universalizability. (1) Since the 1920s, the moral criterion implicit in Kant’s first formulation of the categorical imperative: ‘Act only on that maxim that you can at the same time will to be a universal law,’ often called the principle of universality. A maxim or principle of action that satisfies this test is said to be universalizable, hence morally acceptable; one that does not is said to be not universalizable, hence contrary to duty. (2) A second sense developed in connection with the work of Hare in the 1950s. For Hare, universalizability is ‘common to all judgments which carry descriptive meaning’; so not only normative claims (moral and evaluative judgments) but also empirical statements are universalizable. Although Hare describes how such universalizability can figure in moral argument, for Hare ‘offenses agains. . . universalizability are logical, not moral.’ Consequently, whereas for Kant not all maxims are universalizable, on Hare’s view they all are, since they all have descriptive meaning. (3) In a third sense, one that also appears in Hare, ‘universalizability’ refers to the principle of universalizability: ‘What is right (or wrong) for one person is right (or wrong) for any similar person in similar circumstances.’ This principle is identical with what Sidgwick (The Methods of Ethics) called the Principle of Justice. In Generalization in Ethics (1961) by M. G. Singer (b.1926), it is called the Generalization Principle and is said to be the formal principle presupposed in all moral reasoning and consequently the explanation for the feature alleged to hold of all moral judgments, that of being generalizable. A particular judgment of the form ‘A is right in doing x’ is said to imply that anyone relevantly similar to A would be right in doing any act of the kind x in relevantly similar circumstances. The characteristic of generalizability, of presupposing a general rule, was said to be true of normative claims, but not of all empirical or descriptive statements. The Generalization Principle (GP) was said to be involved in the Generalization Argument (GA): ‘If the consequences of everyone’s doing x would be undesirable, while the consequences of no one’s doing x would not be, then no one ought to do x without a justifying reason,’ a form of moral reasoning resembling, though not identical with, the categorical imperative (CI). One alleged resemblance is that if the GP is involved in the GP, then it is involved in the CI, and this would help explain the moral relevance of Kant’s universalizability test. (4) A further extension of the term ‘universalizability’ appears in Alan Gewirth’s Reason and Morality (1978). Gewirth formulates ‘the logical principle of universalizability’: ‘if some predicate P belongs to some subject S because S has the property . . . then P must also belong to all other subjects S1, S2, . . . , Sn that have Q.’ The principle of universalizability ‘in its moral application’ is then deduced from the logical principle of universalizability, and is presupposed in Gewirth’s Principle of Generic Consistency, ‘Act in accord with the generic rights of your recipients as well as yourself,’ which is taken to provide an a priori determinate way of determining relevant similarities and differences, hence of applying the principle of universalizability.
The principle of universalizability is a formal principle; universalizability in sense (1), however, is intended to be a substantive principle of morality. See also ETHICS, KANT. M.G.S.