Every student of philosophy is aware of the number of seeming impasses into which the theory of knowledge has been led. There are four general types of subject-matter whose rival claims to be the objects of true knowledge have to be either disposed of or in some way accommodated to one another. At one pole, are immediate sense-data which are said to be the immediate and accordingly most certain objects in knowledge of existence: the original material from which knowledge of nature must set out. At the other pole, are mathematical and logical objects. Somewhere between them lie the objects, of physical science, the products of an elaborate technique of reflective inquiry. Then there are the objects of everyday experience, the concrete things of the world in which we live and which, from the standpoint of our practical affairs, our enjoyments and sufferings, form the world we live in. To common sense these are the most important if not the most real of all objects of knowing. Recent philosophy has been increasingly occupied with the problems which grow out of the titles of these various kinds of objects to jurisdiction over the field of knowledge. From some point of view, the pretensions of each seem to be supreme.

The problem, however, is far from being a purely technical one. There has been repeated occasion to note that the claim of physical objects, the objects in which the physical sciences terminate, to constitute the real nature of the world, places the objects of value with which our affections and choices are concerned at an invidious disadvantage. The mathematician often doubts the claims of physics to be a science in the full sense of the word; the psychologist may quarrel with both; and the devotees of physical inquiry are suspicious of the claims of those who deal with human affairs, historians and students of social life. The biological subjects which stand between and form a connecting link are often refused the title of science if they adopt principles and categories different from those of strict physics. The net practical effect is the creation of the belief that science exists only in the things which are most remote from any significant human concern, so that as we approach social and moral questions and interests we must either surrender hope of the guidance of genuine knowledge or else purchase a scientific title and authority at the expense of all that is distinctly human.

Those who have followed the previous discussions will not be surprised to hear that, from the standpoint of experimental knowing, all of the rivalries and connected problems grow from a single root. They spring from the assumption that the true and valid object of knowledge is that which has being prior to and independent of the operations of knowing. They spring from the doctrine that knowledge is a grasp or be holding of reality without anything being done to modify its antecedent state—the doctrine which is the source of the separation of knowledge from practical activity. If we see that knowing is not the act of an outside spectator but of a participator inside the natural and social scene, then the true object of knowledge resides in the consequences of directed action. When we take this point of view, if only by way of a hypothesis, the perplexities and difficulties of which we have been speaking vanish. For on this basis there will be as many kinds of known objects as there are kinds of effectively conducted operations of inquiry which result in the consequences intended.

The result of one operation will be as good and true an object of knowledge as is any other, provided it is good at all: provided, that is, it satisfies the conditions which induced the inquiry. For if consequences are the object of knowing, then an archetypal antecedent reality is not a model to which the conclusions of inquiry must conform. One might even go as far as to say that there are as many kinds of valid knowledge as there are conclusions wherein distinctive operations have been employed to solve the problems set by antecedently experienced situations. For operations dealing with different problems never exactly repeat one another and do not determine exactly the same consequences. However, as far as logical theory is concerned, operations fall into certain kinds or types. It is the bearing of our principle upon the validity of these kinds that we are directly concerned with.

It is only repeating what has been said to assert that no problem can be solved without a determination of the data which define and locate it and which furnish clews or evidence. In so far, when we secure dependable sense-data, we know truly. Again, the systematic progress of inquiry in dealing with physical problems requires that we determine those metric properties by means of which correlations of changes are instituted so as to make predictions possible. These form the objects of physical science, and if our operations are adequate they are truly known. We develop operations, through symbols, which connect possible operations with one another; their outcome gives the formal objects of mathematics and logic. As consequences of suitable operations these too are truly known. Finally, when these operations, or some combination of them, are used to solve the problems which arise in connection with the things of ordinary perceived and enjoyed objects, the latter, as far as they are consequences of these operations, are themselves truly known. We know whenever we do know; that is, whenever our inquiry leads to conclusions which settle the problem out of which it grew. This truism is the end of the whole matter—upon the condition that we frame our theory of knowledge in accord with the pattern set by experimental methods.

The conclusions, however, are not truistic; they certainly are not trivial. The more complex the conditions with which operations are concerned, the fuller and richer are their consequences. Consequently, the more significant, although not the truer, is the resulting knowledge. The advantage of physical knowledge depends upon the fact that it deals with fewer conditions, those of a narrower and more isolated range, by means of operations that are more precise and more technical. There is no difference in principle between knowledge of them and knowledge of the most complex human affairs, but there is a decided practical difference. To be an object of specifically physical knowledge is the same thing as being an object of operations that discriminate definitely fundamental relations of the experienced world from others, and that deal with them in their discriminated character. The gain is great. But the objects thus known lay no claim to be final. When used as factors for inquiring into phenomena of life and society they become instrumental; they cease to be inclusive, and become part of a method for understanding more complex phenomena.

