>>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