¹ Like every other unit of behavior, the act of scientific investigation has four recognizable parts: (1) impulse (in this case, stimulus of lack of automatic method of response), (2) perception (in this case perception of the problem, perception of data and method), (3) manipulation (in this case (a) thought about problem, data and method and (b) muscular activities of collection and analysis), (4) attainment (in this case drawing a conclusion which temporarily or permanently reestablishes the investigator's equilibrium with reference to the problem). Cf. Mead, G. H., The Philosophy of the Act, University of Chicago Press, 1938; and Smith, Mapheus, “An Approach to the Study of the Social Act,” Psychological Review, 1942, 49, 422–440.

² The use of the term hypothesis to refer to two distinct meanings is, however, not sound semantic practice. Since there is no difference between a summing-up hypothesis and what has been referred to as a conclusion, or what is often called an interpretation, it seems advantageous to substitute the term interpretation for the summing-up kind of hypothesis. It is invariably conducive to accurate communication of ideas to distinguish between two parts of an investigation that function in different ways by the use of different terms to designate the parts. Thus it is of advantage to use hypothesis to designate a conditional outcome of an investigation anticipated prior to that outcome, in order to distinguish hypothesis from the conclusion and interpretation resulting from the investigation. When hypothesis signifies both of these referends it follows that there is a certain lack of precision in thought and communication when the word is used.

To be sure, a conclusion or provisional interpretation of a fact or facts may anticipate the interpretation of a set of facts to be collected and analyzed later. That is to say, hypothesis as a provisional explanation may play the part of anticipating further investigation yielding further support. But this merely means that one investigative act may follow another and that the interpretation phase of one investigative act may serve as the hypothetical phase of another. This is true, but as far as one investigative act is concerned, anticipation (hypothesis) and conclusion-interpretation cannot be the same mental activities and therefore should be thought of and named differently. Concluding and anticipating behavior are not functionally the same activity nor is one act the same as another act, although part of one act may serve as part of a subsequent act. Even this latter concession does not go so far as to admit that an interpretation of an investigation being concluded is identical with the supposition that another investigation may produce results that will support the previous investigation.