¹ Thus: J. R. Kantor, “Principles of Psychology”, 1924, vol I, p. xvi; Kurt Lewin, “The Conflict between Aristotelian and Galilean Modes of Thought in Psychology”, J. Gen. Psychol., 1931, vol 5, 141-177.

² The psychologists often try to camouflage their fairies. The physicist usually takes his in primitive forms. The difference, however, is not great.

³ Those who have only casual acquaintance with the word ‘concept’ will be surprised both at the extent and at the chaos of its use. Among 22 contributors to two issues of this magazine in 1936, 18 used the word from one to 40 times each. Of the others, one used a still cruder word as substitute, two had very short contributions, and only one was notable for abstention. Classifications of its application or ‘meaning,’ based on a wider study of contributions, gave a) slipshod, b) impressionistic, c) dishonestly evasive, d) honestly hesitant, and e), in the very rare case, cautiously constructive with respect to ‘postulate’ and ‘theory.’ Logicians were the worst offenders, exhibiting at times incoherences of so criminal a type that, in comparison, the exhibits to be offered later in this paper drop to the level of petty misdemeanors.

⁴ See a review of Bridgman's latest book by Karl Darrow in the Review of Scientific Instruments, 1936, p. 374, for a physicist's opinion of Bridgman's critical procedures closely akin to that which I here assume.

⁵ In the pages of Philosophy of Science, and without any effort at a complete survey, I have noted about a score of writers naming him, or taking positive orientation towards his operational procedure. The chaos of appraisal is astonishing. The opposition of Margenau and Lindsay will be examined later in the text, and Malisoff's extended criticism will be referred to. Among psychologists, Tolman (II, 364) lists Bridgman as a “logical positivist” and proposes to parallel in psychology the good job Bridgman and his associates have done for physics; Stevens, however (III, 93, 100), casts out the logical positivists, but retains Bridgman, and is inspired to exhibit a psychological operation, namely ‘discrimination,’ which will be at one and the same time the foundation of psychology and of ‘operationism’ as well. Among physicists, Bender (I, 259, 265-6) accepts the operational view, but sees a possible differentiated place for the ‘configurational.’ Northrop (III, 230), discussing probability in quantum mechanics with the aid of 43 ‘concepts’ in 17 pages, and with no attempt whatever to indicate what a concept may be, assigns what little plausibility he is willing to admit for the ‘operational theory’ to the manner in which its proponents hide the fundamental distinctions. Reiser (I, 199, II, 118) holds that an operational theory of concepts merely limits the range of application of terms. Feigl (I, 20, 424) rates Bridgman as an enlightened mind; Benjamin (I, 232) thinks Bridgman's ‘operational definition’ is “simply an act of thought”; Norris (III, 286-7) generalizes all logic as ‘operational.’ Other references or comments are by Wheeler (III, 53), Rosenzweig (IV, 105), Frank (II, 210-11), Carnap (IV, 38), and Gruen (III, 331-3). An inspection of the first fifty papers in the magazine showed sympathy and antagonism about equally divided. The opportuneness of Bridgman's discussion is shown not only in the wide adoption of his specialized word ‘operational,’ but by the way various philosophers and logicians seek affiliation with him, by the way certain psychologists and biologists pattern after him, and above all by the vigor with which rationalists of all schools unite to belittle him.

⁶ Space cannot be taken in this paper to discuss Bridgman's “Dimensional Analysis”, but no appraisal of his main theory is well grounded which does not build directly from this work. The word ‘concept’ does not appear in it at all, and the word ‘operation’ only in the early chapters and in a special technical application. The objective throughout is, however, to expel the mysticism, and allot the physical dimensions a sound operational status.

⁷ Take either ‘gnome’ you prefer as base for this adjective.

⁸ In this he is at the far pole from the ‘logical’ positivists who claim affiliation with him.

⁹ For example: “The Nature of Physical Theory”, p. 9; “At any moment our concepts are coextensive with the system of existing knowledge.”

¹⁰ Bridgman is criticised both as “too subjective” and for “expelling the subjective.” The one type applies to his incidental phrasings; the other expresses the temperament of his critic.

¹¹ For current carelessness in discussing Pavlov, see some comments by Liddell in his essay on the conditioned reflex in the volume “Comparative Psychology” edited by Moss.

¹² This does not mean that Pavlov was a scientific paragon. He was always sticking out his neck, getting into trouble, and jerking back. His laboratory made some serious mistakes, but he was never ashamed to admit it and start over.

¹³ Such ‘things’ we have still with us today in many places where they ought not to be. A pleasant confession of faith from the eighteenth century is that of Thomas Reid: “Every object of sense, of memory, or of consciousness, is an individual object. All the good things we enjoy or desire, and all the evils we feel or fear, must come from individuals; and I think we may venture to say, that every creature which God hath made, in the heavens above, or in the earth beneath, or in the waters under the earth is an individual.” (Essays on the Intellectual Powers of Man; Essay V, chap. i).

