>>>OK, I will simplify it even more:
>>>
>>>A. I think your sister is pretty
>>>B. I don't think she is very pretty
>>>A. Your sister is the prettiest girl in the world
>>>B. Prove it...
>>>
>>>My point is that it's not WHAT is argued that is important, it's HOW it's argued.
>>
>>I don't think using an example of "adjectives" which are purely subjective (and only opinion not fact) is appropriate.
>
>OK, a third, and last, example:
>
>A. I support my mayor because he lives in my neighborhood
>B. I don't like him since he doesn't support building a new hospital
>A. He doesn't support building a new hospital because he has other priorities
>B. Prove it

Still not a good example. The 3rd line is presented as a factual statement not an opinion and should be supported by providing a list of his priorities or statements from the mayor.

Besides, if the statement was an opinion or view only (and not based on evidence), then all the poster would have to do is reply "I don't have to prove it, it's only my view just as you do not have to prove your view." Opinions don't have to be proven scientifically or with supporting studies if they are purely subjective opinions.

It still does not justify your demanding that Kevin participate by different rules (that do not even make sense) than everyone else. It's like stating that you acknowledge that he is the better debater so he must play by separate rules (handicapped) with one arm behind his back. If you cannot support your argument, then that should be stated. You could simply state: there is no evidence supporting this (yet), but my view is... or you could simply state it as an opinion and not fact. If the only way you can win a discussion is to cheat, then it's not a discussion at all.

Also, everyone benefits from a discussion. Sometimes it is just learning new information, facts, or even - yes - opinions and views. It's ok to have a view that is not supported by facts. Just don't state your view as a fact or if you do, be prepared to support it with evidence or studies or facts or to restate it as a view. Sometimes opinions are proven as factual later when more studies, experiments or facts arise.