VOLUME 91
Founded by Wilfrid S. Sellars and Keith Lehrer
Editor
Keith Lehrer, University of Arizona, Tucson
Associate Editor
Stewart Cohen, Arizona State University, Tempe Board of Consulting Editors
Lynne Rudder Baker, University of Massachusetts at Amherst Radu Bogdan, Tulane University, New Orleans
Marian David, University of Notre Dame Allan Gibbard, University of Michigan Denise Meyerson, Macquarie University François Recanati, Institut Jean-Nicod, EHESS, Paris
Stuart Silvers, Clemson University
Barry Smith, State University of New York at Buffalo Nicholas D. Smith, Lewis & Clark College
PHILOSOPHY, PSYCHOLOGY,
AND PSYCHOLOGISM
Critical and Historical Readings on the Psychological Turn
in Philosophy
Edited by
DALE JACQUETTE
The Pennsylvania State University,University Park, PA, U.S.A.
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notions, — our ability to conceive of a class, and to designate its individual members by a common name...A successful attempt to express logical propositions by symbols...should be founded upon the laws of the mental processes which they represent...
— George Boole, A Mathematical Analysis of Logic, 1847
No description of...mental processes which precede the forming of a judgement of number...can ever take the place of a genuine definition of the concept. It can never be adduced in proof of any proposition of arithmetic; it acquaints us with none of the properties of numbers. For number is no whit more an object of psychology or a product of mental processes than, let us say, the North Sea is. The objectivity of the North Sea is not affected by the fact that it is a matter of our arbitrary choice which part of all the water on the earth’s surface we mark off and elect to call the “North Sea”. This is no reason for deciding to investigate the North Sea by psychological methods.
PREFACE
ACKNOWLEDGMENTS
INTRODUCTION: PSYCHOLOGISM THE PHILOSOPHICAL SHIBBOLETH
Dale Jacquette
PSYCHOLOGISM IN LOGIC: BACON TO BOLZANO Rolf George
BETWEEN LEIBNIZ AND MILL: KANT’S LOGIC AND THE RHETORIC OF PSYCHOLOGISM
Carl Posy
PSYCHOLOGISM AND NON-CLASSICAL APPROACHES IN TRADITIONAL LOGIC
Werner Stelzner
THE CONCEPT OF ‘PSYCHOLOGISM’ IN FREGE AND HUSSERL
J.N. Mohanty
PSYCHOLOGISM AND SOCIOLOGISM IN EARLY TWENTIETH-CENTURY GERMAN-SPEAKING PHILOSOPHY
Martin Kusch
THE SPACE OF SIGNS: C.S. PEIRCE’S CRITIQUE OF PSYCHOLOGISM
Vincent Colapietro
QUINEAN DREAMS OR, PROSPECTS FOR A SCIENTIFIC EPISTEMOLOGY
Michael Bradie
LATE FORMS OF PSYCHOLOGISM AND ANTIPSYCHOLOGISM Joseph Margolis vii ix xiii 1 21 51 81 113 131 157 181 195
PROPOSITIONS AND THE OBJECTS OF THOUGHT Michael Jubien
THE CONCEPTS OF TRUTH AND KNOWLEDGE IN PSYCHOLOGISM
John H. Dreher
PSYCHOLOGISM REVISITED IN LOGIC, METAPHYSICS, AND EPISTEMOLOGY
Dale Jacquette
WHY THERE IS NOTHING RATHER THAN SOMETHING: QUINE ON BEHAVIORISM, MEANING, AND
INDETERMINACY Paul A. Rhoth
COGNITIVE ILLUSIONS AND THE WELCOME PSYCHOLOGISM OF LOGICIST ARTIFICIAL INTELLIGENCE
Selmer Bringsjord and Yingrui Yang INDEX 215 229 245 263 289 313
Among the dichotomies that have divided philosophers, the rift between psychologism and antipsychologism represents some of the most heated metaphilosophical debate. The problem of whether and in what sense logic, mathematics, philosophical semantics, epistemology, and metaphysics are explanatorily related to psychology has been a fundamental watershed in the contemporary philosophy.
The battlelines between psychologism and antipsychologism were first drawn in the mid-nineteenth-century. If logic, to take a conspicuous example, studies patterns of inference from thoughts to thoughts, then it has appeared to some theorists that logic is a branch of psychology that can best be understood in terms of the most advanced psychological science. Against this psychologistic view of logic, anti-psychologistic opponents have argued that logic is not a descriptive theory of how we actually think, but a prescriptive account of how ideally we ought to think. Logic on this conception is independent of the empirical facts of psychology. The inherently subjective nature of thought content appears diametrically opposed to the objectivity of the eternal truths of logic, and of philosophy of language and mathematics. To preserve the objectivity required of a rational
a priori rather than empirical a posteriori science, antipsychologists have
rejected the idea that philosophy is grounded in even the most rigorously scientific psychology.
The psychologism-antipsychologism dispute can thus be interpreted as a deeper controversy about how philosophy can best be made scientific. There are two conflicting desiderata of science that provide a basis for the opposition between psychologism and antipsychologism. Science wants both to be objective and dependent on empirical facts. In physics, chemistry, biology, astronomy, and the other hard sciences, there is no collision of these values. It is peculiarly in the case of psychology, where the empirical facts of psychological experience have at least traditionally been regarded as essentially subjective, that a division has emerged between two opposed ways of trying to make logic and other philosophical subdisciplines (broadly, according to one ideology or another) ‘scientific’. The comparatively late development of psychology as a science as well as the subjectivity of psychological phenomena can be seen in this light as partly responsible for the dialectical confrontation between psychologism and
antipsychologism. The two categories signify the legitimate but incompatible interests of these fundamentally irreconcilable requirements for a scientific psychology.
If we could arrive at a satisfactory metaphysics of mind, then the apparently insurmountable impasse between psychologism and antipsychologism might simply disappear. Instead, we find only further manifestations of these two different ways of thinking about the empirical facts of subjective psychological occurrences reflected also in the philosophy of mind. Here they appear in longstanding oppositions between phenomenology and cognitive science, or between nonreductive intentional-ist substance or property mind-body dualisms and eliminative or reductive behaviorism, materialism, functionalism, or computationalism in the cognitive psychological sciences.
The disagreement over scientific ideals for psychology might be expected to fuel an inexhaustible dialectic between psychologism and antipsychologism. Such an interaction could provide the basis for a healthy and fruitful exchange in which competition from opposing sides could be harnassed for the sharpening of distinctions and refinement of arguments. To a limited extent, the opposition has continued and remains alive and well in the form of conflicts between realism and intuitionism or conceptualism, and between proponents and opponents of the program to naturalize or scientifically psychologize some of the traditionally nonpsychological philosophical disciplines like epistemology and metaphysics. In most ways, however, the psychologism-antipsychologism dispute has not exhibited this type of productive dialectical synergy. The rhetoric surrounding especially antipsychologistic philosophical discussions is revealing for its extraordinary degree of animus; it suggests the perception of a very ingrained division in outlook that cannot be overcome by a consideration of arguments with shared presuppositions, but that is directed polemically out of desperation at the presuppositions themselves.
