Historical method

Historical method is the collection of techniques and guidelines that historians use to research and write histories of the past. Secondary sources, primary sources and material evidence such as that derived from archaeology may all be drawn on. The historian's skill lies in identifying these sources, evaluating their relative authority, and combining their testimony appropriately in order to construct an accurate and reliable picture of past events and environments.
In the philosophy of history, the question of the nature, and the possibility, of a sound historical method is raised within the sub-field of epistemology. The study of historical method and of different ways of writing history is known as historiography.
Though historians agree in very general and basic principles, in practice "specific canons of historical proof are neither widely observed nor generally agreed upon" among professional historians. Some scholars of history have observed that there are no particular standards for historical fields such as religion, art, science, democracy, and social justice as these are by their nature 'essentially contested' fields, such that they require diverse tools particular to each field beforehand in order to interpret topics from those fields.

Procedures for contradictory sources

and Langlois & Seignobos proposed a seven-step procedure for source criticism in history:

If the sources all agree about an event, historians can consider the event proven.
However, majority does not rule; even if most sources relate events in one way, that version will not prevail unless it passes the test of critical textual analysis.
The source whose account can be confirmed by reference to outside authorities in some of its parts can be trusted in its entirety if it is impossible similarly to confirm the entire text.
When two sources disagree on a particular point, the historian will prefer the source with most "authority"—that is the source created by the expert or by the eyewitness.
Eyewitnesses are, in general, to be preferred especially in circumstances where the ordinary observer could have accurately reported what transpired and, more specifically, when they deal with facts known by most contemporaries.
If two independently created sources agree on a matter, the reliability of each is measurably enhanced.
When two sources disagree and there is no other means of evaluation, then historians take the source which seems to accord best with common sense.

Subsequent descriptions of historical method, outlined below, have attempted to overcome the credulity built into the first step formulated by the nineteenth century historiographers by stating principles not merely by which different reports can be harmonized but instead by which a statement found in a source may be considered to be unreliable or reliable as it stands on its own.

Core principles for determining reliability

The following core principles of source criticism were formulated by two Scandinavian historians, Olden-Jørgensen and Thurén Torsten :

Human sources may be relics such as a fingerprint; or narratives such as a statement or a letter. Relics are more credible sources than narratives.
Any given source may be forged or corrupted. Strong indications of the originality of the source increase its reliability.
The closer a source is to the event which it purports to describe, the more one can trust it to give an accurate historical description of what actually happened.
An eyewitness is more reliable than testimony at second hand, which is more reliable than hearsay at further remove, and so on.
If a number of independent sources contain the same message, the credibility of the message is strongly increased.
The tendency of a source is its motivation for providing some kind of bias. Tendencies should be minimized or supplemented with opposite motivations.
If it can be demonstrated that the witness or source has no direct interest in creating bias then the credibility of the message is increased.
Criteria of authenticity

Historians sometimes have to deal with deciding what is genuine and what is not in a source. For such circumstances, there are external and internal "criteria of authenticity" that are applicable. These are technical tools for evaluating sources and separating 'genuine' sources or content from forgeries or manipulation.
External criteria involve issues relating to establishing authorship of a source or range of sources. It involves things like if an author wrote something themselves, if other sources attribute authorship to the source, agreement of independent manuscript copies on the content of a source.
Internal criteria involve formalities, style, and language for an author; if a source varies from the environment it was produced, inconsistencies of time or chronology, textual transmission of a source, interpolations in a source, insertions or deletions in a source.
Various recurring criteria of authenticity are used in diverse ancient historical fields.

Eyewitness evidence

R. J. Shafer offers this checklist for evaluating eyewitness testimony:

Is the real meaning of the statement different from its literal meaning? Are words used in senses not employed today? Is the statement meant to be ironic ?
How well could the author observe the thing he reports? Were his senses equal to the observation? Was his physical location suitable to sight, hearing, touch? Did he have the proper social ability to observe: did he understand the language, have other expertise required ; was he not being intimidated by his wife or the secret police?
How did the author report?, and what was his ability to do so?
# Regarding his ability to report, was he biased? Did he have proper time for reporting? Proper place for reporting? Adequate recording instruments?
# When did he report in relation to his observation? Soon? Much later? Fifty years is much later as most eyewitnesses are dead and those who remain may have forgotten relevant material.
# What was the author's intention in reporting? For whom did he report? Would that audience be likely to require or suggest distortion to the author?
# Are there additional clues to intended veracity? Was he indifferent on the subject reported, thus probably not intending distortion? Did he make statements damaging to himself, thus probably not seeking to distort? Did he give incidental or casual information, almost certainly not intended to mislead?
Do his statements seem inherently improbable: e.g., contrary to human nature, or in conflict with what we know?
Remember that some types of information are easier to observe and report on than others.
Are there inner contradictions in the document?

Louis Gottschalk adds an additional consideration: "Even when the fact in question may not be well-known, certain kinds of statements are both incidental and probable to such a degree that error or falsehood seems unlikely. If an ancient inscription on a road tells us that a certain proconsul built that road while Augustus was princeps, it may be doubted without further corroboration that that proconsul really built the road, but would be harder to doubt that the road was built during the principate of Augustus. If an advertisement informs readers that 'A and B Coffee may be bought at any reliable grocer's at the unusual price of fifty cents a pound,' all the inferences of the advertisement may well be doubted without corroboration except that there is a brand of coffee on the market called 'A and B Coffee.'"

Indirect witnesses

Garraghan says that most information comes from "indirect witnesses", people who were not present on the scene but heard of the events from someone else. The historian Louis R Gottschalk says that a historian may sometimes use anecdotal evidence when no primary texts are available.

Oral tradition

Gilbert Garraghan maintains that oral tradition may be accepted if it satisfies either two "broad conditions" or six "particular conditions", as follows:

Broad conditions stated.
# The tradition should be supported by an unbroken series of witnesses, reaching from the immediate and first reporter of the fact to the living mediate witness from whom we take it up, or to the one who was the first to commit it to writing.
# There should be several parallel and independent series of witnesses testifying to the fact in question.
Particular conditions formulated.
# The tradition must report a public event of importance, such as would necessarily be known directly to a great number of persons.
# The tradition must have been generally believed, at least for a definite period of time.
# During that definite period it must have gone without protest, even from persons interested in denying it.
# The tradition must be one of relatively limited duration.
# The critical spirit must have been sufficiently developed while the tradition lasted, and the necessary means of critical investigation must have been at hand.
# Critical-minded persons who would surely have challenged the tradition - had they considered it false - must have made no such challenge.

Other methods of verifying oral tradition may exist, such as comparison with the evidence of archaeological remains.
More recent evidence concerning the potential reliability or unreliability of oral tradition has come out of fieldwork in West Africa and Eastern Europe.

Anonymous sources

Historians do allow for the use of anonymous texts to establish historical facts.

Synthesis: historical reasoning

Once individual pieces of information have been assessed in context, hypotheses can be formed and established by historical reasoning.