The Architecture of the Mind

Massive Modularity and the Flexibility of Thought




“A magnificent defense of the massive modularity thesis, showing how this view of the mind - and only this view - is compatible with both our understanding of human evolution and of human creativity.”

Steven Mithen FBA, Professor of Early Prehistory, University of Reading


“It is a sweeping synthesis, covering a vast range of material, while arguing persuasively for an architecture of the mind (and brain!) that is more all encompassing but somewhat weaker than Fodorian modularity. For anyone interested in the current status of the modularity hypothesis, this is a must-read.”

Randy Gallistel, Professor of Psychology and Cognitive Science, Rutgers University


The Architecture of the Mind is as brave as it is massive. At a time when most mainstream cognitive psychologists have dismissed the possibility that the mind might be importantly modular, Carruthers has launched a valiant, state-of-the-art defense, touching on insights from biology, animal behavior, and experimental psychology. If you care about the modularity hypothesis – and every cognitive scientist should – you owe it to yourself to read this book.”

Gary Marcus, Department of Psychology, New York University, and Director of the NYU Infant Language Learning Center


“For over a decade, the massive modularity hypothesis has been center-stage in debates about cognitive architecture and evolutionary psychology. In this bold, wide-ranging and ambitious book, Carruthers sets out and defends what is, by far, the clearest and most plausible version of the massive modularity hypothesis to be found in the literature. He also explores the often surprising implications of his version of massive modularity for a wide range of issues including creativity, consciousness, norms and scientific reasoning. This is the best sort of interdisciplinary research – innovative, broadly informed, and crystal clear. It is essential reading for anyone interested in how the human mind works and how it evolved.”

Stephen Stich, Board of Governors Professor of Philosophy and Cognitive Science, Rutgers University


“Claims about the architecture (or overall structure) of the mind play a key role in explanations of virtually every fundamental feature of human existence - from our capacity for science and creativity, to practical reasoning and morality. Carruthers's book - ostensibly a defense of “massive modularity” - provides what is surely the richest and most complete picture of the mind to date, laying out the structure of human and animal minds with unparalleled empirical richness and philosophical rigor. It is one of the most important books in the philosophy of mind in decades. A truly monumental achievement.”

Stephen Laurence, Professor of Philosophy and Director, Arts and Humanities Research Board project on Culture and the Mind, University of Sheffield




it is huge in its ambition and scope: it aims at no less than giving us a comprehensive picture of the mind, its components and workings, its evolutionary origins and its characteristic capabilities. …. it could arguably be regarded as a kind of Anglo-Saxon, empirically based, 21st-century analogon to Kant’s Critique of Pure Reason. Kant’s is a hard act to follow, but Carruthers’ book is a worthy attempt for a new era.”

            Synthesis Philosophica, 43 (2007).


brings together diverse empirical results and theoretical explanations connecting them coherently into a powerful and rigorous narrative that provides an entry point into some of the burning and unresolved questions in the cognitive sciences. The book succeeds in its versatile interdisciplinary defense of the modularity thesis, painting ‘the big picture’ underlying the scattered details. Carruthers once again proves the remarkable ability of philosophers to traverse smoothly through disciplinary boundaries, as Lockean ‘under-laborers of science’.”

            Minds and Machines, 18 (2008).


“There is much to admire about this book. Peter Carruthers is a cognitive scientist as well as a philosopher of mind. He has wide knowledge of cognitive psychology (human and animal) and neuroscience, as well as his own subject. He has persuaded us to take seriously two hypotheses that we have previously had little time for - massive modularity and "global broadcasting"...a most stimulating and informative discussion of the mind...this work is a heroic effort, and brave in the way it addresses so many of the relevant literatures and confronts many objections that might be made to its argument. Whether or not we fully agree with Carruthers' architecture of the mind, this is vastly stimulating and important contribution that is well worthy of careful study by all those engaged in cognitive science.”

            Thinking and Reasoning, 14 (2008).


