crying.
But if the universe is[br]necessary, then it seems
that everything that happens[br]in the universe is necessary.
So throughout all of history,[br]from a billion years ago,
it was always going to be[br]true the baby would cry.
This eliminates contingency altogether.
Most people find this too hard to give up.
So, back to the line of contingent causes.
That circle, is it necessary?
If the reasoning above is persuasive,
then we have to say, "No, it's[br]not necessary. It's contingent."
Here, we step in and[br]apply our earlier rule:
if it is contingent, then it must be
caused by something else.
Now, could this other thing that caused
the entire chain be[br]itself a contingent thing?
Well, there are three choices.
One: the whole chain is contingent
and caused by something inside the chain.
Now this is really implausible,
because we don't usually think that a part
can cause the whole of which it is a part.
For starters, it would be causing itself,
which, as we've already talked about,
just seems too absurd to consider.
So secondly, the whole chain is contingent
and caused by something else contingent.
Does this work?
Well, the worry here is that we haven't
really made any progress.
Instead, we've started what's[br]called an infinite regress.
We now have a contingent thing
causing this chain of contingent things.
But, applying our earlier principle,
doesn't that new contingent[br]thing itself need a cause?
And doesn't that need a cause?
And that, and that?
And we're off again on the same problem
repeated over and over forever.
The third option then is[br]that the whole chain really
is contingent but it's caused[br]by something necessary.
This seems to be the only option left.
And since God, as traditionally described
by monotheistic religions,[br]is a necessary being,
it looks like we just found[br]a modal, cosmological argument
for the existence of God.
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