NOTE TO USERS This reproduction is the best copy available. ® UMI PSYCHOLOGISM, SEMANTICS AND THE SUBJECT MATTER OF LOGIC By DAVID M. GODDEN, B.A.(HONS.), M.A. A Thesis Submitted to the School of Graduate Studies in Partial Fulf:tlment ofthe Requirements for the Degree Doctor of Philosophy McMaster University © Copyright by David M. Godden, April 2004 PSYCHOLOGISM, SEMANTICS AND THE SUBJECT MATTER OF LOGIC DOCTOR OF PHILOSOPHY (2004) McMaster University (Philosophy) Hamilt on, Ont ario TITLE: Psycholo gism, Semantics and the Subject Matter of Logic AUTHOR: David M. Godden, B.A. (Hons.) (Wilfrid Laurier University) M.A. (Y ork University) SUPERVISOR: Pro fessor Nicho las Griffin NUMBER OF PAGES: x, 353 ii Abstract Despite a pronoWlced rejection ofpsycho log ism at the tum of the previous century, contemporary epistemolo gy has witnessed its pervasive return This inquiry seeks to contribute to a philosophical resolution of the psychologism de bate, not by defending anti­ psychologism against its historical and contemporary objectors, but by offering a persp ective from which a viable anti-psychologism might be articulated. Psychologism about logic is a family of views asserting a dependency of logic on psycholo gy. Typically, such a dependence jeopardizes the o~ectivity and necessity of logic. Frequently, this dependency is established through the metaphysical claim that the subject matter of logic is psychological in nature. Metaphysical accoWlts oflogic explain its status and foundation in terms ofits subject matter. Standard accounts have portrayed the subject matter of logic as a class of mental entities (ideas), abstract entities, or concrete, particular entities. Following a review of Frege's critiqu e of psycho logism (the first opt ion), I consider histo rical rep resent atives 0 f the two remaining alternatives: Frege's Platonism and Mill's empiricism. Witnessing the failings of each ofthese theories, I turn to a positivistic account which provides logic with a linguistic, rather than a metaphysical, foundation. As an alternative to metaphysical accounts, I consider the view that logic has no subject matter. I argue that metaphysical accounts oflo gic may be equivalently expressed as theses concerning the semantics of the logical ~xicon. Specifically, the question of psychologismmay be seen as the question of how to properly explain the semantics of the logical lexicon. I engage Quine's response to positivistic accounts of logic, arguing that his naturalised holism misconstrues logic's function in theory and its fuundation. I suggest that a pragrrntic accoWlt oflogic, focussing on the linguistic fWlction oflogicalexpressions in our language, may provi:le a viable alternative for explaining the nature and foundation of logic. iii Acknowledgements I would like to gratefully acknowledge the contributions and guidance ofmy supervisor Prof. Nicholas Griffm, as well as the two other members of my supervisory committee Dr. Rockney Jacobsen and Prof. David Hitchcock. My frequent afternom crnversatims with Nick were undoubtedly the most eq oyable part of the research and comprnitionprocess, andI willdefmitely miss them. It was through those conversations that the argument of this thesis matured. Further, Nick's mirthful remarks could always lift my spirits. My thanks also to Rocky, for his sympathetic and constructive insight, especially with chapter 4, which he always offered even though I know he disagrees with many of my own views. Rocky has been teacher and role-model to me since my undergraduate days at Wilfrid La uri er, and I was both fortunate and delight ed to wor k with him on my disserta tion. Finally, I extend my thanks to Da vid for his devotion and his careful reading of my thesis. I only realised the extent of David's devotion to his graduate students when I received his conments on one of my chapters on Christmas day! David's questions were always insightful and would often take me weeks to answer. H is comments clarified and strengthened the argument of this dissertation, and were especially valuable in chapters 1 and 3. I hope that my future in philosophy will allow me to remain in contact with each of you I would also like to thank the members of my examining committee: my external examiner Dr. Rob Stainton (Univeristy ofWestern Ontario), as well as my two internal examiners Dr. Greg Moore (Mathematics), and Dr. Lee Brooks (Psychology). In addition, special thanks are due to Prof. Wil Waluchow, for his unceasing support of my efforts, and to Prof. Samantha Brennan(UniversityofWestern Ontario) whosekindness helped support me through my last year of study. Also, I would like to thank Dr. Stuart Shanker (York) for providing the initial catalyst for this inquiry. Over the course ofmy graduate