Download The Cosmological Argument: Aquinas' Second and Third Way and more Study notes Cosmology in PDF only on Docsity!
The cosmological argument
Jeff Speaks
April 17, 2014
The cosmological argument is an attempt to argue from certain very general features of the cosmos to the existence of God. We’ll talk about a few different versions of this form of argument.
1. AQUINAS’ SECOND WAY
Aquinas’ second way seems to depend on the following assumptions:
- Some things are caused to exist.
- Nothing can be the cause of itself.
- There can’t be infinite causal chains.
He seems to be arguing from these assumptions to the following conclusion:
There is a first cause (i.e., something which causes other things to exist, but was not itself caused to exist).
Can you construct a valid argument using these premises for this conclusion?
Does the argument show that there is exactly one first cause, or that there is at least one first cause?
A problem: circular causal chains. How to modify the argument to avoid this problem.
Is Aquinas right that there cannot be infinite causal chains? How does he argue against this possibility?
A contemporary attempt to argue against the possibility of an infinite causal chain: the example of Thomson’s lamp.
Aquinas says that if a first cause exists, then we would all agree that this first cause is God. Is he right about this?
- Aquinas’ second way ....................................................................................................... 1
- Aquinas’ third way .......................................................................................................... 2
- The principle of sufficient reason .................................................................................... 2
2. AQUINAS’ THIRD WAY
One way to respond to the problems we found with Aquinas’ second way involves the notions of necessity and possibility.
Using these notions we can explain what it means to exist contingently: something exists contingently just in case it exists, and it is possible that it not exist. You and I presumably exist contingently, as do tables, chairs, and pretty much everything around us, it seems.
This raises the question: does everything exist only contingently? Aquinas tries to argue that (i) something must exist necessarily, and (ii) this something must be God. Let’s look at how his argument works. One way to lay out his argument is as follows:
- Some things now exist.
- If a thing exists only contingently, then there is some time at which it did not exist.
- If everything exists contingently, then at one time nothing existed. (2)
- If at one time nothing existed, nothing now exists.
- It is not the case at that one time nothing existed. (1,4)
- It is not the case that everything exists contingently. (3,5) C. Something exists necessarily.
Suppose that the conclusion is true. Would that give us good reason to believe that God exists? (This is analogous to the question we asked above about the existence of a first cause.)
Is the argument valid? Are the independent premises of the argument true?
3. THE PRINCIPLE OF SUFFICIENT REASON
Even if Aquinas’ way of arguing for the existence of a necessary being is flawed, the general strategy seems promising. It does seem like the fact that the world exists is something which we should be able to explain in some way — and this would not need explanation any less if we found that the world always existed. Even in this case we should still be able to ask: Why is there something rather than nothing? And it seems like this question should have an answer.
One way to try to improve upon Aquinas, which is discussed in the reading from Taylor, makes use of the following principle:
The principle of sufficient reason Any contingent fact about the world must have an explanation.
2
