It is commonly said that rights have their corresponding duties. But if this expression is to be used, it must be {141} remembered that the duty which "corresponds" to a right, as a matter of fact, is either included in that right or simply identical with it. The identity between the right and the duty, then, consists in this, that the notion of a right belonging to a person is identical with the notion of a duty towards him. Rights and duties are not identical in the sense that it is always a duty to insist on a right, though this has been urged.[19] If anybody prevents me from making use of my right it may no doubt be deemed a duty on my part not to tolerate the wrong committed against me, but nothing of the kind is involved in the concept of a right. And the same may be said with reference to the assertion that a right to do a thing is always, at the same time, a duty to do it--an assertion which is a consequence of the doctrine that there is nothing morally indifferent and nothing that goes beyond duty; in other words, that all conduct of responsible beings is either wrong or obligatory. Even if this doctrine were psychologically correct--which it is not--even if there were a constant coincidence between the acts which a person has a right to perform and acts which it is his duty to perform, that would not constitute identity between the concepts of rights and duties. According to the meaning of a right, A's right may be B's duty towards A, but A's right cannot be A's duty towards B or anybody else. [Footnote 19: Alexander, _op. cit._ p. 146 _sq._] Closely connected with the notions of wrongness and rightness are the notions of _injustice_ and _justice_. Injustice, indeed, is a kind of wrongness. To be unjust is always to be unjust to somebody, and this implies a doing of wrong to somebody, a violation of somebody's right. "Justice," again, is a kind of rightness. It involves the notion that a duty to somebody, a duty corresponding to a right, is fulfilled;[20] we say that justice "demands" that it should be fulfilled. As an act is "right" if its omission {142} is wrong, so an act is "just," in the strict sense of the word, if its omission is unjust. But, like the adjective "right," the adjective "just" is also sometimes used in a wider sense, to denote that something is "not unjust." As non-obligatory acts that are "not wrong" can hardly be denied to be "right," so non-obligatory acts that are "not unjust" can hardly be denied to be "just," although they are not demanded by justice. [Footnote 20: According to the _Institutiones_ of Justinian (i. 1. 1) "justice is the constant and perpetual will to render to each one his right,"--"justitia est constans et perpetua voluntas jus suum cuique tribuens."]