Changes in the teachings of the nonhistorical sciences consequently must involve a rewriting of history. Every generation must treat anew the same historical problems because they appear to it in a different light. The theological world view of older times led to a treatment of history other than the theorems of modern natural science. Subjective economics produces historical works very different from those based on mercantilist doctrines. As far as divergences in the books of historians stem from these disagreements, they are not an outcome of alleged vagueness and precariousness in historical studies. They are, on the contrary, the result of the lack of unanimity in the realm of those other sciences which are popularly called certain and exact.
To avoid any possible misunderstanding it is expedient to emphasize some further points. The divergences referred to above must not be confused:
1. With purposeful ill-intentioned distortion of facts.
2. With attempts to justify or to condemn any actions from a legal or moral point of view.
3. With the merely incidental insertion of remarks expressing value judgments in a strictly objective representation of the state of affairs. A treatise on bacteriology does not lose its objectivity if the author, accepting the human viewpoint, considers the preservation of human life as an ultimate end and, applying this standard, labels effective methods of fighting germs good and fruitless methods bad. A germ writing such a book would reverse these judgments, but the material content of its book would not differ from that of the human bacteriologist. In the same way a European historian dealing with the Mongol invasions of the thirteenth century may speak of “favorable” and “unfavorable” events because he takes the standpoint of the European defenders of Western civilization. But this approval of one party’s standard of value need not necessarily interfere with the material content of his study. It may—from the viewpoint of contemporary knowledge—be absolutely objective. A Mongolian historian could endorse it completely but for such casual remarks.
4. With a representation of one party’s action in diplomatic or military antagonisms. The clash of conflicting groups can be dealt with from the point of view of the ideas, motives, and aims which impelled either side’s acts. For a full comprehension of what happened it is necessary to take account of what was done on both sides. The outcome was the result of the interaction of both parties. But in order to understand their actions the historian must try to see things as they appeared to the acting men at the critical time, not only as we see them now from the point of view of our present-day knowledge. A history of Lincoln’s policy in the weeks and months preceding the outbreak of the Civil War is of course incomplete. But no historical study is complete. Regardless of whether the historian sympathizes with the Unionists or with the Confederates or whether he is absolutely neutral, he can deal in an objective way with Lincoln’s policy in the spring of 1861. Such an investigation is an indispensable preliminary to answering the broader question of how the Civil War broke out.
Now finally, having settled these problems, it is possible to attack the genuine question: Is there any subjective element in historical understanding, and, if so, in what manner does it determine the result of historical studies?
As far as the task of understanding is to establish the facts that people were motivated by definite value judgments and aimed at definite ends, there cannot be any disagreement among true historians, i.e., people intent upon cognition of past events. There may be uncertainty because of the insufficient information provided by the sources available. But this has nothing to do with understanding. It refers to the preliminary work to be achieved by the historian.
But understanding has a second task to fulfill. It must appraise the effects and the intensity of the effects brought about by an action; it must deal with the relevance of each motive and each action.
Here we are faced with one of the main differences between physics and chemistry on the one hand and the sciences of human action on the other. In the realm of physical and chemical events there exist (or, at least, it is generally assumed that there exist) constant relations between magnitudes, and man is capable of discovering these constants with a reasonable degree of precision by means of laboratory experiments. No such constant relations exist in the field of human action outside of physical and chemical technology and therapeutics. For some time economists believed that they had discovered such a constant relation in the effects of changes in the quantity of money upon commodity prices. It was asserted that a rise or fall in the quantity of money in circulation must result in proportional changes of commodity prices. Modern economics has clearly and irrefutably exposed the fallaciousness of this statement.17 Those economists who want to substitute “quantitative economics” for what they call “qualitative economics” are utterly mistaken. There are, in the field of economics, no constant relations, and consequently no measurement is possible. If a statistician determines that a rise of 10 per cent in the supply of potatoes in Atlantis at a definite time was followed by a fall of 8 per cent in the price, he does not establish anything about what happened or may happen with a change in the supply of potatoes in another country or at another time. He has not “measured” the “elasticity of demand” of potatoes. He has established a unique and individual historical fact. No intelligent man can doubt that the behavior of men with regard to potatoes and every other commodity is variable. Different individuals value the same things in a different way, and valuations change with the same individuals with changing conditions.18
Outside of the field of economic history nobody every ventured to maintain that constant relations prevail in human history. It is a fact that in the armed conflicts fought in the past between Europeans and backward peoples of other races, one European soldier was usually a match for several native fighters. But nobody was ever foolish enough to “measure” the magnitude of European superiority.
The impracticability of measurement is not due to the lack of technical methods for the establishment of measure. It is due to the absence of constant relations. If it were only caused by technical insufficiency, at least an approximate estimation would be possible in some cases. But the main fact is that there are no constant relations. Economics is not, as ignorant positivists repeat again and again, backward because it is not “quantitative.” It is not quantitative and does not measure because there are no constants. Statistical figures referring to economic events are historical data. They tell us what happened in a nonrepeatable historical case. Physical events can be interpreted on the ground of our knowledge concerning constant relations established by experiments. Historical events are not open to such an interpretation.
The historian can enumerate all the factors which cooperated in bringing about a known effect and all the factors which worked against them and may have resulted in delaying and mitigating the final outcome. But he cannot coordinate, except by understanding, the various causative factors in a quantitative way to the effects produced. He cannot, except by understanding, assign to each of n factors its role in producing the effect P. Understanding is in the realm of history the equivalent, as it were, of quantitative analysis and measurement.
Technology can tell us how thick a steel plate must be in order not to be pierced by a bullet fired at a distance of 300 yards from a Winchester rifle. It can thus answer the question why a man who took shelter behind a steel plate of a known thickness was hurt or not hurt by a shot fired. History is at a loss to explain with the same assurance why there was a rise in the price of milk of 10 per cent or why President Roosevelt defeated Governor Dewey in the election of 1944 or why France was from 1870 to 1940 under a republican constitution. Such problems do not allow any treatment other than that of understanding.
To every historical factor understanding tries to assign its relevance. In the exercise of understanding there is no room for arbitrariness and capriciousness. The freedom of the historian