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1 Georg Northoff 2014 All rights reserved. No reproduction, copy or transmission of this publication may be made without written permission. No portion of this publication may be reproduced, copied or transmitted save with written permission or in accordance with the provisions of the Copyright, Designs and Patents Act 1988, or under the terms of any licence permitting limited copying issued by the Copyright Licensing Agency, Saffron House, 6 10 Kirby Street, London EC1N 8TS. Any person who does any unauthorized act in relation to this publication may be liable to criminal prosecution and civil claims for damages. The author has asserted his right to be identified as the author of this work in accordance with the Copyright, Designs and Patents Act First published 2014 by PALGRAVE MACMILLAN Palgrave Macmillan in the UK is an imprint of Macmillan Publishers Limited, registered in England, company number , of Houndmills, Basingstoke, Hampshire RG21 6XS. Palgrave Macmillan in the US is a division of St Martin s Press LLC, 175 Fifth Avenue, New York, NY Palgrave Macmillan is the global academic imprint of the above companies and has companies and representatives throughout the world. Palgrave and Macmillan are registered trademarks in the United States, the United Kingdom, Europe and other countries. ISBN This book is printed on paper suitable for recycling and made from fully managed and sustained forest sources. Logging, pulping and manufacturing processes are expected to conform to the environmental regulations of the country of origin. A catalogue record for this book is available from the British Library. A catalog record for this book is available from the Library of Congress. Typeset by MPS Limited, Chennai, India. Printed and bound by CPI Group (UK) Ltd, Croydon, CR0 4YY.

2 Contents List of Tables and Figures Preface Acknowledgements vii ix xi Introduction 1 Part I Mind and Brain: From Philosophy through Neuroscience to Neurophilosophy 21 1 Philosophy and the Mind: Philosophy of Mind and Phenomenology 23 2 Philosophy and Science: Naturalism 43 3 Mind, Brain and Science: Psychology and Neuroscience 69 4 Brain and Philosophy: Neurophilosophy 91 Part II The Mind Brain Problem: From Philosophy of Mind to Philosophy of Brain Mental Approaches to the Mind Brain Problem Physical and Functional Approaches to the Mind Brain Problem Non-mental and Non-physical Approaches to the Mind Brain Problem Brain-based Approaches to the Mind Brain Problem 212 Part III Philosophy of Psychology and Neuroscience: From Explanation of Mind to Explanation of Brain Philosophy of Psychology: Personal versus Subpersonal Levels of Explanation Philosophy of Psychology: Mind and Meaning Philosophy of Neuroscience: Explanations, Concepts and Observer in Neuroscience Philosophy of Brain: Characterization of the Brain 329 Part IV Neurophilosophy of Consciousness: From Mind to Consciousness Arguments against the Reduction of Consciousness to the Brain Neural Correlates of Consciousness (NCC) Neural Predispositions of Consciousness (NPC) Conceptual, Phenomenal and Methodological Issues in the Investigation of Consciousness 426 v

3 vi Contents Part V Neurophilosophy of Self: From Consciousness to Self Brain and Self Brain and Self-consciousness Abnormalities of Self and Brain in Psychiatric Disorders Brain and Intersubjectivity 512 Epilogue: Is the Brain a Door Opener? 535 References 539 Index 547

4 Introduction Why do we need the brain in philosophy? How can neurophilosophy be non-reductive? It might be that you are puzzled about the title of this book, Minding the Brain. No, that does not go together, you may want to say: Isn t philosophy about the mind and its various mental features like consciousness and self? Rather than minding our brain, we should mind the mind. Traditionally, only the mind can provide a guide to philosophy while the brain shows the road in neuroscience. Hence, the subtitle of the book seems to confuse not only mind and brain but, even worse, philosophy and neuroscience. Is this yet another of those books where one is forced to read nothing but the latest neuroscientific data explaining the mind? Those sorts of efforts are typical in the recently developed field of neurophilosophy. Roughly, neurophilosophy in the current sense of the term aims to apply neuroscientific methods to the investigation of what were originally philosophical concepts (like mind, self, consciousness, etc.). If you are familiar with neurophilosophy you may now want to ask about the nonreductive qualifier: Doesn t all neurophilosophy seek to reduce the mind to the brain by using neuroscientific methods in place of philosophical methods? The short answer is not any more. The approach to neurophilosophy in this book is nonreductive primarily in the methodological (rather than metaphysical) sense. Now, a longer answer: neurophilosophers so far have not distinguished between the metaphysical question of whether the mind can be reduced to the brain and the more methodological question of whether philosophy of mind should be replaced with neuroscience. To be sure, these matters seem to be tightly related. If the metaphysical claim that the mind is nothing but the brain is accepted, then neuroscience is likely to be championed as an investigative method because it engages with the brain. Similarly, the pace at which neuroscientific research is advancing seems to leave old-fashioned philosophical reflection about the mind behind, which may incline some to accept the superiority of neuroscientific methods over philosophical argumentation in regards to the mind. If one has the impression that neuroscience progresses more quickly than philosophy, then one might infer from this that the mind is nothing but the brain. Thus, acceptance of either the metaphysical claim (the mind is just the brain) or the methodological claim (neuroscience is more effective than pure philosophy) seems to encourage acceptance of the other. This is not mandatory though, and, as this book will show, there are good reasons to separate the issues. One reason is that neuroscientists do not ignore the mind, and increasingly attempt to shed light on mental/philosophical phenomena such as consciousness, or sense of self. These efforts can be facilitated by traditional philosophical considerations, and conversely may fail to address the philosophical issues as philosophers recognize them if the conceptual side of the work is not sufficiently considered. 1

5 2 Introduction Another reason to distinguish between metaphysical and methodological reductionism is that the much sought after reduction of the mind to the brain that has been the vision of neurophilosophy s first wave may be too limited a strategy. It is by no means confirmed that brains all by themselves are sufficient for the phenomenon of mind. The failure to distinguish between metaphysical and methodological reductionism has left neurophilosophy blind to the possibility that phenomena of mind result not just from the brain but from the brain in conjunction with its body and environment. The idea of reducing the mind to just the brain is not a necessary feature of neurophilosophy, and only seems to be so because neurophilosophers have been too busy enshrining the neuroscientific method over and against a traditionally philosophical approach to see that neuroscience and neurophilosophy dangle this philosophical loose end. To sum up, the approach to mental phenomena in this book is non-reductive first and foremost in the methodological sense, meaning that no particular method of investigation will be privileged. Philosophical considerations and empirical methods of neuroscience will both be welcome throughout, rather than either having to be reduced to the other (in a methodological sense). Our approach might also be said to be non-reductive in a subtler, and possibly controversial, way. As we will see, reductionism in the philosophy of mind is taken metaphysically to be more or less synonymous with reduction to the brain. By adding the body and the environment to the store of phenomena that can be appealed to in order to explain mental phenomena, our approach contrasts with mainstream reductivism about the mind. If non-reductive neurophilosophy as practiced in the book is compared with, say, Descartes philosophy of mind, it will appear thoroughly reductionist in that we reject the view that minds exist over and above brains, bodies and environments. However, if it is compared with standard neurophilosophy, it can be said to be non-reductive in rejecting the often tacitly presupposed metaphysical orthodoxy of the brain s sufficiency for mental phenomena (a relatively subtle metaphysical adjustment). While in methodological regard, most importantly, non-reductive neurophilosophy does not aim to reduce the practice of philosophy of mind to the practice of neuroscience but rather to profit from, and refine each. To reinforce this contrast between neurophilosophy as it has been practiced so far, and the approach of this book, we will use the phrase reductive neurophilosophy to refer to extant neurophilosophy, and non-reductive neurophilosophy to refer to the approach just outlined. Our burden is thus to show that neurophilosophy is possible without having to assimilate (and ultimately replace) philosophy to (by) neuroscience. It is to this end that we develop non-reductive neurophilosophy as distinguished from its currently predominating reductive sibling (see Part I). This will allow us to generate what I call a brain-based rather than brain-reductive approach to the mind and the mind-brain problem (see Parts II and III). To see how this can work, and work well, we first need to understand the concept of mind and how it originates in the history of philosophy. Mind and brain in past times: from the presence of mind to philosophy of mind Philosophy has always had a concern with the mind, and the custom of relating minds to specific organs in the body is typically ancient. For example, the ancient

