Now, although the main object of metaphysics, the cause of all causes, the beginning of all beginnings, the nature of things, causes little inconvenience to modern science, and even though the needs of the present have overcome the leaning for speculation, this practical downfall of speculation does not suffice for the solution of its problems. So long as the theoretical law is not understood, according to which reason requires some concrete object for its operation, there is no hope of abandoning objectless thought, this malpractice of speculative philosophy, which pretends to generate knowledge without intercourse with objective reality. Our naturalists demonstrate this very clearly as soon as they turn from their tangible specialties to abstract things. The dispute over questions of life's wisdom, of morality, or the quarrel over the wise, good, right, or bad, reveals that here is the boundary of scientific agreement. The scientific explorers of the exact sciences abandon every day their inductive method when dealing with social problems, and stray off into the regions of speculative philosophy. Just as in physics they believe in imperceptible physical truths, in "things themselves," so in social matters they believe in the reasonable, wise, right, or bad, in the sense of "things themselves," of absolute phases of life, of unconditional conditions. It is here where the outcome of our studies, of the critique of pure reason, must be applied.
In recognizing that consciousness, the nature of understanding, the mental activity in its general form, consists in developing general concepts out of concrete objects, we circumscribe this insight by stating that reason develops its understanding out of contradictions. It is the nature of the mind to perceive, in given phenomena of different dimensions and different duration, the nature of things by their semblance, and their semblance by their nature; to distinguish in wants of various degrees the most essential and necessary from the less pressing; to measure within a certain circle of magnitudes the large by the small and the small by the large, or in other words to compare the contrasts of the world with one another, to harmonize them by explanation. Common parlance instinctively calls understanding judging; judging requires a certain standard. Just as surely as we cannot perceive any objects which are "in themselves" great or small, hard or soft, clear or dark, just as surely as these terms denote certain relations and require a certain standard by which their relations can be determined, even so does reason require a certain standard for the determination of that which is reasonable.
The fact that we consider certain actions, institutions, conceptions, maxims of other periods, nations, or persons unreasonable is simply due to the application of a different standard, because we ignore the premises, the conditions, which cause another's reason to differ from our own. Men who differ in their mental estimates, in their understanding of things, may be likened to the thermometers of Reaumur and Celsius, one of which designates the boiling point by 80 and the other by 100. A different standard is the cause of this different result. On the so-called moral field there is no scientific agreement, such as we enjoy in some physical matters, because we lack the uniform standard which natural science has long since found. It is still attempted to perceive the reasonable, good, right, etc., without empirical data, by speculative reasoning without experience. Speculation seeks the cause of all causes, the immeasurable cause; truth "itself," the unconditional and standardless truth; the unlimited good, the unboundedly reasonable, etc. The absence of a standard is the essence of speculation, and its practice is characterized by unlimited inconsistency and disagreement. If there are followers of certain positive religions who agree in the matter of morals, they owe this to the positive standard which certain dogmas, doctrines and commandments have given them. But if any one tries to perceive things by "pure" reason, the dependence of this reason on some standard will be demonstrated by its "impure," that is to say individual, perceptions.
Sense perception is the standard of truth, or of science in general. The phenomena of the outside world are the standard of physical truths, and man with his many wants is the standard of moral truth. The actions of man are determined by his wants. Thirst teaches him to drink, need to pray. Wants are regulated in the South by southern conditions, in the North by northern conditions. Wants rule time and space, nations and individuals. They induce the savage to hunt and the gourmand to indulge. Human wants give to reason a standard for judging what is good, right, bad, reasonable, etc. Whatever satisfies our need is good, the opposite is bad. The physical feeling of man is the object of moral standards, the object of "practical reason." The contradictory variety of human needs is the basis for the contradictory variety of moral standards. Because a member of a feudal guild prospered in a restricted competition, and a modern knight of industry in free competition, because their interests differ, therefore their views differ, and the one justly considers an institution as unreasonable which the other regards as reasonable. If the intellect of some person attempts to define by mere introspection the standard of reasonableness as a general thing, this person makes himself or herself the standard of humanity. If reason is credited with the faculty of finding within itself the source of moral truth, it commits the speculative mistake of attempting to produce understanding without perceptible objects. The same mistake is to blame for the idea that man is subordinate to the authority of reason, for the demand that man submit to the dictates of reason. This idea transforms man into an attribute of reason, while in reality reason is an attribute of man.
The question whether man depends on reason or reason on man is similar to the one whether the citizen exists for the state or the state for the citizen. In the last and highest instance, the citizen is the primary fact and the state is modified according to the requirements of the citizen. But whenever the dominant interests of the citizenship have acquired the authority in the state, then the citizen is indeed dependent on the state. This is saying in so many words that man is guided in minor matters by more important ones. He sacrifices the less important, minor, particular things to the great, essential, general things. He subordinates his desire for more individual indulgence to his fundamental social needs. It is not pure reason, but the reason of a weak body or of a limited purse which teaches man to renounce the pleasures of dissipation for the benefit of the general welfare. The wants of the senses are the material out of which reason fashions moral truths. To single out the essential need among different physical needs of various degrees of intensity or extension, to separate the true from the individual, to develop general concepts, that is the mission of reason. The difference between the apparently and the truly reasonable reduces itself to the difference between the special and the general.
