Habermas writes that hermeneutics shows that linguistic spheres are never monadically shut but are, rather, permeable from without as well as from within. From without, because a language is open, and can in principle express everything that can be said and understood. its horizon therefore is in continuous expansion. From within, because linguistic agents can distance themselves from their own expressions in order to interpret them, reflect on them, etc. All this, Habermas learned from Gadamer: that language can transcend itself and thereby exhibits potential for rationality.
This in contrast to Wittgenstein. In Wittgenstein's thesis that linguistically constituted life forms were closed, as if each agent were monadically trapped in its language world, Habermas discerned traces of positivism.
(Jean Grondin, Introduction to Philosophical Hermeneutics, New Haven and London: Yale Univ. Press, 1994, 130)