Chesterton on the difference between Impartiality and having No Opinion

"What people call impartiality may simply mean indifference, and what people call partiality may simply mean mental activity... If his bias is one of interest, of class, or creed, or notorious propaganda, then that fact certainly proves that he is not an impartial arbiter. But the mere fact that he did form some temporary impression from the first facts as far as he knew them--this does not prove that he is not an impartial arbiter--it only proves that he is not a cold-blooded fool...

The man who took the trouble to deduce from the police reports would probably be the man who would take the trouble to deduce further and different things from the evidence. The man who had the sense to form an opinion would be the man who would have the sense to alter it...

In much more serious matters it is assumed that the agnostic is impartial; whereas the agnostic is merely ignorant... The pure and starry perfection of impartiality would be reached by people who not only had no opinion before they had heard the case, but who also had no opinion after they had heard it. In the same way, there is in modern discussions of religion and philosophy an absurd assumption that a man is in some way just and well-poised because he has come to no conclusion; and that a man is in some way knocked off the list of fair judges because he has come to a conclusion. It is assumed that the sceptic has no bias; whereas he has a very obvious bias in favour of scepticism...

The argument thus stood in a charmingly convenient form: "All men that count have come to my conclusion; for if they come to your conclusion they do not count.""

--- The Error Of Impartiality / G. K. Chesterton