It argues that an ideal speech situation is found when communication between individuals is governed by basic, implied rules.
In an ideal speech situation, participants would be able to evaluate each other’s assertions solely on the basis of reason and evidence in an atmosphere completely free of any nonrational “coercive” influences, including both physical and psychological coercion.
In this work he no longer spoke of a known ideal speech situation but instead of a new moral system ("Discourse ethics") that could be derived from the "presuppositions of argumentation".
These, in turn, could initially be postulated by philosophical analysis in the same way that Immanuel Kant tried to justify his own moral system through transcendental arguments.
However, unlike Kant, Habermas recognizes that the presuppositions of argumentation can be tested in practice by a device he terms "performative contradiction".