Shifting the burden of proof is a specialized form of the argumentum ad ignorantiam. It consists of putting forward an assert-ion without justification, on the basis that the audience must disprove it if it is to be rejected.
Normally we take it that the new position must have sup-porting evidence or reason adduced in its favour by the person who introduces it. When we are required instead to produce arguments against it, he commits the fallacy of shifting the burden of proof.
'Schoolchildren should be given a major say in the hiring of their teachers. '
'Why should they?'
'Give me one good reason why they should not. '
(It always looks more reasonable than it is. You could equally ask that the janitor, the dinner-ladies and the local bookie be given a say. Come to think of it, they might do a better job.)
It is the proposal itself which has to be justified, not the resistance to it. The source of the fallacy is the implicit pre-sumption that something is acceptable unless it is proved otherwise. In fact the onus is upon the person who wishes to change the status quo to supply reasons. He has to show why our present practices and beliefs are somehow inadequate, and why his proposals would be superior.
I believe that a secret conspiracy of llluminati has clandestinely directed world events for several hundred years. Prove to me that it isn't so.
(We don't have to, anymore than we have to prove that it isn't done by invisible elves or Andromedans living in pyramids under the Ber-muda triangle.)
The maxim of William of Occam, usually shortened to ‘entities should not be multiplied beyond necessity’, tells us not to introduce more by way of explanation than is needed to explain. World events are already explained by divine purpose, evolutionary progress or sheer random chaos. We do not need llluminati added to the brew, and he who would introduce them must show what evidence requires them to explain it.
Shifting the burden is a very widespread and common fallacy. Popular conception has it that he who says ‘prove it’ and he who says ‘prove it isn’t’ are on equal ground. It is a misconception. The one who asks for proof is simply declaring an intention not to accept more than the evidence requires. The other is declaring his intent to assume more than that.
This particular fallacy is the frail prop on which rests the entire weight of unidentified flying objects, extrasensory perception, monsters, demons and bending spoons. Advocates of these, and many other, ethereal phenomena try to make us accept the burden of establishing falsity. That burden, once taken up, would be infinite. Not only is it extraordinarily difficult to show that something does not exist, but there is also an infinite load of possibilities to test.
You will need shifting the burden of proof if you intend to foray into the world of metaphysical entities. Instead of resorting to the simple ‘you prove it isn’t’, you should clothe your fallacy in more circumlocutious form,
Can you show me one convincing piece of evidence which actually dis-proves that… ?
(This tempts the audience into supplying instances, giving you a chance to slide into 'refuting the example' instead of giving any arguments in favour of your case.)
The popular misconception about the onus of proof will enable you to put forward views for which there is not a shred of evidence. You can back gryphons, the perfectibility of man, or the peaceful intentions of religious fundamentalists.