Psychologism has largely withered away under the criticism of historically influential antipsychologists. The objections have appeared both from within analytic and in the so-called continental schools. Among analytic philosophers, the most strident assault on psychologism originates principally with Gottlob Frege and his many followers, including Bertrand Russell, Ludwig Wittgenstein, Rudolf Carnap, and others; while in the nonanalytic European tradition, Edmund Husserl and Martin Heidegger are perhaps the most noteworthy ostensible antipsychologists. The friends of psychologism, whether or not they would be willing to identify themselves as such, have continued the struggle under a variety of different banners, which is itself an important feature of the rhetoric of psychologism and antipsychologism.
To consider these problems, I invited a slate of distinguished scholars to present their perspectives on the history, philosophy, and rhetoric of psychologism. The papers with some overlap are presented roughly in historical sequence, by which the reader can trace certain themes through the development of the most significant episodes of the psychologism-antipsychologism debate. The present collection of essays draws on three distinct sources of recent discussion of the philosophical problems of psychologism. The papers by Rolf George, Carl Posy, J.N. Mohanty, Joseph Margolis, and my Introduction were first published in a special issue of the journal Philosophy & Rhetoric, which I guest-edited in 1997, and which are reprinted here with the permission of Penn State University Press. Earlier versions of the essays by Michael Jubien, John H. Dreher, and myself were presented as feature contributions to an invited symposium on ‘Psychologism: The Current State of the Debate’ at the American Philosophical Association, Pacific Division, Albuquerque, NM, April 5-8, 2000. Finally, the essays by Werner Stelzner, Martin Kusch, Vincent Colapietro, Michael Bradie, Paul A. Roth, and Selmer Bringsjord and Yingrui Yang were specially commissioned for inclusion in this volume. Altogether, the expositions of critical and historical dimensions of psychologism offer a detailed picture of recent thinking about the problems and opportunities for philosophical understanding posed by various proposals for taking a psychological turn in philosophy.
Dale Jacquette Mexico City - 21 December 2001
I am grateful to the authors for their excellent contributions; to Rudolf Rijgersberg, my former editor at Kluwer, to my current editor Floor Oosting, and to Keith Lehrer, editor of the Philosophical Studies series, for supporting and encouraging my work on this project. I would like to thank Henry W. Johnstone, Jr., departed friend and founding editor of Philosophy &
Rhetoric, for inviting me to guest-edit a special issue of the journal on The
Dialectics of Psychologism, 30, No. 3, 1997. This volume constitutes the original nucleus of the present collection. The essays from that source, many with revisions, include: Dale Jacquette, ‘The Dialectics of Psychologism’, reprinted here as the Preface, v-viii; Rolf George, ‘Psychologism in Logic: Bacon to Bolzano’, 213-42; Carl J. Posy, ‘Between Leibniz and Mill: Kant’s Logic and the Rhetoric of Psychologism’, 243-70; J.N. Mohanty, ‘The Concept of “Psychologism” in Frege and Husserl’, 271-90; Joseph Margolis, ‘Late Forms of Psychologism and Antipsychologism’, 291-311; Dale Jacquette, ‘Psychologism the Philosophical Shibboleth’, 312-31. All are copyrighted 1997 by The Pennsylvania State University, and reproduced by permission of The Pennsylvania State University Press. Michael Jubien’s essay, ‘Propositions and the Objects of Thought’ is reprinted with the permission of Kluwer Academic Publishers from Philosophical Studies, 104, 2001, 47-62. Martin Kusch’s essay, ‘Psychologism and Sociologism in Early Twentieth-Century German-Speaking Philosophy’ is reprinted with the permission of Elsevier Science from Studies in History and Philosophy of
Science, Vol. 30, No. 4, 1999, 651-85, where it originally appeared under the
title, ‘Philosophy and the Sociology of Knowledge’. Dale Jacquette’s essay, ‘Psychologism Revisited in Logic, Metaphysics, and Epistemology’, is reprinted with the permission of Blackwell Publishers from Metaphilosophy, 32, 2001, 261-78. I wish to thank Scott K. Templeton and the graphics staff at The Onion for invaluable technical assistance. This book is dedicated to Tina with love.
INTRODUCTION
PSYCHOLOGISM THE PHILOSOPHICAL SHIBBOLETH
The charge of psychologism has been made against my theory of knowledge. This is a word which has lately come into use and when it is spoken many a pious philosopher — like many an orthodox Catholic when he hears the term Modernism — crosses himself as though the devil himself were in it.
— Franz Brentano, The Classification of Mental Phenomena (1911) Appendix XI, ‘On Psychologism’
1. A Psychologism Miscellany
All theory is the product of thought, even when its subject matter is nonpsychological. Psychology, moreover, is widely recognized as a legitimate field of study for science and philosophy. Why then has ‘psychologism’ become the watchword of a fundamental antagonism from nineteenth-century to contemporary philosophy, particularly in logic, semantics, philosophy of language and philosophy of mathematics, but also in metaphysics and epistemology?
There are many kinds of psychologism, and many ways of defining the concept of psychologism. Martin Kusch, in his recent book, Psychologism:
A Case Study in the Sociology of Philosophical Knowledge, offers a
taxonomy of distinct schools of psychologism in German philosophy between 1866 and 1931, of which additional variations can also be identified. What can so many different versions of psychologism have in common? To further complicate the picture, Kusch observes that most of the widely recognized critics of psychologism were themselves accused of being psychologistic by antipsychologistic opponents who were even more zealous in their intolerance. Why has ‘psychologism’ become such a dirty word that even avowed antipsychologists are subject to its anathema?
As the name suggests, psychologism is not a branch of psychological science, but a philosophical ideology based on psychology. More
1
D. Jacquette (ed.), Philosophy, Psychology, and Psychologism, 1-19.
particularly, psychologism includes any attempt to ground philosophical explanation in psychological phenomena. Psychologism is a family of proposals for invoking different aspects of psychological occurrences in different ways to develop different styles of philosophical theory. The objections if not the vehemence with which antipsychologists frequently raise objections against psychologism can generally be attributed to the assumption that an empirical psychology of subjective thought cannot be expected to explain logically necessary objective truths, especially those of logic, semantics, and mathematics, but also of any field of discourse where a sharp distinction is supposed to hold between objective truths and subjective perceptions of the truth.
Kusch describes the psychologism flora and fauna in the particular period in which he is interested, when he writes:
An initial perspective on the inflation that the term ‘psychologism’ underwent between 1900 and 1930 can be gained by examining the (grammatical) attributes with which the term occurred.
First of all, writers distinguished between different forms of psycho-logism according to the fields of philosophy and the human sciences in which psychologism needs to be combated. Thus one finds ‘psychologism’ qualified as ‘metaphysical’, ‘ontologica’, ‘epistemological’, ‘logical’, ‘ethical’, ‘aesthetic’, ‘sociological’, ‘religious’, ‘historical’, ‘mathematical’, ‘pedagogical’ and ‘linguistic’.
Second, psychologism was also broken down into species according to the distinctive versions of psychologism that various schools were accused of proposing. Such adjectives included ‘empiricist’, ‘aprioristic’, ‘sensualist’, ‘rationalist’, ‘critical-teleological’, ‘evolutionary’, ‘pragmatist’ and ‘transcendental’.
Third, versions of psychologism were distinguished on the basis of their age, their ‘degree of truth’ and the boldness with which they were supposedly put forward. That is to say, ‘psychologism’ could be ‘old’, ‘new’, ‘false’, ‘true’, ‘objective (intersubjective)’, ‘justified’ (wohlverstanden), ‘one-sided/tendentious’, ‘extreme’, ‘moderate’, ‘universal’, ‘open’, ‘hidden’, ‘inverse’, ‘obvious’, ‘delicate’, ‘strict’ and ‘loose’.
And finally, we also find distinctions between ‘intellectual’ and ‘emotional’ psychologism, as well as between ‘immanent’ and ‘transcendent’ psychologism. (108)
2. The Rhetoric of Antipsychologism
The rise of antipsychologism is a chapter of philosophical rhetoric. Antipsychologism has had an enormous impact on the practice of philosophy and on philosophy’s self-image of its proper method and direction, and on its developing sense of what is to count as legitimate philosophical inquiry. Thus, in his recent study of Wittgenstein’s Place in
Twentieth-Century Analytic Philosophy, P.M.S. Hacker explains that:
non-psychological orientation” (4).
The rhetorical dimensions of antipsychologism are evidenced by the language of the arguments in which objections to psychologism are typically expressed. Although there are respectable philosophical criticisms of psychologism, there is also a large percentage of unreflective psychologism-bashing in the rejection of psychologism without thorough-going criticism. Indeed, the reasons for rejecting psychologism often encountered in contemporary philosophical literature often amount to little more than an appeal to the authority of prominent antipsychologists in the history of philosophy who with or without good justification themselves have taken an influential stand against psychologism. Brentano, ex-priest and philosopher, does not exaggerate when he says that in his day too the philosophical bad-mouthing of psychologism had virtually assumed the proportions of religious zeal. It is not enough to discredit psychologism like any mistaken theory by demonstrating its disadvantages — we must exorcise psychologism from philosophy, hold it off with garlic, shoot it with a silver bullet and drive a stake through its heart.
One of the most remarkable statements of antipsychologism appears in Arthur Pap’s influential study, Semantics and Necessary Truth: An Inquiry
into the Foundations ofAnalytic Philosophy. What is especially noteworthy
is that the statement occurs in the Glossary appended to Pap’s book as a definition of psychologism. Pap writes of “Psychologism” that it is “the tendency to confuse logical issues with psychological issues; e.g. if one tried to answer a question of logical validity by investigating actual beliefs (however, the meaning of this deprecatory word is unclear to the extent that the meaning of ‘logical’ is unclear)” (435). By definition, then, psychologism for Pap is a ‘confusion’ and the word alone is ‘deprecatory’. So it is no surprise to find Pap speaking negatively of psychologism throughout the body of the book. In an early section, he writes: “If [Immanuel] Kant’s conception of analyticity, then, is to be condemned as ‘psychologistic’, at least he will enjoy the company of many subtle contemporary analysts of reputation” (30). And near the end of the book, he similarly states: “Thus the old criticism, going back to presemantic days, of the Kantian analytic-synthetic distinction...as being relative to psychological conditions, cannot be simply exorcized as a symptom of ‘psychologism’” (246).
Alongside Pap’s antipsychologistic propoganda, we may consider Herbert Feigl’s pronouncement that: “Ever since [Gottlob] Frege’s and [Edmund] Husserl’s devastating critiques of psychologism, philosophers should know better than to attempt to reduce normative to factual categories. It is one thing to describe the actual regularities of thought or language; it is an entirely different sort of thing to state the rules to which thinking or speaking ought to conform” (1963, 250). Alan Musgrave in a similar vein remarks that: “Nowadays only a few cranks officially subscribe to that view
[psychologism]...There is progress in philosophy after all!” (1972, 593, 606). A final epitaph among indefinitely many that might be added is given by Gerhard Radnitzky when he relegates psychologism to the dustbin of ideas that have once and for all been refuted: “Thanks largely to the pioneering work of Frege and Husserl, psychologism in logic and metamathematics is largely a thing of the past: the attempt to reduce the norms of logic to laws of thought is now merely a historical curiosity” (1976, 505).1
In the semantic McCarthyite antipsychologistic hysteria of the times, there was no protection in declaring oneself a card-carrying antipsychologist by discovering and denouncing other thinkers as guilty of psychologism. The leading antipsychologists were themselves pilloried in print for latent psychologistic tendencies. Kusch quotes Rudolf Eisler in his 1907
Einführung in die Erkenntnistheorie, as saying: “...there is hardly an
antipsychologist, from Kant up to [Hermann] Cohen and Husserl, who has not been accused of ‘psychologism’ by some even more extreme thinker. In the end one no longer knows just who is a psychologicist and who isn’t” (1907, 19; translated in Kusch 116).2 Later Kusch recalls that:
Authors who were willing to regard themselves as ‘psychologists’, however, formed but a small minority in German-language philosophy between 1900 and 1930. As indicated earlier, most philosophers regarded psychologism as a gross philosophical error that needed to be ruthlessly identified in the thought of their contemporaries. We have already seen how all philosophical schools participated in this merry-go-round of charge and countercharge, and how practically every single German philosopher, dead or alive, was unmasked as a proponent of psychologism. Not surprisingly, this merry-go-round was possible only because the criteria for attributing a psychologistic stance to another philosopher were extremely flexible. While the different schools agreed on the fact that psychologism entailed a mistaken grounding of philosophy in psychology, they disagreed sharply as to what constituted such grounding. (115)
The antipsychologistic polemic is explicit in these objections. All the elements are present. There is an appeal to authority in the person of eminent antipsychologistic thinkers as having definitively exposed psychologism as a ‘confusion’ and ‘symptom’ of faulty reasoning, that has contributing to its becoming a mere ‘historical curiosity’. Other writers speak of theories that are ‘guilty’ of the ‘sin’ of psychologism, which they may ‘commit’. An equally significant mark of the pervasiveness of antipsychologism is the accusation of psychologism with no accompanying perjorative as condemnatory in and of itself. It is as though to classify a theory as psychologistic is enough automatically to disprove it, as though everyone already understands and agrees that psychologism is a defect or mistake, and that we should all be grateful for its having been thoroughly exploded in a heroic past age of philosophy.
