Habermas's term for social interaction oriented to reaching mutual understanding by offering reasons that others can accept or contest, as opposed to strategic action oriented to achieving one's own success.
In more detail
Every speech act, on Habermas's account, raises validity claims to truth, normative rightness and sincerity. Agreement is rationally motivated only when participants are free to question any claim and no coercion distorts the discussion. The idea underlies his discourse ethics and his theory of law and democracy, and is criticised as an unattainable ideal by agonistic theorists.