Titchener referred to himself as a psychophysi- cal parallelist concerning the mind–body relation- ship, and indeed much of his writing reflects that position. Occasionally, however, he appeared to embrace Spinozian double aspectism and at other times epiphenomenalism. Titchener’s uncharacteris- tic equivocation in his position on the mind–body relationship reflected disinterest rather than shoddi- ness in his thinking. For him attempting to explain the mind–body relationship came dangerously close to metaphysical speculation, and that was foreign to his positivism. Essentially, Titchener believed that physiological processes provide a substrate that gives psychological processes a continuity they otherwise would not have. Thus, for Titchener, although the nervous system does not cause mental events, it can be used to explain some of their characteristics. Ultimately then, neurophysiological processes are the why of mental life, if why is understood to mean a description of the circumstances under which mental processes occur.
We have seen that interest in the mind is as old as history itself, and the question of how the mind is related to bodily processes goes back at least as far as the early Greeks. Because both empiricists and rationalists alike believed the senses were the gate- ways to the mind, it is no surprise that sensory pro- cesses were among the first things science focused upon when it was applied to humans. From there it was but a short, logical step to looking at neu- ral transmission, brain mechanisms, and finally con- scious sensations.