BURDEN of PROOF
In a dispute between one whose point is provable and one whose point is not provable, b.o.p. is a social obligation on him whose point is provable to do so.
No one can be compelled to accept burden of proof. If burden of proof is on someone, and he refuses to accept it, that person is simply not worth talking to. Can I prove that statement? Not logically, but I'm justified in ignoring anyone who doesn't agree with it. B.o.p. can be applied to person vs. person or statement vs. statement. When it's person vs. person, the only rules are those agreed on by the opponents. When it's statement vs. statement, some epistemic rules can be applied. e.g.
Joe asserts, "X has been done."
Fred asserts, "No it hasn't."
B.o.p. is on Joe to show that X has been done.
If the above were a case of person vs. person, the initiator is the aggressor, and therefore should be required to at least present an argument for, if not proof of, his point. But if it's statement vs. statement, it makes no difference who initiates. Suppose the above confrontation were reversed:
Fred asserts, "X has not been done."
Joe asserts, "Yes, it has."
B.o.p. is still on Joe to show that X has been done.
All the following assume a case of statement vs. statement.
Joe asserts, "I can prove X."
Fred asserts, "No you can't."
B.o.p. is on Joe to do what he says he can do. If he doesn't, he’s simply not worth talking to.
Joe asserts, "X can be done."
Fred asserts, "No it can't."
If Joe means X can be done now, then b.o.p. is on Joe to show that X can be done.
If Joe means X can be done in the future, then b.o.p. doesn't apply.
Joe asserts, "All S are P."
Fred asserts, "Some S are not P."
B.o.p. is on Fred to show at least one S that is not a P, not on Joe, who must show all of set S in order to prove none of them is a P.
Joe asserts, "If A, then B."
Fred asserts, "Not necessarily."
Not necessarily is different from Some S are not P. Fred is only asserting that it is theoretically possible for an S to be a P. He doesn't have to show an example. But he does have to demonstrate logical possibility.
B.o.p. is on Fred to demonstrate logical possibility. Now that possibility may be ridiculously improbable. And if so, Joe may cross him off as not worth talking to.
Joe asserts, "Some S are P."
Fred asserts, "No S are P."
B.o.p. is on Joe to show at least one S that is a P, not on Fred, who must show all of set S in order to prove none of them is a P.
Joe asserts, "Some S are P."
Fred asserts, "Not necessarily."
B.o.p. is on Joe to show that it is logically possible for one S to be a P.
Joe asserts, "X is relevant."
Fred asserts, "X is irrelevant."
B.o.p. is on Joe to show relevance. Irrelevance is shown by lack of evidence for relevance.
Joe asserts, "If A, then B."
Fred asserts, "Not necessarily."
B.o.p. is on Fred to show at least one A that does not result in B, not on Joe, who must show all instances of A in order to prove they all result in B. Of course if A is a one time event, then the statement can't be proven until A happens. In that case b.o.p. doesn't apply.
Joe asserts, "X is logically possible."
Fred asserts, "No it isn't."
B.o.p. is on Fred to show a logical impossibility if X is the case.
Joe asserts, "X is ontologically possible."
Fred asserts, "No it isn't."
B.o.p. is on Joe to show an example of X being the case.
Joe asserts, "X is ontologically impossible."
Fred asserts, "No it isn't."
B.o.p. is on Joe to show that there is no way for X to be the case. This can only be done when X can happen within an observable range. No one is justified in saying anything is ontologically impossible in all possible worlds - unless possibility in this sense is confined to a limited range (e.g. within logic).
Joe asserts, "X is epistemically possible."
Fred asserts, "No it isn't."
B.o.p. is on Fred. X is always epistemically possible until proven impossible.
Joe asserts, "X is epistemically impossible."
Fred asserts, "No it isn't."
I really don't know how to do this one. I suspect that there may be no such thing as epistemic impossibility.
Joe asserts, "X is inconceivable."
Fred asserts, "No it isn't."
B.o.p. is on Fred to show conceivability.
In a dispute between one whose point is more provable and one whose point is less provable, b.o.p. still exists in a diminished capacity. B.o.p. is on him whose point is more easily provable, and proportional to the ease of proving it.
Joe asserts, "X exists in this box."
Fred asserts, "No it doesn't."
B.o.p. is equal or not applicable. Just open the box and see if X is in it.
Joe asserts, "X exists in this building."
Fred asserts, "No it doesn't."
B.o.p. is shifting to Joe proportional to the ease of searching the building. But it never shifts to Fred, regardless of how difficult it is to search the building.
Joe asserts, "X exists within observable space/time."
Fred asserts, "No it doesn't."
B.o.p. is unclear. If X does exist, how difficult is it to observe it? If X doesn't exist, how difficult is it to prove it? Must Fred show all of observable space/time in order to prove X is not in it? Unless these difficulties are shown to be unequal, b.o.p. does not apply.
Joe asserts, "X exists outside of this universe."
Fred asserts, "No it doesn't."
B.o.p. is inapplicable. They might as well be talking God vs. Spaghetti Monster.
Joe asserts, "There is no alternative to X."
Fred asserts, "Yes, there is."
B.o.p. is on Fred to show an alternative.
But they may be talking about a logical alternative, or a presently known alternative. What if it is a presently known alternative?
Fred asserts, "I disagree. I don't know of an alternative, but science may discover one in the future."
B.o.p. is still on Fred. But Fred may be right.
In a dispute between one whose point is commonly accepted and one whose point is a minority opinion, neither point is likely to be provable, but a burden of showing a greater weight of evidence exists on him who holds the minority opinion. e.g.
Joe asserts, "Marlowe wrote the plays attributed to Shakespeare."
Fred asserts, "Shakespeare wrote them."
Burden of showing a greater weight of evidence is on Joe.
It can be argued that b.o.p. is to probability as inertia is to physics, a bias in favor of the status quo. And though most of us would agree that a pattern, once established, is likely to continue, there are no logical rules to force a person who argues for a break in pattern to accept b.o.p. There are also no moral rules to forbid those of us who perceive probability normally to dismiss such a person as unworthy of attention, if he fails to accept b.o.p.
For you XKCD fans, here's a knock off:
