The purpose of the methods of science is to achieve a description and understanding of nature (the universe). By description I mean the definition, cataloguing, or classification of events, objects, and phenomena which define nature, and the statement of empirical relationships associated with these events, objects, and phenomena. By understanding I mean the reduction to the smallest possible number of general laws which would account for the various specific facts. The descriptive part of science is concerned with research per se; what I have called understanding is usually achieved through theory.
This particular book is concerned with the scientific method as a means of studying behavior, particularly by those who call themselves psychologists. I will try to reflect faithfully various research practices in psychology; but, in spite of the manifest enthusiasm which I have for my profession, I find a great deal to criticize in these research practices. When I am critical it is in the interests of betterment of psychological research, not because of any overpowering urge to censure. For certainly, it seems to me, we need to maintain a continuous review or inspection of the attempts to apply scientific method to the study of behavior. Some of these attempts make science look ludicrous and they must be evaluated for what they are. Probably there is no other area of human endeavor which so badly needs a thoroughgoing application of the scientific method as does psychology, for probably in no other area are there so many misconceptions, so many half-truths, and so many abortive attempts to understand behavior.