From this point of view, the objects of our common sense world (by which is signified that in which we live, with our loves and hates, our defeats and achievements, our choices, strivings and enjoyments) have a double status. When they precede operations of competent directed inquiry, they are not matters of knowledge; they are experienced just as they happen to occur. They thus set problems for inquiry, problems of varied scope. But they are of such a nature that things of the most limited range, the purely physical, are the first to be successfully dealt with. But in the degree in which fuller and more complex social and moral affairs—which of course include physical and biological conditions and relations within themselves—are transformed by becoming consequences of operations made possible by the limited forms of knowing, they also are objects of knowledge. While they are not more real, they are richer and more significant objects than are those of any other type of knowledge.

The special results of science are always finding their way back into the natural and social environment of daily life and modifying it. This fact does not of itself cause the latter to be known objects. A typical example is the effect of physical science upon a worker in a factory; he may merely become an attachment to a machine for a number of hours a day. Physical science has had its effect in changing social conditions. But there has been no correspondingly significant increase of intelligent understanding. The application of physical knowledge has taken place in a technical way for the sake of limited consequences. But when the operations in which physical science is used are such as to transform distinctively human values in behalf of a human interest, those who participate in these consequences have a knowledge of the things of ordinary perception, use and enjoyment as genuine and fuller and deeper than that of the scientist in his laboratory. Were we to define science not in the usual technical way, but as a knowledge that accrues when methods are employed which deal competently with problems that present themselves, the physician, engineer, artist, craftsman, lay claim to scientific knowing.

These statements go contrary to the philosophic tradition. They do so for just one reason. They rest upon the idea that known objects exist as the consequences of directed operations, not because of conformity of thought or observation with something antecedent. We may, for reasons which I hope will appear later, give the name intelligence to these directed operations. Using this term, we may say that the worth of any object that lays claim to being an object of knowledge is dependent upon the intelligence employed in reaching it. In saying this, we must bear in mind that intelligence means operations actually performed in the modification of conditions, including all the guidance that is given by means of ideas, both direct and symbolic.

The statement may sound strange. But it is only a way of saying that the value of any cognitive conclusion depends upon the method by which it is reached, so that the perfecting of method, the perfecting of intelligence, is the thing of supreme value. If we judge the work of a scientific inquirer by what he does and not by his speech when he talks about his work (when he is likely to talk in terms of traditional notions that have become habitual) we shall have little difficulty, I think, in accepting the idea that he determines the cognitive claims of anything presented to him on the basis of the method by which it is reached. The import of this doctrine is simple. It becomes complicated, however, the moment we contrast it with the doctrines which have dominated thought. For these all rest on the notion that a reality in Being independently of the operations of inquiry is the standard and measure of anything said to be known. Viewed in this connection, the conception just advanced involves hardly less than a revolutionary transformation of many of our most cherished convictions. The essential difference is that between a mind which beholds or grasps objects from outside the world of things, physical and social, and one which is a participant, interacting with other things and knowing them provided the interaction is regulated in a definable way.

In discussion up to this point we have depended upon the general pattern of experimental knowing. It is asserted that when we frame our theory of knowledge and the known object after this pattern, the conclusion is inevitable. But the point is of such importance that we may gratefully acknowledge the support given the conclusion by one of the definite conclusions reached in recent physical science. For this one result is of a crucially decisive nature. It is known technically as Heisenberg’s principle of indeterminancy. The basic philosophy of the Newtonian system of the universe is closely connected with what is termed the principle of canonic conjugates. The fundamental principle of the mechanical philosophy of nature is that it is possible to determine exactly (in principle if not in actual practice) both the position and the velocity of any body. Knowing this for each particle which enters into any change, as a motion, it is possible to calculate mathematically, that is exactly, just what will happen. The laws or physical equations that express the relations of the particles and bodies under different conditions are then assumed to be a “governing” framework of nature to which all particular phenomena conform. Knowing volumes and momenta in a particular case we can by the aid of fixed laws predict the subsequent course of events.

The philosophy in question assumed that these positions and velocities are there in nature independent of our knowing, of our experiments and observations, and that we have scientific knowledge in the degree in which we ascertain them exactly. The future and the past belong to the same completely determinate and fixed scheme. Observations, when correctly conducted, merely register this fixed state of changes according to laws of objects whose essential properties are fixed. The implications of the positions are expressed in Laplace’s well-known saying that were there a knowledge (in mechanical terms) of the state of the universe at any one time its whole future could be predicted—or deduced. It is this philosophy which Heisenberg’s principle has upset, a fact implied in calling it a principle of indeterminancy.