6 Introduction 3 Egyptians, dating as far back as the third millennium BCE, thought the heart was the locus of our mind. Interestingly, there are old scripts showing that they were aware of the brain. Later, in ancient Greece, there was the medical doctor and philosopher Hippocrates who reasoned that the brain is the origin of mind: Men ought to know that from the brain and the brain only arise our pleasures, joys, laughter, and jests as well as sorrows, pain, griefs, and tears It is the same thing which makes us mad or delirious. Inspires us with dread and fear, whether by night or by day, brings us sleeplessness, inopportune mistakes, aimless anxieties, absent mindedness, and acts that are contrary to habit (Hippocrates, The Sacred Disease ). However, despite Hippocrates emphasis on the brain, ancient Greek philosophers like Plato and Aristotle associated mental features with a mind or soul. Then throughout the medieval ages and all the way through the sixteenth century, European philosophers reasoned that the mind should be associated with a specific mental substance. This mental substance, thought the French philosopher Rene Descartes ( ), must be distinguished from the physical substance that characterizes a person s body. Despite seeing them as fundamentally distinct sorts of entities, Descartes believed that the mind and body were connected in the brain s pineal gland. Descartes can be considered the first modern investigator of the relationship between mind and brain. He sought to give a clear definition of mind, and explain how its existence and reality relates to the physical world, including bodies and brains. This question regarding the existence and reality of mind and body/brain is called the mind body problem or the mind brain problem. Descartes interest in explaining how the mind interacts with the world has been shared by philosophers ever since (see Part II). Some even attempted to prove the existence of a mind experimentally. For example, at the beginning of the twentieth century, the physician Dr. Duncan MacDougall (1907) of Boston in an attempt to provide evidence for the existence of a mind or soul as mental substance weighed his patients shortly before and immediately after their death. He assumed that the mind or soul leaves the body after death and that as a mental substance the mind should have some kind of weight. This led him to suggest that the body would be lighter after death, since as the soul leaves the body, the weight of the deceased person will decrease. Indeed, MacDougall observed that two of his patients were lighter after death; this difference in weight he attributed to the mind or soul and its mental substance. In contrast, he did not observe this change in weight in dogs, which were assumed not to have a soul. Based on his experiment, MacDougall assumed the weight of the mind to be 21 grams. To him, this was proof enough that the mind or soul is a mental substance that is distinct from the body. What does this imply for the relationship between mind and brain? It shows that there is what philosophers call a dualism between the two: mind and brain can be characterized by different kinds of existence, namely the mental and the physical. This position can be traced back to Descartes and is still held by many philosophers today (see Chapter 5). The evaluation of different dualistic theories of the mind brain relation is a central concern for contemporary philosophy of mind. To put it in a nutshell, philosophy of mind investigates the existence or metaphysical nature of the mind and particular mental features like consciousness, free will, self, etc.

7 4 Introduction Mind and brain in present times: from the elimination of mind to reductive neurophilosophy Today, we seem to know much more than any of the historical figures discussed in the previous section. We now have much better tools and methods for investigating the brain and the mind. Neuroscience, the discipline that investigates the brain scientifically, provides unprecedented access to the brain and its neuronal states. It also investigates how the brain and its neuronal states relate to mental features like consciousness, the self, free will, emotions, etc. Neuroscience is widely taken to show that the mind is nothing but the brain. For example, neuroscientists can observe how the brain s neural activity changes in its different regions during experiences of emotion or the exertion of free will. We can inspect the difference between brains in conscious states and unconscious states, or investigate how the brain creates an experience of self. For instance, your feeling of excitement while reading these lines is accompanied with neural activity in specific regions of the brain that are different from those that are activated when you experience boredom. This type of investigation is made possible by functional brain imaging techniques like functional magnetic resonance imaging (fmri), which create visual representations of neural activity within specific regions of the brain. In addition to the facts about regional activities within the brain, neuroscience provides insight into the functioning of the brain s cells, the neurons, how they work and how their firing rate changes during mental tasks. This cellular investigation of neural activity is further complemented by additional research about biochemical substances, molecules, and genes in the brain. As we will see in this book, neuroscientists are actively working to explain mental features like self and consciousness by reference to these sorts of features of the brain. What does this imply for the mind brain problem? We must assume that the mind neither exists nor is real. There is simply nothing but the brain and its physical features. Mental features like consciousness, emotion, free will, etc., can then be traced back to neural features. This amounts to materialism, or physicalism as it is called in the current mind brain discussion (see Chapter 6). Despite this position having all the support of the neuroscience s success, it remains a controversial view. While most philosophers agree that bodies, environments, and brains are the entities that comprise the real world, the implications of this materialism/physicalism remain disputed. There are more or less radical interpretations of materialism/physicalism. Some philosophers acknowledge that the mind has an existence or reality of sorts which can be traced back to the brain and its physical features. Other philosophers go one step further and declare any assumption of a mind to be superfluous, and motivated by illusion; mental concepts like consciousness, free will, etc., are then regarded as illusions that need to be replaced completely by the terms and concepts of neuroscience. For instance, instead of describing emotions in mental terms like sorrow and grief, one could refer to these states by describing activation patterns in certain regions of the brain. This standpoint is called eliminativism in the current mind brain debate (see Chapter 6). Eliminativism has serious implications for the conventional view of philosophy as an autonomous discipline. According to eliminativism, any mental features

8 Introduction 5 including those underlying philosophy itself and our ability to philosophize must be reduced to (and ultimately eliminated in favour of) the terms of neuroscience. As explained above, the term neurophilosophy commonly refers to the work of eliminativist philosophers. Briefly, neurophilosophy refers to the investigation and application of neuroscientific methods to traditionally philosophical concerns like consciousness, self, free will, etc. (see Chapter 4). More specifically, the eliminativist viewpoint recently discussed falls under what I call reductive neurophilosophy. Briefly, reductive neurophilosophy refers to work wherein the mind in general, and mental features in particular, are taken to be completely and exclusively reducible to the brain and its neuronal features (see Chapter 4). Reductive neurophilosophy is therefore really just a part of neuroscience, more specifically its theoretical branch, where traditionally philosophical questions are investigated in the context of neuroscience. More technically, reductive neurophilosophy can be characterized by the search for those neural conditions, the neural correlates that are sufficient to generate mental features. For example, reductive neurophilosophers, who investigate consciousness, are commonly concerned with locating the neural correlates of consciousness (NCC) (see Chapter 14). Role of the brain: from neural correlates to neural predispositions The sceptics among you may now want to raise some doubt as to whether mental features like consciousness, the self, free will, etc., can be reduced to and consequently be located in the brain. Not even the most elaborate scanner has ever shown consciousness in the brain. All we see in images of the brain are visualizations of various forms of neural activity in different regions, cells, proteins, etc. This raises the possibility that since consciousness and the other mental features cannot be found within the brain, they cannot be completely reduced to forms of neural activity. In contemporary philosophy of mind, this view is called non-reductive physicalism. Most philosophers who are not eliminativists express non-reductive physicalist positions. Non-reductive physicalists have many different names for the sort of causal relation that holds between mental and physical phenomena (emergentism, supervenience, functionalism, etc. see Chapter 6), but they are united in the view that when claims about mental phenomena are put in purely neural terms their original content is lost. Non-reductive physicalists arguments for preserving a fundamental distinction between the mental and the physical casts doubt on the prospect of using neuroscience to shed light on the mind. However, the idea that neuroscience is not capable of shedding such light is also rather implausible, given the abundance of neuroscientific findings that demonstrate the contribution of the brain and its neural features to the generation of mental states. Let us review the dilemma at hand. We have presented the two main currents in contemporary philosophy of mind (eliminativism and non-reductive physicalism) and found both to be flawed. The eliminativist s vision of a complete reduction of mental features to the neural features of the brain may be empirically implausible because evidence that clearly indicates a location in the brain for mental features is difficult to find. However, non-reductive physicalism, whether it be emergentist, functionalist or based on supervenience does not seem to be empirically implausible

9 6 Introduction either. To deny that neuroscientific claims can be explanatory with respect to the mind clashes with a considerable body of neuroscientific findings. Thus both eliminativism and non-reductive physicalism seem not to be in sync with actual neuroscientific findings. Since neither eliminativism nor non-reductive physicalism is an attractive option, we need to find another way to make allies of neuroscience and philosophy. The alternative I present in this book involves a distinction between two different ways in which neural activity could be understood to underlie mental phenomena. As mentioned above, philosophers of mind typically inquire after the neural correlates of mental features, like consciousness. Those who search for neural correlates of mental features are trying to find neural processes that are sufficient for mental phenomena. In contrast, the non-reductive neurophilosophical approach outlined in this book (as inspired by Immanuel Kant and his transcendental method; see Part II), will investigate neural processes as necessary but not sufficient for mental phenomena. This subtle change allows us to begin investigating the brain s connection to the mind in a new and powerful way. Instead of the neural correlates that are meant to be sufficient for mental phenomena, we will study the neural predispositions of mental features. The neural predispositions of mental features are necessary for the possible (rather than actual) occurrence of those mental features, but they do not bring them about, e.g. their actual occurrence, by themselves. Technically, the concept of neural predisposition refers to the necessary conditions of the possible generation of mental features. This distinguishes neural predispositions from neural correlates, which are sufficient to actually realize and implement mental features (see Chapters 14 and 15 for the application of this distinction in the context of consciousness). General aim: from neural predispositions to non-reductive neurophilosophy We can now say more about what non-reductive neurophilosophy is. Put in a nutshell, non-reductive neurophilosophy considers the brain as relevant to philosophy but, unlike its reductive sibling, does not completely and exclusively reduce mental features to the brain and its neural features (see Chapter 4 for details). Instead, non-reductive neurophilosophy targets the relation of the brain s neural features to the vegetative features of the body and the social features of the environment (see Chapters 8 and 20). In addition to its distinction from reductive neurophilosophy, non-reductive neurophilosophy also needs to be distinguished from traditional philosophy and neuroscience. In contrast to traditional philosophy, non-reductive neurophilosophy explicitly considers the relevance of the brain for philosophical questions, and confronts issues that go beyond questions of mind (see Part III). For this, a specific methodological strategy that allows the linking and integration of conceptual and empirical approaches will be developed (see Chapters 2 and 4). How about neuroscience? Neuroscience focuses on the brain and aims to reveal the various neural mechanisms that operate in it. In non-reductive neurophilosophy, the focus is not so much on the inside of the brain itself but rather on how the brain s neural features relate and link the brain to the world beyond the brain: the body and the environment. Thus non-reductive neurophilosophy strives to put the brain and its neural features into bodily and environmental contexts.

