Presuppositions: There are certain classes of people who think they don’t have them. Interestingly, it is usually these people who also think they’re the most in touch with reason and philosophically astute. Take an atheist for example (Why? Because they‘re the easiest to make examples of). Atheists consider themselves to be the most objective people on nobody’s green earth. If you’re of any other opinion than theirs it’s because you’re an irrational idiot . A Christian will deliver an argument from Scripture and the atheist will quickly retort, “You’re begging the question!” Many Christian apologists are intimidated by this. Some may even share the atheist’s sentiments, “you can’t just quote from the Bible when the person you’re trying to convince doesn’t believe it”.
It is supposed that to debate with someone you must have “common ground” on which to debate. The atheist doesn’t believe in God, so he also doesn’t believe in the Bible. To convince the atheist, you must argue from where he will agree with you, like the general reliability of the senses, or some commonly accepted cosmological “truth” like the law of thermo-dynamics. From there you need to prove there is a God and that this God revealed Himself through an inscripturated Word (an impossible fete, I will explain why later). Only this would comply with the atheist’s mandate for “rationality“.
Here is a bit of philosophical profundity that many people don’t seem to think of: In order for an argument to begin it must have a starting point, because without it no argument could begin. The atheist is sure to counter, “What! You flipping moron; are you saying I’m just arguing from my own prior notions?”
If your argument doesn’t have a starting point it didn’t start and is therefore not an argument. If your argument has started it started from a presupposition. So then, quite literally, no matter what you think, you’re a presuppositionalist, because you can only think in terms of your presuppositions. That is the function of logic.
Logic is defined as the study necessary inference. Logic therefore, must have some subject to infer from. Logic requires presuppositions. If you don’t have presuppositions, you’re not thinking logically. I will use the textbook example to explain: All men are mortal, Socrates is man, therefore, Socrates is a mortal. Could one reply against this idea as well with an exclamation of “you’re begging the question”? Of course. Someone may not believe Socrates is a man. Begging the question is a fallacy in which the proposition being concluded is already present (even if only implicitly) in one or more of the premises. Logic however, requires the subject of the conclusion to be present in one or more premises. Quite obviously, Socrates is a man, all men are mortal, therefore, the polar icecaps are melting is not logical. Why? Because the polar icecaps were not mentioned in the premises.
I say all of this to make two points:
First, while the fallacy of begging the question has a legitimate function, it is not to point out the obvious and necessary fact that someone’s argument started with the idea he is deducing from. If those who use the fallacy in this manner (atheist and Christian alike) would apply it to their own thinking, they would understand how they’ve misuse it.
Secondly, because presuppositions are necessary, it is imperative that the Christian have the proper presuppositions. Why is it impossible to argue from cosmology prove the Triune God of Scripture? Because you are arguing from empirical presuppositions to arrive at a non-empirical, non-corporeal entity — God. This isn’t just applicable to the Christian. Ask an atheist to justify the non-empirical laws of logic (or any other abstract concept) he claims to believe in and comedy hour ensues.
The Christian starting point for all his arguments must be from Scripture, because the Christian faith is deduced from Scripture. Let the atheists have their presuppositions. Let them attempt to develop a viable world and life view from them. It will be a failure as it has always been a failure. Likewise, any Christian argument attempting to start from atheistic presupposition will be a failure. We must begin with the Bible for only the Bible equips us for every good work.