It is true that critics had attacked the Newtonian scheme on the basis of a logical flaw in it. It first postulates that the position and velocity of any particle can be determined in isolation from all others. Then it postulates that there is a complete and continuous interaction of all these particles with one another. Logically, the two postulates nullify each other. But as long as the principles involved gave satisfactory results this objection was brushed aside or ignored. Heisenberg’s principle compels a recognition of the fact that interaction prevents an accurate measurement of velocity and position for any body, the demonstration centering about the rôle of the interaction of the observer in determining what actually happens.

The scientific data and the mathematical reasonings which led him to his conclusion are technical. But fortunately they do not concern us. The logic of the matter is not complicated. He showed that if we fix, metrically, velocity, then there is a range of indeterminateness in the assignment of position, and vice-versa. When one is fixed, the other is defined only within a specified limit of probability. The element of indeterminateness is not connected with defect in the method of observation but is intrinsic. The particle observed does not have fixed position or velocity, for it is changing all the time because of interaction: specifically, in this case, interaction with the act of observing, or more strictly, with the conditions under which an observation is possible; for it is not the “mental” phase of observation which makes the difference. Since either position or velocity may be fixed at choice, leaving the element of indeterminancy on the other side, both of them are shown to be conceptual in nature. That is, they belong to our intellectual apparatus for dealing with antecedent existence, not to fixed properties of that existence. An isolation of a particle for measurement is essentially a device for regulation of subsequent perceptual experience.

Technically, the principle of Heisenberg is connected with recent determinations regarding observation of phenomena of light. The principle as far as the rôle of the conditions of observation is concerned is simple. We should all, I suppose, recognize that when we perceive an object by means of touch, the contact introduces a slight modification in the thing touched. Although in dealing with large bodies this change would be insignificant, it would be considerable if we touched a minute body and one moving at high speed. It might be thought that we could calculate the displacement thus effected, and by making allowances for it determine exactly the position and momentum of the thing touched. But this result would be theoretical, and would have to be confirmed by another observation. The effect of the last observation cannot be eliminated. Failure to generalize this conclusion was due presumably to two facts. Until recently physics dealt mainly with bodies of relatively large volume and relatively low velocity. Experiences with these bodies were carried over to minute particles of any velocity; these were treated as mathematical points located at fixed, unchanging, instants of time. The second cause is that vision does not involve interaction with the thing seen as obviously as does touch.

But the situation changed when it came to dealing with minute bodies moving at high speed. Also, it became clear that a continuous field or even flow of light cannot be observed and measured. Light can be observed only as an individual object, a drop, pellet or bullet. The presence of at least one such bullet is required to make, say, an electron visible, and its action displaces to some extent the object observed; the displacement or jog, being involved in the observation, cannot be measured by it. As Bridgman says: “A cat may look at a king but at least one bullet of light must pass if any light at all passes, and the King cannot be observed without the exertion of that minimum amount of mechanical repulsion which corresponds to the single bullet.”1

To a layman the full import of the discovery may not seem at first sight very great. In the subject-matter of scientific thought it calls for only slight changes of formulation, insignificant for all macroscopic bodies. The change for the underlying philosophy and logic of science is, however, very great. In relation to the metaphysics of the Newtonian system it is hardly less than revolutionary. What is known is seen to be a product in which the act of observation plays a necessary rôle. Knowing is seen to be a participant in what is finally known. Moreover, the metaphysics of existence as something fixed and therefore capable of literally exact mathematical description and prediction is undermined. Knowing is, for philosophical theory, a case of specially directed activity instead of something isolated from practice. The quest for certainty by means of exact possession in mind of immutable reality is exchanged for search for security by means of active control of the changing course of events. Intelligence in operation, another name for method, becomes the thing most worth winning.

The principle of indeterminancy thus presents itself as the final step in the dislodgment of the old spectator theory of knowledge. It marks the acknowledgment, within scientific procedure itself, of the fact that knowing is one kind of interaction which goes on within the world. Knowing marks the conversion of undirected changes into changes directed toward an intended conclusion. There are left for philosophy but two alternatives. Either knowledge defeats its own purpose; or the objective of knowing is the consequences of operations purposely undertaken, provided they fulfill the conditions for the sake of which they are carried on. If we persist in the traditional conception, according to which the thing to be known is something which exists prior to and wholly apart from the act of knowing, then discovery of the fact that the act of observation, necessary in existential knowing, modifies that preexistent something, is proof that the act of knowing gets in its own way, frustrating its own intent. If knowing is a form of doing and is to be judged like other modes by its eventual issue, this tragic conclusion is not forced upon us. Fundamentally, the issue is raised whether philosophy is willing to surrender a theory of mind and its organs of knowing which originated when the practice of knowing was in its infancy.

