The problem of this paper may be stated simply. It is that, in dealing with the nature of reality, it is not only possible, but more fruitful and more accurate, to deal with the category of order or design, meaning by this, the structure or relationship of the parts of a whole, without associating this idea with that of purpose or teleology, than it is to conjoin these concepts. It is the purpose of the paper to show why this separation is advisable, and to indicate the background of the problem which tends to make difficult the separation of these two concepts.

The progress of psychology as scientific theory has been handicapped by the circumstance that it has been inclined to deal with two kinds of problems: on the one hand, with emotions, instincts, complexes, ideas, etc.; on the other, with the working of the sense-organs and of the central and sympathetic nervous system. To approach the first task it has had to create a system of mentalistic or introspective concepts, like the ones mentioned; to deal with the second enterprise it has adopted the physical language used by the natural sciences.

Two chief problems of the theory of knowledge are the question of meaning and the question of verification. The first question asks under what conditions a sentence has meaning, in the sense of cognitive, factual meaning. The second one asks how we get to know something, how we can find out whether a given sentence is true or false. The second question presupposes the first one. Obviously we must understand a sentence, i.e. we must know its meaning, before we can try to find out whether it is true or not. But, from the point of view of empiricism, there is a still closer connection between the two problems. In a certain sense, there is only one answer to the two questions. If we knew what it would be for a given sentence to be found true then we would know what its meaning is. And if for two sentences the conditions under which we would have to take them as true are the same, then they have the same meaning. Thus the meaning of a sentence is in a certain sense identical with the way we determine its truth or falsehood; and a sentence has meaning only if such a determination is possible.

Metaphysical problems may be solved by the methods of inference employed in the empirical sciences. So we are told by many realists and pragmatists, among whom may be mentioned Professors J. B. Pratt, William Savery, and Donald Williams. Mr. Williams and Mr. Pratt have argued for the use of inductive methods in establishing the existence of an external world. Mr. Savery has asserted that all philosophical inference as to matter of fact is inductive. This naturalistic attitude is by no means unusual—in fact it is so common in this age in which the speculations of scientists as well as their achievements have captivated the popular imagination, that even philosophers have for the most part failed to examine its validity and presuppositions. It is the purpose of this paper to present such an examination, not of the philosophic employment of inductive methods in general, but in regard to one specific problem; namely, that of the existence of an external world. What I purpose then is to present and evaluate the view that the existence of an external world may be established by inductive methods as employed in the empirical sciences.

In view of the importance of the philosophical method argued in Mr. C. I. Lewis's “Experience and Meaning,” I wish to call attention to ambiguities which may have an important bearing on one of his conclusions. The method for which he argues is a certain empirical test of meaningfulness. It is his ‘positivistic’ inference from this method which I wish to challenge. To do so I shall present four points: (1) A summary of his empirical test of meaningfulness; (2) A ‘non-positivistic’ (or ‘dualistic’) hypothesis which Mr. Lewis rejects; (3) An analysis of this hypothesis in view of his test; (4) The theory of universals implied in my analysis.

One is tempted to look upon the positive and the logical somewhat as one looks upon the quick and the dead. Yet the issue is hardly that sharp. Viability has strange possibilities and varied forms, and must often be appraised with an eye directed as much towards the environment as towards the claimant organism. Stretching the application of the word ‘viable’ to complexes of behavior such as the philosophies and theories of knowledge, we may ask: Is the combination of the positive and the logical in logical positivism viable? And is this logical positivism itself as it stands either positive or logical?

In what follows I shall consider symbols only in their function as conveyors of meanings. That symbols have emotive and volitional properties as well, that they have elaborate and complicated relations to the self which uses them, that they are themselves physical counters, i.e., noises, visual objects, etc.,—all of these facts I recognize but choose to neglect. When symbols are considered merely as instruments for the transfer of meanings, only one important assumption is involved, viz., symbols which are precisely defined are to be preferred to symbols which either are undefined or are defined inadequately. In other words, the task of a theory of meaning is that of showing how symbols take on a maximum degree of precision in significance.

What can we say of space and time when we consider them as attributes of nature and as attributes of nature in the context of experience? The following is an examination of this question in the light of those portions of the writings of Locke and Kant which were concerned with it. Since men have no difficulty in speaking about and utilizing the familiar spatial and temporal relations of things, we begin with these and shall avoid definition and debate except insofar as it is pertinent to the present inquiry. Nor shall we consider it necessary to examine space and time in any other context as, for example, that of modern physics. The familiar world is the necessary condition for the conception of any intellectual development of it, and to begin with the intellectual development is to render it unintelligible. This is evidenced in several ways. When we begin with physics and mathematics, we cannot account for the world within which we live and consequently end in scepticism about it, whereas this is not the case when we begin with the actual world itself. Furthermore, the manifestly perceptible is indispensible to scientific enquiry for we must employ instruments and objects directly accessible to experience. Without these there would be neither experiment, observation nor inference. Communication would be impossible without it as well as discussion about subject matters such as logic and esthetics. It is for these reasons, therefore, that we begin with the familiar spatial and temporal relations of things.

