Okay I'll try to lay out my reasoning from base up. I hope you'll find some time to indulge my brain dump and let me know at which point we begin to diverge in our reasoning.

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We can only be sure of two things with 100% certainty.

G1: "I" exist.

G2: logical truths.

Everything else is contingent, right? We observe certain things with our senses. And we're trying to surmise what it is. How it works. What's causing it. Etc. And any knowledge we gain can never be given 100% certainty, can it? Because our senses are fallible. Can we guarantee we are not living in a simulation, being experimented on by showing Divine events such as a resurrection just to see how we react? Can we guarantee that we are not a brain in vat being fed signals that generate our universe. Can we guarantee there is no unknown unknowns we can't even think of because of our vantage point in reality? I don't think we can. And until we can eliminate these logically valid causes, we can only talk about how likely one possibility is over another. We can try to do the best we can, but we have to be humble. But as long as we are dependent on our own senses, no other knowledge we gain can ever go up to 100% certainty apart from G1 and G2. I hope there is not much to disagree about here?

(For the purpose of our discussion, let's eliminate the other possibilities and assume that the world we see is "real" with say 99.99% certainty. Thus G1 implies "I" and world we see.)

Using G1 and G2, we can come to a conclusion with 100% certainty that:

C1: An eternal First Cause exists.

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What piqued my interest in this conversation was the book's claim that a personal God can be shown with 100% certainty, just from logic. If true, that'd be amazing. We'd settle the question of God once and for all. I won't be able to deny logical truths.

But I don't think the book succeeds. It shows FC for sure. But it does not succeed in showing that FC has free will. My claim is that there are still (at least) two possibilities for FC: FC is a personal God or FC is a set of impersonal rules. Both these possibilities can explain everything we see in the world. And our quest is to try figure out which one reflects the True nature of FC.

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> Of all the possible rulesets that could exist, why this one and not another?

If you notice, G1 is also an observation. By which I mean that it could have been the case that I didn't exist, right? Which means even FC doesn't have a 100% certain reason to exist. Given G1, FC definitely exists. But:

P1: it is logically possible that nothing (neither I nor FC) existed.

I'd love it if you could show that P1 isn't a valid possibility.

So given P1, we can then ask the question: why does FC exist in the first place, right? From our vantage point, we are asking, what causes/sustains us and the world we see. The answer is FC. But what causes FC? Well:

C2: FC is a brute force fact of reality.

Given G1, FC always has to have existed. We can ask "why FC?", but is has no answer. I think you'd agree to this?

So let's say FC=God. That is, God is real and He caused G1. We can ask the question: why does God exists? And the answer is C2. He just does. I've heard it put this way: that God is His own cause. So the takeaway is that C2 is valid: base reality FC can (and must) exist without any reason attached to it. Makes sense?

Thus, when you ask: "why this one and not another?", my answer is the same: C2. That it is a brute-force fact of reality. We cannot expect a reasonable answer to the question because there isn't any. The difference is what we are applying C2 to. Theism applies it to FC=God. Naturalism applies it to FC=base ruleset.

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> So case 1: the FC actualizes the rules, but is distinct from them; in case 2, the FC is identified with the rules. To me that seems a contradiction.

Right sorry. The difference to me is which rules we are talking about. One is the rules of our universe. General relativity. Quantum mechanics. Whatever base rules lie underneath them. However, I am thinking in more general terms. As I said in the first paragraph, it is not necessarily the case that there is FC and then our universe, right? It could be the case that our universe is a simulation in supercomputers of another universe. It could be the case that I am a brain in vat being fed signals that match the rules of our universe. More realistically, we could be one out of many universes originating from eternal inflation. And FC would then be some base rules causing base realities, inside which the rules for the universe we actually see embedded in an emergent way.

So more generally, I think of: FC -> emergence1 -> emergence2 -> ... -> our universe -> physics -> ... -> lions.

I don't know if you agree yet, the idea is that the explanations for the world we see comes in layers of what I am calling emergence. Why lions? Because biology. Biology can completely explain lions, except the question: why biology? Then we say because chemistry. Why chemistry? Because physics. Why physics? Because FC. Why FC? Brute force fact. (Note that there could be more layers between physics and FC, as per above.)

The important takeaway I want to convey is that FC can be just an impersonal set of rules out of which everything emerges

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> So the existence of events such as E would not imply a "willing" FC. You could equally well say that events such as E are, nonetheless, acting according to the FC's necessary actions.

Words are tricky. Especially in discussions like this one. When I said "in favor of", I meant more in a probabilistic manner. E wouldn't imply with 100% certainty that there is a personal God. But it will make Him more likely than it is currently.

Let me put it this way. Take Conway's Game of Life (GoL). We humans created this "GoL universe" that runs on a grid based on a simple set of rules. Say I am running a GoL instance on my computer
with an initial generation G0. G0 is a choice. There are infinite number of possibilities for G0 and I chose one of these to start with. But as soon as I fixed G0, the state of G1 to G-infinity is then automatically implied, right? I don't have to then setup G1, G2, etc. I can just let it run according to the rules. But I can intervene at any generation if I want to. At any generation Gi, I can modify the state in a arbitrary manner without regard to the rules and the state of Gi-1.

Now let's posit some observers embedded inside GoL. Say they start observing at generation k, such that 0<k<i. And say they don't know the base rules when they start. What will they see? For generations Gk to Gi-1, they might eventually be able to figure out that the state changes in a highly regular manner and thus surmise what the base rules are. However at Gi, they will see that the rules they thought were true break down.

So then reality for these observers could be 3 possibilities. Reminder that this is an analogy, so focus is on the ideas rather than the details.

P1: FC=I, sdht0. I setup the computer and choose to run GoL instead of say chess, and I chose the state of G0. This explains why the rules broke down at Gi.

P2: FC=rules of GoL + G0 (+ the computer). In this case, I sdht0, don't exist. Base reality started with G0.

P3: FC=rules of GoL + G0 + unrelated changes at Gi not implied by G0. This basically implies a discontinuous function for the rules.

I hope you can see how the analogy maps to our universe. (The random change at Gi is the popping in of unicorns.) So yes, as you said, we can never eliminate P3. But my point is: say we're only choosing between P1 and P2, theism vs naturalism, the fact that unicorns popped into existence would make P1 more likely. Conversely, the fact the universe has never broken its regularity would imply P2 is highly likely, because then God will be an extra things that we would not need to explain what we see. But none of the cases can be asserted with 100% certainty.

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> Likewise, the fact that things behave in observably regular ways does not, of itself, imply that the FC is bound to act in a certain way.

Again, "bound to act" is a claim of certainty that I'm not making. I'm only saying it makes it highly possible that regular rules is all there is to it.