THE PREFACE

The present work is an attempt to state systematically the essential problems of epistemology. These problems are real; they can be stated clearly, and they can, I am convinced, be solved. What do we mean when we say that we know a thing? What are the conditions of such knowledge? These questions and the numerous other questions to which they lead are as empirical as any questions to be found in the special sciences and, so far as I can see, just as susceptible of being answered in a satisfactory way. But the individual thinker who approaches them must rid his mind of prejudices and be prepared to spend some time in a preliminary survey of the facts. He must, moreover, be willing to regard his conclusions as tentative and of the nature of hypotheses. Such is the spirit which I have tried to maintain throughout the present work.

The positions which I am setting forth in the following pages are the summary of many years of teaching and of hard and pretty constant thinking, inside the class-room and without. As time passed, I found myself drifting ever more decidedly toward realism and naturalism. I became increasingly aware of the realistic structure of the individual's experience and noted those distinctions and meanings in which this structure was expressed. Whether these distinctions and meanings could be justified was the question uppermost in my mind. While the pressure of my reflection was evidently toward realism, I was dissatisfied with the customary realisms and felt that idealism had the better of the argument so far as generally accepted principles were concerned. It was at the very best a drawn battle between them.

Every realist who wishes to justify the faith that is in him must meet the arguments of Berkeley, not only his more formal principle that to be for the sensible world is to be perceived, but also his argument from content that all objects can be analyzed into sensations. Hume, and in our own day, F. H. Bradley, have also driven home to philosophy the psychical character of everything which is directly present in the field of experience. My knowledge of psychology and of logic made me realize the pervasive influence of mental activity; made me able to bear in mind the processes which made possible those apparently stable products which presented themselves to me so ready-made and external. The problem which

was formulating itself was to reach a position which would do justice to both the idealistic motives in experience and the realistic structure and meanings. Was there not some way out? Could not some more adequate standpoint be reached? I determined to analyze the nature of scientific knowledge to see whether it would give me a clue.

A careful study of modern science in the light of my epistemological problem did give me a clue which it took some time to work out. Do not both Locke and Berkeley have essentially the same view of knowledge? For each of them-if there is to be knowledge of the physical world — it must be of the nature of direct or indirect apprehension. Either the physical world itself or a substitute copy must be present to the understanding when we think. Berkeley meets Locke on this ground and overcomes him. The physical world cannot be like our ideas; hence, we cannot know it. Therefore, there is no good reason to assume its existence.

But is actual scientific knowledge an attempt to achieve images which faithfully copy the physical world? Does not this knowledge consist, instead, of propositions which claim to give tested knowledge about the physical world? I want the reader to get clearly in mind. the difference of outlook which this suggestion involves. It involves a relinquishment of all attempts to picture the physical world. Science offers us measurements of things and statements of their properties, i.e., their effects upon us and upon other things, and of their structure; but it unconsciously swings ever more completely away from the assumption that physical things are open to our inspection or that substitute copies are open to our inspection.

This result of the study of actual scientific knowledge was illuminating. I immediately saw how Berkeley's arguments could be out-flanked. They were based on a conception of knowledge which did not hold for science. The scientist-as-such was not aware of the problem, nor was he in a position to see the exact bearing of his own results upon epistemology. That was the task of the philosopher. The systematic development of this new point of view was the problem I set myself. Gradually a full-fledged theory of knowledge formulated itself in my mind. For want of a better name, I have called it Critical Realism.

To be understood properly, Critical Realism must be connected 'with a non-apprehensional view of knowledge. Scientific knowledge about the physical world consists of propositions which do not attempt to picture it. It is upon this principle that I take my stand. These propositions must be tested immanently or within experience, but, after being so tested, they are considered as being

knowledge about that which can never be literally present within the field of experience, although it controls the elements in the field. But the reader will understand this position better as he follows the detailed argument. This much of anticipation may, however, act as a guide.

My thesis is, then, that idealism and realism have had essentially the same view of knowledge and that the large measure of sterility which has accompanied philosophical controversy is due to this constant assumption that knowledge always involves the presence of the existent known in the field of experience. Philosophy limited itself to a controversial study of the subject-object duality and did not lift its eyes to the triad consisting of subject, idea-object (in science analyzable into propositions), and physical existent. It is to this triad that Critical Realism calls attention. It is my persuasion that this more complex form of realism does justice to the truth contained on both sides in the old antithesis. And it is this inclusiveness as much as anything else that convinces me that I am on the right track.

But my thinking has, from the first, been very much influenced by the mind-body problem. I have always thought that this age-old problem would be the crucial test of any philosophical system. There can be no doubt that constant brooding over this tantalizing question exerted a pressure on me in the direction of realism and, at the same time, controlled my thinking. How could I obtain a realism without a dualism? Chapter IX gives my solution. Consciousness is a variant within those highly evolved parts of the physical world which we call organisms. Perhaps the most novel idea in the chapter is that consciousness is actually extended. I feel certain that the reader will find many parts of the chapter extremely interesting. I have no doubt that many critics will speak of the position as Materialism; I prefer to call it Naturalism. The reason for this preference is that Materialism has never had an adequate theory of knowledge back of it and, therefore, has misleading associations in regard to the nature of the physical world. If the critic desires to follow the present liking for the word "new" he is at liberty to call my position Neo-Materialism or the New Materialism. What I particularly desire both critic and general reader to do, however, is to see the solution of the mind-body problem in the light of Critical Realism as a theory of knowledge.

The reader may, perhaps, be helped to grasp the rather long and intimately connected argument of the book if I point out its general movement.

Chapter I begins with a description of the plain man's outlook,

which is called Natural Realism. The plain man believes that the physical thing itself is present in his field of vision. I try first to show how natural this belief is and then to point out fatal objections to it. The conclusion arrived at is that we perceive percepts, or thingexperiences, and not physical things. The physical world retreats into the background and the perceptual experience is thought of as under two controts, the physical thing and the body. We begin to suspect that perception and knowledge are not the same, but do not yet know what knowledge is.

Chapter II examines Natural Realism in the light of science and points out the growth of what may be called scientific realism. The percept and the physical thing are pretty well distinguished, but the reach of scientific knowledge remains vague. When the problem of knowledge is raised, reflective scientists divide themselves into at least three groups, but there is no clear consensus of opinion. The tendency to picture the physical world still lingers.

Chapter III concerns itself with the Advance of the Personal. Both percepts and concepts are seen to be personal, and the meaning "commonness" gives way to "correspondence." We have correspondent percepts and concepts; we do not see the same things nor have the same ideas. This result is entitled mental pluralism, and is considered a reflective level of an empirical sort to be sharply opposed to idealism which is a theory.

Chapters IV and V contain analyses of the field of the individual's experience. The essential distinctions of what I call the coexistential dimension of the field are seen in the light of the temporal, or process, dimension. These chapters complete the empirical foundation.

Chapter VI includes an examination of both subjective and objective idealism. The principles of these systems are shown to be fallacious. I would especially call the attention of the reader to the criticism of the assertion, characteristic of the objective idealist, that the causal category has validity only within experience. This assertion is shown to be ambiguous. If knowledge has a reference to that which is outside of the field of the individual's experience, the causal category, which is a part of the framework of that knowledge, must follow this reference. The error of idealism turns out to be the assumption that knowledge demands the presence in experience of that which is known. Here I make appeal to the triad referred to above.

Chapter VII exhibits the inadequacy of mental pluralism. Seven problems are developed in some detail to demonstrate the pressure within experience to the acceptance of an external control of experience and a continuous medium within which minds live and

move and have their being. The thought of the physical world comes back with renewed force.

Chapter VIII discusses certain epistemological problems of particular interest. I would call the attention of the reader to the criticism of the assumption, characteristic of panpsychism, that the mental cannot contain knowledge of the non-mental. This assumption is shown to rest on the idea of knowledge, cherished by Natural Realism, that knowledge involves the presence of the existent known, so that the very material of the existent must be revealed. Here, again, the new meaning of knowledge stands us in good stead. Scientific knowledge is not an intuition of the stuff of the physical world. Thus Critical Realism establishes itself as the only satisfactory hypothesis which will solve the problems raised by reflection.

Chapter IX concerns itself with the mind-body problem as a crucial test of Critical Realism. As we have already referred to the conclusions drawn, we can omit any further summary.

Chapter X is given to a study of the new meaning of knowledge and the experiential structure which makes extra-experiential reference possible. The reader will find the discussion of denotation. particularly important. I have tried to show that there is nothing mysterious in the mechanism of reference; that it depends upon the realistic structure of the field of experience. The new meaning of knowledge is now seen to contain two elements: the idea-object which is accepted or believed, and the moment of reference. The idea-object is knowledge and also knowledge-about. And this knowledge is just the kind of knowledge which it purports to be. We can eliminate from science all attempt to intuit or picture the physical world. Any such tendency is a hold-over from Natural Realism. We have out-flanked Berkeley. One more point is taken up in this chapter the meaning of truth. I try to show that truth is a contrast-meaning whose opposite is error. Both presuppose knowledge, but they arise as a consequence of the experience of disappointSome idea-objects accepted as knowledge turn out later not to be knowledge. Truth is thus a purely empirical meaning connected with idea-objects. The criteria of truth have been worked out in scientific method. The study of these criteria is the work of the logician who really knows his science. Pragmatism had considerable meaning as a criticism of the vaguenesses of the traditional idealisms, but it has encouraged looseness of thought. The reason for this is that it was not founded on an adequate theory of knowledge.

The present work was completed in the spring of 1913. Since