In a recent issue of Philosophy of Science Merrit H. Moore contends that it is not only possible but methodologically desirable to separate design in nature from purpose. The main part of his argument is devoted to a support of the proposition that “design” is objective, by which he means that design in the physical world is independent of mind. That which gives interest to Mr. Moore's argument is essentially the Kantian doctrine that the forms of the understanding, and consequently of knowledge, are furnished by the mind and are, in a sense, imposed upon sense-experience thereby making them rational. In contrast to the Kantian view stands the Humean doctrine that knowledge is analyzable into and limited by sense-impressions.

In Physical Theory Mr. Lenzen writes, “Thus the concept of thing is the concept of a class of aspects which are in the past, present, or future for several minds.” Again, in Mind and the World-Order, Mr. Lewis defines “thing” as “… a complex of properties or qualities, recognizable by some uniformity of appearance.” Without questioning the metaphysics implied in these two definitions of “thing” I shall accept them as quite compatible and as useful in defining the rôle of experience in the construction of scientific objects. If in “Pragmatism and Metaphysics” Mr. Morris has not established proof of the existence of objects independent of any and all experience of them, he certainly has shown conclusively that the possibility of experiencing objects is independent of any and all observers.

Mathematical continuity, in the technical sense, is a precisely definable mathematical notion which refers to certain properties of numbers and number sequences. The continuity of the physical world, on the other hand, is rather different from mathematical continuity, since it is a directly experienced attribute of nature and does not require, for being understood, any mathematical theory of properties of numbers.

Deduction has frequently been condemned as a useless intellectual instrument because of its tautological character. To thoroughgoing opponents of rationalism, the pretensions of deduction are on the same level with those of induction. Both presume to yield more knowledge from the fact that we have some knowledge; and this is an impossible paradox, which not even so powerful an opponent of the “Philosophy of Experience” as Bradley could resolve to his own satisfaction. I wish in this brief note to indicate how this semblance of paradox may very easily be removed without having to deny, as has often been thought necessary, the tautologicality of deduction.

Though some doubts about the principle that every proposition is either true or false were entertained even by Aristotle, both the number and the vigor of criticisms of this principle have been increasing in recent years. This paper attempts a restatement and a re-examination of the issues involved in this dispute, and in particular an evaluation of the effects on the argument of such recent discoveries as that of the “many-valued logics.”

Ockham realized the value of a careful study and application of the mathematical theory of continuity, even though he possessed no conclusive empirical evidence that it adequately explained the continuity experienced in the world of sense. He also clearly perceived a relation of continuity to infinity, since continuity, as a property of an order which is possible only to a series of terms, must have an infinite number of terms. “A continuous series must have an infinite number of terms.”

The logician has not been conspicuous for his contributions to scientific knowledge, nor has the scientist been noted for his knowledge of logic. One might readily infer from these observations that there is no necessary connection between science and logic, but I think he would be in error. As one who makes no claim to being either a scientist or a logician, I am perhaps well qualified to say something significant about the logic of science!

The logical pattern underlying twentieth century science is strikingly uniform from physics through biology and psychology to social science. Our purpose will be to analyze and illustrate this pattern, to trace its development, especially from the Middle Ages to the present time, and to suggest some possible consequences for the future.

The distinction between psychology, logic, and epistemology is a commonplace. The first treats of experience as an act, experience in its relation to the individual observer. The second concerns itself with the internal marks by which truth may be distinguished from error, and in so far as it deals with experience, has to do with some sort of validity of the experience as evidence of a truth. The third discusses in a general way all the elements—observer, object, immediate presentation—which enter into the experience.

In this paper I wish to offer a suggestion in support of the thesis that if a given set of facts is explained by two rival explanations A and B, where A consists of a single hypothesis H1, and B consists of at least two independent hypotheses H2 and H3, then, other things being equal, A is more probable than B. That this view is true is seldom questioned, though I have never seen any reason given for it, which would justify the methodological value so many philosophers attribute to it. It is not my purpose to discuss simplicity of explanation in general, but simply to point out that the Multiplicative Axiom of the calculus of probabilities justifies the above thesis. I shall call this thesis the Principle of Parsimony.

Attention has been drawn, particularly since Kant, to propositions which can not have negative instances. They used to be called a priori, axioms, first principles. Today, they are usually called postulates—C. I. Lewis uses both the old and new terminology—because there is a growing recognition of the fact that at least some of them are not “necessary” in the traditional sense. Kant placed a limitation on the apriorism of the continental rationalists. Current epistemologists and logicians have outstripped Kant in the direction signalled by him. Both he and they, however, concur in the opinion that apriori propositions are subject to negation of a sort. The Kantian dinge-an-sich, though they can not contradict these propositions by being negative instances of them, do nevertheless stand to them in the relation of insubordination, thereby exerting on them a “negative action” of a sort. And, according to current views, there are instances which, though they fall outside the range of significance of a proposition or system and hence can not contradict it, do nevertheless tend to bring about a revision of it by a negative action of some sort. The purpose of this brief essay is to coin a convenient name for such instances and to describe certain properties of their peculiar negative action.

For the most part, this paper is an attempt to understand such a statement as this: “The proposition represents the fact by virtue of a structural identity between it and the fact.” The statement is a familiar and important one in modern philosophy. It is, for example, one of the tenets of Logical Positivism.