10 Introduction 7 Consciousness in philosophy: the hard problem of the brain Can neuroscience solve the mind brain problem? Despite the impressive progress that researchers have made on general and regional neural activity, and even on cellular and molecular-genetic factors, neuroscience has not yet revealed the neural mechanisms underlying mental features like consciousness and self. While there are plenty of suggestions for possible neuronal mechanisms that might make consciousness possible, we have not yet solved the mind brain problem. We still do not know why there are mental features like consciousness and self, or how they are related to and yielded by a brain that on its own is not conscious and does not possess a self. Doubts about whether neuroscience promises to explain the mind usually appeal directly to consciousness. What is consciousness? The crucial characteristic of consciousness is that it is subjective, meaning that it is tied to an individual s first-person perspective as opposed to the objective (or third-person perspective) from which science describes the world. For example, while reading these lines, you may be experiencing a sense of boredom. Only you can experience that boredom. Your classmate, sitting just next to you, cannot experience your sense of boredom, even though she/he is forced to read the very same book. The way that consciousness seems to always involve the particular subjective experience of an individual seems to suggest that the phenomenon of consciousness is just not the sort of thing that can be discovered in the brain and its neural activity, which can only be observed from the third- person perspective. The question of how something as subjective as consciousness can be related to the objective brain has been perplexing philosophers since Descartes. Today, eliminativist philosophers and the neuroscientific work they draw on would claim that there is no real problem here. According to this sort of work, which I call reductive neurophilosophy, what seem like subjective states of consciousness will in due time be shown to be nothing but objective neuronal states of the brain. No way, you might say. I do not experience my brain. Nor do I experience any neuronal state; I experience boredom and the book in front of me. You are appealing to what philosophers call a mental state. In response to the many neuroscientists and philosophers who claim that all the mental states you experience as a conscious being are nothing but the neuronal states of your brain, the more non-reductively minded philosophers tend to ask why it is that nothing in the fancy scans of my brain can show me my particular mental states or what makes them conscious. Those who claim that consciousness can be reduced to neural activity are routinely challenged to explain why all the bright colours of brain scans fail to reveal an individual s subjective experience. Since consciousness seems to be a paradigmatically subjective phenomenon, while brains seem to be part of the objective world investigated by science, both skeptics and supporters of reducing the mind to the brain treat consciousness as a sort of Holy Grail for the field. Whether neuroscience promises to unlock the secrets of the mind is widely taken to turn on the question of whether a brain-based account of consciousness can be found. Thus, philosophers of mind ask Why is there consciousness at all?, or more specifically, How is it possible for the objective and nonconscious brain to give rise to something as subjective as consciousness? This is what the Australian philosopher David Chalmers described as the hard problem. The hard problem is a metaphysical problem that addresses the following

11 8 Introduction question: Why and how is there consciousness at all rather than none? Reformulated within the context of the brain, the hard problem becomes: How is it possible for the brain, which independently is nonconscious, to yield consciousness? Note that the hard problem of the brain is as metaphysical as the hard problem of consciousness : it shifts the brain from the empirical context of neuroscience to the metaphysical context of philosophy (see below). Metaphorical comparison: hard problem of the heart Can neuroscience solve the hard problem of the brain? Neuroscientists have provided considerable insight into the brain and how its neuronal states are related to mental states, and various suggestions have been put forward for the neuronal mechanism of consciousness, the so-called neural correlates of consciousness (NCC). However, none of these candidates for the NCC has yielded a definitive answer to the hard problem. We still do not know why and how something as non-conscious as the brain and its neuronal states gives rise to consciousness. How can we better understand the current shortcomings of neuroscience with regard to consciousness? Let us draw an analogy to the heart. The heart is a pump that circulates blood throughout the whole body. Just as the brain gives rise to consciousness, the heart gives rise to the pumping of blood throughout the body. One can ask what it is about the heart that results in blood-pumping, just as philosophers ask what it is about the brain that results in consciousness. If an explanation of how the heart pumps blood was still being sought, then there would be something like a hard problem of the heart. People would be pondering how something as odd as a heart could do the job of circulating blood throughout the body: Why is there pumping rather than none? As it is, we already know what it is about the heart that accounts for it being able to pump blood, and it is not simply a matter of this function needing to be performed somewhere in the body. The heart is a muscle that contracts repeatedly and continuously, and it is precisely this activity that results in the circulation of blood throughout the body. The continual contraction of a heart is sufficient in itself to explain how blood is circulated throughout the body. That the heart behaves in this way makes the pumping of blood unavoidable (or necessary). This allows us to clarify what is distinctive about the hard problem of consciousness. While it is widely accepted that the brain does give rise to consciousness, we do not yet know what it is about the brain that makes the generation of consciousness unavoidable (or necessary). Unlike the heart, of which we know both how it pumps blood and why it must, even the most cutting-edge neuroscience has yet to explain what it is about the brain that makes the generation of consciousness not only possible but unavoidable, i.e. necessary. While the hard problem of the brain remains unresolved at this point in time, the secrets of the heart were discovered some time ago. They are both organs of the body, however, and we will therefore continue to turn to the example of the heart to clarify the sorts of questions asked about brains. We have already clarified that the hard problem of the brain seeks not just to discover what it is about brains that generates consciousness, but rather seeks an explanation of what it is about brains that makes the generation of subjective conscious experience unavoidable in the

