QuestionsWhat makes something right?A rule is valid if everyone it affects could accept it in a free discussion
What makes something right?Duty

A rule is valid if everyone it affects could accept it in a free discussion

Discourse ethics; the principle of universalization (U)

Jürgen Habermas 1929 · 2026A rule is just if everyone it affects could accept it in a free discussion.
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What it claims

Moral rightness consists in acting on rules that all those concerned could accept in a free discussion, not on what each decides alone.

Why

A rule is valid only if everyone it affects can accept it, and only a discussion with them can show whether they do.

The same idea through history
Immanuel Kant1785Kant asks us to test our maxim by asking whether it could hold for all. Habermas keeps the idea of universality but replaces the solitary test with a real discussion.
Jürgen Habermas1983
In short

"A rule is valid if everyone it affects could accept it in a free discussion" is an argument by Jürgen Habermas (Moral Consciousness and Communicative Action, 1983, 1983) on the question "What makes something right?" (answer: duty). Its claim: Moral rightness consists in acting on rules that all those concerned could accept in a free discussion, not on what each decides alone. According to AskPhilosophy's logic check (Z3 solver), the argument is valid only if one grants a premise the author leaves unstated (P4). AskPhilosophy presents 3 objections, 2 of them with a documented reply, and the original text behind each premise, checked word for word.

Moral Consciousness and Communicative Action, 1983
Valid with an implicit premise

Kant said: act only on a maxim you can will as a universal law. Habermas thinks this test is done too much alone: each person decides in his own head what "everyone" would accept. He proposes doing it together. A moral rule is valid if everyone it affects could accept it in a discussion where everyone can speak, be heard and face no pressure except that of the better argument. It is a morality of duty, but one where duty is discovered by talking with others.

P1A norm can claim to be valid only if it meets (or could meet) the approval of all, as participants in a practical discourse.
P2For a norm to be valid, all those affected must be able to accept the consequences and side effects its general observance will have for the satisfaction of everyone's interests, and prefer them to the effects of the known alternatives.
P3This test cannot be done alone. It is not enough that I can will my maxim as a universal law: I must submit it to all others so that together they examine its claim to hold for all.
P4 · implicit premiseWhat is morally obligatory is what the norms valid in this sense prescribe. A duty is therefore a rule that all could accept after discussion.
Therefore moral rightness consists in acting on rules that all those concerned could accept in a free discussion, not on what each decides alone.

click a premise to reject it

If you accept every premise, logic forces you to accept the conclusion. So the debate is about the premises.
Checked by a logic solver: the premises cannot all be true while the conclusion is false.
Without the implicit premise: Without P4, the computer finds a case where a norm is acceptable to all in a free discussion, and yet there is a duty no discussion justifies, for instance because it comes from the nature of things or from God.
With P4 the argument is valid. Without P4, Habermas says under what conditions a norm is valid, but not that moral duty reduces to that validity. He accepts it in one sense: for him, morality is the part of our norms that can be justified before everyone, while questions about the good life remain particular to each community.
Analogy. The rules of a board game are fair when all the players could accept them before starting, not when one person decided them alone, thinking of everybody.

Objections

3

Each objection is a conversation: click to see who replies and where the debate stands.

Carol Gilligan 1982 · attacks premise 2

Gilligan criticises Kohlberg's theories of justice, on which Habermas relies. For her, a morality that retains only universality and everyone's rights misses another moral voice, that of care and responsibility toward particular people in concrete relationships. A universalization test, even done together, treats people as similar cases.

Habermas replies
summary: their text is not yet in our corpus see the argument
Jürgen Habermas 1986 · Habermas's reply
Summary: in "Justice and Solidarity", Habermas argues that justice and solidarity are two sides of one morality. Morality arose from a web of solidary relations, and justice (equal respect for each) merely generalises it. He maintains, however, that moral rightness rests on justice.
S
Seyla Benhabib 1992
Summary: in Situating the Self, Benhabib argues that the procedure can do justice to persons only if it includes the "concrete other", with his history and needs, and not only the generalised other. She proposes keeping the spirit of discourse ethics while opening it to what Gilligan described.
Where the debate stands (our summary)Both camps admit that solidarity and care matter. The core disagreement: are they elements of morality itself, or of an ethics of the good life distinct from justice? Habermas distinguishes them; Benhabib and her allies find the boundary hard to hold.
Charles Taylor 1989 · attacks premise 4

Habermas gives priority to the right (what all can accept) over the good (what gives life meaning). But our moral obligations draw their force from what we hold precious: one cannot decide what is owed to each without an idea of what matters.

a defender replies
Jürgen Habermas defender of the argument · 1991
Summary: Habermas distinguishes moral discourses, which concern what is equally in everyone's interest, from ethical discourses, which concern the good life for us, in a community with shared values. He gives priority to morality, in the sense that no ethical value can override a valid moral norm.
Where the debate stands (our summary)Habermas and Taylor agree that shared values weigh in moral life. The core disagreement: can a universal norm be fixed without passing through an idea of the good, as Habermas holds, or does the good come before the right, as Taylor thinks?
A
Amy Allen 2016 · attacks premise 1

The justification of principles (D) and (U) rests on a theory of modernisation that sees modern Western society as the most advanced stage of moral learning. This assumes that other societies are "behind": it is a Eurocentric position, which confines the discussion to the viewpoint of a single history.

no reply
Habermas did reply, but that text is not yet in our corpus.
The debate goes on (our summary) Habermas answered postcolonial critics in other texts, which we have not collected. His defenders note that discourse ethics aims to be open to everyone, including non-Western voices, without judging them in advance. The core disagreement: can the universality of the procedure be defended without presupposing a particular history of moral learning?