The rhetoric of antipsychologism must further take account of the fact that in some philosophical circles ‘psychologism’ unalloyed has become a term of abuse, that deep-rooted hostility against psychologism, and even against the name ‘psychologism’ when applied to theories that many otherwise ardent antipsychologists find acceptable. Kusch explains that: “Aware of the danger that whatever they wrote on logic and epistemology would immediately be accused of the taint of psychologism, some philosophers tried to anticipate such criticism and to counter it by rhetorical means. [Anton] Marty went for an argumentum ad misericordiam by drawing attention to the fact that characterising a philosophical position as ‘psychologistic’ was to label it in a ‘disparaging’ way...” (117). The rhetoric directed against psychologism is interesting among other reasons for its precedent of substituting a mixture of appeal to authority and invective in place of open-minded philosophical argument. The very term ‘psychologism’ has become a philosophical shibboleth, an expression by which warring factions identify comrades and distinguish foes, like the ancient Israelites when they asked unfamiliar persons they encountered to pronounce this harmless word for a sheaf of grain.
3. Psychologism in a New Key
To give a more balanced picture of the conflict, it should also be observed that some commentators have made responsible unbiased critical assessments of psychologism. Among the most important examples must be included Kusch’s sociological study of Psychologism, and the philosophical appraisals offered in Michael Dummett’s The Interpretation of Frege’s
Philosophy and G.P. Baker and P.M.S. Hacker’s Frege: Logical Excavations.
Kusch, for example, though not writing as a logician or philosopher, and targeting especially the impact of antipsychologism on the politics of German universities in the hiring practices of philosophy and psychology departments, reports that: “...I am more impressed by the force of [Brian] Ellis’s, [Theodor] Lipps’s and [Moritz] Schlick’s defences of psychologism, or by [Wilhelm] Jerusalem’s psychologism-cum-sociologism, than by Husserl’s or Frege’s attacks” (275). Baker and Hacker note the rhetorical overtones by which Frege tries to compensate for a distinct lack of argument against certain of the perceived implications of psychologism. They write that:
Frege’s most general criticisms spill over into an onslaught upon idealism in general. Although his conclusions are unexceptionable, the supporting arguments are shallow, akin to a Johnsonian foray into the refutation of idealism. [Frege] found [the idealism implied by psychologism] absurd. No doubt it is. But his tirade simply relies on the assumption that there is
The distinctive amalgam of Cartesianism and Platonism in Frege’s thinking must characterize any reasoning that could be called an extention [sic] of his arguments against psychologism. It would also deprive any such reasoning of real philosophical value. Both the Cartesian myths about the realm of the psychological and the Platonic myths about the realm of the logical generate deep philosophical confusions, and hence these central ingredients of Frege’s thinking are themselves in dire need of philosophical investigation and clarification. The only conceivable sources of light must be alien to his framework of thought. Consequently, we must conclude that Frege’s crusade against the incursions of psychology into logic is now largely obsolete. His way of drawing the distinction between logic and psychology is mistaken in detail and dangerous in its wider implications. Only somebody who shares a large measure of his Cartesian and Platonist mythology will find any seeds of the Tree of Knowledge scattered in his antipsychologistic polemic. (62) accessible to us an objective domain of mind-independent entities. (50-1)
After a painstaking investigation of Frege’s objections to psychologism, in the final paragraph of their chapter on ‘Psychologism and the Theory of Content’, Baker and Hacker maintain:
Other assessments of psychologism and antipsychologism that do not rely on ad verecundium or diatribe, and that do not necessarily fall in lockstep with the predominant antipsychologistic mainstream opinion in the philosophy of logic, semantics, and mathematics, might easily be multiplied. Moreover, there is a countermovement that has sought to reinstate a modified concept of psychologism in contemporary philosophy. This has taken the form of an effort to naturalize epistemology and metaphysics in somewhat the fashion of the British empiricists John Locke, George Berkeley, David Hume, and John Stuart Mill, but recast in the vocabulary and involving the new methods and discoveries of cognitive psychological science.
Analytic philosophy today is not averse to all attempts to incorporate the findings of empirical psychology. W.V.O. Quine is conspicuously in the vanguard of recent philosophical projects to introduce scientific psychology into philosophical epistemology. In his 1969 essay, “Epistemology Naturalized”, the original subtitle of which was “Or, the Case for Psychologism”, Quine observes that: “The old epistemology aspired to contain, in a sense, natural science; it would construct it somehow from sense data. Epistemology in its new setting, conversely, is contained in natural science, as a chapter of psychology” (83). Related philosophical proposals that seek to make psychology the foundation of traditionally purely rationalist a priori subdisciplines are indicated by the titles of such works as Jerry A. Fodor’s Psychosemantics and Patricia Smith Churchland’s
Neurophilosophy.3 Dummett blames Frege and Husserl for not
distinguishing sufficiently clearly between psychology and logic in such a way as to preclude the recent upsurge of neopsychologisms, when he argues:
Where both [Frege and Husserl] failed was in demarcating logical notions too strictly from psychological ones...These failings have left philosophy open to a renewed incursion from psychology, under the banner of ‘cognitive science’. The strategies of defence employed by Husserl and Frege will no longer serve: the invaders can be repelled only by correcting the failings of the positive theories of those two pioneers. (1991, 287)
Whether Frege and Husserl could or would have wanted to stave off the onslaught of cognitive psychology into the domain of philosophy, there have all along been psychologistic strains in many phases of modern philosophy’s development, from the late nineteenth century to the present day. In logic and mathematics, psychologism changed its name to intuitionism and constructivism, but continued to assume that thought processes and the limitations of ideas are the only basis for understanding logical and mathematical relations. In ontology and the metaphysics of universals, psychologism persisted in a different form under the less inflammatory but equally psychologically oriented label of conceptualism. In moral philosophy, value theory, and aesthetics, a kind of psychologism developed in different guises as naturalism, intentionalism, consequentialism, or emotivism.
The distinction between psychologism and antipsychologism in its most general terms demarcates such a far-reaching schism that it is only reasonable to expect it to endure throughout the most challenging philosophical revolutions and intellectual upheavals. As Ernst Cassirer remarks: “...psychologism...still cannot be regarded as defeated. For although its form and justification have changed since Husserl’s sharp and trenchant criticism, we must note that psychologism has, to a high degree, the ability to appear in ever new guises” (1927, 32; translated in Kusch, 121). Quine’s suggestion that epistemology be naturalized was fully prefigured in his earlier philosophical semantics. In Word and Object, Quine develops a dispositional behaviorism of stimulus meanings by which language gains meaning in practical activity, without invoking abstract ‘thoughts’ or propositions like Fregean Gedanken, or objective entirely mind-independent Sätze an sich, as Bernard Bolzano advocated in his 1837
Wissenschaftslehre.4 The dialectic of psychologism and antipsychologism in
this broad sense continues to transform itself in different ways, holding open the radical choice between including or excluding the content of thoughts and the empirical facts of psychology as a touchstone for philosophy. Psychology in the form of extratheoretical appeal to mental content, or as phenomenology, behaviorism, cognitive science, or Freudian psychoanalytic theory, stands ready to make different types of contributions to different types of philosophical explanation.