12 Introduction 9 way that the heart s continuous contraction makes blood-pumping necessary and thus unavoidable. We are not interested just in the functions or purposes of mental phenomena as they appear to common sense, but in the actual mechanisms underlying these phenomena, whether they are purely neural or connected to bodily and/ or social phenomena. Knowledge of the brain: dark spots and the explanatory gap problem How can we get to work on the hard problem? One clear option would be to simply combine our knowledge about both mental and neuronal states. We can describe mental states in terms of mental concepts like boredom, excitement, etc., and pool these facts with all our knowledge about the brain s neuronal activity. Then we could simply investigate which mental concepts correspond to which neuronal concepts. The hard problem is not that easy of course. One would soon notice that the concepts used to describe the brain and its neuronal states (neuronal concepts) do not overlap at all with those used to refer to mental states (mental concepts). In other words, there seems to be an explanatory gap between neuronal and mental concepts: neither sort of concept can be used to explain the other. Let s go into more detail. Mental concepts do not contain any reference to the brain and its neuronal states. You do not experience your brain, let alone the neuronal states of your consciousness. For instance, one can experience excitement due to an upcoming soccer match. One does not, however, experience the specific neuronal activity pattern that is supposed to underlie the experience of excitement. Thus, mental concepts seem unrelated to the brain and its neuronal states. What about starting with neuronal concepts and trying to link them with mental concepts? We use neuronal concepts like the action potential of neurons or degrees of signal changes in specific brain areas to describe the brain s neural activity on cellular and regional levels. Nothing in these neuronal concepts, however, refers to the mental concepts one uses to describe experience or mental states. Hence, these neuronal concepts do not themselves imply anything about mental concepts. The result is a gap in our knowledge about neuronal and mental concepts. This gap between our neuronal and mental explanations is described as the explanatory gap problem in current philosophy of mind. Rather than being a metaphysical problem about the existence and reality of the mind, the explanatory gap problem is epistemological, referring to a gap in our knowledge of mental and neuronal states. Metaphorical comparison: explanatory gap in our knowledge of the heart How can we better illustrate the explanatory gap problem? Let s invoke the comparison with the heart again. We can discuss the activity of the heart with two different kinds of concepts. First, we have the concepts that describe the heart as an example of a pump; these are engineering concepts like dynamics, velocity, etc. Second, there are those concepts that describe the processes underlying the heart s muscle contractions in physiological or biological terms; examples of these physiological concepts include adenosine, ATP, etc.

13 10 Introduction How are the physiological and engineering concepts with which we can describe the heart related to each other? At first glance, they are as distinct as the mental and neuronal concepts with which the mind or brain can be described, because nothing about the physiological concepts seems to tell us about the engineering concepts, and vice versa. For example, the biochemical adenosine is a physiological concept that does not contain any reference to velocity, an engineering concept. If scientists still lacked an understanding of how the physiological characteristics of the heart make its engineering characteristics inevitable or necessary, there would be an explanatory gap between our understanding of what the heart is and what it does. In the case of the mind and the brain, we do not yet have an analogous understanding of how the brain s neuronal features account for the mental features it generates. The explanatory gap refers to a specific dark spot in our current explanations, a lack of knowledge that would explain why mental features must result from the brain s neuronal characteristics. In response to the explanatory gap, non- reductive neurophilosophy makes a methodological move: rather than attempt to analyze concepts of mind in such a way that assimilates them with neuronal concepts (a mind-based metaphysical pursuit), we investigate different ways of thinking about brains to try to discover what neuronal concepts can imply about mental concepts (a brain-based empirical pursuit). Problems in philosophy: concept(s) of the brain We have looked at three key problems concerning the mind and brain. Since Descartes, the mind body problem has challenged philosophers to explain how the mind and the body can both be real and related to each other despite seeming to have different sorts of existence or reality. The more contemporary hard problem singles out consciousness as the aspect of mind for which it is most difficult and thus also most important to provide a physicalist or brain-based explanation. Lastly, the explanatory gap problem describes the missing knowledge that would be needed to connect neuronal and mental concepts. How can we solve these problems? Philosophy in general and philosophy of mind in particular discusses these questions in predominantly conceptual ways. Philosophers of mind define and analyze the various concepts of concern in all sorts of ways in order to get nearer to solutions for these problems. While this has stirred much lively discussion, none of the problems has been solved. And so it has been suggested that the predominantly conceptual methodology of philosophy of mind will not be able to solve these puzzles on its own, however effectively it exposes them. This claim is common in neuroscience and usually explicit in its recent theoreticalphilosophical branch (usually just called neurophilosophy, which we refer to as reductive neurophilosophy). Rather than discussing these problems in a conceptual way, reductive neurophilosophers address these questions empirically, drawing on experimental findings from neuroscience. According to reductive neurophilosophy, the deep philosophical questions about the mind and its mental features should be resolved by careful observation of the brain. Why, then, consider the brain in the context of philosophy, as suggested by the title and sub-title of this book? If neuroscience can provide all the answers, why

