Digital Companion to C. S. Peirce
1902 | Minute Logic: Chapter II. Prelogical Notions. Section I. Classification of the Sciences (Logic II) | CP 7.365

What the psychologists study is mind, not consciousness exclusively. Their mistake upon this point has had a singularly disastrous result, because consciousness is a very simple thing. Only take care not to make the blunder of supposing that Self-consciousness is meant, and it will be seen that consciousness is nothing but Feeling, in general, – not feeling in the German sense, but more generally, the immediate element of experience generalized to its utmost.

1905 | Issues of Pragmaticism | EP 2:347; CP 5.440

…anti-synechistic thinkers wind themselves up in a factitious snarl by falsifying the phenomena in representing consciousness to be, as it were, a skin, a separate tissue, overlying an unconscious region of the occult nature, mind, soul, or physiological basis. It appears to me that in the present state of our knowledge a sound methodeutic prescribes that, in adhesion to the appearances, the difference is only relative and the demarcation not precise.

1907 | Pragmatism | MS [R] 318:75-6

…I am far from holding consciousness to be an “epiphenomenon,” though the doctrine that it is so has aided the development of science. To my apprehension, the function of consciousness is to render self-control possible and efficient. For according to such analysis as I can make the true definition of consciousness is connection with an internal world; and the first impressions of sense are not conscious, but only their modified reproductions in the internal world.

1907 | Pragmatism | EP 2:418-9; CP 5.493

…it must not be inferred that I regard consciousness as a mere “epiphenomenon”; though I heartily grant that the hypothesis that it is so has done good service to science. To my apprehension, consciousness may be defined as that congeries of non-relative predicates, varying greatly in quality and in intensity, which are symptomatic of the interaction of the outer world, – the world of those causes that are exceedingly compulsive upon the modes of consciousness, with general disturbance sometimes amounting to shock, and are acted upon only slightly, and only by a special kind of effort, muscular effort, – and of the inner world, apparently derived from the outer, and amenable to direct effort of various kinds with feeble reactions, the interaction of these two worlds chiefly consisting of a direct action of the outer world upon the inner and an indirect action of the inner world upon the outer through the operation of habits. If this be a correct account of consciousness, i.e., of the congeries of feelings, it seems to me that it exercises a real function in self-control, since without it, or at least without that of which it is symptomatic, the resolves and exercises of the inner world could not affect the real determinations and habits of the outer world. I say that these belong to the outer world because they are not mere fantasies but are real agencies.