The peaceful coexistence of new varieties of psychologism with the antipsychological heritage of Frege and Husserl in the current analytic philosophical climate is largely a result of two considerations. The first
mitigating factor is that the term ‘psychologism’ by common consent has for the most part been consigned to quixotic attempts to explain the necessary truths of logic, semantics, and mathematics on the concrete empirical facts of subjective thought and mental content. In this application, psychologism remains as suspicious to most mainstream philosophers as it was for Frege, Russell, Wittgenstein, and their followers, and might better be called ‘mentalism’ than ‘psychologism’. The second mitigating factor is that the specific kinds of psychologism that have gained respectability in contemporary analytic philosophy are not forms of mentalism and are not supposed to explain the objective truths of logic and mathematics. At most, psychology is lately invoked to account for semantics in the sense of understanding the contextual pragmatics of meaning in language use for speech act theory, and of some of the softer topics in the philosophical gamut such as epistemology, as in Quine’s proposal for using cognitive psychological science to explain how epistemic subjects go about discovering and justifying some of their beliefs as knowledge. When Quine in Philosophy of Logic, for example, analyzes the logical truth of a sentence, he does so in terms of objective truth conditions and the preservation of truth under any uniform substitution of its extralogical terms. He says that: “Our new definition of logical truth, then, can also be put thus: a logical
truth is a sentence that cannot be turned false by substituting for lexicon.
When for its lexical elements we substitute any other strings belonging to the same grammatical categories, the resulting sentence is true” (58). When he speaks of naturalizing epistemology by making it a part of psychology, however, Quine limits his proposal to natural science: “We are studying how the human subject of our study posits bodies and projects his physics from his date, and we appreciate that our position in the world is just like his. Our very epistemological enterprise, therefore, and the psychology wherein it is a component chapter, and the whole of natural science wherein psychology is a component book — all this is our own construction or projection from stimulations like those we were meting out to our epistemological subject. There is thus reciprocal containment, though containment in different senses: epistemology in natural science and natural science in epistemology” (1969, 83).
All this complicates the problem of psychologism. The rhetoric of anti-psychologism is filtered through many layers of many different thinker’s understanding of different meanings of the word, shaped by their opinions about whether any particular form of psychologism is acceptable or unacceptable when applied to distinct kinds of philosophical subjects. To gain a better understanding of the complex rhetorical situation in the psychologism-antipsychologism dispute, we shall try next briefly to assess the most important philosophical arguments that have been raised against psychologism.
Logic is exact; psychology is inexact. The criticism is that logic cannot be reduced to psychology because of an inherent difference in their respective attainable degrees of precision. The argument directly reflects the fundamental opposition that is supposed to obtain between the objective
4. Arguments Against Psychologism...and Some Replies
In this section, I shall not try to deal exhaustively or even especially systematically with objections to psychologism. My purpose is only to say enough to make it plausible to conclude that there may be more to the psychologism-antipsychologism controversy than has often been appreciated. I want to show that the dispute is not so one-sidedly in favor of antipsychologism as many antipsychologists have uncritically assumed.
The decisive refutation of psychologism as an approach to the philosophy of logic, philosophical semantics of meaning, and philosophy of mathematics in my view has yet to be given. If my counterarguments are correct, then the debate will have to proceed along different lines and by means of more carefully elaborated arguments than those that I consider. I shall review without detailed historical scholarly apparatus the principal criticisms that have appeared against psychologism in the philosophical literature. I argue that all of the problems said to be entailed by psychologism can be related in different ways to philosophical disapproval of the subjectivity of thought as a foundation for objective scientific theory. Then I indicate some of the considerations by which problems about the subjectivity of thought can be disarmed, so that a more thorough reconsideration of the psychologism-antipsychologism imbroglio may be warranted in which the refutation of psychologism is no longer presupposed. Here are eight related arguments against psychologism. I have arranged them approximately according to my perception of their increasing strength, from less to greater difficulty as objections to the theory. In each case, I give a succinct statement of the criticism, explain how it is related to the general question of the subjectivity of psychological occurrences, and offer a brief reply in support of my claim that not every version of psychologism is necessarily the lost cause its opponents have polemically portrayed it as being. For simplicity, I limit consideration to arguments against efforts to reduce logic to psychology, with the understanding that similar criticisms with appropriate adjustments might be offered at least against semantics and mathematics, and philosophy of language and philosophy of mathematics. All of the arguments attempt to identify some essential difference between logic and psychology that prevents logic from being reducible to psychology.5
eternal truths of logic and the subjective contingent truths of psychology. An objection of this sort may have held more sway in the days of psychology’s infancy, when there seemed little prospect of making psychology into an exact science. The terminology, experimental methods, and explanation of empirical discoveries in contemporary psychological science are in some ways as exact as in physics or chemistry. The conclusions psychologists reach may not be as universal as in the harder physical sciences, but this has nothing immediately to do with the question of their relative exactitude. If psychological laws are only statistical, that in principle does not place them at any disadvantage in comparison with the statistical laws of quantum physics. Statistics, moreover, is every bit as formally mathematically precise as the most rigorously developed formal symbolic logic. If we turn from cognitive science to phenomenology, we can interpret the efforts of philosophers like Husserl and Maurice Merleau-Ponty to achieve a philosophical theory of mind that, if successful, would also be as exact as symbolic logic, albeit according to a different paradigm of science with a different set of requirements for exactitude.
Equivalent exactitude in any case is not a prerequisite for reducing one science to another. Biology is inexact when compared to chemistry. It is unclear whether the bacteriophages studied in biology are or are not living things, but it would be hard to find a comparable gray area of categories in chemistry. Yet most theorists agree that biology is fully reducible to chemistry. Nor does logic as it is understood today compare favorably as against psychology on other metatheoretical grounds. Logic is deductively incomplete according to proofs by Kurt Gödel and Alonzo Church, and there are undecided and even undecidable questions of modern logic, just as there are unsettled questions and unproven and undisproven hypotheses in psychology, as in other exact sciences at an early stage of their development.6
Finally, the question of just how exact logic is, and the benchmark of precision it affords, is softened by the fact that the exactness of logic is itself a quality judged by thought, and to that extent can only reflect the exactness of some psychological occurrences that must translate at least in principle into a corresponding exact psychological theory that must somehow be adequate to the explanation of such exact psychological phenomena.
Argument 2
Logic is a priori; psychology is a posteriori. The empirical nature of psychology by contrast with the necessary truths of logic is sometimes offered as a decisive refutation of psychologism. Problems of exactness aside, if logic concerns a body of necessary judgments whose proof is independent of experience, and if psychology is or is about a body of logically contingent empirical judgments whose justification requires
experience, then there might be no prospect for reducing logic to psycho-logy. This objection is indirectly related to the subjectivity of psychology as opposed to the objectivity of logic, because it is the subjectivity of thought by which it is immediately accessible only to the first-person subject of experience that entails that psychology unlike logic can only be known a
posteriori. It is customary in explaining this type of objection to distinguish
between contexts of concept acquisition and justification, and to admit that while all concepts might be acquired only a posteriori, concepts like those of logic do not stand in need of experience a posteriori for their justification.