We recall that reason requires sense perceptions for its existence and operation, that it needs some object which it can perceive. Existence is the condition or premise of all understanding. Just as the understanding of true existence is the function of natural science, so the understanding of reasonable existence is the function of wisdom. Reason in general has the mission of understanding things as they are. As physical science it has to understand what is true, as wisdom, what is reasonable. And just as true may be translated by general, so reasonable may be translated by generally appropriate to need. We saw a while ago that a sense perception is not true "in itself," but only relatively true, that it is called true or general only in relation to other perceptions of lesser importance. In the same way, no human action can be reasonable or appropriate "in itself," it can be reasonable only in comparison with some other action which attempts to accomplish the same purpose in a less practicable, that is an impracticable, form. Just as the true, the general, is conditioned on the relation to some other object, on a definite quantity of phenomena, on definite limits, so the reasonable or practicable is based on definite conditions which make it reasonable or unreasonable. The end in view is the measure of the practicable. The practicable can be determined only by some definite object that is wanted. Once this object is known, then that action is called reasonable which accomplishes it in the fullest, most general way, and all other actions appear unreasonable compared to it.
In view of the law which we evolved by our analysis of pure reason and which showed that all understanding, all thought, is based on some perceptible object, on some quantity of sense perceptions, it is evident that everything distinguished by our faculty of distinction is a certain quantity and that, therefore, all distinctions are only quantitative, not absolute, only graduated, not irreconcilable. Even the difference between the reasonable and the unreasonable, or in other words between that which is momentarily or individually reasonable and that which is generally reasonable, is merely a quantitative distinction, like all others, so that the unreasonable may be conditionally reasonable, and nothing is unreasonable but that which is supposed to be unconditionally reasonable.
If we understand that reason requires some perceptible object, some perceptible standard, then we shall no longer try to understand the absolutely reasonable, the purely reasonable. We shall then limit ourselves to look for the reasonable, as for all other things, in concrete objects. The definite, accurate, certain, uniform result of some understanding depends on the definite formulation of the task, on the accurate limitation of the perceptible quantity which is to be understood. If a certain moment, a certain person, a certain class, a certain nation are given and at the same time an essential need, a general and predominating purpose, then the question regarding the reasonable or suitable is easily answered. It is true that we may also know something of things which are generally reasonable for mankind in the aggregate, but in that case our standard must be abstract mankind instead of some concrete part of it. Science may study the anatomical structure of some concrete body as well as the general type of the human body, but this again it can do only when it supplies the faculty of understanding with general instead of individual material. If science divides the whole human race into four or five races, by establishing a certain standard of physiognomy, and later on discovers some individuals or tribes whose characters are so peculiar and rare that they cannot be classed under any of the established races, the existence of such exceptions is not a crime against the physical order of the world, but merely a proof of the inadequacy of our scientific classification. If, on the other hand, some conventional mode of thought considers a certain action as universally reasonable or unreasonable and then encounters opposition in actual life, convention fancies itself exempt from the work of understanding and assumes to deny civic rights in the moral order of the world to its opponents. Instead of realizing the limited applicability of its rules by the existence of opposing practices, convention seeks to establish an absolute applicability of its rules by simply ignoring the cause of the opposition. This is a dogmatic procedure, a negative practice, which ignores facts on the pretense that they are irrational, but it is not a positive understanding, not an intelligent knowledge, such as manifests itself by the conciliation of contradictions.
If our study aims to ascertain what is universally human and reasonable, and if these predicates are given only to actions which are reasonable and practicable for all men, at all times, and under all conditions, then such concepts are absolute, indeterminate, and to that extent meaningless, indefinite generalities. We are stating such universal and indeterminate, and therefore unimportant and unpractical concepts, when we say that physically the whole is greater than a part, or that morally the good is preferable to the bad. The object of reason is that which is general, but it is the generality of some concrete object. The practice of reason deals with individual and concrete objects, with the things which are the opposite of the general, with special and concrete knowledge. In order to perceive in physics whether we are dealing with a part or with the whole object, we must handle definite and concrete objects or phenomena. If we desire to ascertain what is morally preferable as good or bad, we must start out with a definite quantity of human needs. Abstract and general reason, with its socalled eternal and absolute truths, is a phantasmagoria of ignorance which binds the rights of the individual with crushing chains. Real and true reason is individual, it cannot produce any other but individual perceptions, and these perceptions cannot be generalized to any greater extent than the general material with which they operate. Only that is universally reasonable which is acknowledged to be so by all reasons. If the reason of some time, class, or person is referred to as rational, and if some other time, class or person considers it irrational; if, for instance, the Russian noble considers serfdom a rational institution and the English bourgeois the so-called liberty of his wage worker, both of these institutions are not absolutely rational, but only relatively, only in a more or less limited circle.