The inherent fallacies of Rhology's presuppositionalism

Matthew Hughes wrote a funny science fiction novel a few years ago, Black Brillion, which contains one the greatest lines of dialogue I've ever read: "You have only just begun to gauge the depth of your ignorance yet you use it as the foundation for a towering confidence."

In following Rhology's attempts to debate us on morality, one notes that the bulk of his argument rests on the stated assumption atheists have "no basis" to determine right from wrong. Naturally, any atheist reading that will immediately know that Rhology's full of crap. But why does Rhology feel so confident as to root his whole argument in such a bold and arrogant claim, and how does he think this claim will help support his conclusion that "the Christian worldview [is] a much more reasonable and fitting (not to mention existentially satisfying) alternative to the atheistic one"?

As the always interesting if long-winded Dawson Bethrick points out, presuppositional apologetics is rife with logical fallacies. And in this case, Rhology is taking a page from Greg Bahnsen's book and employing the argument from ignorance fallacy. When presuppositionalists state that atheists cannot account for morality or whatever, if they were honest, they would have to admit that they simply are not aware of what basis atheists employ to draw such conclusions. But presups like Rhology, rather than honestly admit to their simple lack of knowledge as to how atheists think, would rather declare as an axiom that atheists just cannot draw any conclusions on moral or other issues. Stated as a syllogism, what the presup wants to argue is this:

1. If the atheist worldview cannot account for morality (or whatever), then the Christian worldview is true.
2. The atheist worldview cannot account for morality.
3. ...So the Christian worldview is true.

Where Rhology and his fellow presups fall on their faces is that they never present any evidence to support point 2. If any of them were actually able to state an example of any situation where the Christian, using only the Bible as his guide, was capable of accurately assessing the moral rightness or wrongness of the situation, and the atheist simply could not do so by using reason, then they might be on to something. But no presup ever does this, and I submit they cannot. On the occasions they actually confront atheists head-on with their declaration that we have no basis for right and wrong, as Rhology is balls-fully doing here, they are invariably shot down and given ample and detailed explanations of just how atheists do comprehend moral precepts. Yet they ignore or dismiss these explanations so as to hold on to what little argument they have — an argument which is propped up almost in its entirety by the ignorance fallacy, and which attempts to establish the truth of the Christian worldview and even the existence of God Himself based on the presumed inability of atheists to account for such things as right and wrong.

As long as presuppositionalists insist on rooting their arguments in premises that they not only haven't established as true, but which can easily shown to be false — like atheists' having "no basis" to account for whatever the presup wishes to claim validates Christianity — then their entire method of arguing will be undermined by fallacies from the get-go. In ignoring these fallacies, and by insisting on restating their flawed premises as axioms no matter how often they are corrected, the presuppositionalist is like a homeowner who thinks that brand-new wall-to-wall carpeting is sufficient to deny the fact that all of their flooring has been eaten away by termites.