As with other criticisms of psychologism, the question of whether or not there is a difference between logic and psychology on the grounds of aprioricity or aposterioricity can be regarded as circular. If logic is part of or reducible to psychology, and if logic is a priori, then part of psychology is also a priori. The distinction between contexts of concept acquisition and of concept justification can further be invoked in defense of certain versions of psychologism. It is true that psychology is an empirical science that proceeds among other ways by an a posteriori method of hypothesis testing and confirming or disconfirming hypotheses through observation and experiment. This is not to say that psychology cannot acquire or discover by
a posteriori investigations concepts that are only justified a posteriori. The
problem of whether logic can be reduced to psychology if psychology as an empirical science does not provide a priori justifications again begs the question of whether psychology is a purely empirical discipline that does not contain logic with its a priori justifications of logical truths as one part of its formal theory of the workings of the mind.7
Argument 3
Logic is prescriptive; psychology is descriptive. This argument seeks to establish a stronger distinction between logic and psychology. Psychology as an empirical science describes psychological occurrences. Logic is different because it does not merely describe how we reason, but prescribes standards for correct thinking, or of how we should or ought to reason. Again, whether or not psychology is purely descriptive depends on whether or not we have good independent reasons for deciding whether or not logic is a part of psychology. If logic is a part of psychology, and if logic is prescriptive, then psychology is also not purely descriptive, but partly prescriptive. Still, it might be said that psychology as a science cannot imply standards for correct reasoning. There is an implicit complaint against the subjectivity of psychology in this objection, in the idea that psychology can only describe the phenomenological contents of individual minds. Needless to say, this is just one way of thinking about psychology. But it also appears in the case of more ‘scientific’ cognitive psychology, behaviorism,
neuropsychology, and the information sciences that such disciplines can at best teach us how we think, whereas logic looks very much to be the normative set of guidelines for how we ought to think.8
By way of reply, it is worth remarking first that phenomenological and scientific psychology are not purely descriptive, but, like other sciences, they try to explain the phenomena by adducing lawlike regularities and general principles or laws. Insofar as psychology succeeds in advancing general principles, it is more like traditional logic than a purely descriptive science such as morphology and taxonomy. It is standard to maintain that we should expect a complete psychology but not a complete logic to include all the errors of reasoning a subject happens to make. Yet the traditional study of logic also includes discussion of invalid inferences and formal and rhetorical fallacies. Moreover, logic can be understood as descriptive of how some reasoning occurs, at the very least of the reasoning of certain logicians. There is no need to deny the hypothetical imperative or prescriptive element of logic as it is usually presented. If we want to reason correctly, then we ought to accept and to make our reasoning conform, say, to modus ponendo ponens, and to reject and avoid the fallacy of affirming the consequent. There are similar marriages between pure science and recommendations for practice in other areas of knowledge that pose no obstacle to theoretical reduction. Engineering and medicine are two obvious examples. In engineering one learns how to build a bridge ‘correctly’ so that it will bear its load properly, withstand windsheer and other kinds of stress, minimize metal fatigue and the like, just as in logic one learns how to reason ‘correctly’ to draw sound and avoid fallacious inferences. Similarly in medicine. When we learn to build bridges or perform heart surgery or reason correctly, we also learn what not to do relative to presumed practical purposes. We want the bridge to safely span the gorge and not to collapse, the patient to recover with improved health and not die on the operating table, and our reasoning to expand our knowledge and improve our decision-making ability, and not to lead us from truth to falsehood. Now I think that most theorists would be reluctant to conclude that engineering and medicine are not reducible to physics and biology, but rather that their respective practices combine these sciences with an assumption about the goals they can be assumed to help their practitioners achieve. Why should things be different with respect to logic as an applied discipline grounded in the psychology of reasoning?
Argument 4
Logic is universal; (human) psychology is (human) species-specific. The attempt to distinguish logic from psychology by discerning a relevant species-relative difference between them is perhaps clear enough. The objectivity of logic and subjectivity of psychology is explicit at the
differential species level.
The intent of the argument is more difficult to assess. What is it supposed to mean to contrast the universality of logic with the human species specificity of psychology? Does psychology apply only to humans, while logic is the same for humans, apes, and giraffes — or perhaps for angels and extraterrestrials? Animal psychology is of course a legitimate subdiscipline of contemporary scientific psychology, and much that we have come to know about human psychology depends on or was originally suggested by observation and experiment involving nonhuman animals, some of which concerns nonhuman problem solving and extralinguistic reasoning abilities. It is not clear furthermore whether and to what extent our standard logics can be regarded as appropriate for other species who do not have and are unable to use our or any other language.
The situation in logic today in any case is rather different than in the heyday of antipsychologism. There is no longer thought to be just one monolithic universal logic that is assumed to be correct for all reasoning. Rather, logicians have developed families of different logics, some of which are not even mutually compatible, that logicians tend to regard as individually suited to particular kinds of reasoning about particular kinds of topics. There are Boolean and non-Boolean logics, extensional and a variety of intensional logics, modal logics, deontic logics, bivalent and many-valued logics, and so on. In this regard, logic has followed the proliferation of non-Euclidean geometries like the Riemannian and Lobachevskian, where in the past the parallel assumption was equivalently that there could be only one ‘correct’ geometry. It would not shock most logicians or philosophers of logic nowadays, if alien beings were discovered who did not use any of our logics but had a different and possibly more advanced logic distinct from any that we have used. The aliens’ unique reasoning might still recognizably constitute a logic, that we might learn about only by studying their psychology expressed in their language and behavior, as a reflection of their nonhuman psychology.
Argument 5
Logic is discovered, not invented; logic is therefore presupposed by its discovery in thought, contrary to the claims of psychologism. The objectivity of logic as something already existing to be discovered as opposed to the subjective invention of logical systems to express the eternal truths of logic is obvious. I think, nevertheless, that the presupposition of the objection is as questionable as it is question-begging. It is not clear in light of the many different systems of logic available that logic is not a product of certain kinds of thought rather than a body of necessary truth waiting to be discovered by and expressed in thought. This indeed is one of the most intriguing problems for an undogmatic philosophy of logic to investigate.
Regardless of how opinions may vary on this issue, the criticism does not establish any relevant distinction by which logic must be independent of psychology. The reason is that the truths of psychology themselves are not invented, but discovered by the honest hardworking efforts of the phenomenologist or more conventionally scientific psychologist. Psychology as much as logic is the objective study of thought, wherein logic as a part of psychology, for all that this objection has to say, might well be the objective study of particular kinds or particular aspects of thought.
Argument 6
Logic is presupposed by any theory, including psychology, rather than the other way around, so that logic cannot be reduced to psychology. Here the difference between logic and psychology is supposed to be that logic is objective in a very ultimate sense, as preceding other disciplines, including psychology.
