Oh, sorry, I should have addressed an earlier point first. I, for one, do not know if anyone's opinion is based on ignorance or not. I can make certain assumptions about the opinions of others based on my trust of them but I have no way of telling if their opinion is correct or not. If it was certain to be correct it would not be an opinion but a fact. Going back to my original point. If I do not reveal the knowledge that led me to form that opinion, does that make my opinion less valid? It is simply a question of trust surely? I would trust the opinion of a leading philosopher and social activist but I would not trust anything I read or hear in the popular press. That is purely my opinion of course but a lifetimes experience has led me to it. If my opinion is not trusted by some, fine, I accept that. But to say it is worthless because my experience and qualifications for that opinion are unknown is rather unjust is it not?