Page:Philosophical Review Volume 2.djvu/695

. 6.] metaphysical theory laid as the foundation for a science that should be empirical I do not need to speak, although probably few things have done more injury to our science than the general belief that the new psychology finds its justification for existence in such speculations. We can also readily see why even professed psychologists put forward the plea that there is no use in being exact in their measurements. At present we know absolutely nothing of the nature of the brain processes to which mental phenomena correspond; if the only way to trace any connection between mental phenomena is to first get at the brain processes, it is really very hard to see why we should make any experiments at all.

We shall, however, be obliged to reject these and all other metaphysical theories at the outset, and confine ourselves to the facts. In doing so we take up the development of psychology just where the old psychology left it. The material of the new psychology is exactly the same as that of the old psychology, the facts of immediate experience; the only difference lies in the substitution, wherever possible, of exact records and measurements in place of vague descriptions in general terms. The older attempts at applying the method of introspection led to results as often erroneous as true; with the introduction of experimental methods a trustworthy application of the fundamental method of introspection (or reflection), became for the first time possible.

Measurement in General.–The fundamental form of measurement is the expression of the judgment that the quantity measured is equal to or unequal to the standard. The primitive method of weighing articles was by balancing them in the two hands; we measure off a yard of cloth by laying a yard-stick down on it and cutting off enough to be equal to the stick; we run the eye over one line, then over the other to see if they are equal; we measure lights by determining that they are alike or unlike in intensity, tones by judging that they are alike in pitch.