One important result of acknowledgment of the philosophic modification involved in the principle of indeterminancy is a definite change in our conception of natural laws. The individually observed case becomes the measure of knowledge. Laws are intellectual instrumentalities by which that individual object is instituted and its meaning determined. This change involves a reversal of the theory which has dominated thought since the Newtonian system obtained full sway. According to the latter, the aim of science is to ascertain laws; individual cases are known only as they are reduced to instances of laws. For, as we saw earlier, the Newtonian philosophy allowed itself to become entangled in the Greek metaphysics according to which the immutable is the truly real and our thought is adequate in the degree in which it approximates a grasp of what is antecedently fixed in existence.

In content, or subject-matter, Newton’s philosophy effected a revolutionary change. The unchanging reality had been thought to consist of forms and species. According to Newtonian science, it consists of fixed relations, temporal and spatial, designated by exact enumeration of changes between fixed ultimate substances, the masses of atoms. The discovery that mass varies with velocity was the beginning of the end. It deprived physical knowledge of its supposedly ultimate permanent coefficient, one having nothing to do with configuration or motion, and one in terms of which all interactions were to be exactly described. All “laws” were statements of these ultimate and rigid uniformities of being. While perhaps there was felt to be something metaphorical in speaking of laws as if they “governed” changes and of the latter as if they “obeyed” laws, there was nothing figurative in the notion that laws stated the ultimate unchanging properties of natural existence, and that all individual cases, those observed, were only specimen instances of the antecedent properties of the real world formulated in laws. The principle of indeterminancy brings to fruition the scientific transformation initiated in the discovery that the supposition of a permanent coefficient of mass is illusory—a survival, when judged in historical terms, of the old notion that something immutable is the true object of knowledge.

In technical statement, laws on the new basis are formulae for the prediction of the probability of an observable occurrence. They are designations of relations sufficiently stable to allow of the occurrence of forecasts of individualized situations—for every observed phenomenon is individual—within limits of specified probability, not a probability of error, but of probability of actual occurrence. Laws are inherently conceptual in character, as is shown in the fact that either position or velocity may be fixed at will. To call them conceptual is not to say that they are merely “mental” and arbitrary. It is to say that they are relations which are thought not observed. The subject-matter of the conceptions which constitute laws is not arbitrary, for it is determined by the interactions of what exists. But determination of them is very different from that denoted by conformity to fixed properties of unchanging substances. Any instrument which is to operate effectively in existence must take account of what exists, from a fountain pen to a self-binding reaper, a locomotive or an airplane. But “taking account of,” paying heed to, is something quite different from literal conformity to what is already in being. It is an adaptation of what previously existed to accomplishment of a purpose.

The eventual purpose in knowledge is observation of a new phenomenon, an object actually experienced by way of perception. Thus the supposed immutable law supposed to govern phenomena becomes a way of transacting business effectively with concrete existences, a mode of regulation of our relations with them. There is no difference in principle between their use in “pure” science and in an art. We may recur to the case of a physician to which reference was made. The physician in diagnosing a case of disease deals with something individualized. He draws upon a store of general principles of physiology, etc., already at command. Without this store of conceptual material he is helpless. But he does not attempt to reduce the case to an exact specimen of certain laws of physiology and pathology, or do away with its unique individuality. Rather he uses general statements as aids to direct his observation of the particular case, so as to discover what it is like. They function as intellectual tools or instrumentalities.

The recognition that laws are means of calculating the probability of observation of an event signifies that in basic logic there is no difference in the two kinds of cases. The full and eventual reality of knowledge is carried in the individual case, not in general laws isolated from use in giving an individual case its meaning. Thus the empirical or observational theory of knowledge comes to its own, although in quite a different way from that imagined by traditional empiricism.

It is an old remark that human progress is a zigzag affair. The idea of a universal reign of law, based on properties immutably inhering in things and of such a nature as to be capable of exact mathematical statement was a sublime idea. It displaced once for all the notion of a world in which the unaccountable and the mysterious have the first and last word, a world in which they constantly insert themselves. It established the ideal of regularity and uniformity in place of the casual and sporadic. It gave men inspiration and guidance in seeking for uniformities and constancies where only irregular diversity was experienced. The ideal extended itself from the inanimate world to the animate and then to social affairs. It became, it may fairly be said, the great article of faith in the creed of scientific men. From this point of view, the principle of indeterminancy seems like an intellectual catastrophe. In compelling surrender of the doctrine of exact and immutable laws describing the fixed antecedent properties of things, it seems to involve abandonment of the idea that the world is fundamentally intelligible. A universe in which fixed laws do not make possible exact predictions seems from the older standpoint to be a world in which disorder reigns.