"This is an important, timely, and enormously impressive book. The massive  modularity hypothesis is central to much contemporary work in evolutionary psychology, yet it is still to win widespread acceptance and is often misunderstood and rejected out of hand, both by both philosophers and by psychologists. There is thus a need for a clear, comprehensive, and well-argued defence of the hypothesis, suitable for a wide range of readers. Carruthers’s book meets this need superbly, and thereby sets a benchmark for all future discussions of this topic. It is (as Carruthers notes) almost absurdly ambitious, given the range of disciplines relevant to the task, but its ambition is matched by its scholarship and argumentative skill. Carruthers assembles a wealth of evidence from across the cognitive sciences and engages in disciplined but creative abductive reasoning, conducted with exceptional clarity. ....

"It is common to end a positive review by saying that the book reviewed should be read by anyone with a serious interest in the relevant topic. Often this is hyperbole; in this case, it is not. No one will read The Architecture of the Mind without being informed, stimulated, challenged, and inspired. It is a very important book."

            Philosophical Quarterly, 59 (2009).


"a work of excellence and of great clarity." ... "Summing up, I found this book very instructive and thought provoking."

            Pragmatics and Cognition, 18 (2010).




List of figures




1          The Case for Massive Modularity                                                              

1.      Introduction: on modularity

2.      What massive modularity could not be

3.      The argument from design

4.      The argument from animals

5.      In defense of evolutionary psychology

6.      The argument from computational tractability

7.      What does computational frugality really require?

8.      Conclusion


2          The Architecture of Animal Minds                                                            

1.      Invertebrate psychology

2.      Dual visual systems in mammals (and others)

3.      Multiple belief-generating modules

4.      The case against general learning

5.      Multiple motivational modules

6.      Multiple memory systems

7.      The fragmentation of action-control

8.      Mental rehearsal and practical reason

9.      Conclusion


3          Modules of the Human Mind                                                                      

1.      Against the ‘one major new adaptation’ hypothesis

2.      Physics, biology, psychology, and statistics

3.      Mind-reading and mental architecture

4.      Language in mind

5.      Imitation and cultural accumulation

6.      Human motivational modules

7.      Normative reasoning and motivation

8.      Conclusion


4          Modularity and Flexibility: the First Steps                                                

1.      The challenges

2.      Stimulus independence and inner speech

3.      Language as content-integrator

4.      The re-orientation data

5.      Alternative theories of content flexibility

6.      Inner speech and the flexibility of reasoning

7.      What the thesis is and isn’t

8.      Conclusion


5          Creative Cognition in a Modular Mind                                                     

1.      Introduction: constraints on theorizing

2.      The creative-action theory of creativity

3.      Creativity and inner speech

4.      Autism and the evolutionary functions of pretence

5.      A contrasting theory of pretence and creativity

6.      Creativity and metaphor

7.      Scaling up: creativity in adulthood

1.      Conclusion


6          The Cognitive Basis of Science                                                                   

1.      What does it take to be a scientist?

2.      The hunter as scientist

3.      The child as scientist?

4.      System 2 reasoning and science

5.      Fodor on abductive reason

6.      The anatomy of abduction

7.      Two kinds of System 2 belief-formation

8.      Conclusion


7          Distinctively Human Practical Reason                                                       

1.      The challenges

2.      Normative modules again

3.      Theoretical reasoning about desires and goods

4.      Two kinds of practical reasoning and intention

5.      Desires versus reasons

6.      The illusion of conscious will

7.      Conclusion


8          Conclusion to the Volume



            Index of names

            Index of subjects




This book has three main aims. One is to motivate and argue for a massively modular account of the architecture of the human mind. Another is to answer a ‘How possibly?’ challenge to any such approach. In the first part of the book (Chapters 1-3) the positive case for massive modularity is laid out. I also outline how the thesis of massive mental modularity should best be developed, and articulate the notion of ‘module’ that is appropriate to serve within such an account. And then in the second part of the book (Chapters 4-7) I take up the challenge of explaining how a massively modular mind could possibly display the sorts of flexibility and creativity that are distinctive of the human mind. Here the account that I provide finds a central place for representations of natural language sentences, among other things.

The third aim of this book is to give at least a sketch of the ways in which the various components of the mind are likely to be linked up to one another, and to interact with one another - indeed, this will be crucial to demonstrating how it is possible for the human mind, together with its familiar capacities, to be underpinned by a massively modular set of structures and components. Chapter 2 outlines and defends the basic framework of a perception / belief / desire / planning / motor-control architecture, as well as making proposals about many of the likely components and their modes of connectivity. And then in the chapters thereafter many specific claims about the place within this architecture of natural language, of a mind-reading system, and others are explained and motivated.

