Until the last quarter of the 20th century, Western civilization had generally valued history. As the classical Greeks defined it, history (historia) was a process of inquiry into the past. In their lexicon, history was a verb, not a noun: one did history, much as we might refer to someone who is studying history rather than just taking a course in it. There are a couple of fundamental premises on which the whole process of doing history rests: First, it assumes that there are objective realities associated with the past that we can access, or that real objective truth exists; and second, it presupposes that apprehending this knowledge matters.
The process of doing history starts with accessing and interpreting facts. Facts are the basic building blocks of the discipline – bits of information that coincide with past realities. An historical fact is something that rational people generally accept as true based on credible research and our current level of knowledge. Since facts are assumptions and beliefs about truth – not necessarily truth itself – facts can change in the light of new evidence. Ideally, that is what historical revisionism is all about – new understanding based on more recent (and presumably better) information. But we shouldn’t be cavalier about facts. If we value truth, we must be cautious when it comes to altering our interpretations of the past. The burden of proof should fall on the revisionists, not (as is often the case today) the other way around. There should be convincing evidence to the contrary before we rewrite history, and it needs to be based on solid factual evidence, not current ideological trends.
In fact, all history is a complex matrix of contributing (and often conflicting) realities, which is why the greatest challenge facing historians is to sift through the material, select what is salient, organize it in a sensible manner, and present it intelligibly so as to illuminate the past. Otherwise, history is chaotic and meaningless – a mere clutter of often-disconnected and random facts (or as the popular axiom declares, “History is just one damn thing after another”). As all serious students and scholars of history can attest, the real value of history comes when we go beyond the basic facts into the realm of analysis and interpretation. But conclusions must be based on solid factual evidence and rational extrapolations lest we become propagandists who use history merely to promote our own agendas. As in every field of scholarship, some historians are intellectually dishonest. The best ones, however, try to curb their sentiments and let the facts dictate their conclusions.
So history is the process of reconstructing and interpreting the past based on the facts as we understand them: what happened, when it happened, why it happened, how it happened, and who did it? We usually get our facts from two or three means: primary and secondary sources, which are based on written accounts, and oral traditions. Ideally, these are supplemented by corroborating artifactual evidence via art, pottery, or architecture. Primary sources are original, first-hand accounts, and in most cases they are highly-valued. But just because something purports to be an eye-witness account doesn’t necessarily mean it is reliable. It can be misleading, or it can be an outright forgery. Due to bias, people often twist the truth or simply omit crucial information to suit their own purposes.
In best-case scenarios, historians have access to multiple primary source documents that they can compare and contrast in order to construct a more thorough understanding of an issue or event. But this is particularly problematical the farther back we go in time. Oftentimes, we are working off only one or a few sources, so our conclusions are, by necessity, more tentative. Therefore, based on the quantity and the quality of the sources, we can, for example, write the history of the Normandy Invasion of World War II with a much higher degree of probability than that of the Norman conquest of Britain in 1066.
Secondary sources also play a vital role in historical research. Although not written by those who actually witnessed an event, they can still enhance our understanding depending upon (1)how long after the fact the account was written (as a general rule, the sooner the better), and (2)how knowledgeable and objective was the author? As with primary sources, those who write secondary accounts of an event have their biases and limitations, and part of the challenge of doing history is learning to evaluate documents for factual inaccuracies as well as unwarranted premises and hidden agendas.
In some cases, our main source of information comes via oral traditions. In terms of reliability, oral sources are even more problematical than written ones. Especially in lieu of any corroborating evidence, oral source material has to be evaluated with a good measure of prudent skepticism.