Historical method

The historical method comprises the techniques and guidelines by which historians use primary sources and other evidence to research and then to write history. The question of the nature, and indeed the possibility, of sound historical method is raised in the philosophy of history, as a question of epistemology. The following summarizes the guidelines commonly used by historians in their work, under the headings of external criticism, internal criticism, and synthesis.

External Criticism: Authenticity and Provenance
Garraghan divides criticism into six inquiries (A Guide to Historical Method, 168):


 * 1) When was the source, written or unwritten, produced (date)?
 * 2) Where was it produced (localization)?
 * 3) By whom was it produced (authorship)?
 * 4) From what pre-existing material was it produced (analysis)?
 * 5) In what original form was it produced (integrity)?
 * 6) 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." (A Guide to Historical Method, 118)

Higher Criticism
R. J. Shafer writes, "Determination of authorship and date involves one or all of the following: (a) content analysis, (b) comparison with the content of other evidence, (c) tests of the physical properties of the evidence." (A Guide to Historical Method, 120) Content analysis includes examinations of anachronisms in language, datable references, and consistency with a cultural setting. Comparison with other writings may involve palaeography, the study of style of handwriting, the study of stylometry and comparison of literary style with known authors, or something as simple as a reference to the document's author in another one of his works or by a contemporary. Physical properties include the properties of the paper, the consistency of the ink, and the appearance of a seal, as well as the results of radioactive carbon dating.

Lower Criticism
Lower criticism is more frequently known as "textual criticism," and it is concerned with determining an accurate text in cases where we have copies instead of the original. Approaches to textual criticism include eclecticism, stemmatics, and cladistics. At the heart of eclecticism is that one should adopt the reading as original that most easily explains the derivation of the alternative readings. Stemmatics attempts to construct a "family tree" of extant manuscripts to help determine the correct reading. Cladistics makes use of statistical analysis in a similar endeavor.

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 (A Guide to Historical Method, 157-158):


 * 1) 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)?
 * 2)  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?
 * 3) How did the author report?, and what was his ability to do so?
 * 4) Regarding his ability to report, was he biased?  Did he have proper time for reporting?  Proper place for reporting?  Adequate recording instruments?
 * 5) When did he report in relation to his observation?  Soon?  Much later?
 * 6) 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?
 * 7)  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?
 * 8)  Do his statements seem inherently improbable: e.g., contrary to human nature, or in conflict with what we know?
 * 9)  Remember that some types of information are easier to observe and report on than others.
 * 10)  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 Augusutus.  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.'" (Understanding History, 163)

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 (A Guide to Historical Method, 292). 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.  In so far as this 'original' source is an accurate report of primary testimony, he tests its credibility as he would that of the primary testimony itself." (Understanding History, 165)

Oral Tradition
Gilbert Garraghan maintains that oral tradition may be accepted if it satisfies either two "broad conditions" or six "particular conditions", as follows (A Guide to Historical Method, 261-262):


 * 1) Broad conditions stated.
 * 2) 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.
 * 3) There should be several parallel and independent series of witnesses testifying to the fact in question.
 * 4) Particular conditions formulated.
 * 5) The tradition must report a public event of importance, such as would necessarily be known directly to a great number of persons.
 * 6) The tradition must have been generally believed, at least for a definite period of time.
 * 7) During that definite period it must have gone without protest, even from persons interested in denying it.
 * 8) 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.]
 * 9) The critical spirit must have been sufficiently developed while the tradition lasted, and the necessary means of critical investigation must have been at hand.
 * 10) Critical-minded persons who would surely have challenged the tradition &mdash; had they considered it false &mdash; 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. (See J. Vansina, De la tradition orale. Essai de méthode historique, in translation as Oral Tradition as History, as well as A. B. Lord's study of Slavic bards in The Singer of Tales. Note also the Icelandic sagas, such as that by Snorri Sturlason in the thirteenth century, and K. E. Bailey, "Informed Controlled Oral Tradition and the Synoptic Gospels", Asia Journal of Theology [1991], 34-54.  Compare Walter J. Ong, Orality and Literacy.)

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

Argument to the Best Explanation
C. Behan McCullagh lays down seven conditions for a successful argument to the best explanation (Justifying Historical Descriptions, 19):


 * 1) 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 'the hypothesis', and the statements describing observable data, 'observation statements'.)
 * 2) The hypothesis must be of greater explanatory scope than any other incompatible hypothesis about the same subject; that is, it must imply a greater variety of observation statements.
 * 3) The hypothesis must be of greater explanatory power than any other incompatible hypothesis about the same subject; that is, it must make the observation statements it implies more probable than any other.
 * 4) The hypothesis must be more plausible than any other incompatible hypothesis about the same subject; that is, it must be implied to some degree by a greater variety of accepted truths than any other, and be implied more strongly than any other; and its probable negation must be implied by fewer beliefs, and implied less strongly than any other.
 * 5) The hypothesis must be less ad hoc than any other incompatible hypothesis about the same subject; that is, it must include fewer new suppositions about the past which are not already implied to some extent by existing beliefs.
 * 6) It must be disconfirmed by fewer accepted beliefs than any other incompatible hypothesis about the same subject; that is, when conjoined with accepted truths it must imply fewer observation statements and other statements which are believed to be false.
 * 7) It must exceed other incompatible hypotheses about the same subject by so much, in characteristics 2 to 6, that there is little chance of an incompatible hypothesis, after further investigation, soon exceeding it in these respects.

McCullagh sums up, "if the scope and strength of an explanation are very great, so that it explains a large number and variety of facts, many more than any competing explanation, then it is likely to be true." (Justifying Historical Descriptions, 26)

Statistical Inference
McCullagh states this form of argument as follows (Justifying Historical Descriptions, 48):


 * 1) There is probability (of the degree p1) that whatever is an A is a B.
 * 2) It is probable (to the degree p2) that this is an A.
 * 3) Therefore (relative to these premises) it is probable (to the degree p1 x p2) that this is a B.

McCullagh gives this example (Justifying Historical Descriptions, 47):


 * 1) In thousands of cases, the letters V.S.L.M. appearing at the end of a Latin inscription on a tombstone stand for Votum Solvit Libens Merito.
 * 2) From all appearances the letters V.S.L.M. are on this tombstone at the end of a Latin inscription.
 * 3) Therefore these letters on this tombstone stand for Votum Solvit Libens Merito.

This is a syllogism in probabilistic form, making use of a generalization formed by induction from numerous examples (as the first premise).

Argument from analogy
The structure of the argument is as follows (Justifying Historical Descriptions, 85):


 * 1) One thing (object, event, or state of affairs) has properties p1 . . . pn and pn + 1.
 * 2) Another thing has properties p1 . . . pn.
 * 3) So the latter has property pn + 1.

McCullagh says that an argument from analogy, if sound, is either a "covert statistical syllogism" or better expressed as an argument to the best explanation. It is a statistical syllogism when it is "established by a sufficient number and variety of instances of the generalization"; otherwise, the argument may be invalid because properties 1 through n are unrelated to property n + 1, unless property n + 1 is the best explanation of properties 1 through n. Analogy, therefore, is uncontroversial only when used to suggest hypotheses, not as a conclusive argument.