[QUOTE=Mangetout]
Anyone making an affirmative argument is expected to support that argument with factual evidence, etc. The burden of proof rests with the person bringing an assertion, there is no ‘burden of disproof’ for those who hear it and disagree.
But is it always possible to objectively determine who is making the affirmative argument? I’m pretty sure I’ve seen debates where someone asserts a point; their opponent says ‘prove it!’, and they refuse, restating (or appearing to) the opponent’s objection in a form that itself appears to be an affirmative argument.
So is there always a method by which it can be determined who bears the burden of proof?
[/QUOTE]
Here’s how I understand it, based on having seen discussions like this, but not having actually studied or read up on forensics.
If a statement can be aptly paraphrased in a form “There is at least one X such that Y w.r.t. X,” then the “burden of proof” is on the oe who has made this statement. He must produce the X so described, so to speak.
Not all statements can be so paraphrased. For example, “No unicorns exist” can not be so paraphrased.
Where I am not sure is about universal statements, for example, “Any unicorn would have a horn.” In my opinion, it is the negation of this statement which is paraphraseable in a form like the one I gave, to wit: “There is a unicorn such that it does not have a horn.” I call this latter an affirmative. But I suspect debators would call “any unicorn would have a horn” an affirmative as well.
I am not sure that is the best way to think about it, but it is what I suspect debators would say.
If “All X are Y” is supposed to be an affirmative, I don’t know how it is supposed to be proved.
Anyway, with such statements, if they are affirmatives, then (as I’ve demonstrated) so are their negations, so in such debates, it seems to me, both people should have the burden of proof.
-Kris