When two parties are in a discussion and one makes a
claim that the other disputes, the one who makes the claim typically has a
burden of proof to justify or substantiate that claim especially when it challenges a perceived
status quo.
[1] This is also stated in
Hitchens's razor, which declares that "what may be asserted without evidence, may be dismissed without evidence." Carl Sagan proposed a related criterion – "extraordinary claims require extraordinary evidence" – which is known as the
Sagan standard.
[2]
...
One way in which one would attempt to shift the burden of proof is by committing a logical fallacy known as the
argument from ignorance. It occurs when either a
proposition is assumed to be true because it has not yet been proven false or a proposition is assumed to be false because it has not yet been proven true.
[8][9]