14 Introduction 11 should we bother with philosophy at all? The oddness of considering the brain as its own philosophical subject can be further reinforced by the idea that the brain is simply not a subject for philosophy because it is already the subject of neuroscience. Many would say that consciousness, the self, and the mind are subjects of philosophy but that the brain belongs to science. Hence, shifting the brain into the context of philosophy may be a kind of methodological mismatch similar to, say, studying the Mona Lisa with a spectrometer. Rather than arguing directly against these vague charges, the whole of this book will serve as counter-evidence to the claim that philosophers should leave the brain to the neuroscientists. We will simply proceed to consider the brain in the context of philosophy and let the accumulation of results speak for themselves. The challenge at hand is to put the brain into the context of philosophy without reducing philosophy to neuroscience, as in reductive neurophilosophy. To avoid this kind of reductionism, we simply need to consider different ways of conceptualizing the brain, just as philosophers have been doing with the mind. One way of doing this is to generate and evaluate the results of defining the brain according to the different features without which the brain would no longer be a brain. The non-reductive neurophilosophical approach investigates the brain and the features that account for it as a brain, rather than the brain features that correlate with mental features (see Chapters 8 and 12 for details). The advantage of taking the brain to be conceptualizable in multiple ways is that we can fine-tune our brainbased approach according to the problem at hand, rather than treating the brain merely as the mind s empirical counterpart. Rather than investigating the brain in solely empirical terms, as is done in neuroscience, we will tackle the brain conceptually by proposing different concepts of the brain. This methodological agility is the crucial difference between non-reductive neurophilosophy and its better-known reductive variants. Welcoming the brain into the context of philosophy allows the non-reductive neurophilosopher to investigate the old problems of mind in many new ways. While neuroscientists continue to study actual brains, and philosophers go on pondering the mysteries of mind, we will focus on the concept of the brain, which will enable us to incorporate both the empirical results from neuroscience and the conceptual gains of philosophers. Investigation of the brain in philosophy: brain in different domains How can we investigate the brain in philosophy? The usual answer, common to reductive neurophilosophy as well as traditional philosophy, is simply that we can t. The brain belongs to the empirical domain which is the stronghold of the discipline of neuroscience. In contrast, philosophy is traditionally insensitive to the empirical domain and more occupied with the metaphysical and the epistemological domain. Since the brain does not belong to either, the brain is simply not a subject of philosophy. (See the illustrations in Figure 1.). As discussed, this is regarded as simply unacceptable by the reductive neurophilosopher. Neuroscience shows that the brain must be attributed a central role, and this has inspired some philosophers to give up the mind and focus on the far more observable brain. Thus reductive neurophilosophy, which has dominated the field of

15 12 Introduction Metaphysical domain: Existence and reality Epistemological domain: Knowledge Mind Figure I.1 Different disciplines and their domains Figure I.1a Philosophy of mind The figure illustrates different domains in philosophy, neuroscience and neurophilosophy, and how they relate to mind and brain. (a) The figure shows the traditional association of the mind with the domains of metaphysics and epistemology as it has been (and still is) dealt with in philosophy in general and philosophy of mind in particular. Empirical domain: Observation in thirdperson perspective Figure I.1 Different disciplines and their domains Figure I.1b Neuroscience (b) The figure shows the association of the brain with the empirical domain as the hallmark feature of neuroscience. neurophilosophy up to now, is both a methodological endorsement of neuroscience and a methodological indictment of traditional philosophy. It seems that if we focus on the mind, as in traditional philosophy, we must sacrifice accountability to neuroscientific facts, while if we focus on the brain, as in neuroscience, we must sacrifice accountability to the conceptual arguments of philosophers. To resolve this dispute, we will chart a third way. Direct engagement with the concept of the brain is not a part of either traditional philosophy or reductive

