My earlier poston Peirce and Habermas was based exclusively on Habermas' interpretation of Peirce as found in Knowledge & Human Interest. So in order not to give any wrong impression I would add here a paragraph from Swindal which fruitfully summarises Habermas' later views on Peirce.
"It is important to note, however, that Habermas later modifies his early interpretation of Peirce. In "Peirce and Communication" (in Postmetaphysical Thinking) he presents a more sanguine view of the categories of representation present in Peirce' s logic of language. Habermas now acknowledge the intersubjectvity implied in Peirce' s claim that every sign has both a "quasi-utterer" and a "quasi-interpreter" (Postmetaphysical Thinking, pp. 88-89). He admits that Perice expanded the realm of sign usage into the realm of linguistic forms of expression by showing that the indexical and iconic functions refer to "analogous" actuality and object-relations independent from mere propositional representation. For Habermas these two functions open up Peirce's theory of meaning to the realms of the aesthetic and social. But Habermas continues to criticize Peirce for ignoring the broader "world-disclosing" function of signs.*
Habermas continues to level the criticism, however, that Peirce attempted to anchor the chain of signifiers in reality and, like the later Husserl in Experience and Judgment, "decended[ed] from the method of a logical genesis of judgments of perception into the realm of pre-predicative experience"(Texte und Kontexte
, p. 98). Such semantic realism insufficiently accounts for the distinction between first-and second- person discourse, a claim that Habermas develops more fully after Knowledge and Human Interests. Habermas argues that learning processes must be grounded, not in a metaphysical concept of nature, a position which the later Peirce adopted but in actual argumentation with others about practical conflict. Habermas claims that we cannot break out of the sphere of language and argumentation: "we can only establish the relation to reality, which is not equivalent to 'existence,' by projecting a 'transcendence form within'"(Postmetaphysical Thinking, p. 103).**
For Habermas this view of inner transcendence both respects the 'objectivity' of the intersubjectivity of understanding that has become reflexive and avoids the ontologization of reality. He argues that if the learning processes of human species are limited to mirror only w hat is already contained in nature, they lose the convincing power of the better argument, and he espouses instead a kind of "intersubjective realism": agreement always occurs between ego an about something in the world. Both the topic of the agreement and the other with whom agreement is reached give the intersubjective dialogue an objectivity. Habermas claims that the later Peirce abandoned the very moment of "secondness" that limits and distinguishes the self from the other(Postmetaphysical Thinking, p. 110-111). Peirce thus could not account for the fact that an actor maintains the facticity of his difference and uniqueness (Eigensinn) even in the process of successful communication with the other." [Reflection Revisited: Jurgen Habermas's Discursive Theory of Truth, pp. 96-97]
* Habermas makes a similar point against Quine in his Truth and Justification p. 23.
** Incidentally this would be Habermas' answer to those who accuse him of returning to pre-critical ontology by presupposing a "weak naturalism".