Updated: Jan 23, 2020
Some atheists & other non-presuppositionalists claim that the presuppositions/ preconditions of intelligibility cannot be justified since in order to try to justify them is to engage in circular reasoning. They adopt a view known as classical foundationalism, which is the belief that all knowledge rest ultimately on foundations of unjustifiable beliefs.
Some examples would be
the laws of logic
the uniformity of nature
reliability of the senses etc.
Classical foundationalism is ultimately a blind faith commitment and arbitrary in nature since it disallows one from providing a rational grounding for the preconditions of intelligibility in order to see if their worldview makes sense of reality. Moreover classical foundationalism rests on a categorical fallacy, and also, as Dr. Greg Bahnsen would call it, the crackers in the pantry fallacy: The big mistake that many atheists make is that they assume that things must be proven the exact same way, which is untrue. There are different types of arguments for different types of things.
For example, proving a complex math problem is not the same thing as proving something in ancient history. Circular reasoning is only a fallacy when it comes to your normative day-to-day arguments or activities. But when it comes to metalevel paradigmatic things, the circularity is broader and unavoidable. There are two different types of circularities. The philosopher John Frame labels them as "Broad Circularity" & "Narrow Circularity". The circularity within the normative realm is not the same circularity within the metalevel realm.
To confuse the two is to commit a categorical fallacy and crackers in the pantry fallacy. Arguing metalevel things (Ex. Laws of logic, uniformity of nature etc..) while engaging in circularity is a lot more broader, fundamental and different from engaging in circularity in arguing normative level things (Ex. Whose car drives faster, whose internet connection is better, etc). The preconditions of intelligibility can be justified, but they cannot be justified with normative logical arguments, otherwise that would be question begging (narrowly circular). They can only be justified with meta logical arguments. And the transcendental argument is a meta logical argument in where we argue that the God of Scripture is the necessary precondition for all of intelligibility, and that without him you cannot prove nor make sense of anything.