I will let Butterfield speak for himself today, except in my excerpting him. From The Whig Interpretation of History:
Behind all the fallacies of the whig historian there lies the passionate desire to come to a judgement of values, to make history answer questions and decide issues and to give the historian the last word in a controversy. He imagines that he is inconclusive unless he can give a verdict ...
... unless he can attain to something like this he feels that he has been working at a sum which had no answer, he has been wasting himself upon mere processes, he has been watching complication and change for the mere sake of complication and change. Yet this, which he seems to disparage, is precisely the function of the historian.
The result of historical study is precisely the demonstration of the fallacy of our arm-chair logic – the proof of the poverty of all this kind of speculation when compared with the surprise of what actually did take place.
It is a study of the complexity that underlies any generalization that we can make.
[And yet] the art of the historian is precisely the art of abridgement; his problem is this problem.
It is perhaps a tragedy that the important work of abridging history is so often left to writers of text-books and professional manufacturers of commercial literature.
[A]gainst Acton’s view that history is the arbiter of controversy, the monarch of all she surveys, it may be suggested that she is the ... drudge of all the drudges. The historian ministers to the economist, the politician, the diplomat, the musician; he is equally at the service of the strategist and the ecclesiastic and the administrator. He must learn a great deal from all of these before he can begin even his own work of historical explanation; and he never has the right to dictate to any one of them. He is neither judge nor jury; he is in the position of a man called upon to give evidence; and even so he may abuse his office and he requires the closest cross-examination, for he is one of these "expert witnesses" who persist in offering opinions concealed within their evidence.
History is all things to all men. She is at the service of good causes and bad. In other words she is a harlot and a hireling, and for this reason she best serves those who suspect her most.