As to why there's one theory, at all, "A Theory", has that otherwise there's always an infinite regression, then the idea is that there's an A-Theory, theatheory, say, that's already ad infinitum instead of ad absurdam, as, "ab absurdam".
Then practical working theories can simple enough live in it, and also it makes for weighing and judging practical working theories without necessarily being beholden to either.
This is also for a "The Logic".
It's known since antiquity that axioms are stipulations, and also that any scheme of induction has another refuting it.
Often it's simple as that there exists real "Truth" at all, and, you know, "at all".
Then of course there's quite a consideration of the inter-subjective, then to get above the merely phenomenological, by supplementing the usual animal's or machine's sense perceptions with a notion of sense as object-sense, word-sense, number-sense, time-sense, and a sense of the continuum, as noumenological, thusly equipping the considerations of the phenomenological and noumenological and resolving age-old debates.
Of course, such a theory is "paradox-free", or rather, it would need be.
Otherwise, don't you have a theory?