The Science of Right

Author: Immanuel Kant  | Date: 1790



A. What the Science of Right is.

The Science of Right has for its object the principles of all the laws which it is possible to promulgate by external legislation. Where there is such a legislation, it becomes, in actual application to it, a system of positive right and law; and he who is versed in the knowledge of this system is called a jurist or jurisconsult (jurisconsultus). A practical jurisconsult (jurisperitus), or a professional lawyer, is one who is skilled in the knowledge of positive external laws, and who can apply them to cases that may occur in experience. Such practical knowledge of positive right, and law, may be regarded as belonging to jurisprudence (jurisprudentia) in the original sense of the term. But the theoretical knowledge of right and law in principle, as distinguished from positive laws and empirical cases, belongs to the pure science of right (jurisscientia). The science of right thus designates the philosophical and systematic knowledge of the principles of natural right. And it is from this science that the immutable principles of all positive legislation must be derived by practical jurists and lawgivers.

B. What is Right?

This question may be said to be about as embarrassing to the jurist as the well-known question, "What is truth?" is to the logician. It is all the more so, if, on reflection, he strives to avoid tautology in his reply and recognise the fact that a reference to what holds true merely of the laws of some one country at a particular time is not a solution of the general problem thus proposed. It is quite easy to state what may be right in particular cases (quid sit juris), as being what the laws of a certain place and of a certain time say or may have said; but it is much more difficult to determine whether what they have enacted is right in itself, and to lay down a universal criterion by which right and wrong in general, and what is just and unjust, may be recognised. All this may remain entirely hidden even from the practical jurist until he abandon his empirical principles for a time and search in the pure reason for the sources of such judgements, in order to lay a real foundation for actual positive legislation. In this search, his empirical laws may, indeed, furnish him with excellent guidance; but a merely empirical system that is void of rational principles is, like the wooden head in the fable of Phaedrus, fine enough in appearance, but unfortunately it wants brain.

1. The conception of right- as referring to a corresponding obligation which is the moral aspect of it- in the first place, has regard only to the external and practical relation of one person to another, in so far as they can have influence upon each other, immediately or mediately, by their actions as facts. 2. In the second place, the conception of right does not indicate the relation of the action of an individual to the wish or the mere desire of another, as in acts of benevolence or of unkindness, but only the relation of his free action to the freedom of action of the other. 3. And, in the third place, in this reciprocal relation of voluntary actions, the conception of right does not take into consideration the matter of the matter of the act of will in so far as the end which any one may have in view in willing it is concerned. In other words, it is not asked in a question of right whether any one on buying goods for his own business realizes a profit by the transaction or not; but only the form of the transaction is taken into account, in considering the relation of the mutual acts of will. Acts of will or voluntary choice are thus regarded only in so far as they are free, and as to whether the action of one can harmonize with the freedom of another, according to a universal law.

Right, therefore, comprehends the whole of the conditions under which the voluntary actions of any one person can be harmonized in reality with the voluntary actions of every other person, according to a universal law of freedom.

C. Universal Principle of Right.

"Every action is right which in itself, or in the maxim on which it proceeds, is such that it can coexist along with the freedom of the will of each and all in action, according to a universal law."

If, then, my action or my condition generally can coexist with the freedom of every other, according to a universal law, any one does me a wrong who hinders me in the performance of this action, or in the maintenance of this condition. For such a hindrance or obstruction cannot coexist with freedom according to universal laws.

It follows also that it cannot be demanded as a matter of right, that this universal principle of all maxims shall itself be adopted as my maxim, that is, that I shall make it the maxim of my actions. For any one may be free, although his freedom is entirely indifferent to me, or even if I wished in my heart to infringe it, so long as I do not actually violate that freedom by my external action. Ethics, however, as distinguished from jurisprudence, imposes upon me the obligation to make the fulfillment of right a maxim of my conduct.

The universal law of right may then be expressed thus: "Act externally in such a manner that the free exercise of thy will may be able to coexist with the freedom of all others, according to a universal law." This is undoubtedly a law which imposes obligation upon me; but it does not at all imply and still less command that I ought, merely on account of this obligation, to limit my freedom to these very conditions. Reason in this connection says only that it is restricted thus far by its idea, and may be likewise thus limited in fact by others; and it lays this down as a postulate which is not capable of further proof. As the object in view is not to teach virtue, but to explain what right is, thus far the law of right, as thus laid down, may not and should not be represented as a motive-principle of action.

