William James on the Stream of Consciousness

William James was heir, not only to Descartes’ 1641 Meditations, but to all of the later psychological discoveries made between 1641 and his own 1878 signing of a contract to write a psychology textbook. Later, in the fifth of his 1906-07 Pragmatism lectures, he made it clear that common sense could not accommodate the discoveries of modern physics and later philosophy. "Science and critical philosophy thus burst the bounds of common sense. With science naïf realism ceases: ‘Secondary’ qualities become unreal; primary ones alone remain. With critical philosophy, havoc is made of everything. The common-sense categories one and all cease to represent anything in the way of being; they are but sublime tricks of human thought, our ways of escaping bewilderment in the midst of sensation’s irremediable flow." (Writings II:567) This ‘bursting of the bounds’ began with the recognition by Descartes that the brain is a barrier that prevents direct contact between the mind and any outside-the-brain reality. For the same reason, the brain prevents any outside-the-brain reality from directly affecting the mind without it first affecting the brain. The corollary to that premise-conclusion is that humans do not directly know the outside world by means of sensation. Sense-experience will always serve as clues for deciding how our inner thoughts relate to the external world. We are not, however, eye-witnesses of that external world. We are jurors who must rely on personal, even private evidence to decide which of our thoughts about that unseen-by-us external world are true.