Non-Referring Concepts* by Sam Scott, B.Sc., M.C.S. A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy Cognitive Science Program Institute of Interdisciplinary Studies Carleton University Ottawa, Ontario February 26, 2003 © 2003 Sam Scott * Carleton University Cognitive Science Technical Report 2003-03 URL http://www.carleton.ca/iis/TechReports © 2003 Sam Scott ii To Anne iii Abstract Non-referring concepts are mental representations of nonexistent things like dragons and time machines. Non-referring words are the words that express those concepts. In reference-based approaches to formal semantics, there is a well-known puzzle about how non-referring words and concepts get their meanings. The default solution is that they are special cases, with a different semantic structure from their referring counterparts. Despite over a century of debate in formal semantics, the issue of non-reference has, until now, been ignored in the psychological literature on concepts. But it is not obvious in advance what the psychological structure and processing of non- referring concepts will be like. Furthermore, experimental evidence about non-referring concepts can help resolve issues fundamental to both semantics and psychology, such as the nature of meaning, the nature of concepts, and the debate over representational externalism. I used the methods of experimental psychology to provide the first empirical test of the claim that non-referring concepts are a special kind of concept. I found that non- referring concepts have a very similar structure to referring concepts. This finding suggests that many popular versions of reference-based semantics are flawed, perhaps fatally. I also found that non-referring concepts take measurably longer to process than referring concepts. I argue that the best way of reconciling the second result with the first is to make a distinction between the knowledge that is constitutive of a concept and the knowledge that is external to it. Non-referring concepts are processed more cautiously because we know that their referents do not exist – a fact that is about the world rather than the concept itself. This distinction is consistent with the apparently contradictory evidence that motivates “Theory Theory” accounts of conceptual structure on one hand, and similarity-based accounts such as prototype and exemplar theories on the other. This dissertation concerns the following topic areas: cognitive psychology, cognitive science, concepts, empty names, externalism, internalism, mental representation, nonexistent objects, non-referring concepts, philosophy of language, philosophy of mind, prototypes, reference, semantics, similarity, and Theory Theory. iv Acknowledgements I am enormously indebted to my supervisor, Rob Stainton, for five years of unwavering support, encouragement, and guidance. The influence he has had on my intellectual maturation extends well beyond the scope of this dissertation. I am also very grateful to Craig Leth-Steensen for detailed advice and assistance on the experimental portions of the dissertation. The statistical analyses in particular benefited tremendously from his expert guidance. I am extremely thankful to Andy Brook, not only for his instruction, support and critical commentary, but also for being so central to the establishment of a rich and vibrant cognitive science program. I would also like to thank Jo-Anne LeFevre for her keen interest in my work, her helpful comments, and her great assistance in the planning of further experimental work. It was a real pleasure to have Jesse Prinz as my external examiner. His detailed questions and comments made the defense both challenging and enjoyable. I thank Anne for being a great friend and loving partner, and also for many years of discussions about language, cognition, politics, and everything else. I’ve learned a lot from her. I owe a great debt to the following instructors and supervisors, who helped guide me through my education in the cognitive sciences: Ken Barker, Martin Davies, Rob Gaizauskas, Helen Goodluck, Chris Herdman, Rob Holte, Miroslav Kubat, Stan Matwin, Franz Oppacher, Bruce Pappas, Shu Hui Wu, and Helmut Zobl. My years as a PhD student were vastly improved by the intellectual and emotional support, as well as the friendship, of my fellow students and postdocs. Thanks to them, I’ll be leaving with many warm memories of my time at Carleton. I am extremely grateful to all my other fantastic friends, and in particular to Al, Fred, Gabi, Isabel, Jen, Julie, Martine, and Mélissa, who came through for me at a crucial moment. My parents have always been fully supportive throughout my endless years of schooling, without once asking me why I was bothering. I love them for that. Finally, I gratefully acknowledge the financial support of Carleton University and the National Science and Engineering Research Council. v Table of Contents Chapter 1: Introduction 1 Superman vs. Mighty Mouse 1 What Is A Concept? 