D. Right is Conjoined with the Title or Authority to Compel.

The resistance which is opposed to any hindrance of an effect is in reality a furtherance of this effect and is in accordance with its accomplishment. Now, everything that is wrong is a hindrance of freedom, according to universal laws; and compulsion or constraint of any kind is a hindrance or resistance made to freedom. Consequently, if a certain exercise of freedom is itself a hindrance of the freedom that is according to universal laws, it is wrong; and the compulsion of constraint which is opposed to it is right, as being a hindering of a hindrance of freedom, and as being in accord with the freedom which exists in accordance with universal laws. Hence, according to the logical principle of contradiction, all right is accompanied with an implied title or warrant to bring compulsion to bear on any one who may violate it in fact.

E. Strict Right may be also Represented as the Possibility

of a Universal Reciprocal Compulsion in harmony with

the Freedom of All according to Universal Laws.

This proposition means the right is not to be regarded as composed of two different elements- obligation according to a law, and a title on the part of one who has bound another by his own free choice to compel him to perform. But it imports that the conception of right may be viewed as consisting immediately in the possibility of a universal reciprocal compulsion, in harmony with the freedom of all. As right in general has for its object only what is external in actions, strict right, as that with which nothing ethical is intermingled, requires no other motives of action than those that are merely external; for it is then pure right and is unmixed with any prescriptions of virtue. A strict right, then, in the exact sense of the term, is that which alone can be called wholly external. Now such right is founded, no doubt, upon the consciousness of the obligation of every individual according to the law; but if it is to be pure as such, it neither may nor should refer to this consciousness as a motive by which to determine the free act of the will. For this purpose, however, it founds upon the principle of the possibility of an external compulsion, such as may coexist with the freedom of every one according to universal laws. Accordingly, then, where it is said that a creditor has a right to demand from a debtor the payment of his debt, this does not mean merely that he can bring him to feel in his mind that reason obliges him to do this; but it means that he can apply an external compulsion to force any such one so to pay, and that this compulsion is quite consistent with the freedom of all, including the parties in question, according to a universal law. Right and the title to compel, thus indicate the same thing.

The law of right, as thus enunciated, is represented as a reciprocal compulsion necessarily in accordance with the freedom of every one, under the principle of a universal freedom. It is thus, as it were, a representative construction of the conception of right, by exhibiting it in a pure intuitive perception a priori, after the analogy of the possibility of the free motions of bodies under the physical law of the equality of action and reaction. Now, as in pure mathematics, we cannot deduce the properties of its objects immediately from a mere abstract conception, but can only discover them by figurative construction or representation of its conceptions; so it is in like manner with the principle of right. It is not so much the mere formal conception of right, but rather that of a universal and equal reciprocal compulsion as harmonizing with it, and reduced under general laws, that makes representation of that conception possible. But just as those conceptions presented in dynamics are founded upon a merely formal representation of pure mathematics as presented in geometry, reason has taken care also to provide the understanding as far as possible with intuitive presentations a priori in behoof of a construction of the conception of right. The right in geometrical lines (rectum) is opposed, as the straight, to that which is curved and to that which is oblique. In the first opposition, there is involved an inner quality of the lines of such a nature that there is only one straight or right line possible between two given points. In the second case, again, the positions of two intersecting or meeting lines are of such a nature that there can likewise be only one line called the perpendicular, which is not more inclined to the one side than the other, and it divides space on either side into two equal parts. After the manner of this analogy, the science of right aims at determining what every one shall have as his own with mathematical exactness; but this is not to be expected in the ethical science of virtue, as it cannot but allow a certain latitude for exceptions. But, without passing into the sphere of ethics, there are two cases- known as the equivocal right of equity and necessity- which claim a juridical decision, yet for which no one can be found to give such a decision, and which, as regards their relation to rights, belong, as it were, to the "Intermundia" of Epicurus. These we must at the outset take apart from the special exposition of the science of right, to which we are now about to advance; and we may consider them now by way of supplement to these introductory explanations, in order that their uncertain conditions may not exert a disturbing influence on the fixed principles of the proper doctrine of right.

F. Supplementary Remarks on Equivocal Right.

(Jus Aequivocum).

With every right, in the strict acceptation (jus strictum), there is conjoined a right to compel. But it is possible to think of other rights of a wider kind (jus latum) in which the title to compel cannot be determined by any law. Now there are two real or supposed rights of this kind- equity and the right of necessity. The first alleges a right that is without compulsion; the second adopts a compulsion that is without right. This equivocalness, however, can be easily shown to rest on the peculiar fact that there are cases of doubtful right, for the decision of which no judge can be appointed.

