When the student of logic is first initiated into the problem of the relation of implication as expressed by the hypothetical proposition, he enters into a portion of logic which seems to him an impenetrable jungle. Elementary statements of the meaning of implication, as he is acquainted with them, are so meagre that they have failed to give any indication of the problems and paradoxes involved. Adequate discussions, on the other hand, are so abstruse that the initiate is lost in their incomprehensibility, for these are issues discussed by the technical logicians largely among themselves. When one considers the important bearings implicit in the interpretation of implication, such a state of affairs is greatly to be deplored. Through a simple but adequate presentation of the meaning of a hypothetical proposition one may be led not only to an understanding of a fundamental paradox of logic but to the whole question of modal logic and of the philosophy of logic. It is my purpose in what follows to present as simply as possible the various interpretations of the meaning of implication and to show their relations to modal logic. Having done this I believe it will be possible to state the case in favor of material implication in a new light.

In my recent paper on Living Systems and Non-living Systems I considered briefly the question of the special rôle assignable to the psychic, as natural factor associated with yet different from the physical, in the activities of living organisms. The general conclusion was reached that this rôle is primarily integrative, in correspondence with the integrative character which is the essential distinguishing feature of the psychic in our experience. As integrative, the psychic factor has a special relation to the synthetic activity so highly developed in living organism, since synthesis is by its nature integration or whole-formation. Originative or novelty-producing activity is the special prerogative of the psychic, rather than simple repetition or routine; the latter, as exemplifying the stable or conservative side of nature, belongs in the field of the physical. According to this conception, the psychic is the source of initiative when action takes on a novel or creative form, as in conscious voluntary activity or (in a broader sense) in natural creative action in general. For example, in animals vegetative or routine processes may be purely physiological and unconscious, while actions requiring special initiative or innovation demand conscious effort and attention.

The determination of the place of life in nature has been a major philosophic issue. Some, in their attempt to show the continuity of nature, have resorted to the reductive method and have argued that the living differ in no significant sense from the non-living, unless it be in their complexity; others, in their desire to emphasize the qualitatively varied aspects of nature, have drifted to disjunctive method and have claimed that there is an unbridgeable gap between the living and the non-living. Yet life in its natural setting presents both continuity with the physical world and a distinctive difference from it. One need neither sunder the continuity in nature nor deny the empirically observable qualitative differences. It is this principle that will guide the present discussion of life.

In his epistemological system Mead begins with that which the chief philosophers rejected, the novel or exceptional, and makes it central. It is central in a respect which should be carefully explained. The novel or emergent is that with reference to which a present is defined, and a present is the seat of reality. In saying this Mead does not mean that “the past” (more precisely, “a past” and “a future”) and “the future” are meaningless terms. Nor does he reduce them to a present. Rather he holds that neither the past (of the realist or the materialist) nor the future (of the finalist) exists. In fact, they are meaningful only in relation to a present and the various pasts and futures referred to in our statement of causal conditions and predictions belong to a present, which is their seat. Mead escapes the metaphysical problem as to whether the past or the future has some sort of being even now. Certainly in so far as he has a metaphysics at all it derives from his epistemology which is primary and represents a pioneering attempt to develop a theory of knowledge answering to experimental science. Consciously or unconsciously most contemporary scientists are still under the influence of bygone epistemological and metaphysical doctrines in their explicit statements of what constitutes reality and knowing. Yet in so far as they are successful in practice obviously they are free from the blind alleys and dead ends which these older theories lead to logically. However no one, not even the philosopher, has been able to formulate a consistent set of epistemological principles from which experimental scientific procedure follows logically. One thing, Mead contends, has been wholly neglected. It is the emergent.

In the opinion of many, the philosophy of Alfred North Whitehead is a novel emergent which, like the magician's rabbit, amazes the naive but does not seriously impress the enlightened.

One of the most fundamental criticisms of the philosophy of Whitehead has come from Professor Wilbur Urban. To The Philosophy of Alfred North Whitehead (The Library of Living Philosophers, Vol. 3) Urban has contributed a very thought provoking article entitled: “Whitehead's Philosophy of Language and Its Relation to His Metaphysics.” This, we are told, is a restatement of previous studies.

The supposed communication of one mind with another at a distance, without any means known to physical or psychological science, is a generally accepted definition of telepathy. Thus when persons sensorially isolated from each other experience congruence and coincidence of thoughts, emotions or actions they are considered as being in telepathic communication. Clairvoyance surmises the apprehension of particular objects and stimuli also without the employment of any of the agencies of the five senses. Although telepathy and clairvoyance have been thus recognized as distinct conjectures, either or both comprise features of Extra Sensory Perception (ESP). Both are conceived of as transcending the anatomical structures and physiological functionings that comprise the five senses. They therefore constitute a mysterious, additional sense which as yet cannot be ascribed to material bases or causes. However, the operations, if not the exact natures, of these recondite abilities have been, it is claimed, experimentally and precisely ascertained.

