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HERE are now current two general theories of the place of mind in nature. The one of these, and the one which it is easier to state in precise terms, regards the processes of the material universe (including those of the physical organism) as a closed chain of cause and effect, which is altogether removed from any psychical influence. Mental process is a concomitant of certain highly complex material processes, but not anything that affects these processes themselves. Whether or not it is a constant concomitant, and thus a valid index or symptom of the nature of the underlying material processes, is a question which science must settle by appeal to the facts. Modern psychology answers it in the affirmative, though she offers no explanation—cannot, in the nature of the case, offer an explanation—of the 'why' of the connection. Mind exists; mental processes run their course in constant parallelism to bodily processes; they never interfere with these processes. This is the first view, and the view which I myself, at the present time, consider to be the more tenable.

The alternative theory regards mind as capable of causal interaction with body. Mind and body have developed together, and it stands to reason that they mutually influence each other. This is a common sense point of view; it seems, at first sight, to have everything in its favor, and to be just as intelligible as the other.

We must, however, go a little deeper. And, in order to keep things clear, let us give the theory of interaction a more concrete form. One of the strongest arguments in support of the theory, or perhaps we might rather say one of its necessary implications, which appears to many psychologists to be borne out by the facts, is that 'consciousness' has a 'survival value,' that mind is a factor in organic evolution. Now we must sharply distinguish between two different uses of the term 'consciousness,' which are oftentimes confused by the advocates of interaction. Consciousness may mean knowledge or awareness, our acquaintance with the world about us, or it may mean simply (as on the first theory it always must mean) a complex of mental processes. In the former meaning, it covers the great functions of cognition, memory, reasoning, imagination, etc. And this is the point at which confusion enters. Cognition, memory, and the rest, are not purely