vossler said:
As you say, it is difficult to distinguish, how can we categorically state that He didn't 'tweak the neurotransmitters' of plant and animal life. If one has to believe in evolution why not say God did the tweaking? Otherwise providence appears to be an escape for TEs to lump all unknowns into.
No, but since we believe that God created nature (with all of its various laws), we treat providence as the general case and miracle as the exception. This is not so unreasonable because if providence is not the general case, why create nature at all? Even if you don't think nature exists as a physical reality (apropos Bishop Berkeley and Idealism), providence is still the general rule. Basically, attributing the consistency of the world to providence is an old, old idea. It's one of the things that permitted science to rise out of natural philosophy.
It's easy to see where the idea of providence fits in with Christian theology, though. Again, it would be difficult for a Christian to say that God is not present in every work of the world. But if the cosmos acts in consistent ways, what will we call that consistency? Not something which is autonomous. But not something which is puppeteer'ed, either. The solution that Aquinas proposed was that God moves nature, even as nature moves itself. This is not presupposed by Scripture, but it is consistent with it.
Thus, you might see why TEs are confused(?) by Christians who reject the findings of science. If the word, "naturalism," in the term, "methodological naturalism," bothers you, simply think of it as "God's providential activity" expressed in a way that is friendly to Atheists.
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Finally, for application of providence vs. application of miracle, it is typically parsimonious to say that it is providence. If we are wrong, then we are wrong. But it is still from God, so at least we have the correct source. If we call it miracle but it was actually providence, then there is no question of trying to understand it apart from its purpose. If you are a social worker and see various young, unwed mothers, you can argue that perhaps they are the products of virgin births. It has been known to happen. But I think you will agree that it is not the general case, and that it won't help us to consider the possibility every time we see a young, unwed mother. It would take exceptional circumstances to lead us to consider that possibility. Again, not that the next young, unwed mother who walks into your office is not the recipient of miraculous reproductive occurrences. It would be unexpected.