The feeling is psychologically natural. But it arises from the hold which intellectual habits have over us. The traditional conception displaced in fact lingers in imagination as a picture of what the world ought to be; we are uneasy because the fact turns out not to be in accord with the picture in our minds. As a matter of fact, the change, viewed in a perspective of distance, is nothing like so upsetting. All the facts that were ever known are still known, and known with greater accuracy than before. The older doctrine was in effect an offshoot not of science but of a metaphysical doctrine which taught that the immutable is the truly real, and of a theory of knowledge which held that rational conceptions rather than observations are the vehicle of knowledge. Newton foisted a fundamental “rationalism” upon the scientific world all the more effectually because he did it in the name of empirical observation.

Moreover, like all generalizations which go beyond the range of possible as well as of actual experience, a price was paid for the sublime and inspiring ideal of a reign of universal and exact law: the sacrifice of the individual to the general, of the concrete to the relational. Spinoza’s magnificently sweeping dictum that “the order and connection of ideas is the order and connection of things” was in effect, although not avowedly as it was with Spinoza, the current measure of the intelligibility of nature. And a universe whose essential characteristic is fixed order and connection has no place for unique and individual existences, no place for novelty and genuine change and growth. It is, in the words of William James, a block universe. The fact that in detailed content it is a thoroughly mechanistic world is, one may say, a mere incident attending the fact that it is a fixed and closed world.

Probably everyone has heard of the child who expressed surprise at the fact that rivers or bodies of water are always located conveniently near great cities. Suppose every one had had engrained in his mind the notion that cities, like rivers, are works of nature. Suppose it was then suddenly ascertained that cities were man made and were located near bodies of water in order that the activities of men in industry and commerce might be better carried on and human purposes and needs be better served. We can imagine that the discovery would bring with it a shock. It would be upsetting because it would seem unnatural; for the ordinary measure of the natural is psychological; it is what we have become accustomed to. But in time the new idea in becoming familiar would also become “natural.” If men had always previously conceived of the connection between cities and rivers as one which was intrinsic and fixed by nature, instead of being a product of human art, it is moreover probable that in time a liberation would be experienced by discovery that the contrary was the case. Men would be led to take fuller advantage of the facilities afforded by natural conditions. These would be used in new and more diversified ways when it was realized that cities were near them because of and for the sake of the uses they provide.

The analogy suggested seems to me close. From the standpoint of traditional notions, it appears that nature, intrinsically, is irrational. But the quality of irrationality is imputed only because of conflict with a prior definition of rationality. Abandon completely the notion that nature ought to conform to a certain definition, and nature intrinsically is neither rational nor irrational. Apart from the use made of it in knowing, it exists in a dimension irrelevant to either attribution, just as rivers inherently are neither located near cities nor are opposed to such location. Nature is intelligible and understandable. There are operations by means of which it becomes an object of knowledge, and is turned to human purposes, just as rivers provide conditions which may be utilized to promote human activities and to satisfy human need.

Moreover, just as commerce, carried on by natural bodies of water, signifies interactions within nature, by which changes are affected in natural conditions—the building of docks and harbors, erection of warehouses and factories, construction of steamships and also in invention of new modes of interaction—so with knowing and knowledge. The organs, instrumentalities and operations of knowing are inside nature, not outside. Hence they are changes of what previously existed: the object of knowledge is a constructed, existentially produced, object. The shock to the traditional notion that knowledge is perfect in the degree in which it grasps or beholds without change some thing previously complete in itself is tremendous. But in effect it only makes us aware of what we have always done, as far as ever we have actually succeeded in knowing: it clears away superfluous and irrelevant accompaniments and it concentrates attention upon the agencies which are actually effective in obtaining knowledge, eliminating waste and making actual knowing more controllable. It installs man, thinking man, within nature.

The doctrine that nature is inherently rational was a costly one. It entailed the idea that reason in man is an outside spectator of a rationality already complete in itself. It deprived reason in man of an active and creative office; its business was simply to copy, to re-present symbolically, to view a given rational structure. Ability to make a transcript of this structure in mathematical formulæ gives great delight to those who have the required ability. But it does nothing; it makes no difference in nature. In effect, it limits thought in man to retraversing in cognition a pattern fixed and complete in itself. The doctrine was both an effect of the traditional separation between knowledge and action and a factor in perpetuating it. It relegated practical making and doing to a secondary and relatively irrational realm.

Its paralyzing effect on human action is seen in the part it played in the eighteenth and nineteenth century in the theory of “natural laws” in human affairs, in social matters. These natural laws were supposed to be inherently fixed; a science of social phenomena and relations was equivalent to discovery of them. Once discovered, nothing remained for man but to conform to them; they were to rule his conduct as physical laws govern physical phenomena. They were the sole standard of conduct in economic affairs; the laws of economics are the “natural” laws of all political action; other so-called laws are artificial, man-made contrivances in contrast with the normative regulations of nature itself.