Although these three main strands in the book are mutually supporting, they are also to some degree independent of one another. Someone might find the arguments for massive modularity convincing, for example, while being unconvinced of my account of human flexibility, and while disagreeing with the overall architecture of components that I lay out. Or someone might think that the case for massive modularity is weak, while agreeing that my account of human flexibility and the component-architecture underpinning it are along the right lines - only requiring far fewer elements than a massive modularist would allege. And so on. But taken together, I believe that the claims that I make under each of these three headings should add up to be (or rather multiply to be) an attractive overall package that is greater than the mere sum of its individual parts.

            Our topic is massive modularity. But unfortunately there exists a wide variety of different notions of modularity, put to work in a diverse range of literatures, extending from biology (Schlosser and Wagner, 2004), through computer science and artificial intelligence (Bryson, 2000, McDermott, 2001), to psychology (Karmiloff-Smith, 1992), to philosophy (Fodor, 1983, 2000; Samuels, 1998). Of these, Fodor’s (1983) conception of a module has been especially influential, and many of the uses of the notion of modularity within cognitive science are to some degree variations upon it. In addition, a number of different researchers in cognitive science have argued for a form of massive mental modularity, and have done so in a variety of distinct ways (Tooby and Cosmides, 1992; Sperber, 1996; Pinker, 1997). But they, too, are by no means in complete agreement with one another about what modules, as such, are.

            The way out of this morass is to line up the arguments for massive modularity with the notion of modularity that those arguments support. This is what I do in Chapter 1. I present and defend the cogency of three main arguments for massive modularity, while carefully teasing out the notion of ‘module’ that would be supported if those arguments are, indeed, cogent. The result is a notion of modularity that is some distance from Fodor’s (in particular, modules needn’t be informationally encapsulated). It is much closer to the use of the term ‘module’ in biology, and it is even closer to the notion used by researchers in artificial intelligence. On this account, a module is a functionally distinct processing system of the mind, whose operations are at least partly independent of those of others, and whose existence and properties are partly dissociable from the others. Moreover, modular systems must be frugal in their use of information and other cognitive resources, and they will have internal operations that are widely inaccessible to other systems. The thesis of massive mental modularity is then the claim that the mind is composed of many functionally isolable processing systems which possess such properties, and which have multiple input and output connections with others.

Chapter 2 then defends the major premise of one of the main arguments for massive modularity, claiming that the minds of non-human animals – from insects to chimpanzees - are massively modular in their organization. The chapter also locates those modules within a basic perception / belief / desire / practical reason / motor-control architecture, which will serve as the framework for the account of the structure of the human mind provided in later chapters. It also puts in place many specific ideas that will be needed in later chapters, including the claim that there is a limited capacity for mental rehearsal of action present in the minds of some of our primate cousins.

In Chapter 3 I discuss the modules that are likely to have been added, or enhanced, in the transition from the minds of the great-ape common-ancestors to our own. I defend the view that these are multiple, and argue at some length against the competing ‘one major new adaptation’ hypothesis. They include a mind-reading system, a natural language system, and systems for normative belief, reasoning, and motivation. In each case I discuss the probable internal organization of the module in question, and the ways in which it is likely to be embedded into the overall architecture of the mind.

Chapter 4 starts to take up the challenge of explaining the distinctive flexibility of the human mind in massively modular terms. It distinguishes a number of different kinds of flexibility, arguing that some are relatively easy to address while others are harder to explain. It then discusses how the language faculty may be responsible for flexibility of content, combining together the outputs of other conceptual modules into a single representation that can then be mentally rehearsed, ‘globally broadcast’ (in the sense of Baars, 1988), and received as input by a whole suite of conceptual modules once again. Increasingly flexible cycles of modular processing thereby become possible, as do new kinds of reasoning.

