The criticism by Habermas et al levelled against Heidegger’s conception of Truth is based on two premises:
1) Heidegger conflates meaning with reference [This is basically derived from Lafont (see her The Linguistic Turn in Hermeneutic Philosophy but has been accepted by Habermas and of course also by Brunkhorst].
2) Heidegger levels out the dialectical relation between the truth as disclosure and innerworldly learning processes. Habermas and others agree with Heidegger that it is indeed the case that we cannot know without the prior disclosing function of language but they go on to claim that this disclosing function should not be understood statically and in one way. Our innerworldly learning experiences in turn modify the “disclosure” which was first the condition of any such process. Thus Habermas and others object to what they understand to be Heidegger's conception of truth as historical destiny (Seinsgeschick).
The above points are well demonstrated in the following (rather extended quotes from Brunkhorst):
“If we want to solve the categorical problem of modern egocentrism we have to draw a clear distinction between reference to things and the descriptions of them. Reference does not – as Heidegger claims- depend completely on description. Whether things are as they are is not determined by our descriptions of them. Heidegger and other linguistic idealists are right when they argue that there is no access to a real world of objects and objective relations other than through our descriptions that always and already are part of the whole network of a historical language. But the linguistic idealists are wrong when they extend this thesis to ‘reference’, and argue that things are way they are because of our descriptions. “
“In so far as Heidegger goes back to a historical apriori which can never be an object of immanent critique, his own thinking neglects and represses the non-identical of everyday experiences in life, art and science as well. Not being fallibilist, Heidegger’s History of Being becomes itself a paradigm of what Adorno calls ‘identity thinking’.” (Adorno and Critical Theory, p. 98)
“Heidegger, who was prey to an extreme intensionalism (the thesis that meaning determines reference, that language determines truth, etc.), did not succeed in solving the problem of reference in the final analysis and relapsed into the higher-level egocentrism of poetry and thought . . . . It is not until we open ourselves, to put it slightly metaphysically but vividly, to what Hugo Dingler (or even Charles S. Peirce) calls the ‘resistance of the real’ and thereby give the entities that have not been identified in advance by Being space to breathe, that we have the innerworldly experiences which compel us at some point to renounce the egocentric projection of an imaginary world. And precisely that is the experience which we have always made in the factual development process of modern science, art and culture. The egocentrism of the modern age, the metaphysics of a subject certain of itself, has long since crashed on the rocks of modern art and science . . . . The ‘clearing’ of the modern understanding of self no longer reveals a higher, a priori truth, but merely knowledge which, in Quine’s sense, is more central than everything else and therefore is more rarely brought into question, but, like all knowledge, is open to question. Falliblism has become a deep-seated understanding of self, an ‘essential feature’ of the clearing of Being and the ground plan of Western culture and its normal sciences.” (Adorno and Critical Theory, pp. 98-99)
“. . . Adorno goes along with Heidegger in rejecting the instrumental theory of language from Plato to Kant and replacing it with the notion of ‘historical constellations’. But his ‘historical constellations’ are no longer historical a prioris like Heidegger’s world-disclosing poetry. They do not determine the realm of contingent, empirical, and material entities, which Adorno also calls the ‘non-identical’. The world-disclosing power of great-poetry (like that of Jesus, Hölderlin, Newton or Marx) is not power enough to overcome the dialectical tension between language as a whole and particular material entities. And it is precisely this tension that opens world-disclosing poetry and the ‘historical constellation’ determined by this poetry for innerworldly experiences of falsification, immanent critique and learning processes. Here Adorno and post-empiricist philosophers are at one in criticising Heidegger’s metaphysics of Seinsgeschick (‘historical destiny’).” (Adorno and Critical Theory, p. 99)
Now I do not want to say I concur with what Habermas or following him Brunkhorst in their reading of Heidegger, but I certainly agree with Habermas and Brunkhorst in claiming a dialectical relationship between “world disclosing function” of language and “innerworldly learning process.” However I want to point out that Habermas and following him Brunkhorst might be underestimating the hold that “world disclosing function” have on us and might be overestimating the efficacy of innerworldly learning process in modifying our presuppositions, on which such process depend for their existence. The point is to say that “our presuppositions” do change, but they change over long periods of time and whenever they change they do not necessarily change according to pre-determined rational plan (The point of brilliant ‘histories’ of Foucault, for example, is precisely to show this). In other words, in my opinion, Habermas underestimates ‘our finitude’ (something he himself, otherwise, emphasises in his work). In so doing he happens to be a child of our long past Modernity, indeed the last great “Enlightenment thinker”!
For the best critique (that I know of) of Habermas’ critique of Heidegger (and Foucault) presented here see Rudi Visker “Habermas on Heidegger and Foucault: Meaning and Validity in the "Philosophical Discourse of Modernity" Radical-Philosophy Sum 92; 61: 15-22.
See also a related post by Gary over philosophical conversations