Introduction to the study of history

by Charles Victor Langlois; Charles Seignobos

For the purpose of introducing quantity into formulæ we have at our disposal several methods, of various degrees of imperfection, which help us to attain the end in view with various degrees of precision. Arranged in descending order of precision they are as follows:—

(1) Measurement is a perfectly scientific procedure, for equal numbers represent absolutely identical values. But a common unit is necessary, and that can only be had for time and for physical phenomena (lengths, surfaces, weights). Figures relating to production and sums of money are the essential elements in the statement of economic and financial facts. But facts of the psychological order remain inaccessible to measurement.

(2) Enumeration, which is the process employed in statistics,[204] is applicable to all the facts which have in common a definite characteristic which can be made use of for counting them. The facts which are thus comprehended under a single number do not all belong to the same species, they may have in common but a single characteristic, abstract (crime, lawsuit) or conventional (workman, lodging); the figures merely indicate the number of cases in which a given characteristic is met with; they do not represent a homogeneous whole. A natural tendency is to confuse number with measurement, and to suppose that facts are known with scientific precision because it has been possible to apply number to them; this is an illusion to be guarded against, we must not take the figures which give the number of a population or an army for the measure of its importance.[205] Still, enumeration yields results which are necessary for the construction of formulæ relating to groups. But the operation is restricted to those cases in which it is possible to know all the units of a given species lying within given limits, for it is performed by first ticking off, then adding. Before undertaking a retrospective enumeration, therefore, it will be well to make sure that the documents are complete enough to exhibit all the units which are to be enumerated. As to figures given in documents, they are to be distrusted.

(3) Valuation is a kind of incomplete enumeration applying to a portion of the field, and made on the supposition that the same proportions hold good through the whole of the field. It is an expedient to which, in history, it is often necessary to have recourse when documents are unequally abundant for the different divisions of the subject. The result is open to doubt, unless we are sure that the portion to which enumeration was applied was exactly similar to the remainder.

(4) Sampling is a process of enumeration restricted to a few units taken at different points in the field of investigation; we calculate the proportion of cases (say 90 per cent.) where a given characteristic occurs, we assume that the same proportion holds throughout, and if there are several categories we obtain the proportion between them. In history this procedure is applicable to facts of every kind, for the purpose of determining either the proportion between the different forms or usages which occur within a given region or period, or the proportion which obtains, within a heterogeneous group, between members belonging to different classes. This procedure gives us an approximate idea of the frequency of facts and the proportion between the different elements of a society; it can even show what species of facts are most commonly found together, and are therefore probably connected. But in order that the method may be employed correctly it is necessary that the samples should be representative of the whole, and not of a part which might possibly be exceptional in character. They should therefore be chosen at very different points, and under very different conditions, in order that the exceptions may compensate each other. It is not enough to take them at points which are distant from each other; for example, on the different frontiers of a country, for the very circumstance of situation on a frontier is an exceptional condition. Verification may be had by following the methods by which anthropologists obtain averages.

(5) Generalisation is only an instinctive process of simplification. As soon as we perceive a certain characteristic in an object, we extend this characteristic to all other objects which at all resemble it. In all human concerns, where the facts are always complex, we make generalisations unconsciously; we attribute to a whole people the habits of a few individuals, or those of the first group forming part of the people which comes within our knowledge; we extend to a whole period habits which are ascertained to have existed at a given moment. This is the most active of all the causes of historical error, and one whose influence is felt in every department, in the study of usages and of institutions, even in the appreciation of the morality of a people.[206] Generalisation rests on a vague idea that all facts which are contiguous to each other, or which resemble each other in some point, are similar at all points. It is an unconscious and ill-performed process of sampling. It may therefore be made correct by being subjected to the conditions of a well-performed process of sampling. We must examine the cases on which we propose to found a generalisation and ask ourselves. What right have we to generalise? That is, what reason have we for assuming that the characteristic discovered in these cases will occur in the remaining thousands of cases? that the cases chosen resemble the average? The only valid reason would be that these cases are representative of the whole. We are thus brought back to the process of methodical sampling.

The right method of conducting the operation is as follows: (1) We must fix the precise limits of the field within which we intend to generalise (that is, to assume the similarity of all the cases), we must determine the country, the group, the class, the period as to which we are to generalise. Care must be taken not to make the field too large by confusing a part with the whole (a Greek or Germanic people with the whole Greek or Germanic race). (2) We must make sure that the facts lying within the field resemble each other in the points on which we wish to generalise, and therefore we have to distrust those vague names under which are comprehended groups of very different character (Christians, French, Aryans, Romans). (3) We must make sure that the facts from which we propose to generalise are representative samples, that they really belong to the field of investigation, for it does happen sometimes that men or facts are taken as specimens of one group when they really belong to another. Nor must they be exceptional, as is to be presumed in all cases when the conditions are exceptional; authors of documents tend to record by preference those facts which surprise them, hence exceptional cases occupy in documents a space which is out of proportion to their real number; this is one of the chief sources of error. (4) The number of samples necessary to support a generalisation is the greater the less ground there is for supposing a resemblance between all the cases occurring within the field of investigation. A small number may suffice in treating of points in which men tend to bear a strong resemblance to each other, either by imitation and convention (language, rites, ceremonies), or from the influence of custom and obligatory regulations (social institutions, political institutions in countries where the authorities are obeyed). A large number is requisite for facts where individual initiative plays a more important part (art, science, morality), and sometimes, as in respect of private conduct, all generalisation is as a rule impossible.

VI. Descriptive formulæ are in no science the final result of the work. It still remains to group the facts in such a way as to bring out their collective import, it still remains to search for their mutual relations; these are the general conclusions. History, by reason of the imperfection of its mode of acquiring knowledge, needs, in addition, a preliminary operation for determining the bearing of the knowledge acquired.[207]

The work of criticism has supplied us with nothing but a number of isolated remarks on the value of the knowledge which the documents have permitted us to acquire. These must be combined. We shall therefore take a whole group of facts entered under a common heading—a particular class of facts, a country, a period, an event—and we shall summarise the results yielded by the criticism of particular facts so as to obtain a general formula. We shall have to take into consideration: (1) the extent, (2) the value of our knowledge.

(1) We shall ask ourselves what are the blanks left by the documents. By working through the scheme used for the grouping of facts it is easy to discover what are the classes of facts on which we lack information. In the case of evolution, we notice which links are missing in the chain of successive modifications; in the case of events, what episodes, what groups of actors are still unknown to us; what facts enter or disappear from the field of our knowledge without our being able to trace their beginning or end. We ought to construct, mentally at any rate, a tabulated scheme of the points on which we are ignorant, in order to keep before our minds the distance separating the knowledge we have from a perfect knowledge.