Procedures with the help of wickipidia
Bernheim (1889) and Langlois & Seignobos (1898) proposed a seven-step procedure for source criticism in history:
- If the sources all agree about an event, historians can consider the event proved.
- 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.
External criticism: authenticity and provenance
Garraghan divides criticism into six inquiries
- When was the source, written or unwritten, produced (date)?
- Where was it produced (localization)?
- By whom was it produced (authorship)?
- From what pre-existing material was it produced (analysis)?
- In what original form was it produced (integrity)?
- What is the evidential value of its contents (credibility)?
The first four are known as higher criticism; the fifth, lower criticism; and, together, external criticism. The sixth and final inquiry about a source is called internal criticism.
R. J. Shafer on external criticism: "It sometimes is said that its function is negative, merely saving us from using false evidence; whereas internal criticism has the positive function of telling us how to use authenticated evidence."
 Internal criticism: historical reliability
Noting that few documents are accepted as completely reliable, Louis Gottschalk sets down the general rule, "for each particular of a document the process of establishing credibility should be separately undertaken regardless of the general credibility of the author." An author's trustworthiness in the main may establish a background probability for the consideration of each statement, but each piece of evidence extracted must be weighed individually.
 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 (i.e., mean other than it says)?
- 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 (e.g., law, military); was he not being intimidated by his wife or the secret police?
- How did the author report?, and what was his abilityto 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.'"
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. Gottschalk says that a historian may sometimes use hearsay evidence. He writes, "In cases where he uses secondary witnesses, however, he does not rely upon them fully. On the contrary, he asks: (1) On whose primary testimony does the secondary witness base his statements? (2) Did the secondary witness accurately report the primary testimony as a whole? (3) If not, in what details did he accurately report the primary testimony? Satisfactory answers to the second and third questions may provide the historian with the whole or the gist of the primary testimony upon which the secondary witness may be his only means of knowledge. In such cases the secondary source is the historian's 'original' source, in the sense of being the 'origin' of his knowledge. Insofar as this 'original' source is an accurate report of primary testimony, he tests its credibility as he would that of the primary testimony itself."
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. [Elsewhere, Garraghan suggests a maximum limit of 150 years, at least in cultures that excel in oral remembrance.]
- 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 Wa &eu
Synthesis: historical reasoning
Once individual pieces of information have been assessed in context, hypotheses can be formed and established by historical reasArgument to the best explanation
C. Behan McCullagh lays down seven conditions for a successful argument to the best explanation:
- The statement, together with other statements already held to be true, must imply yet other statements describing present, observable data. (We will henceforth call the first statement