I. Equity.

Equity (aequitas), regarded objectively, does not properly constitute a claim upon the moral duty of benevolence or beneficence on the part of others; but whoever insists upon anything on the ground of equity, founds upon his right to the same. In this case, however, the conditions are awanting that are requisite for the function of a judge in order that be might determine what or what kind of satisfaction can be done to this claim. When one of the partners of a mercantile company, formed under the condition of equal profits, has, however, done more than the other members, and in consequence has also lost more, it is in accordance with equity that he should demand from the company more than merely an equal share of advantage with the rest. But, in relation to strict right- if we think of a judge considering his case- he can furnish no definite data to establish how much more belongs to him by the contract; and in case of an action at law, such a demand would be rejected. A domestic servant, again, who might be paid his wages due to the end of his year of service in a coinage that became depreciated within that period, so that it would not be of the same value to him as it was when he entered on his engagement, cannot claim by right to be kept from loss on account of the unequal value of the money if he receives the due amount of it. He can only make an appeal on the ground of equity,- a dumb goddess who cannot claim a bearing of right,- because there was nothing bearing on this point in the contract of service, and a judge cannot give a decree on the basis of vague or indefinite conditions.

Hence it follows, that a court of equity, for the decision of disputed questions of right, would involve a contradiction. It is only where his own proper rights are concerned, and in matters in which he can decide, that a judge may or ought to give a hearing to equity. Thus, if the Crown is supplicated to give an indemnity to certain persons for loss or injury sustained in its service, it may undertake the burden of doing so, although, according to strict right, the claim might be rejected on the ground of the pretext that the parties in question undertook the performance of the service occasioning the loss, at their own risk.

The dictum of equity may be put thus: "The strictest right is the greatest wrong" (summum jus summa injuria). But this evil cannot be obviated by the forms of right, although it relates to a matter of right; for the grievance that it gives rise to can only be put before a "court of conscience" (forum poli), whereas every question of right must be taken before a civil court (forum soli).

II. The Right of Necessity.

The so-called right of necessity (jus necessitatis) is the supposed right or title, in case of the danger of losing my own life, to take away the life of another who has, in fact, done me no harm. It is evident that, viewed as a doctrine of right, this must involve a contradiction, For this is not the case of a wrongful aggressor making an unjust assault upon my life, and whom I anticipate by depriving him of his own (jus inculpatae tutelae); nor consequently is it a question merely of the recommendation of moderation which belongs to ethics as the doctrine of virtue, and not to jurisprudence as the doctrine of right. It is a question of the allowableness of using violence against one who has used none against me.

It is clear that the assertion of such a right is not to be understood objectively as being in accordance with what a law would prescribe, but merely subjectively, as proceeding on the assumption of how a sentence would be pronounced by a court in the case. There can, in fact, be no criminal law assigning the penalty of death to a man who, when shipwrecked and struggling in extreme danger for his life, and in order to save it, may thrust another from a plank on which he had saved himself. For the punishment threatened by the law could not possibly have greater power than the fear of the loss of life in the case in question. Such a penal law would thus fail altogether to exercise its intended effect; for the threat of an evil which is still uncertain- such as death by a judicial sentence- could not overcome the fear of an evil which is certain, as drowning is in such circumstances. An act of violent self-preservation, then, ought not to be considered as altogether beyond condemnation (inculpabile); it is only to be adjudged as exempt from punishment (impunibile). Yet this subjective condition of impunity, by a strange confusion of ideas, has been regarded by jurists as equivalent to objective lawfulness.

The dictum of the right of necessity is put in these terms: "Necessity has no law" (Necessitas non habet legem). And yet there cannot be a necessity that could make what is wrong lawful.

It is apparent, then, that in. judgements relating both to "equity" and "the right of necessity," the equivocations involved arise from an interchange of the objective and subjective grounds that enter into the application of the principles of right, when viewed respectively by reason or by a judicial tribunal. What one may have good grounds for recognising as right, in itself, may not find confirmation in a court of justice; and what he must consider to be wrong, in itself, may obtain recognition in such a court. And the reason of this is that the conception of right is not taken in the two cases in one and the same sense.


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Chicago: Immanuel Kant, "Introduction to the Science of Right.," The Science of Right, trans. W. Hastie Original Sources, accessed June 14, 2024,

MLA: Kant, Immanuel. "Introduction to the Science of Right." The Science of Right, translted by W. Hastie, Original Sources. 14 Jun. 2024.

Harvard: Kant, I, 'Introduction to the Science of Right.' in The Science of Right, trans. . Original Sources, retrieved 14 June 2024, from