Laissez-faire was the logical conclusion. For organized society to attempt to regulate the course of economic affairs, to bring them into service of humanly conceived ends, was a harmful interference.

This doctrine is demonstratively the offspring of that conception of universal laws that phenomena must observe which was a heritage of the Newtonian philosophy. But if man in knowing is a participator in the natural scene, a factor in generating things known, the fact that man participates as a factor in social affairs is no barrier to knowledge of them. On the contrary, a certain method of directed participation is a precondition of his having any genuine understanding. Human intervention for the sake of effecting ends is no interference, and it is a means of knowledge.

There is thus involved more than a verbal shift if we say that the new scientific development effects an exchange of reason for intelligence. In saying this, “reason” has the technical meaning given to it in classic philosophic tradition, the nous of the Greeks, the intellectus of the scholastics. In this meaning, it designates both an inherent immutable order of nature, superempirical in character, and the organ of mind by which this universal order is grasped. In both respects, reason is with respect to changing things the ultimate fixed standard—the law physical phenomena obey, the norm human action should obey. For the marks of “reason” in its traditional sense are necessity, universality, superiority to change, domination of the occurrence and the understanding of change.

Intelligence on the other hand is associated with judgment; that is, with selection and arrangement of means to effect consequences and with choice of what we take as our ends. A man is intelligent not in virtue of having reason which grasps first and indemonstrable truths about fixed principles, in order to reason deductively from them to the particulars which they govern, but in virtue of his capacity to estimate the possibilities of a situation and to act in accordance with his estimate. In the large sense of the term, intelligence is as practical as reason is theoretical. Wherever intelligence operates, things are judged in their capacity of signs of other things. If scientific knowledge enables us to estimate more accurately the worth of things as signs, we can afford to exchange a loss of theoretical certitude for a gain in practical judgment. For if we can judge events as indications of other events, we can prepare in all cases for the coming of what is anticipated. In some cases, we can forestall a happening; desiring one event to happen rather than another, we can intentionally set about institution of those changes which our best knowledge tells us to be connected with that which we are after.

What has been lost in the theoretical possibility of exact knowledge and exact prediction is more than compensated for by the fact that the knowing which occurs within nature involves possibility of direction of change. This conclusion gives intelligence a foothold and a function within nature which “reason” never possessed. That which acts outside of nature and is a mere spectator of it is, by definition, not a participator in its changes. Therefore it is debarred from taking part in directing them. Action may follow but it is only an external attachment to knowing, not an inherent factor in it. As a mechanical addendum, it is inferior to knowledge. Moreover, it must either issue automatically from knowledge or else there must be some intervening act of “will” to produce it. In any case, because of its externality it adds nothing to intelligence or knowledge. It can only increase personal shrewdness in prudential manipulation of conditions.

We may, indeed, engage during knowing in experimentation. But according to the classic logic the effect was not to reorganize prior conditions, but merely to bring about a change in our own subjective or mental attitude. The act no more entered into the constitution of the known object than traveling to Athens to see the Parthenon had any effect on architecture. It makes a change in our own personal attitude and posture so that we can see better what was there all the time. It is a practical concession to the weakness of our powers of apprehension. The whole scheme hangs together with the traditional depreciation of practical activity on the part of the intellectual class. In reality, it also condemns intelligence to a position of impotency. Its exercise is an enjoyable use of leisure. The doctrine of its supreme value is largely a compensation for the impotency that attached to it in contrast with the force of executive acts.

The realization that the observation necessary to knowledge enters into the natural object known cancels this separation of knowing and doing. It makes possible and it demands a theory in which knowing and doing are intimately connected with each other. Hence, as we have said, it domesticates the exercise of intelligence within nature. This is part and parcel of nature’s own continuing interactions. Interactions go on anyway and produce changes. Apart from intelligence, these changes are not directed. They are effects but not consequences, for consequences imply means deliberately employed. When an interaction intervenes which directs the course of change, the scene of natural interaction has a new quality and dimension. This added type of interaction is intelligence. The intelligent activity of man is not something brought to bear upon nature from without; it is nature realizing its own potentialities in behalf of a fuller and richer issue of events. Intelligence within nature means liberation and expansion, as reason outside of nature means fixation and restriction.

The change does not mean that nature has lost intelligibility. It rather signifies that we are in position to realize that the term intelligible is to be understood literally. It expresses a potentiality rather than an actuality. Nature is capable of being understood. But the possibility is realized not by a mind thinking about it from without but by operations conducted from within, operations which give it new relations summed up in production of a new individual object. Nature has intelligible order as its possession in the degree in which we by our own overt operations realize potentialities contained in it. The change from intrinsic rationality in the traditional sense to an intelligibility to be realized by human action places responsibility upon human beings. The devotion we show to the ideal of intelligence determines the extent in which the actual order of nature is congenial to mind.

