Introduction to the study of history

by Charles Victor Langlois; Charles Seignobos

V. When several statements agree, it is still necessary to resist the natural tendency to believe that the fact has been demonstrated. The first impulse is to count each document as one source of information. We are well aware in matters of every-day life that men are apt to copy each other, that a single narrative often serves the turn of several narrators, that several newspapers sometimes happen to publish the same correspondence, that several reporters sometimes agree to let one of their number do the work for all. We have, in such a case, several documents, several statements—have we the same number of observations? Obviously not. When one statement reproduces another, it does not constitute a new observation, and even if an observation were to be reproduced by a hundred different authors, these hundred copies would amount to no more than one observation. To count them as a hundred would be the same thing as to count a hundred printed copies of the same book as a hundred different documents. But the respect paid to "historical documents" is sometimes stronger than obvious truth. The same statement occurring in several different documents by different authors has an illusory appearance of multiplicity; an identical fact related in ten different documents at once gives the impression of being established by ten agreeing observations. This impression is to be distrusted. An agreement is only conclusive when the agreeing statements represent observations which are independent of each other. Before we draw any conclusion from an agreement we must examine whether it is an agreement between independent observations. Two operations are thus required.

(1) We begin by inquiring whether the statements are independent, or are reproductions of one and the same observation. This inquiry is partly the work of that part of external criticism which deals with the investigation of sources;[173] but that investigation only touches the relations between written documents, and stops short when it has determined which passages of an author are borrowed from other authors. Borrowed passages are to be rejected without discussion. But the same work remains to be done in reference to statements which were not committed to writing. We have to compare the statements which relate to the same fact, in order to find out whether they proceeded originally from different observers, or at least from different observations.

The principle is analogous to that employed in the investigation of sources. The details of a social fact are so manifold, and there are so many different ways of looking at the same fact, that two independent observers cannot possibly give completely coincident accounts; if two statements present the same details in the same order, they must be derived from a common observation; different observations are bound to diverge somewhere. We may often apply an a priori principle: if the fact was of such a nature that it could only be observed or reported by a single observer, then all the accounts of it must be derived from a single observation. These principles[174] enable us to recognise many cases of different observations, and still more numerous cases of observations being reproduced.

There remains a great number of doubtful cases. The natural tendency is to treat them as if they were cases of independent observation. But the scientific procedure would be the exact reverse of this: as long as the statements are not proved to be independent we have no right to assume that their agreement is conclusive.

It is only after we have determined the relations between the different statements that we can begin to count them and examine into their agreement. Here again we have to distrust the first impulse; the kind of agreement which is really conclusive is not, as one would naturally imagine, a perfect similarity between two narratives, but an occasional coincidence between two narratives which only partially resemble each other. The natural tendency is to think that the closer the agreement is, the greater is its demonstrative power; we ought, on the contrary, to adopt as a rule the paradox that an agreement proves more when it is confined to a small number of circumstances. It is at such points of coincidence between diverging statements that we are to look for scientifically established historical facts.

(2) Before drawing any conclusions it remains to make sure whether the different observations of the same fact are entirely independent; for it is possible that one may have influenced another to such a degree that their agreement is inconclusive. We have to guard against the following cases:—

(a) The different observations have been made by the same author, who has recorded them either in the same or in different documents; special reasons must then be had before it can be assumed that the author really made the observation afresh, and did not content himself with merely repeating a single observation.

(b) There were several observers, but they commissioned one of their number to write a single document. We have to ascertain whether the document merely gives the statements of the writer, or whether the other observers checked his work.

(c) Several observers recorded their observations in different documents, but under similar conditions. We must apply the list of critical questions in order to ascertain whether they were not all subject to the same influences, predisposing to falsehood or error; whether, for example, they had a common interest, a common vanity, or common prejudices.

The only observations which are certainly independent are those which are contained in different documents, written by different authors, who belonged to different groups, and worked under different conditions. Cases of perfectly conclusive agreement are thus rare, except in reference to modern periods.