Perhaps I'm misunderstanding things, but it seems that in some ways this blogger (with whom I have had some brief interchanges recently) is trying to have things both ways when it comes to presuppositionalism and objectivity.
Exhibit A: A post in which he rejects evidentialism. Now whether he is right or wrong about what he says here is beside the point at present (although I think he probably goes a bit far); what is significant for now is that he says in that post that his is a "dogmatic presuppositionalism": "I know why I can trust my senses and the scientific method: because God has revealed Himself to be an orderly God and the world to be a place run by law" (he also says, with what I think can be described as common presuppositionalist triumphalism, "I can trust my senses - I know that I can because the Bible tells me so. God has revealed the truth of His Word to me, and consequently I know that I can trust it." Oh really? And how did God reveal this truth? By means of his human senses?)
Exhibit B: A comment attached to Exhibit A, in which (in response to another's question) our blogger says of the grammatical-historical hermeneutic (GH): "I'm inclined to think that it is epistemically neutrally. I would tend to view any hermeneutic as existing at a different noumic layer." Okay, he's got me on "noumic": I can't find a definition of that anywhere, so I don't know if it's a typo or if it's a technical philosophical term omitted even from the OED :-) Perhaps he means "noumenal"?
But I digress :-)
It seems to me that what he has said in A and B is contradictory, unless he means that GH is "neutral" in the sense that a hammer is "neutral": that is, it is just a "thing", so to speak, until it is actually picked up and wielded by a human being, and then it might become a tool, or even a weapon.
But I wonder whether there isn't some presuppositional blindness in play here too, or at least possibly an unwillingness to acknowledge something about GH: namely, the fact that precisely because GH is pursued by man, it is not possible for it to be done neutrally. The grammatical-historical method is wielded by Baptists, Presbyterians, Lutherans, Methodists, and charismatics...and yet they all still have significant differences of opinion on what exactly the meaning of the text is supposed to be when it comes to justifying their theological distinctives.
How can this be? It seems rather obvious (to me, anyway) that the usefulness of GH must be understood as limited: it cannot by itself resolve any theological difficulties (and as may be seen from the variety of viewpoints held among its practitioners, it may even perpetuate those difficulties). So it seems that GH is not useful as a means by itself for resolving questions about the meaning of the Bible.
What else is there that might make this difficulty soluble? Perhaps one could say that the illumination of the Holy Spirit is required. This is certainly a worthy suggestion, but it still doesn't solve the problem for all but the most radically-oriented people. The folks who have theological differences must surely all be presumed to be Christians, and as such we must charitably presume that (given that the illumination of the Spirit is necessary, and given that He will grant it equally to all Christians) Christians in each of those camps are guided by the Holy Spirit. And yet...they disagree. How can this be?
Or...let us suppose that for some reason the Spirit does not grant illumination equally to all Christians, so that some folk simply get it wrong in places. Setting aside the more foundational question as to why God would leave some of His people in such a state of uncertainty, there is a more practical question. Who has God illumined the most? And that question simply cannot be answered by any human means I can imagine. And that means that the differences of opinion amongst the various camps above simply cannot be resolved by a mere appeal to the grammatical-historical method. It is impossible.
Well, suppose someone objects that the areas of dispute are matters of indifference. Someone might say that Christians (well, Protestants anyway) are agreed about the "big issues", and the issues that divide them are really matters of trivial theological dispute.
My response to that is twofold. In the first place, I would object that very few (if any) Protestants really believe such a thing: because if they did, their peculiar habit of settling disagreements by schism would be inexcusable (in light of the Lord Jesus Christ's unquestionable will that Christians be united), wherein they habitually insist that union is simply intolerable. So it seems to me that the claim is disingenuous at best.
My second objection is related to the first. Not only do their actions betray an implicit denial of the claim that their differences are purely trivial, but I would also say that it is objectively false that their differences are adiophora. For example: they disagree about the sacraments. They disagree as to their meaning. They disagree about their importance. They differ as to their matter (e.g., whether grape juice may be used in place of wine). They differ as to their number (Anglicans hold more or less to seven while most hold to only two). It is simply not credible even to hypothesize that the sacraments are a matter of indifference to God. Consequently we are forced to ask: which of them is correct? And how do we know this to be the case?
And that is a question that they cannot answer. In the end, it boils down to plain subjectivism: I will decide for myself what is true.
But this is nonsense. God has not left us without a means of knowing the truth that we need to know. He has not given us a black box from which we cannot extract certainty. He has given us the Holy Spirit speaking in and through the Magisterium. He has given us an objective means of knowing what we must believe and how we must live. He has given us the Catholic Church.
So when this same blogger issues impressive-sounding exegetical challenges, I must confess that I do not understand the point. In the first place, from my Catholic vantage point, this seems like a waste of time unless his hope is to make more Calvinists. But if I understand things rightly, I don't even see the sense of it on what it seems his own terms are. In the first place, it is absurd to claim that GH is somehow "neutral". How can a hermeneutic be neutral? That is: how can a framework for interpretation be "epistemically neutral"?? It seems to me that it's self-contradictory even to suggest it: an interpretation is intrinsically non-neutral. So: let us say that he mis-spoke and that he does not really think that GH is genuinely objective. If that is the case, then all this challenge will amount to is a dispute between folks who will never agree, assuming that they are equally skilled exegetically and rhetorically. I do not see the point - unless he wants to make more Calvinists. In that case: well, knock yourself out. But even that seems like simply moving one's eggs from one subjective basket into another.