These conclusions connect directly with the question raised at the outset of this chapter. When knowledge is defined from the standpoint of a reality to which the conclusions of thought must accommodate themselves, as a photograph must be faithful to its original, there will always be disputes as to whether this or that subject can possibly be treated scientifically. But if the measure of knowledge is the quality of intelligence manifested in dealing with problems presented by any experienced subject-matter, the issue takes on a different aspect. The question always at issue is the possibility of developing a method adequate to cope with problems. The conclusions of physical knowledge do indeed set a standard for knowing. But it is because of their elaboration of competent method that this statement is true, not because of any superior claim to reality on the part of physical subject-matter. All materials of experience are equally real; that is, all are existential; each has a right to be dealt with in terms of its own especial characteristics and its own problems. To use philosophical terminology, each type of subject-matter is entitled to its own characteristic categories, according to the questions it raises and the operations necessary to answer them.

The difference between various types of knowledge thus turns out to be a difference in fullness and range of conditions involved in subject-matter dealt with. When one considers the success of astronomy in attaining understanding of phenomena occurring at enormous distances one may well be lost in admiration. But we should also reflect upon how much is omitted from inquiry and conclusion. Our knowledge of human affairs on this earth is inexact and unorganized as compared with some things which we know about bodies distant many, many, light years. But there are vast multitudes of things about these bodies that astronomy makes no pretense of inquiring into. The relative perfection of its conclusions is connected with the strict limitation of the problems it deals with. The case of astronomy is typical of physical science in general as compared with knowledge of human affairs. The essence of the latter is that we cannot indulge in the selective abstractions that are the secret of the success of physical knowing. When we introduce a like simplification into social and moral subjects we eliminate the distinctively human factors:—reduction to the physical ensues.

The principle is exemplified in the difference which is found between results obtained in the laboratory and in manufacturing processes carried on for commercial purposes. The same materials and relations may be involved. But under laboratory conditions elements are isolated and treated under a control not possible in the factory, where the same rigid isolation would defeat the aim of cheap production on a large scale. Nevertheless, in the end, the researches of scientific inquiries transform industrial production. Possibilities of new operations are suggested, and the laboratory results indicate ways of eliminating wasteful operations and make manifest conditions which have to be attended to. Artificial simplification or abstraction is a necessary precondition of securing ability to deal with affairs which are complex, in which there are many more variables and where strict isolation destroys the special characteristics of the subject-matter. This statement conveys the important distinction which exists between physical and social and moral objects. The distinction is one of methods of operation not of kinds of reality.

In other words, what is meant by “physical” in distinction from other adjectives that are prefixed to subject-matter is precisely an abstraction of a limited range of conditions and relations out of a total complex. The same principle applies to mathematical objects. The use of symbols designating possible operations makes possible a greater degree of exactness and intellectual organization. There is no disparagement of abstraction involved. Abstraction is simply an instance of the economy and efficiency involved in all intelligent practice:—Deal first with matters that can be effectively handled, and then use the results to go on to cope with more complex affairs. Objection comes in, and comes in with warranted force, when the results of an abstractive operation are given a standing which belongs only to the total situation from which they have been selected. All specialization breeds a familiarity which tends to create an illusion. Material dealt with by specialized abstractive processes comes to have a psychological independence and completion which is converted—hypostatized—into objective independence and self-sufficiency.

In addition there is a definite social reason for abstractive simplification. Intercourse of human individuals with one another makes it necessary to find common ground. Just because individuals are individuals, there is much in the experience of each which is unique; being incommunicable in and of itself, it is in so far a bar to entering into relations with others. For the purposes of communication, dissection is necessary. Otherwise the personal element is a bar to agreement and understanding. If one follows out this line of thought, it will be evident that the more widely extended is the notion of mutual comprehensibility, the more completely all individual traits tend to get excluded from the object of thought. In arriving at statements which hold for all possible experiencers and observers under all possible varying individual circumstances we arrive at that which is most remote from any one concrete experience. In this sense, the abstractions of mathematics and physics represent the common denominators in all things experienceable. Taken by themselves they seem to present a caput mortuum. Erected into complete statements of reality as such, they become hallucinatory obsessions. But in practice, there is always an accompanying reverse movement. These generalized findings are employed to enrich the meanings of individualized experiences, and to afford, within limits of probability, an increased control of them.