As individuals and as communities we have suddenly awakened to find ourselves enveloped in a welter of unprecedented changes—social, political, economic and scientific. If our minds are to keep pace with the restless current on which we are being carried along, if our senses are to become alert to the teeming dislocations that mark the present, it will be necessary to raise our sights to the farther reaches of a rapidly oncoming future. In this hurrying hour the outstanding domains of man's thought are found wanting. Accepted tenets in many fields of his activity are giving way to rapidly broadening concepts. In this moment of new assessments it is safe to predict that the field of psychopathology must also gird itself for very radical alterations. It is safe to predict that present-day preoccupations with interpersonal affects, domestic transferences, sexual irregularities, marital conflicts, psychotic episodes, and the vast array of neurotic symptoms that comprise our psychiatric systems will in the scientific reckoning of the future appear to us quite obsolete and inept. They will appear to us as humdrum and archaic, I feel sure, as old wives' tales when contrasted with the basic and encompassing constructs of an organismic phylobiology.

Two distinct attitudes have been adopted by investigators in the field of the sociology of knowledge. One of them may be called speculative; the other, empirical. The central interest of an investigator having the speculative attitude lies in developing a theory of the sociology of knowledge. The central interest of investigators having the empirical attitude lies in finding out or explaining concrete phenomena; the theory is employed, implicitly or explicity, for this purpose. The existence of the two attitudes may be in part explained, as far as the German sociology of knowledge is concerned, by reference to the history of this school, which has grown out of and has been determined by a Marxist and materialistic philosophy, and especially by the use of this philosophy as a political instrument in the struggle of the emerging proletariat against the bourgeoisie. This statement, however, must be supplemented by a short location of the four most important contributors to the theory of the German sociology of knowledge. Max Scheler approaches the problem phenomenologically; he was the first and only one to ask the fundamental question, “What is knowledge?” Karl Mannheim, though markedly influenced by the Marxist viewpoint, particularly by Lukács, seems to me more adequately characterized by stressing his development from a more exclusively speculative to a more decidedly empirical attitude, which latter is especially evident in his most recent book, Man and Society in an Age of Reconstruction (1940). Alexander von Schelting's main contribution is his thorough logical analysis of Mannheim's theory in the light of Max Weber's methodology. Ernst Grünwald has given the most complete survey of the forerunners, the history, and the various contributions of the sociology of knowledge. These four thinkers are indirectly dependent on the historically determined emphasis of the movement on ideology in that they remain on the level of a theoretical discussion without arriving at factual research.

Psychological research and theory has been in the past, and is at present, vitiated by three groups of presuppositions and tendencies. Firstly, by a rigid ideal of preciseness, which produces in the mind of psychologists a biased predilection for selecting and emphasizing those facts which lend themselves best to a precise investigation, and for neglecting those facts with which this is not the case. Secondly, by certain psychological presuppositions rooted in the ideological background of the society to which the psychologist himself belongs; these presuppositions induce him often to state, unwittingly, certain of his problems along the lines suggested by the predominant ideology. And thirdly, by the tendency to overlook, or to neglect, certain very important facts because these facts appear to be quite “obvious”.

Social conflicts of ever widening scope have in recent years emphasized the importance of the problem of the relation of facts and values. This problem has received increasing attention from researchers and theorists in both the physical and social sciences. A number of interesting but by no means compatible solutions have been proposed.

Perhaps the simplest and most striking is the position of Carnap, Russell, and others, that value sentences, such as “A ought not to kill B” or “Killing is evil” are merely commands or expressions of wish and, as such, are emotional ejaculations or expletives but not statements which have any theoretical sense or enter (except as subject matter) into science. On this view the problem of the relation of fact and value statements is meaningless, or at least is not worth considering further.

A problem of tremendous import confronts the social scientists of our day. Having accumulated a vast amount of detailed data on human relations the social scientists are now being asked about the significance of their data. Two major aspects of this questioning are these: How can we synthesize all available scientific data on human relations so that this knowledge can be successfully applied to the solution of current social problems; and secondly, since some of the data accumulated so far has been defined and organized in terms of concepts imitative of older (Newtonian) physical (and sometimes biological) concepts—the appropriateness of which to human relations as subject matter is questionable—should we not evaluate these basic concepts with a view to laying new conceptual foundations for our knowledge of human relations? Thus we shall open the way for new social research and at the same time develop a methodologically sounder basis for our knowledge of human relations. Briefly, our knowledge of human relations at present is at loose ends, and in this condition is not as applicable to the solution of pressing social problems as it would be if it were unified into a comprehensive and more flexible science of human behavior. Such a unification would demand not only a synthesis of the data of the social sciences but also the critical evaluation of many of the basic concepts of these sciences.

Constitutional schemata have been of continuing interest in medicine and psychology ever since the time of Hippocrates. With the work of Sheldon, Stevens and Tucker (5, 6), biotypology has been placed on a new basis. The reader who wishes to orient himself quickly and without too much detail, to the subject matter of typology, will find an interesting and substantial review by Anastasi (1). Wertheimer and Hesketh (7) have produced a comprehensive, but brief, historical and analytic treatment of the constitutional approach in their rather short monograph on the subject. Hempel and Oppenehim (2) have examined the concept of psychological type in a novel fashion from the standpoint of modern logic and positivist philosophy. Typology has been of more interest to continental writers than to American writers. Numerous medical school dissertations at European universities attest to this fact. Medical and psychological literature on the subject is also more frequently of European or Latin American origin, than of United States origin, as a cursory glance at the Index Medicus (4) or the Surgeon General's Catalogue (3) will quickly reveal. The work of Sheldon has raised fresh theoretical considerations which we propose to outline to some extent in this paper and the above sources, we feel certain, will furnish sufficient orientation to those readers who come to this subject with little or no previous acquaintance with it. Before going any further the reader is urged to read Chapter V of the “Varieties of Human Physique” (5).