Russell - A Very Short Indroduction by A. C. Grayling

bottom, realism and anti-realism are indeed differing theses about the relation of contents to objects, and thus are epistemological theses, idealism is a metaphysical thesis about the nature of the world, namely, that it is ultimately mental in character. This point is frequently missed in philosophical debate, so Russell is in good company.) All these difficulties can be avoided, Russell claims, if we adopt a version of William James’s ‘neutral monist’ theory.
    Neutral monism
    James argued that the single kind of metaphysically ultimate raw material is arranged in different patterns by its interrelations, some of which we call ‘mental’ and some ‘physical’. James said his view was prompted by dissatisfaction with theories of consciousness, which is merely the wispy inheritor of old-fashioned talk about ‘souls’. He agreed that thoughts exist; what he denied is that they are entities. They are, instead, functions: there is ‘no aboriginal stuff or quality of being, contrasted with that of which material objects are made, out of which our thoughts of them are made; but there is a function in experience which thoughts perform, and for the performance of which this quality of being is invoked. That function is knowing ’ (James, Essays in Radical Empiricism , 3–4).
    In James’s view the single kind of ‘primal stuff’, as he called it, is ‘pure experience’. Knowing is a relation into which different portions of primal stuff can enter; the relation itself is as much part of pure experience as its relata.
    Russell could not accept quite all of this view. He thought that James’s use of the phrase ‘pure experience’ showed a lingering influence of idealism, and rejected it; he preferred the use made by others of the term ‘neutral stuff’, a nomenclatural move of importance because whatever the primal stuff is, it has to be able – when differently arranged – to give rise to what could not appropriately be called ‘experience’, for example stars and stones. But even with this modified view Russell only partially agreed. It is right to reject the idea of consciousness as an entity, he said, and it is partly but not wholly right to consider both mind and matter as composed of neutral stuff which in isolation is neither; especially in regard to sensations – an important point for Russell, with his overriding objective of marrying physics and perception. But he insisted that certain things belong only to the mental world (images and feelings) and others only to the physical world (everything which cannot be described as experience). What distinguishes them is the kind of causality that governs them; there are two different kinds of causal law, one applicable only to psychological phenomena, the other only to physical phenomena. Hume’s law of association exemplifies the first kind, the law of gravity the second. Sensation obeys both kinds, and is therefore truly neutral.
    Adopting this version of neutral monism obliged Russell to abandon some of his earlier views. One important change was that he gave up the notion of ‘sense-data’. He did this because sense-data are objects of mental acts, whose existence he had now rejected; therefore, since there can be no question of a relation between non-existent acts and supposed objects of those acts, there can be no such objects either. And because there is no distinction between sensation and sense-datum – that is, because we now understand that the sensation we have in seeing, for example, a colour-patch just is the colour-patch itself – we need only one term here, for which Russell adopts the name ‘percept’.
    Before accepting neutral monism Russell had objected to it on a number of grounds, one being that it could not properly account for belief. And as noted, even when he adopted the theory he did so in a qualified form; mind and matter overlap on common ground, but each has irreducible aspects. Nevertheless what at last persuaded him