It is in this sense that all reflective knowledge as such is instrumental. The beginning and the end is the things of gross everyday experience. But apart from knowledge the things of our ordinary experience are fragmentary, casual, unregulated by purpose, full of frustrations and barriers. In the language previously used, they are problematic, obstructive, and challenges to thought. By ignoring for a time their concrete and qualitative fullness, by making abstractions and generalizations, we ascertain certain basic relations upon which occurrence of the things experienced depend. We treat them as mere events, that is, as changes brought about in a system of relationships, ignoring their individualizing qualities. But the qualities are still there, are still experienced, although as such they are not the objects of knowledge. But we return from abstractive thought to experience of them with added meaning and with increased power to regulate our relations to them.

Reflective knowledge is the only means of regulation. Its value as instrumental is unique. Consequently philosophers, themselves occupied in a fascinating branch of reflective knowledge, have isolated knowledge and its results. They have ignored its context of origin and function and made it coextensive with all valid experience. The doctrine was thus formed that all experience of worth is inherently cognitive; that other modes of experienced objects are to be tested, not here and there as occasion demands but universally by reduction to the terms of known objects. This assumption of the proper ubiquity of knowledge is the great intellectualistic fallacy. It is the source of all disparagement of everyday qualitative experience, practical, esthetic, moral. It is the ultimate source of the doctrine that calls subjective and phenomenal all objects of experience that cannot be reduced to properties of objects of knowledge.

From this derogation of the things we experience by way of love, desire, hope, fear, purpose and the traits characteristic of human individuality, we are saved by the realization of the purposefully instrumental and abstract character of objects of reflective knowledge. One mode of experience is as real as any other. But apart from the exercise of intelligence which yields knowledge, the realities of our emotional and practical life have fragmentary and inconsistent meanings and are at the mercy of forces beyond our control. We have no choice save to accept them or to flee from them. Experience of that phase of objects which is constituted by their relations, their interactions, with one another, makes possible a new way of dealing with them, and thus eventually creates a new kind of experienced objects, not more real than those which preceded but more significant, and less overwhelming and oppressive.

Thus the recognition that intelligence is a method operating within the world places physical knowledge in respect to other kinds of knowing. It deals with those relations which are of the broadest scope. It affords a sure foundation for other more specialized forms of knowing:—not in the sense that these must be reduced to the objects in which physical knowledge terminates, but in the sense that the latter supply intellectual points of departure, and suggest operations to be employed. There is no kind of inquiry which has a monopoly of the honorable title of knowledge. The engineer, the artist, the historian, the man of affairs attain knowledge in the degree they employ methods that enable them to solve the problems which develop in the subject-matter they are concerned with. As philosophy framed upon the pattern of experimental inquiry does away with all wholesale skepticism, so it eliminates all invidious monopolies of the idea of science. By their fruits we shall know them.

The marking off of certain conclusions as alone truly science, whether mathematical or physical, is an historical incident. It sprang originally from man’s desire for a certainty and peace which he could not attain practically in the absence of the arts of management and direction of natural conditions. When modern physical inquiry began, it had a hard time to get a hearing, or even to be permitted to carry on. The temptation was practically irresistible to treat it as an exclusive and esoteric undertaking. Moreover, as it progressed, it required more and more specialized technical preparation. The motive of defense from social attack and the motive of glorification of a specialized calling conspired together. All the eulogistic connotations that gather about “truth” were called into play.

Thus “science,” meaning physical knowledge, became a kind of sanctuary. A religious atmosphere, not to say an idolatrous one, was created. “Science” was set apart; its findings were supposed to have a privileged relation to the real. In fact, the painter may know colors as well as the physicist; the poet may know stars, rain and clouds as well as the meteorologist; the statesman, educator and dramatist may know human nature as truly as the professional psychologist; the farmer may know soils and plants as truly as the botanist and minerologist. For the criterion of knowledge lies in the method used to secure consequences and not in metaphysical conceptions of the nature of the real. Nevertheless in the end thinkers in all lines are dependent upon the mathematician and the physical inquirer for perfecting of the tools employed in their respective callings.

That “knowledge” has many meanings follows from the operational definition of conceptions. There are as many conceptions of knowledge as there are distinctive operations by which problematic situations are resolved. When it is asserted that reflective knowledge as such is instrumental, it is not meant that there is an a priori form of non-reflective knowledge, one which is immediately given. What is signified is that there is a direct possession and enjoyment of meanings to be had in that experience of objects which issues from reflective knowledge. It is futile to argue whether the conclusions of reflective method as such or the eventual objects enriched in meaning which are capable of direct perception and use more truly deserve the title of knowledge. It is congenial to our idiom to call the reflective conclusions of competent methods by the name of science. But science thus conceived is not a final thing. The final thing is appreciation and use of things of direct experience. These are known in as far as their constituents and their form are the result of science. But they are also more than science. They are natural objects experienced in relations and continuities that are summed up in rich and definite individual forms.

• 1.

  In the March, 1929, number of Harper’s Magazine, in an article entitled The New Vision of Science.