¹⁴ Hamilton had held at one stage of his work that concepts arise from judgments, and at a later stage that judgments are comparisons of concepts. Said Mill: “Coming from a thinker of such ability, it almost makes one despair of one's own intellect and that of mankind, and feel as if the attainment of truth on any of the more complicated subjects of thought were impossible.” (An Examination of Sir William Hamilton's Philosophy; Vol. II, Chap, xviii).

¹⁵ “It seems almost inconceivable that an acute mind could believe … that names … are not … signs of ideas” (The History of Philosophy, Vol. II, p. 26).

¹⁶ I acknowledge that several times in print I have indicated what it is I regard a concept to ‘be.’ I shall try to exhibit the situation in detail at some future time. The difficulties are increased by the fact that almost all programs of psychology in the last two generations have evaded the issues.

¹⁷ Henry Margenau: four papers in Philosophy of Science, as follows: “Meaning and Scientific Status of Causality”, vol. I, pp. 133-148; “Methodology of Modern Physics”, vol. II, pp. 48-72, and pp. 164-187; “Critical Points in Modern Physical Theory”, vol. IV, pp. 337-370. R. B. Lindsay: two papers in the same journal: “The Meaning of Simplicity in Physics” vol. IV, pp. 151-167; “A Critique of Operationalism in Physics”, vol. IV, pp. 456-470. To show the source of citations from any of these papers, the page number in parentheses will be inserted directly in the text. Lindsay's fear is expressed thus: “A thorough-going adherence to the operational method … would necessarily imply the abandonment of the method of theoretical physics” (458). In their book “Foundations of Physics” (1936), p. 412, Lindsay and Margenau describe Bridgman's position as “a short-sighted curtailment of the realm of physics.” Margenau has also three articles in The Monist, 1929, 1931, and 1932.

¹⁸ In his Monist articles, Margenau describes Bridgman as “following Einstein and others,” and objects to “the penumbra of uncertainty” and the “meaningless.” He criticises Bridgman's stress on differential equations in the analysis of causality as “mere description” and as “renouncing all attempts to explain it in terms which it does not itself offer without the intervention of reason” (1929, p. 328). He proposes to improve Bridgman's “principle of essential connectivity” by renaming it “the principle of consistency of nature,” and gives three reasons why the operational theory “cannot be tolerated” (1931, p. 16): namely a) that it would dissolve the world into an unmanageable variety of discrete concepts without logical coherence; b) that it would impede science by emphasizing the changeable; and c) that it would make physical concepts falsely appear to be different from other kinds of concepts. In his later articles in Philosophy of Science I have noted only one reference to Bridgman by name (62), but others will be found or suspected, as pages 139, 144, 170, 174, 343, 345. We may possibly include the remark (63) that ‘constitutive’ definition enables us to reason, seeing that it is the ‘epistemic’ definition alone that is alloted by Margenau to Bridgman.

¹⁹ I doubt if I could find a definite statement to this effect anywhere in Margenau's papers. Lindsay, however, explains the situation thus: “In the interesting paper of Margenau, the term ‘construct’ is introduced in place of ‘concept,’ presumably to empha. size the active constructive rôle of the mind in building physical theories. This is a worthwhile procedure. However the present paper will continue to use the more familiar term with the feeling that no essential ambiguity will result” (161).

²⁰ “On the basis of purely operational definitions, all concepts are strictly empirical and isolated,” (Foundations of Physics, p. 412). Definition by operation “would dissolve the world into an unmanageable variety of discrete concepts without logical coherence” (Monist, 1931, p. 16). “Logically the operational method … implies that each concept is tied to a definite operation”; “the concept must be arbitrarily associated with a particular operation” (Lindsay, 458). Allegations such as the preceding merely apply the older association psychology or the newer psychology of mechanistic reflexes to the opponent without his permission.

²¹ The basic differences between Margenau and Bridgman in actual physical criticism, so far as I am competent to judge, are very slight. Margenau's sketch of his methodological problem (48-52) is alone sufficient to indicate this. To make sure, however, we must first: a) eliminate all conceptualizings and other psychologizings on the part of either man as totally irrelevant; b) eliminate minor elements of technical difference insignificant for the main interpretation; c) capture and banish to some remote, desert island Margenau's overpowering, though partially veiled, interest in issues of ‘reality’ which, when all is said and done, are nothing more than naïvely formulated distinctions of “common language” (346) “between physical objects and the observer's knowledge about physical objects”; and at the same time we must eliminate Bridgman's recent quibblings of comparable nature. We should then have our problem stripped down to what is truly significant: viz., the issues of causality, differential equations, simplicity, consistency, connectivity, and correspondence in the strictly physical sphere. Along with these we could inspect Margenau's “observations,” his “operations” in the two forms, “preparations” and “measurements,” (356-8) and his “states” as he actually uses them, in close comparison with Bridgman's constructions. My present essay began with this type of inquiry; but its continuation is wholly useless until the mythology, mysticism, and sentimentality is cleared away; and when that is done, almost any physicist can be depended on to reach better answers in immediate examination than I can with protracted discussion.

