Howard Zinn said it best.
I'd write a long essay about the unavoidable nature of bias in history class, but Howard Zinn already said it better than I ever could. Check it out!
"It is not that the historian can avoid emphasis of some facts and not of others. This is as natural to him as to the mapmaker, who, in order to produce a usable drawing for practical purposes, must first flatten and distort the shape of the earth, then choose out of the bewildering mass of geographic information those things needed for the purpose of this or that particular map.
My argument cannot be against selection, simplification, emphasis, which are inevitable for both cartographers and historians. But the map-maker's distortion is a technical necessity for a common purpose shared by all people who need maps. The historian's distortion is more than technical, it is ideological; it is released into a world of contending interests, where any chosen emphasis supports (whether the historian means to or not) some kind of interest, whether economic or political or racial or national or sexual.
Furthermore, this ideological interest is not openly expressed in the way a mapmaker's technical interest is obvious ("This is a Mercator projection for long-range navigation-for short-range, you'd better use a different projection"). No, it is presented as if all readers of history had a common interest which historians serve to the best of their ability. This is not intentional deception; the historian has been trained in a society in which education and knowledge are put forward as technical problems of excellence and not as tools for contending social classes, races, nations.
To emphasize the heroism of Columbus and his successors as navigators and discoverers, and to de-emphasize their genocide, is not a technical necessity but an ideological choice. It serves- unwittingly-to justify what was done. My point is not that we must, in telling history, accuse, judge, condemn Columbus in absentia. It is too late for that; it would be a useless scholarly exercise in morality. But the easy acceptance of atrocities as a deplorable but necessary price to pay for progress (Hiroshima and Vietnam, to save Western civilization; Kronstadt and Hungary, to save socialism; nuclear proliferation, to save us all)-that is still with us. One reason these atrocities are still with us is that we have learned to bury them in a mass of other facts, as radioactive wastes are buried in containers in the earth. We have learned to give them exactly the same proportion of attention that teachers and writers often give them in the most respectable of classrooms and textbooks. This learned sense of moral proportion, coming from the apparent objectivity of the scholar, is accepted more easily than when it comes from politicians at press conferences. It is therefore more deadly.
The treatment of heroes (Columbus) and their victims (the Arawaks)-the quiet acceptance of conquest and murder in the name of progress-is only one aspect of a certain approach to history, in which the past is told from the point of view of governments, conquerors, diplomats, leaders. It is as if they, like Columbus, deserve universal acceptance, as if they-the Founding Fathers, Jackson, Lincoln, Wilson, Roosevelt, Kennedy, the leading members of Congress, the famous Justices of the Supreme Court-represent the nation as a whole. The pretense is that there really is such a thing as "the United States," subject to occasional conflicts and quarrels, but fundamentally a community of people with common interests. It is as if there really is a "national interest" represented in the Constitution, in territorial expansion, in the laws passed by Congress, the decisions of the courts, the development of capitalism, the culture of education and the mass media."