People who are not professional historians sometimes assume that historical research is a once-and-for-all process that will eventually produce a single, final version of what happened in the past. We often hear charges of “revisionism” when a familiar history seems to be challenged or changed. But revisiting and often revising earlier interpretations is actually at the very core of what historians do. And that’s because the present is continually changing.

The kinds of people “doing history,” the kinds of questions they ask, and the tools and materials available to them are anything but static. It’s not simply that new facts come to light, but that the shape and meaning of historical events look quite different from different vantage points and time periods.

Historians recognize that individual facts and stories only give us part of the picture. Drawing on their existing knowledge of a time period and on previous scholarship about it, they continually reevaluate the facts and weigh them in relation to other kinds of information, questions and sources. This is inescapably a task of interpreting rather than simply collecting data. Just as with any important shared body of knowledge, then, history is always undergoing reexamination and reconsideration.

For example, no one is likely to question the fact that Christopher Columbus landed in the Caribbean in 1492. But in recent decades we’ve seen a very thorough questioning of what that event meant. Was it a discovery or an invasion? How was it experienced by the indigenous people who were “discovered” as well as the European sailors who were once the heroes of the story? Click here to view an online exhibit from the US Library of Congress that revisits the encounter of 1492 in light of these questions.