You can't prove God doesn't exist
It is not uncommon for apologists to make statements like, "You can't prove God doesn't exist," when they are challenged to support their own claim that God exists. Such statements are intended to shift the burden of proof, and therefore represent a logical fallacy.
Arguments similar to, "[[Belief in proposition X is justified because you can't prove it's not true," are based on the premise that belief in something is justified until sufficient evidence refutes its existence. In this case, the theist is asserting that belief in God is justified even without evidence. While this view may seem reasonable to those who already accept the existence of God, this approach to belief merely represents a form of compartmentalization. If we were to broadly accept the general premise (i.e., "belief is warranted because you can't prove a negative"), we would be unable to develop any useful picture of reality because every claim would be necessarily accepted as true until it was disproved. This is a burden that is impossible to meet when dealing with supernatural claims. The theist is compartmentalizing his or her supernatural beliefs and applying standards different from those applied to other beliefs. To put it more bluntly, a rational person does not seriously claim that leprechauns or unicorns must be assumed to exist because we have not disproved their existence.
Tellingly, apologists typically apply this premise only to questions pertaining to their particular religion — and not to questions pertaining to other religions. The Christian who argues, "You can't prove God doesn't exist," would almost certainly reject such an argument from a Hindu who says, "You can't prove Vishnu doesn't exist!" This compartmentalization, in which one's cherished beliefs are subjected to a special set of standards, is a form of special pleading.
Philosopher Bertrand Russell posed a famous counter-argument to this claim by stating the following:
- "If I were to suggest that between the Earth and Mars there is a china teapot revolving about the sun in an elliptical orbit, nobody would be able to disprove my assertion provided I were careful to add that the teapot is too small to be revealed even by our most powerful telescopes. But if I were to go on to say that, since my assertion cannot be disproved, it is an intolerable presumption on the part of human reason to doubt it, I should rightly be thought to be talking nonsense. If, however, the existence of such a teapot were affirmed in ancient books, taught as the sacred truth every Sunday, and instilled into the minds of children at school, hesitation to believe in its existence would become a mark of eccentricity and entitle the doubter to the attentions of the psychiatrist in an enlightened age or of the Inquisitor in an earlier time."
Great Pumpkin Objection
Many people might object that if belief in God is basic (i.e., rational without evidence), why can't any belief, such as a belief in the Great Pumpkin, also be basic? Alvin Plantinga, a Christian philosopher of theology, responds to this objection by arguing that our culture and our society help form our understandings of rationality, and that we should move away from a foundationalist account for basic beliefs. If the paradigm can be shifted such that belief in God can be considered properly basic, then no further justification is necessary, and the assumption of God's existence is warranted. The problem with Plantinga's response is the absence of universal standards for judging whether a particular belief can be reasonably taken to be basic. Ultimately, shifting the argument to validating God as a basic assumption forms the dubious basis of presuppositional apologetics.