Chapter IV

. But my contention is, that he who has given no thought to the matter may easily fall into error as to the very nature of mental phenomena.

For example, when we approach or recede from a physical object we have a series of experiences which are recognized as sensational. When we imagine a tree or a house we are also experiencing a mental phenomenon. All these experiences _seem_ plainly to have extension in some sense of the word. We appear to perceive plainly part out of part. In so far, these mental things seem to resemble the physical things which we contrast with what is mental. Shall we say that, because these things are mental and not physical, their apparent extension is a delusion? Shall we say that they really have no parts? Such considerations have impelled psychologists of eminence to maintain, in flat contradiction to what seems to be the unequivocal testimony of direct introspection, that the total content of consciousness at any moment must be looked upon as an indivisible, part-less unit.

We cannot, then, depend merely on direct introspection. It is too uncertain in its deliverances. If we would make clear to ourselves what mental phenomena really are, and how they | differ from physical phenomena, we must fall back upon the reflective analysis of our experience which occupies the metaphysician (section 34). Until we have done this, we are in great danger of error. We are actually uncertain of our materials.

Again. The psychologist speaks of the relation of mind and body. Some psychologists incline to be parallelists, some are warm advocates of interactionism. Now, any theory of the relation of mind to body must depend on observation ultimately. If we had not direct experience of a relation between the physical and the mental somewhere, no hypothesis on the subject would ever have emerged.

But our experiences are not perfectly clear and unequivocal to us. Their significance does not seem to be easily grasped. To comprehend it one is forced to that reflective examination of experience which is characteristic of the philosopher (