Falsifiability is a fundamental property of a statement of it being possible to have counter-examples to (the search for these counter-examples is called falsification). According to Karl Popper, claims that are not falsifiable are considered to be outside the realm of science. This criterion is accepted by most of the worldwide scientific community. If the theory a unfalsifiable, the burden of proof that the theory is incorrect cannot lie on a skeptic.
When considering unfalsifiable claims, Bertrand Russell used an analogy of a celestial teapot. If a teapot was drifting in space between the Earth and Mars (making it unobservable), he claimed it would be unreasonable to expect belief of the teapot based on their inability to disprove the teapots existence. He compared the belief in God to the belief in a celestial teapot; in both cases it is not the responsibility of disbelievers to disprove its existence.
- "Many orthodox people speak as though it were the business of sceptics to disprove received dogmas rather than of dogmatists to prove them. This is, of course, a mistake. 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 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. "
"[Y]ou could claim that anything's real if the only basis for believing in it is that nobody's proved it doesn't exist!"
Of course, being able to make this claim is an absurd state of affairs.
Special creation is not falsifiable. There is no test which could show, even theoretically, that things were not specially created if they weren't. There is also no test which could show God didn't hire unicorns to create us if he didn't. It is also conceivable that the universe was created last Thursday with the appearance of great age. Without falsifiability there are an infinite number of alternatives one can't prove, all of which have equal merit.
The existence of God or Gods is unfalsifiable. Gods may exist in an inaccessible spiritual world or be immune from testing. "It is said: 'Do not put the Lord your God to the test." Luke 4:12 For this reason, the burden of proof for the existence of God lays on believers and not with skeptics.
The Theory of Evolution is falsifiable.  Had the fossil record been found to be static, it would have shown that species have not evolved. Had a mechanism been found that prevents, and has always prevented, genetic mutations from accumulating or being inherited, it would make evolution impossible. However, the opposite is true in both cases - those things were instead found to support the theory. Another possible disproof of evolution would be species spontaneously appearing without any likely ancestors. This would be observed in the fossil record as "out of place" species, such as a "precambrian rabbit".
- ↑ Russell, Bertrand. Is There a God? . The Collected Papers of Bertrand Russell, Vol. 11: Last Philosophical Testament, 1943-68. Routledge. pp. 547–548.
- ↑ Harry Potter and the Deathly Hallows, Google Books
- ↑ J.K. Rowling quotations at goodreads.com
- ↑ Talk origins archive, Claim CA211