- Argument from Ignorance
- Argument from Lack of Imagination
- Argument from Personal Incredulity
The claim that a statement is true simply because it has not been proven false, or that a statement is false simply because it has not been proven to be true. More exactly, that if a claim A is incorrect, a separate claim B is automatically correct: it is thus a type of false dilemma, and based on Shifting the Burden of Proof onto whichever side of the argument you want to lose.
- "It's clear from the knife in this man's back that he was murdered.""You don't know for sure that's how the knife got in his back, therefore he was not murdered."
- "Since you haven't found a murder weapon yet, it's obvious this man was poisoned."
The essence of the fallacy is that if the original argument cannot explain everything right now, it must be false: the person committing the fallacy discards the possibility of gathering more evidence. This makes it essentially a claim of personal omniscience; if the arguer cannot imagine a way for something to have happened, it is clearly impossible: it is thus closely related to the Perfect Solution Fallacy, where solution A is discarded due to failing to measure up to an idealised perfect solution B. In addition, it eliminates all other possible explanations in favour of a preferred one: in the second example, for instance, the idea the victim was, say, strangled is simply discarded in favour of the preferred conclusion, without any clear reason.
Famously refuted by Carl Sagan with the statement, "Absence of evidence is not evidence of absence."
- The popular argument "you cannot prove X does not exist, so it does" (or vice-versa) is the typical case. X can be God, aliens, a huge Government Conspiracy, whatever. It's more common with arguments that are harder to prove, one way or the other.
- Opinion Myopia and its subtropes often take this form, believing that one's opinion must be true because they know nobody who would argue otherwise.
- Bill O'Reilly's infamous tide argument, which basically boils down to "I don't understand how tides work, therefore they are completely inexplicable and God exists." The O'Reilly logic proceeds as follows: 1. I'm the smartest living thing ever to grace the Earth with the imprint of his foot, therefore no one else understands anything that I don't. 2. I don't understand what causes tides. 3. Therefore no one else understands what causes tides either. 4. There is no possible explanation for the tides except.... 5. God did it! Thank you Jesus for giving us the miracle of tides! 6. Witches burn because they are made of wood. 7. We can test for witches by seeing if they float on water.
It was later explained to him that we DO know what causes the tides (the moon's gravity) making O'Reilly retract the tide statement... only to apply the same argument to claim there is no explanation of where the moon came from. Just for the record, we also have a pretty good idea why the moon is up there too.
- O'Reilly's lunar argument above is simply a variation of another version of this trope: the God of the Gaps argument. It basically boils down to: "We don't know how 'Thing X' got here or how it works, therefore God, Q. E. D." For instance, if one asks "how does the sun orbit the earth", and the atheist does not know...on and on and on. Of course, one day there will likely be no more gaps for God to populate, and the argument is logically untenable even if there were. This argument was first identified and comprehensively disproved by Dietrich Bonhoeffer, a Christian theologian later executed by the Nazis, who pointed out that even if there is a gap in mankind's knowledge, the theist who says that "oh, so it must have been God" has no logical or factual basis for that decision. This is also a favorite of creationists to deny the effect of evolution, as a lead-in to claiming creationism is then the default alternative. "I can't imagine the preconditions necessary for it to be possible for inanimate matter to turn into life possibly being true, therefore those preconditions aren't valid, therefore life didn't form on its own from inanimate matter, and God did it instead. And in the process he made a garden. With a tree and a forbidden fruit, and a talking snake, and he made the first man out of mud and the first woman out of his rib. Because that's the default alternative."
- The 'Devil's Proof' was a favorite of Battler's early in Umineko: When They Cry. Until Knox's 8th was declared, Beatrice had to knock these down individually, though she once used Hempel's Raven to turn the burden of proof back to Battler eighteen-fold.
- The Bielefeld Conspiracy is a satirical example. Asking a random person "Do you know anybody from Bielefeld? Have you ever been to Bielefeld? Do you know anybody who has ever been to Bielefeld?" is highly likely to garner three "no"s,note so it is "concluded" that the city does not exist.
A similar example exists with the entire state of North Dakota in the USA. It has a very low population compared to other states and very little tourism. This one started as a joke on the Simpsons as a crazy conspiracy theory spouted by a drunk Homer.
- The God of the Gaps style argument is this. Its generalized form is:
A: Explain how X occurred by natural processes.B: I don't know.A: Aha! Therefore the only plausible explanation is (my specific beliefs about) God, and therefore, God must exist.
- B may not know because it is completely unknown, may have solid theories but be forced to admit there is uncertainty, or may even consider the problem uninteresting. "I don't know" is why we investigate the world in the first place!