I both agree and disagree with you.
I would say they are equivalent “for all practical purposes,” but that qualifier is necessary. A low prior on a complicated hypothesis is not as relevant as one might think due to the washing out of priors (which is how we can have subjective priors such as “deciding” that the existence of Thor has low prior probability).
And as I said in another comment, you cannot call a probability of 0.9998 and a probability of 1 equivalent. If they were equivalent, your probability would = 1. If it is not, you cannot be rationally justified in making such an absolute statement.
All right, I think I concede your point. (Not to say I will stop thinking about this issue, of course—have to be in a constant state of “crisis of belief” &c.) I also think we agree fundamentally about a great many of these points you made in this comment to begin with and perhaps I did not verbalize them coherently—such as “behaving for all practical purposes as if a given T were true” and so on. The majority of your last paragraph is new to me, however. Thanks.