"What separates Peirce from both early and modern positivism is his understanding that the task of methodology is not to clarify the logical structure of scienftic theories but the logic of the procedure with whose aid we obtain scientific theories. We term information scientific if and only if an uncompelled and permanent consensus can be obtained with regard to its validity. This consensus does not have to be definitive, but has to have definitive agreement as its goal."
Knowledge & Human Interest, p. 91
"Had Peirce taken seriously the communication of investigators as a transcendental subject forming itself under empirical conditions, then pragmatism would have been compelled to a self-reflection that overstepped its own boundaries. In continuing his analysis, Peirce would have had to come upon the fact that the ground of intersubjectivity in which investigators are always already situated when they attempt to bring about consensus is not the ground of purposive-rational action, which is in principle solitary."
". . . the communication of investigators requires the use of language that is not confined to the limits of technical control over objectified natural processes. It arises from symbolic interaction between societal subjects who reciprocally know and recognize each other as unmistakable individuals. The communicative action is a system of reference that cannot be reduced to the framework of instrumental action."
Knowledge & Human Interest, p. 137
Habermas praises Peirce for focusing on scientific procedures as against the logical structure of theories but criticises him for misconceiving those procedures by interpreting on the model of purposive rational action rather than on the model of communicative action.