studies, I have had the good fortune of being able to cultivate a fertile set of relationships with scholars in the field of Informal Logic and Argumentation Theory. I would like to thank all the members of this academic community for their welcoming accommodation of my endeavours in this field. Mostly though, I would like to express my enduring thanks for the support and understanding of my family: to my parents, especially, who shared with me every disappointment and every triumph, every set-back and every accomplishment, without ever losing faith; and to Robyn Bluhm \\110 kmws, better than anyone, what this project meant to me. Finally I want to give special thanks to Dr. William Mart in, for his eterna I hospitality, and his enlightened conversa tion. He remains a source ofinspira tion to me through his unwavering determination, his devotion to the canon, and his grasp of tradition and the individual talent. Lastly, I am grateful foc the friends I have made at McMaster; I hope that each of you may fulfil your dreams. To David and Elizabeth, Brian and Kiersten, Rashmi and Tim, I wish you all the best and will think of you often. Research for this thesis was made possible by a doctoral fellowship (#752-2000-1279) from the Social Science and Humanities Research Council ofCanada, as well as scholarships from Ontario Graduate Scholarship and McMaster University. IV Table of Contents Abstract iii Acknowledgements IV Introduct ion - The Contemporary Revival of Psychologism 1.1 Psycholo gism, Past and Present 1.2 Psychologism Today: The Contemporary Attitude 3 1.3 The Contribution of the Present Work 7 1.4 Course of the Inquiry to Follow 8 Chapter 1 - The Nature of Psychologism 1.1 Defining the Concept of Psychologism: Context and Approach 15 1.2 The Bias of"Psychologism" 17 1.3 Generic Psychologism 18 1.3.1 Generic Psychologism: An Initial Defmition 18 1.3.2 Generic Psychologism Revised 20 1.3.3 The Relation Between Psychology and Philosophy 22 1.3.4 Psychologism in Epistemology and Logic 23 1.4 Psychologism in Semantics 28 1.4.1 Metaphysical Psychologism 28 1.4.1.1 The Nature of a Subject Matter 29 1.4.1.2 Psychologism and the 'No Subject Matter' Thesis 32 1.4.2 Philosophical Interest of Metaphysical Psycho10gism over Logic 36 1.4.3 Referential Psychologism 39 1.4.4 Philosophical Interest of Referential Psychologism about Logic 42 1.4.5 Entailments Between Metaphysical and Referential Psychologism 43 v 1.4.6 Theoretical Implications of the Equivalence of MP and RP 45 1.4.7 Meaning, Reference and Psychologism 46 l.5 Reductive Psycho10gism 50 l.5.1 Psycho10 gism as a Reductive Thesis 50 1.5.2 Strategies for Rejecting MP and RP 54 1.5.3 Psychologism and the Prescriptive Function of Logic 55 1.5.4 Qualified Referential Psychologism 57 l.5.5 The Problem with Qualified Referential Psychologism 59 l.5.6 The Essential Normativity of Logic Revisited 62 l.5.7 Psychologism Essential versus Exhaustive 65 1.5.8 Strong versus Weak Psychologism 66 l.6 Psychologism and Naturalism 69 1.6.1 Naturalism in Contemporary Epistemology 69 1.6.2 Psychologism and its Relation to Naturalism 73 1.6.2.1 Inferring Psychologism from Naturalism (EN* f- EP*) 76 1.6.2.2 Inferring Naturalism from Psychologism (EP* f- EN*) 79 1.6.3 The Relation of Psycho log ism to Naturalism: Implications 79 1.6.4 Varieties of Psychology and Varieties of Psycho log ism 82 1.6.5 Defining Psychologism in a Climate of Naturalism 84 l.7 "Psychologism": A Working Defmition 94 Chapter 2 - Frege's Anti-Psychologism 2.1 Frege's Semantic Approach to Psychologism 101 2.2 Frege on the Subject Matter of Logic 104 2.2.1 Semantics, Truth and the Nature of Logic 104 2.2.2 The Nature of Truth 107 2.2.3 Thoughts 108 2.2.4 Semantic Psychologism 109 VI 2.2.5 The Nature of Ideas 114 2.2.6 Ideas as the Subject Matter of Logic 116 2.3 The Subject Matter of Logic 117 2.3.1 Psychol0 gy Reduc es Everything to the Su bjective 117 2.3.2 The Relation of Logical Psychologism to Subjective Idealism 118 2.3.3 Objective, Scientific Knowledge 120 2.3.4 Understanding and Connnunication 123 2.3.5 Ideas are Semantic Epiphenomena 124 2.3.6 Physiological Psychology 126 2.3.7 On Thoughts as the Products of Thinking 131 2.3.8 The Nature and Properties of Thought 134 2.4 The Foundations of Logic 137 2.4.1 The Laws of Inference 137 2.4.2 The Relation Between Logic and Truth 138 2.4.3 The Relation Between Justification and Cause 139 2.4.4 Boundary Stones 140 2.4.5 The Laws of Logic Versus Laws of Thinking 141 2.4.6 The Nature and Foundation of Rules ofInference 145 2.4.7 The Nature of Proof and the Representative Function of Logical Laws 147 2.4.8 The Actual Role of Psychology 154 2.5 The Problems with Frege's Picture of Logic 158 2.5.1 Judgement Stroke 158 2.5.2 Geometry 159 2.5.3 The Most Mysterious Process of