The idea that logic must come first as a kind of queen of the sciences is in many ways attractive. But if we take seriously and openmindedly the suggestion that logic might be a part of psychology, then the only conclusion to follow is that one part of psychology must come before the other parts, or that there must be a kind of priority in the order by which the principles of psychology are established. An analogy with chemistry serves to demonstrate a similar lesson. If we think of chemistry primarily as the science of molecular behavior, then we cannot regard atomic theory as part of chemistry, since molecules ontically presuppose atoms. One might wrongly suppose that chemistry for this reason cannot subsume atomic theory because atomic theory is presupposed by chemistry. But if atomic theory is rightly understood as a part of chemistry, then chemistry as a whole will meet its explanatory burden, provided that the atomic theory it contains first explains the chemistry of atomic structures, on which molecular chemistry can build its theory of more complex substances. The same relation might then hold of logic subsumed by psychology. Logic articulates the principles by which sound reasoning takes place, by which means the particular types of reasoning presupposed by the development of the remaining parts of psychology among other theories is provided.
Argument 7
Logic concerns identical objects of distinct thoughts, and so cannot be reduced to the contents of individual psychologies. This is a very popular objection to psychologism. If psychologism were true, and logical entities were merely psychological, then any two different psychological subjects would immanently possess distinct logical entities by virtue of having different thoughts. The subjectivity of psychology by this argument entails
that psychologism leads immediately to idealism, relativism, and even solipsism or skepticism about the existence of other minds.
The problem is most easily illustrated in the case of numbers. If numbers are immanently psychological entities, then there is no single entity such as the number 2 for two different psychological subjects to think about — I will have the number 2 that belongs to my thought, and you will have a different number 2 that belongs to your thought. This implication seems untenable, because we suppose that logic and mathematics has to do with entities and relations that are independent of any particular subject’s thought, but that can be thought about as the same things by many different thinkers. The idealism and relativism that might be thought to follow from psychologism according to the criticism are evident in this description. Solipsism may further be implied by the fact that if even abstract logical and mathematical entities are subjective, then the privacy and epistemic inaccessibility of the contents of thought by which one mind is sealed off from other minds, then there seems to be nothing outside the mind on which there can be a definite meeting of different minds, and thus no justification for belief in the existence of other minds.
Perhaps the best way to meet the objection is firmly to renounce any formulation of psychologism with such idealistic implications. To suppose that logic can be explained in psychological terms is not necessary to try to reduce logical entities to psychological entities. A thought about the Statue of Liberty does not make the Statue of Liberty a mental entity, and a psychological theory that explains the workings of perception need not entail that the objects encountered in perception are subjectively psychological entities. Why then should a psychological theory of logic entail that logical entities are subjectively psychological entities?
Argument 8
Logic is objective; psychology is subjective. The claim that logic cannot be reduced to psychology because logic is objective and psychology is subjective is finally the simplest and most direct statement of the underlying criticism that in different forms drives the rhetoric of antipsychologism. Frege perhaps offers the most famous expression of this objection when in the Introduction to Die Grundlagen der Arithmetik, he offers this methodological heuristic: “Never let us take a description of the origin of an idea for a definition, or an account of the mental and physical conditions on which we become conscious of a proposition for a proof of it. A proposition may be thought, and again it may be true; let us never confuse these two things. We must remind ourselves, it seems, that a proposition no more ceases to be true when I cease to think of it than the sun ceases to exist when I shut my eyes” Later, Frege summarizes his antipsychologistic resolve: “In the enquiry that follows, I have kept to three fundamental
principles: always to separate sharply the psychological from the logical, the subjective from the objective...”
The subjectivity of psychology has often been raised as the final line of defense against psychologistic reductions of an mind-independent objective logic. But while the contents of psychological experiences may be subjective, psychology as the scientific study of thought need not be. The objectivity of logic is moreover rendered at least somewhat doubtful by the fact that different logicians sometimes disagree about issues that to an outsider would appear to be among the most fundamental and unquestionable propositions of logic. An example is the dispute between classical and intuitionist logicians, in which classical logicians accept while intuitionist logicians for plausible if not universally admitted reasons deny the logical truth of the biconditional thesis that a sentence is true if and only if the negation of its negation is true. Intuitionists agree only with the conditional that if S then S, but not with the converse that if
not-not-S is true then not-not-S is true. Nor is it obvious that one side or the other in
disagreements about logic must be wrong. There are different logics for different analytic purposes in modeling different kinds of reasoning about different kinds of things. As a result, the antipsychologist objection that psychologism is beyond redemption in the philosophy of logic because logic is inherently objective and psychology is inherently subjective appears inconclusive.
I make no claim that the above list of objections is complete. Nor do I suppose that my counterobjections to the standard objections against psychologism that I have considered are decisive. It may be possible even where the defense of psychologism appears quite strong to reinforce a particular antipsychologist criticism in such a way as to lend it greater credence as a refutation of psychologism. To choose just one example, it might be granted that psychology can be as exact as logic, but that logic still cannot be reduced to psychology because the precise degree or kind of exactitude demanded by logic cannot be provided by psychology. The present point is only that there is more to the psychologism-antipsychologism dispute than antipsychologists have generally acknowledged, basking in the warm assurance that Frege, Husserl, and other opponents have defeated psychologism so thoroughly that the entire approach is dead, buried, and impossible to resurrect.
5. Toward a Renewed Psychologism-Antipsychologism Dialectic
If I have succeeded to any degree in making psychologism look less disastrous than its critics have tried to portray it, then there may be some hope of reawakening the controversy between psychologism and
antipsychologism. My desire is to rekindle interest in the topic and in a small way to help begin to restore the balance of dispute to what I believe should remain an open, lively, and more actively considered controversy.
There is much to be gained in my view from constantly reevaluating the challenges posed by the psychologism-antipsychologism antithesis. My reason for thinking this goes beyond a general suspicion of fundamental philosophical disagreements ever being definitively resolved in one way or the other. A more particular encouragement is implied by the fact that psychologism demands further reexamination in light of the greening of psychology as a scientific discipline. The changing shape of scientific psychology, and new directions in phenomenology and intentionalist philosophy of mind, may combine to bring about a greater acceptance of objection-resistant formulations of psychologism, that may eventually support a more enthusiastic appraisal of psychologism versus antipsychologism.
If renewed attacks against psychologism determine that its prospects cannot be revived under any aegis, then it will be just as well to satisfy ourselves that this is so. But if there remain good arguments for refined versions of psychologism that can withstand the best assaults of antipsychologism, then we may look forward to a fertile interaction between psychologism and antipsychologism that will continue to inspire a refinement of both positions. Only then can we overcome the stagnation that has been fostered by the rhetoric according to which any form of psychologism must be a hopelessly mistaken relic of nineteenth-century philosophical logic that in more enlightened times has been irretrievably defeated.
Department of Philosophy
The Pennsylvania State University, USA
NOTES 1 Quoted in Philipse (1989), 58.