∗ See footnote 17 for method employed in citing Margenau and Lindsay.

²² In his Monist paper, 1929, Margenau mentions his acquisition of this term from a “philosopher.” Unfortunately he only takes over a small part of the significance of the word, and its extended investigation would be fatal to his “mental custody.” In this same Monist paper he is quite frank in asserting his start from data that are “parts of our consciousness,” in which we are “merely having cognitions.”

²³ The word ‘constitutive’ is derived from Kant who uses it in an entirely different sense. The word ‘epistemic’ is not found in Murray, nor in the technical dictionaries of Baldwin and Warren. The coupling of the two words was made by W. E. Johnson in his “Logic” (1921 to 1924, 3 vol.). It is interesting to note that whereas Johnson introduced the word ‘epistemic’ to replace ‘subjective’ which he disliked, and made it indicate “the relation … to the thinker” (vol. i, p. xxxiv), Margenau attaches his own heavily subjective stress to the opposed word ‘constitutive.’ I mention this merely as a curiosity, not in reproach, since all such terms are so slippery it is impossible to expect anyone to hold steadily to them, not even when criticising them. Observe that Margenau first tells us that the two kinds of definition are “different,” then that they are “interdependent,” and then that epistemic alone will not suffice. His illustration for the electron is worthy of schoolmen in their prime, namely that ‘it’ cannot be measured, but that “we do not question the possibility of measuring its charge or its mass, etc.” (63). Observe also his very first illustration in the case of ‘mass,’ where the ‘constitutive’ is granted superiority, even though requiring auxiliary ‘epistemics’ on which to rest (62).

²⁴ Margenau's “simplest possible way” to form a state is by “a direct assignment” of certain quantities to a system (64), but he assures us that no one-to-one correspondence between constructs and data is involved in his procedure (66). Later, however, he attains the somewhat surprising presentation of a “one-to-one correspondence … between states and probability distributions of observed properties” (341). Historically his definitions of ‘state’ run back to “an agreement to consider those quantities as composing the state of a system which enter into a time free differential equation describing its behavior” (145). Later he defined states for quantum mechanics “by means of stale functions, functions of space and time coordinates which make no explicit reference to quantities” (175). And finally state or representative of state comes to mean in quantum mechanics “a certain function of a suitable number of variables” (340). Elaboration will be found in “Foundations of Physics” (401-413) where a “physical system” is “any object … which in classical physics is thought of as an entity,” its “properties” being called “observables,” and its “state” being “simply a function in configuration space.” In this connection he also tells us that, if classical mechanics is like a report on a man's actions and utterances, the “state” in quantum mechanics gives us “a story of the succession of all his thoughts, sentiments, and volitions” (401-2). Maximum illumination is here apparently cast upon the situation.

²⁵ Alterations in Margenau's views may be in part responsible for his conflicts in expression. Thus as contrasted with his early demand that physics abolish the penumbra of uncertainty (see footnote 18) he now occasionally remarks that his method has no finality (51, 68, 179, 339, et passim). Another difficulty is that at times he regards his program as philosophical (337, and the preface to Foundations of Physics), at other times as not philosophical (187), and at still other times as a method for keeping other physicists from talking inconsistently (338, 345, 346). In the analysis in the text I have limited myself to inconsistencies of a special type. For slightly different illustrations, note how certain formulations such as that of causality can be at the same time both tautological and statements about nature (146); and how Heisenberg's principle can be viewed as a “consequence” of a certain vaguely worded axiom Margenau himself formulated a decade later (341).

²⁶ Page references in the text will be to this book.

²⁷ Reviewers of the book are almost unanimous in deprecating this development, even though each may have a different set of reasons for his objections. Malisoff's discussion in Philosophy of Science, Vol. III, pp. 360-364, covers the ground so fully that we may omit most of the details of criticism here.

²⁸ In fairness we must admit that psychologists and philosophers set him the example. In mathematics E. T. Bell is outstanding for inconsistencies arising from interpretative misuse of the ‘mental.'

²⁹ See also his essay, “A Physicist's Second Reaction to Mengenlehre,” Scripta Mathematica, vol. II, 1934.

³⁰ Brain and nerve research lies in one of the soundest regions of experimental psychology, and K. S. Lashley is outstanding in this field. Here is what he says of his own branch of inquiry: “It is doubtful if we know anything more about the mechanism of learning than did Descartes when he described the opening of the pores in the nerves by the passage of animal spirits. His statement sounds remarkably like the reduction of synaptic resistance by the passage of the nerve-impulse,” “Handbook of Experimental Psychology,” edited by Murchison, p. 493. Lashley's view in this respect is not isolated; rather it is typical of what outstanding investigators in any special branch of psychological inquiry will say of the status of knowledge in their particular branch. An examination of a dozen American psychological systems, under standards such as those that have been used in this essay, will be found in my book, “Behavior, Knowledge, Fact,” 1935.