            Chapter 5 then tackles the problem of creativity. It advances the thesis that all forms of creative cognition reduce, ultimately, to creative action. In contrast with traditional views that see creative thought as prior to creative activity, I here argue the reverse. (Think of creative ‘on-line’ improvisation in jazz, to get a feel for the kind of thing that I have in mind.) The root of all creativity, I claim, lies in the creative activation and rehearsal of action schemata. The first manifestations of this ability are to be found in the problem-solving abilities of chimpanzees, and are then found - greatly enriched - in the pretend play of young children. Indeed, I claim that the function of childhood pretend play is to practice and further enhance that ability.

            Chapter 6 turns to our capacity for science, and for abductive reasoning more generally (sometimes called ‘inference to the best explanation’). Some people have claimed that our capacity for science is one of the remaining deep mysteries (comparable to the problem of consciousness, or the problem of the origin of the universe), and that it presents a formidable challenge for any cognitive theory to explain, let alone a massively modular one (Pinker, 1997; Fodor, 2000). Chapter 6 claims to solve this problem, in outline at least. Once again language and mental rehearsal play an important role in the account, as do principles employed in the interpretation of speech and the evaluation of testimony.

            In Chapter 7 discusses how the thesis of massive modularity can accommodate the distinctive features of human practical reasoning. This chapter is relatively brief, since most of the materials needed for the account have been put into place earlier in the book. What is new in the chapter is the suggestion that human practical reason can exploit the resources of our distinctively-human theoretical reason. And I defend the belief / desire framework that I have adopted throughout against those who claim that, in the case of human beings, it is perceptions of reasons, rather than desires, that motivate our actions (Dancy, 1993, 2000; Scanlon, 1998). I also argue that conscious will is an illusion, developing one of the arguments of Wegner (2002). Chapter 8 then briefly summarizes the book’s arguments and conclusions.

            It hardly needs saying that this book is an ambitious one - indeed, it is almost absurdly so. For it takes as its goal nothing less than the elaboration and defense of a massively modular architecture for the human mind, to which many, many, different bodies of research are relevant. In consequence, there are numerous places where I have had to touch on topics on which I am by no means an expert. And there is, no doubt, a wealth of further evidence and theorizing out there in a variety of literatures that would be thoroughly germane to my project, if only I had the good fortune to know of it. Moreover, there are a wide range of kinds of expertise that are surely relevant to the evaluation of my various claims and proposals, some of which I simply don’t possess. I can only console myself with the thought that someone has to step back from the details and paint the big picture, albeit taking big risks in doing so. And I hope that even if I have made many mistakes, and even if the architecture that I sketch in outline proves incorrect in many of its details, still what I have done might nevertheless be roughly along the right lines. At the very least, I hope that it will provide a useful foil and stimulus for the research of others.

It is worth remarking that many academic philosophers might fail to recognize what occurs within these pages as a form of philosophy. For the book contains very little that can be considered to be conceptual analysis, and most of the arguments are empirically-grounded inferences to the best explanation, rather than deductive in form. If this is so, then so be it, and so much the worse for the philosophers in question. For by the same token much of the work of Aristotle, and of Hume, wouldn’t count as philosophy, either. I believe that I have good role-models. And I believe that naturalistic philosophy, of the sort exemplified here, is the way (or at least, a way) that philosophy should be.

            Many cognitive scientists, likewise, might fail to recognize what occurs within these pages as a form of science. For I report no new data or experiments. And although I do review a great deal of scientific data, I also make proposals and outline theories that go well beyond anything that the current evidence might strictly warrant, and many of the ideas that I defend are avowedly speculative. I can only plead that science always contains what might be called ‘framework assumptions’, as well as detailed theories closely grounded in the empirical data. And the examination and defense of those assumptions can be the work of naturalistically-minded philosophers.

Again Hume (1739) provides us with a model. Although he, too, conducted no experiments, he saw himself as attempting to ground an empirical science of psychology, and the framework that he laid out has proven immensely influential amongst working psychologists ever since. (Even those of us who reject his associationism and empiricism can continue to find much that is of value in his work - see Fodor, 2003.) I should stress that the present book is a good deal less ambitious, of course. I am not attempting to found a massively modular framework for psychology, since much excellent work in that tradition already exists. Instead, I aim to lay out the best case for it, to defend it, and to show how it might be able to overcome its greatest difficulties. I thus see myself in the more-modest role of ‘under-laborer for science’, championed by Locke (1690).