16 Introduction 13 Metaphysical domain: Existence and reality Epistemological domain: Knowledge Empirical domain: Observation in thirdperson perspective Mind Figure I.1 Different disciplines and their domains Figure I.1c Reductive neurophilosophy as brain-reductive approach (c) The figure demonstrates how the epistemological and the metaphysical domains including the mind are reduced to the empirical domain and the brain in neurophilosophy which therefore can be characterized as reductive neurophilosophy. neurophilosophy, but it is sensitive to influences from both areas. Non-reductive neurophilosophy delineates different concepts of the brain as it appears in different discussions, whether they are metaphysical, epistemological, or empirical. To explain how, we need to clarify the concept of a domain. What do we mean by the concept of domain? Originally the concept of a domain comes from the Latin terms dominium, dominus and domus : Dominium describes property, dominus refers to lord, master, or owner, and domus stands for house. These distinct though related meanings are reflected in the various uses of the concept of domain in our current language. Domain in today s usage can describe a territory governed or ruled; a field of action, thought or influence; a region characterized by specific features; and range of significance. Within the present neurophilosophical context, one can for instance, distinguish between different domains like metaphysical, epistemological and empirical: the metaphysical domain concerns questions of existence and reality, the epistemological domain is about the territory of knowledge, while the empirical domain refers to the field of observation. Subject matter and method of investigation: domains and disciplines The term domain is used in different disciplines like biology, mathematics, computer science and physics. Within the present neurophilosophical context, the concept of domain shall describe the territory, topics, issues, areas, or fields of investigation and thus the questions discussed. This means that we need to distinguish the concept of domain from the one of discipline that in addition to the discipline s field also entails a particular methodological strategy (see Chapter 2). Roughly, the concept of domain concerns the field or area of investigation and thus particular issues or questions as independent of and distinguished from the kind of methodological strategy by means of which these questions are investigated. Put in a slightly distinct way, the concept of domain concerns the subject matter whereas the concept of discipline refers more to the method that is applied to investigate that subject matter.

17 14 Introduction Metaphysical domain: Existence and reality Epistemological domain: Knowledge Empirical domain: Observation in thirdperson perspective Mind Figure I.1 Different disciplines and their domains Figure I.1d Non-reductive neurophilosophy as brain-based approach (d) The figure shows that the brain and its originally empirical domain may serve as a basis or neural predisposition for the metaphysical and the epistemological domains and thus for the mind. This implies nonreductive rather than reductive neurophilosophy. We thus distinguish between the subject or matter of investigation, the domain, and the method of investigation, the discipline. More informally, we can describe a particular investigation by distinguishing its matter and its method. The advocate of a traditional discipline like philosophy may want to argue that matter and method of investigation are strongly tied together. For instance, in the history of philosophy the investigation of metaphysical matters, the existence and reality of for instance the mind, has been closely tied to the rational-argumentative method. This may indeed be traditionally so in philosophy. However, the more recent history in especially the second half of the twentieth century shows that such close alignment between matter and method of investigation is no longer a given. Reductive neurophilosophers, for instance, claim that we can investigate metaphysical issues like the existence and reality of the mind in an observational-experimental way rather than using the rational-argumentative method of philosophy. The matter of investigation, the metaphysical domain of existence and reality, becomes here decoupled from its traditional method (and discipline), the rational-argumentative strategy (of philosophy), and then associated with another method, the observational-experimental strategy, and discipline, neuroscience. It is because the line dividing philosophical and scientific investigations has been blurred like this that we must carefully distinguish the domain, the matter of investigation, from the concept of discipline, which signifies the method of investigation. The concept of domain refers to the field, topic or question and thus to the matter of investigation whereas the concept of discipline describes a particular methodological strategy, the method, that is applied to investigate the respective field, the matter. We will see over the course of this book that this distinction between matter and method of investigation and thus between domain and discipline will prove central in understanding how the brain can be profitably incorporated into philosophy. Moreover, we will see how different forms of the relationship between domains and disciplines entail different forms of neurophilosophy, reductive and non-reductive

18 Introduction 15 (see Chapter 4). Hence, I will use the concept of domain and its distinction from disciplines as one of the guiding ideas in this book. Instead of employing the usual classification of disciplines, I will speak more often of domains the fields, questions, or matters of investigation. This will make it possible to approach particular domains with different methodological strategies a hallmark of non-reductive neurophilosophy (see Chapter 4). Brain in philosophy: from philosophy of mind to philosophy of brain In short, we will develop what can be called a philosophy of the brain as distinguished from both philosophy of mind and neuroscience of mind. Philosophy of the brain refers to the investigation of the brain and how it can be defined and conceptualized in different domains (metaphysical, epistemological and empirical), as well as how we can (and cannot) relate the domain-specific definitions of brain to one another (see Chapters 7, 8, 11, and 12 for details). (See Figure 1.1e.) Unlike neuroscience of mind in particular and neuroscience in general, philosophy of the brain is not restricted to the empirical domain but includes the metaphysical and epistemological domains. Similar to neuroscience though, philosophy of the brain focuses on the brain as its main content or subject matter of investigation. However, unlike neuroscience again, philosophy of the brain applies a multitude of different methods to the investigation of the concept of the brain, combining observationalexperimental and conceptual-logical strategies for instance (see Chapters 2 and 4). The overarching goal of this book is to demystify the brain. We do not need to assume special supernatural features like a mental substance to account for what philosophers recognize as mental phenomena. Instead, we can remain within the natural realm of brains, bodies and environments. We will see that a mixture of Metaphysical domain: Existence and reality Epistemological domain: Knowledge Empirical domain: Observation in thirdperson perspective Figure I.1 Different disciplines and their domains Figure I.1e Philosophy of brain (e) The figure illustrates the discussion and investigation of different concepts and definitions of the brain in different domains as the hallmark feature of philosophy of brain.