Alexander Gietelink Oldenziel comments on Just because 2 things are opposites, doesn’t mean they’re just the same but flipped

[Alexander Gietelink Oldenziel]

A simple yet peculiar truth :

A category is not generically isomorphic to its opposite.

[tailcalled]

A notable counterexample is FinVect, which has an equivalence of categories FinVect → FinVect^op.