An Experiment in ‘Steelmanning’: Let’s Try to Formulate a Good Argument from Cosmology Against Naturalism

In the spirit of my last post, I think it would be interesting to engage in some inquiry about whether the kalam cosmological argument is onto something. Rather than try to repair the kalam cosmological argument as it stands, I think it would be interesting to channel Richard Swinburne or Paul Draper and see if there is a good F-inductive argument against naturalism based on known facts in cosmology.

Here’s a quick refresher on notation:

Pr(x): the epistemic probability of any proposition x

Pr(x | y): the epistemic probability of any proposition x conditional upon y

Pr(|x|): the intrinsic probability of any proposition x

“>!”: “is much more probable than”

“>!!”: “is much, much more probable than”

B: background information

T: theism

N: naturalism

E: The expansion of our universe had a beginning.

Here is the relevant background information:

B1. Our universe exists.

B2. Our universe is expanding.

And here is the F-inductive argument:

1. E is known to be true, i.e., Pr(E) is close to 1.

2. N is not intrinsically much more probable than T, i.e., Pr(|N|) is not much greater than Pr(|T|).

3. Pr(E | T & B) >! Pr(E | N & B).

4. Other evidence held equal, N is very probably false, i.e., Pr(N | B & E) !< 0.5.

Notice that this arguments includes in the background information (B1) the fact that our universe exists. By itself, B1 is evidence favoring naturalism over theism. This argument–and premise (3) in particular–says, “Given that our universe exists and is expanding, the fact that its expansion had a beginning is more favorable on theism than on naturalism.” So this argument starts with the general fact which is the topic of the argument from physicality (our universe exists), and attempts to argue that, given the general fact, a more specific fact about cosmology favors theism over naturalism.

Let’s assume that (1) and (2) are true. Can anyone come up with a good reason or reasons to believe (3)?

Please discuss in the combox.