2 See also Mulligan (1995), esp. 19-23. 3 Fodor (1988); Churchland (1986).
4 Quine (1960); Frege (1977); Bolzano (1972). 5 Compare Kusch (1995), 30-94; Rath (1994). 6 Gödel (1931); Church (1935).
7 Boole (1958): “The design of the following treatise is to investigate the fundamental laws
of those operations of the mind by which reasoning is performed; to give expression to them in the symbolical language of a Calculus, and upon this foundation to establish the science of Logic and construct its method; to make that method itself the basis of a general method for the application of the mathematical doctrine of Probabilities; and, finally, to collect from the various elements of truth brought to view in the course of these inquiries some probable intimations concerning the nature of the human mind” (1). Boole sees no incompatibility
between this psychologistic approach to logic, and the generality and certainty of the principles of logic as laws of thought, which he contrasts with inductive empirical methods in the natural sciences: “On the other hand,” he adds, “the knowledge of the laws of the mind does not require as its basis any extensive collection of observations. The general truth is seen in the particular instance, and it is not confirmed by the repetition of instances...For we not only see in the particular example [of a logical law] the general truth, but we see it also as a certain truth,— a truth, our confidence in which will not continue to increase with increasing experience of its practical verifications” (4).
8
Haack (1978), 238-42, distinguishes between the strong psychologistic claim that logic is descriptive of mental processes, and weak psychologisms by which logic is prescriptive of how we ought to think. She maintains that the problem of psychologism stands in need of reevaluation, and rejects strong psychologism while cautiously endorsing some of the advantages of weak psychologism over antipsychologism.
REFERENCES
Baker, G.P. and Hacker, P.M.S. Frege: Logical Excavations. Oxford: Basil Blackwell, 1984.
Bolzano, Bernard. Theory of Science: Attempt at a Detailed and in the Main
Novel Exposition of Logic with Constant Attention to Earlier Authors
[Wissenschaftslehre, 1837]. Ed. and trans. Rolf George. Berkeley, University of California Press, 1972.
Boole, George. An Investigation of the Laws of Thought of which are
Founded the Mathematical Theories of Logic and Probabilities. New
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Brentano, Franz. Psychology from an Empirical Standpoint. Ed. Oskar Kraus. Trans. Linda L. McAlister. London: Routledge & Kegan Paul Ltd., 1973 [includes Appendices from the 1911 revision of Brentano’s
Psychologie vom empirischen Standpunkt (1874), published as Von der Klassifikation der psychischen Phänomena (The Classification of Psychological Phenomena)].
Church, Alonzo. “An Unsolvable Problem of Elementary Number Theory”,
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Churchland, Patricia Smith. Neurophilosophy: Toward a Unified Science of
the Mind-Brain. Cambridge: The MIT (Bradford Books) Press, 1986.
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Dummett, Michael. Frege and Other Philosophers. Oxford: The Clarendon Press, 1991.
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Philosophy of Mind. Cambridge: The MIT (Bradford Books) Press,
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Arithmetik: Eine logisch mathematische Untersuchung über den Begriff der Zahl (1884)]. Trans. J.L. Austin. Oxford: Basil Blackwell, 1974.
Frege, Gottlob. “Thoughts”, in Frege, 1977: 1-30.
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Gödel, Kurt. “Über formal unentscheidbare Sätze der Principia mathematica und verwandter Systeme I”, Monatshefte für Mathematik und Physik, 38 (1931): 173-98.
Haack, Susan. Philosophy of Logics. Cambridge: Cambridge University Press, 1978.
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PSYCHOLOGISM IN LOGIC: BACON TO BOLZANO
I
In a review of Bolzano’s Wissenschaftslehre (WL, 1837), a pseudonymous Dr. P. Menelaos remarked that “throughout, the author assumes the old, strictly objective or dogmatic, viewpoint, in contrast to the contemporary, which is based on the psychological self-consciousness of the thinking mind” (Bolzano 1972, XXIX). It must be granted that Bolzano did not think much of grounding logic in psychological self consciousness, and that he introduced mind independent, timeless, “sentences in themselves,” “objective” propositions, among which relations of consequence, con-sistency, probabilification, etc. obtain. He is now remembered mostly for this theory, which, as a counterpoint to psychologism, earned him the admiration of Husserl (1900, 225 f.), and the titles of a logical Plato and a Bohemian Leibniz. By contrast, Bolzano’s specific logical teachings, though of great and even current interest, have received less attention. It is not the focus of this paper, however, to deal with them.
Dr. Menelaos is correct in saying that Bolzano, unlike many of his contemporaries, did not seek to ground logic in psychology, but it is a mistake to think that he paid no attention to the “manifestations” or “appearances” of propositions in the mind, as the contents of thoughts that come and go: substantial portions of his Wissenschaftslehre are given over to this concern. A second misleading suggestion is that there was an accepted “contemporary” way of thinking about logic in psychological terms, when there were in fact deep divisions on just this issue. Thirdly, it is suggested that Bolzano reverted to an older style of doing logic, not long before then superseded by the modern psychological approach. Although Bolzano gives much space to pointing out, largely as a matter of courtesy, that many earlier logicians must have thought of something like propositions (as mind-independent entities), it is manifest that none of them had
21
D. Jacquette (ed.), Philosophy, Psychology, and Psychologism, 21-49.
explicitly postulated them. He did not, as is claimed, return to a previous practice, but pioneered a new one.
Indeed, there was not all that much previous practice. During the 18th century logic had fallen into a state of disrepair; the Enlightenment was perhaps an age of reason, but it surely was not an age of logic. A reconstruction and rehabilitation of logic had to start very nearly from the ground up. The logic books that were then published were meant to be propaedeutic to philosophical studies, more school book than treatise. Logic’s decline had been brought on, in part, by an increased insistence on its connection to psychology, only much later disparagingly called psychologism, in part by some other factors. I will now chronicle some highlights of this development.
II
It is tempting to think that psychologism made its entry into logical theorizing as a matter of reasoned insight, as a better grounding of the subject than what had gone before. That would be a mistake. It was as much a matter of style, fashion and ideology as of theory. I ask, therefore, the reader’s indulgence as I begin with a ramble through some aspects of the sociology and politics, if I may use that term, of logic in the late 17th and 18th centuries, without, however, neglecting theory altogether.
Older logics of the conservative variety, into the 17th century, usually began with a few perfunctory remarks about thinking and the laws of thought, but then got right down to business, discussing terms, propositions, syllogisms, without much attention to the ontological status of the entities they discussed. One cannot, without anachronism, describe them as either psychologistic or anti-psychologistic — that was not an issue. The pedagogy of logic divided the subject into the logica docens and the logica utens. There is, on the one hand, the subject as it is taught, remembered and practiced in disputations, and on the other hand its use in everyday life, in legal practice, and the like. There was no attention to what later came to be called “natural logic”, that is, the inferential habits of the untutored mind. The distinction between the latter and “artificial logic”, the codification of the logical canon, came later and is found, for instance, in the Logic of Port
Royal. Arnauld says this:
Conceiving, judging, reasoning, ordering are all done quite naturally, and sometimes done better by those ignorant of the rules of logic than by persons instructed in these rules. So logic does not teach us how to conceive, to judge, to reason, or to order; for nature in giving us reason gave us the means to perform these operations. Logic consists, rather, in reflecting on these natural operations.1
