Shifting the Burden of Proof

Also Called
 * Misplaced burden of proof
 * Argument from Ignorance

Generally in a debate, when there is no proof to whether a certain thing happens or not, the logical position would be not to make assumptions about the issue and avoid using it in an argument. The Burden of Proof Fallacy occurs when one side of the debate assumes the truth (or falsehood) of such claim and uses it as an argument solely because there is no proof supporting the opposite side either. In other words, it is the belief that a statement can be made simply due to the lack of proof of its negative, and therefore ignoring the option that the truth or falsehood of the statement is unknown (or not possible to be known).

It should be noted, though, that there can be other good reasons to believe in a statement even if it's not outright proven. Certain considerations should be made regarding the burden of proof in legal, scientific or philosophical issues. In some situations, when something is not proven to exist, it is less risky to assume that it doesn't, though that does not mean it's necessarily the case (actively denying the existence of such thing would still be fallacious, though).


 * In a legal system where the the burden of proof is held by the prosecution, with the defendant regarded as innocent until proven guilty (applies to both common and civil law systems). The requirement is that the prosecution prove that the accused did do it; the defense doesn't have to prove he didn't. This can bite the prosecution badly, especially if the evidence is weak, or has been mishandled. It also doesn't necessarily follow the logical burden of proof, since the defense can demand the prosecution prove a negative. An infamous example of this is the O.J. Simpson trial, where OJ's defense lawyers demanded the prosecution prove an endless series of alternate scenarios were impossible.
 * Meanwhile, since it's extremely hard for the defense to prove that someone definitely didn't commit a crime, when the burden of proof is on them in the media they often have to resort to proving that someone else did do it. That, and it's more exciting that way.
 * It is common, at least in the US legal system, for the party bearing the burden of proof to be required to prove a negative. The most straightforward way to disprove A is to prove B, where B => ~A. That is, evidence inconsistent with the thing to be disproved is introduced. For example, in patent practice, nonreceipt of correspondence can be shown by producing the docket record into which the correspondence, if received, would have been entered.
 * Note that in the US criminal law system, it isn't necessary for the prosecution to definitively prove guilt, merely "guilt beyond a reasonable doubt." That is, far-fetched alternative scenarios that also fit the evidence are not reason to acquit if they do not affect a "reasonable person's" belief in the defendant's guilt. As to which doubts are reasonable and which aren't, no one's really sure about that one. In US civil law however, no one bears a high burden of proof. Jurors decide which side they think is more likely, which is why O. J. Simpson was acquitted of murder but held liable for wrongful death. But if neither side is more likely than the other, then the defense wins.
 * The burden of proof still rests with the prosecution in Australian and UK civil law; they have to prove, on the balance of probabilities, that their position is the correct one.
 * OJ is a complex case, because his acquittal also reflected years of misdeeds by the LAPD, and the main police investigator was proven to lie on the stand while doubt was presented to how the DNA testing was done. Modern law school students, when studying the trial in depth have concluded that as presented to the jury, the evidence is pretty strong that OJ was the victim of a botched frame-up job. He probably did it, but the framing muddied the evidence and increased the doubt.
 * A favourite of many groups; you'll often see demands to prove there is no global conspiracy or that aliens can't possibly have influenced the building of the pyramids.
 * Invoked by both sides with regard to the Turing Test and the question of "strong AI": some people think that as long as you can't prove a machine isn't thinking, it makes compassionate sense to treat it as if it is, based on the fact that it would react in the same way as a human being (and in general, we do assume other humans are thinking creatures). Others counter that since passing a Turing Test only means failing to prove the machine is not thinking, there's still no reason to assume that it is. (Obviously at the moment the debate remains entirely academic.)
 * This is a common tool of internet Trolls. For example, "Birthers" (who claim President Barack Obama was not born in the United States and thus not eligible to be President) will often be asked to prove their allegations, only to reply by saying "Prove it isn't true!" Unfortunately for them, most of their accusations are easily disproven.