Alan Gewirth (November 28, 1912 – May 9, 2004) was an American philosopher, a professor of philosophy at the University of Chicago, and author of Reason and Morality (1978), Human Rights: Essays on Justification and Applications (1982), The Community of Rights (1996), Self-Fulfillment (1998), and numerous other writings in moral philosophy and political philosophy.
Gewirth is best known for his ethical rationalism, according to which a supreme moral principle, which he calls the "Principle of Generic Consistency" (PGC), is logically derivable from the nature and structure of human agency. The principle states that every agent must act in accordance with his or her own and all other agents' generic rights to freedom and well-being.
According to Gewirth's theory, the PGC is derivable from the fact of human agency, but it is derivable only via a dialectically-necessary mode of argumentation. The mode is "dialectical" in the sense that it presents the steps of the argument to the PGC as inferences made by an agent, rather than as statements true of the world itself. Each step is thus a description of what the agent thinks (or implicitly asserts), not what things are like independently of the viewpoint of the agent. Nevertheless, the mode of argumentation is also "necessary" both in the sense that its initial premise is inescapable from any agent's standpoint and that the subsequent steps of the proof are logically deduced from this premise.
The initial premise, which we all must accept insofar as we perform any actions, is simply "I do X for purpose E." All agents implicitly accept this assertion insofar as they perform any voluntary actions; they therefore must accept it on pain of contradicting that they are agents. Subsequent steps of the argument derive from the first and, similarly, can be denied only on pain of contradiction. Gewirth thus holds that any agent must accept the PGC on pain of contradiction because the principle is contained as the inescapable conclusion of any agent's dialectically necessary characterization of his or her own activity.
While Gewirth admits that his argument establishes the PGC only dialectically, he nevertheless claims that the principle is established as necessary, since any and all agents must accept it on pain of contradiction.
In 1991, the philosopher Deryck Beyleveld published The Dialectical Necessity of Morality, an authoritative reformulation of Gewirth's argument including a summary of previously published objections and Beyleveld's own rigorous responses to them on Gewirth's behalf. There is no clear consensus among philosophers regarding the soundness of Gewirth's theory. For at least the past 30 years, philosophers have offered numerous objections to the theory but have nearly all been substantively countered by Gewirth and his adherents. The debate concerning the ideas Gewirth has set forth thus continues.
Gewirth's argument bears a (superficial) resemblance to the discourse ethics type theories of Jürgen Habermas, Karl-Otto Apel, and others. His student Roger Pilon has developed a libertarian version of Gewirth's theory.