In order to shed light on the practical working of this method and to show its results, this would be the place for its application to a number of selected, concrete cases from which its actual working could be learned. It is not possible, however, in so general a study of so vast a subject as we are making, to furnish, at this point, illustrations of the argument I have offered above. For such illustrations would not demonstrate the truth of our proposition sufficiently, unless the facts were analyzed most minutely to the last details. I shall be obliged, therefore, to confine myself for the present, by the aid of what others have already done and adding a few personal observations to what has already become an acknowledged part of legal science, to calling attention to certain important theories. The method of free decision on the basis of legal science, such as I have briefly explained, may be presumed, a priori, to be capable of suggesting probable solutions regarding the problem of supplementing the written law which by itself does not suffice for the needs of daily life. Moreover, I do not claim any intention of deciding the whole matter in a manner sufficient for a systematic treatise. I merely wish to see, if possible, a little progress made, without taking any sides regarding the ultimate solution of problems which would require investigations which I cannot undertake.
In order to limit my task and at the same time make it more definite, I shall take all the following observations (which will necessarily be incomplete and more or less cursory) from a field which one may describe as lying in the very center and constituting the most typical portion of private law, - the rules relating to transactions between living persons, affecting estates of various kinds.
This whole vast subject, and for that matter all other topics in private law, may, as it seems to me, be treated from the point of view of three different orders of ideas, to wit:
Sometimes the regulation of inheritable interests emanates from the free and conscious wills of persons who are capable of binding themselves by contracts. The positive law has nothing to do with it except by recognizing the evidence of such acts of will as evidence of legal transactions. In such cases we have nothing to do except to determine on what terms and to what extent these persons have bound themselves; after that, we must find out what the subject-matter amounts to; and possibly we must supplement the acts of parties, by applying legal presumptions or by interpretation of the terms.
At other times it will happen that the will of the parties cannot become effective because it is repugnant to the requirements of social order. In such cases the law must step in to place limitations on the will of individuals, or to frustrate it altogether. In such cases an overruling and irresistible power substitutes its authority for that of a voluntary arrangement which it prohibits. The positive law itself makes here those rules which it opposes to the divergent wills of individuals so as to govern or restrain them.
Finally, there are cases where there is not, or even cannot possibly be, any action of conscious wills. Instead there are facts or circumstances regarding which the direct influence of free human action cannot be conceived, or at least is not exercised. As a consequence, it becomes the function of the law itself to regulate those interests which in their nature are independent of the wills of individuals.
To these three orders of ideas correspond three kinds of legal rules, which are fairly distinct from each other: one kind merely guides or supplements individual acts of will; the second embodies legal commands or prohibitions; the third constitutes simply regulations of an external sort.
As our social organization is actually constituted, we shall find that each of these three forms of legal rule is governed by a general and essential principle in harmony with the object which each class of rules has in view. Each set of rules, in fact, is the outgrowth of its principle. I think one may reduce these three principles to a simple formula in accordance with our most usual terminology in this manner: 1. The principle of autonomous will. 2. The principle of public order or superior interest. 3. The principle of equilibrium of private interests.
To be sure, these principles, which in practice will often combine and interlace with each other, are found to animate our whole system of law, and can be inferred also from its formal sources, especially the codes, in so far as these contain formal rules relating to each of the spheres indicated above. However, here as everywhere, the formal sources are not sufficient for the purposes of the administration of the law in its entirety. Where they are mute or incomplete, free scientific investigation must supplement them and find the rule which governs such relations in accordance with the method I have proposed above. Now it seems to me that a few brief considerations will make it easily intelligible how the application of this method will help the law to make real and truly scientific progress.