Steve Hays responded to my post on Van Til.
This is Van Til’s way of indicating that if you take the unbeliever’s position to its logical extreme, the unbeliever negates his knowledge of God (or anything else). In principle, the unbeliever knows nothing. ...Van Til does think that unbelievers retain some true knowledge
"Common ground" could stand for common beliefs. What believers and unbelievers both know about God, at a conscious or subconscious level. Or it could stand for common standards. Do believers and unbelievers share the same methods and assumptions?
If this is what Van Til meant, then I don't have a problem with it. But at lest in this respect, his view doesn't seem different than Clark's.
I’d just say that, in Van Til, circular reasoning doesn’t have reference to a fallacious type of syllogistic reasoning. Rather, I suspect that it represents a modification of the coherence theory of truth, a la idealism.
That's different than Clark and that's the scepticism and reliance on Kant that I was referring to.