Help debating a former atheist/newly turned agnostic

[Sword of St. Michael]

Hello fishies!

Asking for help in debating a friend of mine about the existence of God. He is a rationalist to the extreme, and only recently started concede that there may be the possibility of God. This has been a 3 year or so journey for him. Recently, after a long talk about religion in general between myself (catholic) friends (christian of very varying degrees and him (first time this has happened, usually shuns talk about faith), it came out the primary issue he has with religion, and specifically Christianity is the lack of reason that is in it, ie, the emphasis on faith alone to the exclusion of reason to back it all up, a 'believe it because i say so' kind of mentality, specifically with the foundation, proving God. I was the only one that could respond to this, utilizing aquinas and demonstrating that it could be possible to prove the existence of God, not proving God, but prove that He exists. This started in a series of talks between the two of us this last week, focusing on thomas aquinas's book 1, question 2, article 2, and later book 1, question 12. Main point of the debate was that we can use reason to look at the effects and causes of God, and conclude there is a God, but we can't use reason alone to then prove God exists as aquinas describes later. That involves faith.
(utilizing discord so we can talk over a span of time, makes it easier to look things up)

Any help on how to proceed, still learning aquinas so unable to jump to specific areas in discussions. Any help on using aquinas, augustine, aristotle etc, or how best to proceed /word things would be greatly appreciated.

His response has me scratching my head a bit and would like some help:

"I think im tracking with the initial part of this, and I'll use and analogy to expound on it.

If I were walking in the woods, and happened upon a tree whose bark was severely torn and cut, I could infer that some beast possibly attacked the tree. I cannot prove what beast did this, it could have been boar, a moose, a bear...etc. But it seems like some animal altered the tree. HOWEVER, it is still a theory; in fact, a beast may not have been involved at all. It may very well have been a genetically mutated tree whose unusual bark closely resembles the coarseness seen from animal marks, and maybe no animal was involved at all.

In other words; im not seeing how you can use an effect alone to prove a cause. You can reason through possible causes, but you can never technically go from hypothesis to proof without sufficient evidence to show that 1)the possible cause actual exists, and 2) also show that the particular possible cause did in fact exert itself in this case.

'We can use reason use reason to prove the existence of God by looking at the effects of God'- this assumes the conclusion: that the material world is an "effect" and that God is the cause of that effect. This is "begging the question". In order for this to hold up, you need to be able to prove 1) God exists 2) That God actually caused the material world. To use the above analogy, its possible that life as we know it is the mutated tree, and not the animal-altered one.

There is a difference between the scientists posture to theory, and the religious' posture to God.

The scientific community always starts with hypothesis, and/or theory. It never makes the assertion that something "is" without tremendous supporting evidence. And even then, science understands that our saying that something is a "Law" is to really say "We have an extremely high confidence that this is how this works". The scientist is saying "We have a theory that this is how something works, it could be wrong". The religious is saying "We know this is how it works, by faith". This is also why I think the Deist has a stronger position then the Theist; the Deist claims less then the Theist, therefore there is less to prove. The Theist has to prove not only that an animal scratched the tree, but also what kind of animal scratched the tree. The Deist only asserts that some animal scratched the tree. Both could still be wrong though."

[Melkite]

I would say it like this:

"You're right, the evidence doesn't prove that an animal scratched the tree.  It could be a mutation.  But do you have more evidence that it is a mutation than an animal scratch?  If not, then you must assume what has the most evidence until that is disproven.  You don't wait until you have proof to accept where the evidence is pointing - you just leave open the possibility that you may have to adjust your understanding if new evidence presents itself.  So, using your analogy, if you believe that the evidence seems to point to God existing, then you ought to assume that is the explanation until there is better evidence to assume something else.  Yet instead, you are withholding assent with the understanding there is some hypothetical better evidence to the contrary you have yet to discover, that may or may not actually exist.  Why is that?"

[Marmot]

I think there is some useful ammo in chapters 12 and 13 here:

https://isidore.co/aquinas/english/Contr...es1.htm#12

EDIT: Once properly understood, these arguments give certitude that God exists. However, understanding them properly is often somewhat hard and may require the help of someone to explain what each statement means. I think there are resources that explain these arguments in "contemporary" terms.

[SeekerofChrist]

It seems like he's the type of atheist that wants airtight, irrefutable proof of God before he'll believe.  I doubt he expects this for any other belief, at least any of his own beliefs.  I'd ask him what evidence he'd require for the beast in this analogy of his.  If he also found large animal tracks in front of the tree, would he also then think it is reasonable to conclude that it could just as easily be a genetic mutation?  How about a bit of claw left in the bark?  And so on.  Bits and pieces of evidence add up over time, so that one possibility is not only more likely but the other possibilities are highly implausible.  If you find hoofprints in Central Park, assume horses and not zebras.  If all he had was the damaged bark, he might be justified in remaining agnostic.  But that wouldn't be the case.  

The conclusion as it relates to God: you have different reasons to believe in God: fine tuning, objective moral values and duties, various versions of the cosmological argument, design arguments (avoid Paley, though), etc.  While one might construe possible alternatives to many of these, why should we assume that less plausible alternatives will eventually turn out to be true for all of them?  Absent a positive argument in favor of atheism, there's no reason to remain stuck in intellectual neutral.

I also recommend you read up on Alvin Plantinga's Evolutionary Argument Against Naturalism (EAAN).  Though he's a Protestant philosopher, this argument is utterly devastating for the naturalist.  The gist is that, if our minds evolved solely by natural means, that means they evolved for survival and not discovering truth.  Lots of false beliefs could be beneficial for survival.  They didn't evolve to discover objective truth, so that means we cannot trust our own reasoning processes or the conclusions (beliefs) that we draw from there.  There's no way to escape this problem, unless one abandons naturalism in favor of theism.  I'm probably not providing the best explanation of the EAAN so I'll provide a few links about it:

Plantinga’s Evolutionary Argument against Naturalism

Plantinga’s EAAN Once More

[FultonFan]

Well, for one, I’d ask him to elaborate on why he questions universe as being the effect of something having happened. I’d imagine that even most atheists at least believe the universe to be the effect of something. If I remember correctly, Stephen Hawking argued in one of his last works that the universe was perhaps the only known effect we know of that had no cause, viz. the “Big Bang” happened, and, seeing as there was no time or space for anything to have happened to the “initial singularity” (or whatever you call that pre-space-time matter), therefore, it had to have happened without cause. Therefore, the theory rather blatantly discards any concept of eternity, and basically just concludes that there’s a universe because there’s a universe, or that there’s a universe because there somehow “could” be a universe. Very weak, indeed.

I’d ask him to define “nothing”.
Ask him what was before the Big Bang; chances are it’s “nothing”.
Nothing, is by its very essence infinite. It doesn’t mean 0.000000000000000001% of an atom. 
It’s a void of non-existence.
Therefore, if there was ever nothing — viz. no matter, no time, no eternal force to act upon things — there would still be nothing now.