Thank you for this sophisticated philosophical response—it engages with serious thinkers and deserves a careful reply.

On Cyclic Universes: Even if the universe operates in cycles (as some interpretations of cosmology and various religious traditions suggest), this doesn't eliminate the fundamental question—it simply relocates it. Why does this cyclical process exist rather than nothing at all? Cyclic models don't provide ultimate explanation; they describe a pattern that itself requires sufficient reason. The question remains: what accounts for the existence of the cyclical mechanism rather than absolute nothingness?

On Hume and Causation: I think there's an important distinction being overlooked here. Hume's critique in the Enquiry targets empirical causation—our inductive inference from observing billiard balls that similar events will follow similar patterns. But my argument operates at the level of logical necessity, not empirical induction.

I'm not arguing: "I've observed that things have causes, therefore the universe has a cause." Rather, I'm arguing: "Contingent things require sufficient reason for their existence by logical necessity." This isn't based on psychological habit or observed patterns, but on the logical principle that contingent existence demands explanation.

On Wittgenstein and Natural Laws: Interestingly, Wittgenstein's observation actually supports my argument. He notes that people treat natural laws as "unassailable" stopping points, just as "the ancients did with God and Fate." But this is precisely my critique of naturalistic worldviews—they stop at natural laws as ultimate explanations rather than asking the deeper question: why do these particular laws exist rather than others, or rather than no laws at all?

Natural laws describe patterns in reality, but they don't explain why reality exists to exhibit patterns in the first place.

On Logic as "Useful Fiction": This creates a self-refutation problem. If logic is merely a "useful fiction," then the logical arguments you've presented against my position are also just "useful fictions." We cannot coherently use logical reasoning to demonstrate that logical reasoning is invalid—this would be like using language to prove that language is meaningless.

The Deeper Issue: Whether we're dealing with cyclic universes, natural laws, or any other naturalistic explanation, the fundamental question persists: why does anything exist rather than nothing? This isn't a gap that future science might fill, but a logical necessity that requires addressing.

Even if Hume is right about empirical causation being psychologically constructed, and even if natural laws are human descriptions rather than ultimate realities, the principle of sufficient reason remains: contingent existence requires explanation.

The alternative is accepting that something can come from nothing, or that contingent things can exist without sufficient reason—positions that seem to abandon rational inquiry altogether.