4 Why Are Non-Referring Concepts Interesting? 7 Sneak Preview 12 Two Ways To Read This Dissertation 14 Chapter 2: Reference and Reality 16 Semantics and Psychology 16 The Puzzles of Non-Reference 17 Simple Solutions 20 Extreme Solutions 24 Special Case Solutions 33 Predictions 48 Chapter 3: Concepts and Categories 49 Categorization 49 Concepts as Definitions 50 Concepts as Prototypes 56 Ad hoc Concepts 70 Five Possibilities, Two Hypotheses 80 Predictions 90 Chapter 4: Non-Referring Concepts 91 The Plan 91 Experiment 1: Associative Frequency 92 Experiment 2: Typicality 98 Experiment 3: Family Resemblance 114 Experiment 3a: List Context 129 Experiment 4: Speeded Categorization 139 Experiment 4a: Familiarity 153 Summary and Implications 159 Chapter 5: Back to Reality 161 A Quick Recap 161 Structure and Non-Reference 164 Processing and Knowledge 165 A Partly Meinongian Conclusion 174 Future Directions 175 Final Words 178 Notes 181 References 195 Appendices 208 A: Associative Frequency 208 B: Typicality (Experiment 2) 215 C: Family Resemblance 218 D: Typicality (Experiment 3a) 222 E: Speeded Categorization 226 F: Familiarity 228 Index of Names 231 vi Chapter 1: Introduction Vern: You think Mighty Mouse could beat up Superman? Teddy: What? Are you cracked? Vern: Why not? I saw the other day he was carrying five elephants in one hand! Teddy: You don’t know nothing. Mighty Mouse is a cartoon. Superman is a real guy. No way a cartoon could beat up a real guy. Vern: Yeah. Maybe you’re right. Would be a good fight though. – Stand by Me (Columbia Tri Star, 1985). Superman vs. Mighty Mouse Personally, my money’s on Mighty Mouse. All he needs is a chunk of Kryptonite and it’s curtains for the so-called “Man of Steel”. But that’s beside the point. For my purposes, what’s interesting about Vern and Teddy’s debate is that in order to engage in it, they have to make liberal use of what might be called “non-referring” terms. The names “Superman” and “Mighty Mouse” are non-referring in the sense that they fail to refer to existing individuals in the way that ordinary names such as “David Bowie” seem to. They are non-referring terms because their alleged referents, Superman and Mighty Mouse, don’t actually exist in the real world. But Vern and Teddy are not just talking about Superman and Mighty Mouse. They must be thinking about them as well. According to the default assumptions of cognitive science, this means that they must be performing computations on their concepts of Superman and Mighty Mouse. So in addition to making use of non-referring terms, Vern and Teddy are also making use of their corresponding non-referring 1 Chapter 1: Introduction 2 concepts. This distinction between referring and non-referring terms and concepts turns out to be an important one, and the source of quite a bit of trouble for some of the most popular and successful approaches to the linguistic and philosophical study of meaning. This dissertation is a philosophically motivated psychological investigation into the structure and processing of those troublesome non-referring concepts. (For those of you who are still thinking about who would win the fight, perhaps Figure 1-1 will be useful.) Figure 1-1: Who would win the fight? (Pictures may not be to scale.) The dialogue between Vern and Teddy is pretty silly. But trying to account for their ability to have such a dialogue is not silly at all. In fact, a very large portion of natural language utterances contain non-referring terms, and a correspondingly large portion of human thoughts must therefore involve non-referring concepts. A large proportion (possibly the majority) of all published writing is fiction, and much of what human beings do for personal entertainment involves non-written fiction as well. But even when we’re not reading novels, telling stories, watching TV, singing songs, daydreaming, or whatever, our ordinary talk and our day to day thoughts are still full of references to things that don’t, couldn’t, or at least might not, exist. Whenever we hypothesize, plan for the future, express hopes and fears, or try to deceive each other, we risk making use of non-referring terms and concepts. Reference to the nonexistent is not Chapter 1: Introduction 3 just some curious little side product of human nature. It is a central feature of human thought and language. In this dissertation, I will use the techniques of cognitive psychology to answer two main questions. The first concerns the psychological structure of non-referring concepts: What is that structure like, and more specifically, do non-referring concepts have a different psychological structure from that of ordinary referring concepts? The second concerns non-structural psychological differences (e.g., differences in deployment or processing) between referring and non-referring concepts: Are there any other significant psychological differences between non-referring concepts and their referring counterparts? These questions are presented in Figure 1-2 below for easy reference.