The present paper deals thus with some fundamental agreements and disagreements between Peirce and James, on crucial issues such as perception and consciousness. When Peirce first read the Principles, he was sketching his theory of the categories, testing its applications in many fields of knowledge, and many investigations were launched, concerning indexicals, diagrams, growth and development. James's utterances led Peirce to make his own views clearer on a wide range of topics that go to the heart of the foundations of (...) psychology and that involve the relationship between perception and logic, between consciousness and the categories, between abstraction and the 'stream of thought'. The idea is to show that Peirce detected important discoveries and insights in the Principles, but felt that James could not make proper use of them because of logical confusions, and also because of his "clandestine" metaphysics. The point in this essay is thus not to look for remains of psychologism in Peirce's writings,13 but to look at Peirce's comments about James's psychology in an attempt to identify where and why Peirce amended James's views. Since the project to provide some insight on Peirce's extensive reading ofJames's Principles of Psycho/.ogy would deserve a full volume, I shall focus here on three occasions where Peirce explicidy commented on Jarnes's Principles. In the first section, I shall consider bis assessment of James's chapter on space, which was published as a series of articles in 1887, in Mind. I shall then turn to the 1891 review of the Principles in The Nation for important complements on perception as inference. In the third section, I shall deal with Peirce's manuscript "Questions on James's Principles"(Rl099). These "Questions" reveal a deep interest in psychological problems and suggest different ways along which Peirce's new advances in the field of the categories, of continuity, and abstraction could provide a proper basis for the philosophy of mind. (shrink)