Science is one of the fields that prospers most from opinions. Different opinions are what hypothesis build on, which leads to the development of theories and either proving them wrong or right.
Opinions are essential for scientific progress. It just that one of the core concepts about those opinions is that you should be able to proof them right or wrong at some point in time and transform them into scientific facts.
But Science can't accept opinions - maybe hypothesis are born out of opinions in the first place, but it's only when a scientist clearly establish an hypothesis that it becomes "science". I know, this is pure semantics, but I feel the difference is real though !
What I meant essentially is that you can't have an opinion on hard cold facts - like Earth revolving around the Sun. You can't have an opinion on crows being black, because appart from the rare white ones, crows ARE black. Stuff like that.
History doesn't deal in the subjunctive. We can only work on what we have. This is true for all history though, not only art. We don't know what would've happened to France if Robespierre hadn't enacted his Reign of Terror for example.
Yes! That's why the very first time I jumped into the topic, I mentionned that Art is indeed very much like History, and we know the motto "History is written by the victors". Not only are further development of History actually written by the victors, but even Historical facts can be re-written to either dismiss the vanquished, or glorify the victor. Making even History a bit subjective because sources may have been tampered with, out of spite, patriotism, or ideology.
And let's not even start on the religious texts that are written and rewritten to better fit the views of their clergy :p