Clark Globe's comments on a previous post are worth considering so I am putting them here with some brief comments of my own:
"It's interesting that he considers Peirce his biggest influence in epistemology since Peirce didn't really discuss knowledge as such terribly often. He discussed belief and fixing ones beliefs, but epistemology as generally conceived of never appears to have been a focus for him. I think there are reasons for this.
Of course his analysis of truth as what the community of investigators agree upon "in the long run" is very important. Although it is, I think, an idealization never actually reached.
It's also interesting he discusses Heidegger's anthropology and epistemology. I wonder what he means there. I confess I'm woefully ignorant of Habermas, although I enjoyed his critique of Heidegger, Derrida and company even if I think he misread them terribly. But sometimes misreadings can be very interesting on their own."
1) Now I am not a Peirce scholar to be able to give any considered opinion on whether Peirce is an epistemologist or not. However it is clear that Habermas does consider him as having epistemological insights that are worth as much as of Heidegger's "ontologically" oriented "epistemology" if not more. In Knowledge and Human interest as well as in the recent Truth and Justification it is Peirce the epistemologist that is invoked by Habermas, although it is worth mentioning that Habermas does not consider himself to be doing epistemology in the traditional Kantian or empiricist sense. Habermasian epistemology is more of an ontologised epistemology in the manner of early Heidegger ( see The Philosophical Discourse of Modernity: Twelve Lectures pp. 143).
In his very interesting review of Habermas and pragmatism Christopher F. Zurn writes the following:
"In this “Postscript,” Aboulafia receives Habermas’s pithiest response to the question “What are the greatest strengths of pragmatism?”: “The combination of fallibilism with anti-skepticism, and a naturalist approach to the human mind and its culture that refuses to yield to any kind of scientism” (p. 228). Of course, we can read this claim not only as a relatively dispassionate assessment of the history of philosophical movements, but also as a self-attribution of what Habermas himself hopes to have achieved in his work by drawing on specific pragmatist insights and philosophical strategies.
Stylizing somewhat, we might even speculate that Habermas aims for a measure of anti-skeptical fallibilism in his methodological and epistemological projects by drawing on C. S. Peirce’s attempt to save the cognitive content of the Kantian ideas of reason without recourse, however, to a metaphysical appeal to the noumenal realm. Perhaps he hopes to have achieved an anti-scientistic—let us say, anti-reductivist—but nevertheless naturalistic theory of human culture and subjectivity by drawing on G. H. Mead’s account of human ontogenesis and phylogenesis in terms of universal structures developed through intersubjective symbolic interaction. The strategy that Habermas shares with Peirce is two-fold: on the one hand, an empirical, hence fallibilistic, appeal to the unavoidable presuppositions built into the everyday use of language, and, on the other hand, an idealizing, hence anti-skeptical, appeal to the meaning of epistemic presuppositions in terms of an asymptotic progress towards truth and objectivity as achieved by an unlimited community of problem-solving interlocutors. The strategy that Habermas shares with Mead is also two-fold: on the one-hand, an appeal to the best contemporary naturalistic accounts of individual and socio-cultural development in terms of the irreducibly intersubjective structures of language use, without, on the other hand, supposing that one could simply ignore the normativity of such developmental structures through a positivistic reduction of the problems of the social sciences and philosophy to the results of the so-called ’hard’ sciences and thereby sidestep the difficult hermeneutic issues raised by the linguistic milieu of the structures."
I think I agree with what Christopher F. Zurn says here almost completely.
2) Habermas in his recent writings have tried to go beyond the Peircean notion of truth as agreement among investigators "in the long run". Now he claims that agreement even in the ideal conditions cannot be equated with Truth (see On the Pragmatics of Communication, chapter 8). In this context he now differentiates between justification and Truth. Furthermore Habermas would agree that the "idealization is never actually reached." (see TJ, chapter 2).
3)I think what he means by Heidegger's epistemology is his transcendental ontology and his ontological hermeneutics(The Philosophical Discourse of Modernity: Twelve Lectures pp. 143-144). What he means by Heidegger's anthropology is his analysis of Dasein as Being in the world and his linking of "analytic of Dasein . . . with a motif of existential philosophy." (The Philosophical Discourse of Modernity: Twelve Lectures pp. 145).
4) Finally I agree with you that "sometimes misreadings can be very interesting on their own.". I think it is an important insight.