The Conscious Self: Ontology, Epistemology and the Mirror Quest

SPECIAL ISSUE: ORIGINAL ARTICLE THE CONSCIOUS SELF: ONTOLOGY, EPISTEMOLOGY AND THE MIRROR QUEST Alexei V. Samsonovich1 and Giorgio A. Ascoli2 (1Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA, USA; 2Krasnow Institute for Advanced Study and Psychology Department, George Mason University, Fairfax, VA, USA)

ABSTRACT Here we address the notion of the self as the subject of experience, in contrast with its other popular meanings of a state of self-awareness, a body image, or a narrative center. In this perspective, the main player is not consciousness per se (the famous “hard problem”), but its subject. We start by showing that the self as the subject of immediate self-awareness cannot be conceived as an illusion. Then we formulate axioms of the self-concept based on the framework that Chalmers initially developed for consciousness. Using a thought experiments (the “mirror quest”), we show that this framework may require corrections in order to accommodate the subject. We analyze several possibilities that lead to a novel doctrine of “subjective nonreductive functionalism”. As an epistemological model, this position has further important implications for brain sciences. Key words: brain-mind, consciousness, hard problem, self-awareness, subjectivism

INTRODUCTION There are many ways to understand what is the self, or the “I”. Usually when scientists talk about the self in relation to a human subject, they mean either the identity of the individual, as opposed to others, or the narrative center (i.e., the “main hero”) of all subjective experiences and memories in a given individual, or else the subjective feeling of self: self-awareness. The self is seldom considered as the agent-author of cognitive acts or as the target of attribution of mental states, and almost never as the subject who has the firstperson experience (Figure 1, p. 622). Nevertheless, we believe that the latter, the subject, is the main essence of the self-concept, and in this particular aspect the notion of the conscious self is addressed in the present work. The study of the concept of the self has a long history, and its popularity is growing with time. The concept of a soul was known at the times of Plato and Aristotle, however, the division between the physical and the mental known now as the Cartesian cut was formalized only some 300 years ago by Descartes. At the same time Descartes introduced the concept of “I”, or the self, together with its main fundamental properties, such as individuality, indivisibility, localization and continuity in time (Descartes, 1637/1985). Descartes identified the notion of the self with the notion of mind and posited the existence of “I”, or the self, as a fundamental substance that is not material, is not located anywhere in the physical world, but exists continuously over time as an atomic entity. Descartes claimed that each of us is Cortex, (2005) 41, 621-636

a “union” of two sorts of substance: mental and material. The existence of the self as a purely mental entity (known as a Cartesian soul) was intuitively obvious to Descartes: “I know that I exist; the question is, what is this ‘I’ that I know?” (Descartes, 1637/1985, vol. 2, p. 18), although he did not make an explicit distinction between phenomenal and functional aspects of the self. Relationships between the two substances, however, could not be clarified within the Cartesian dualism, and thus alternative theories were called into existence. Spinoza (1677/1955) introduced a unified parallelist view, regarding the mind and the body as merely different aspects of a single substance. Berkeley (1710/1734) rejected the existence of the physical reality in favor of the mind taken as the primary substance. Hume (1739/1965) separated the notions of the mind and of the self, rejecting the existence of the latter as a real entity. According to Hume, the self is merely an illusion constructed by a conscious mind: “For my part, when I enter most intimately upon what I call myself, I always stumble upon some particular perception or other, of heat or cold, light or shade, love or hatred, pain or pleasure…” (Hume, 1739/1965, vol. 1, p. 6). The “entity-illusion” dilemma related to the self-concept was not satisfactorily clarified by the criticism of Kant (1781/1929), for whom the fundamental errors of the mind were the main issue, nor does it stand as a resolved issue at present. Several modern philosophers defend the concept of the self understood as a mental reality. For example, according to Strawson (1997), the self “…exists at any given moment of

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Fig. 1 – Three different meanings of “self” can be exemplified by three instances of Mary, each of a different nature. A: a subject of awareness. Mary, a person, is a subject of awareness with respect to her mental image of an apple – an object. In addition, in this case Mary may be also a subject-observer with respect to the real apple; however, the first relation is more important for us in the context of the present work. B: a target of attribution of beliefs. In John’s mind, a concept of Mary is the target of attribution of a concept of a belief about an apple. In other words, John attributes to Mary a belief that there is an apple. A similar act of attribution could be done by Mary herself, even though she may not believe that there is an apple in this case: e.g., Mary can assume theoretically that she has this belief, without having the belief in the first place and without assuming that there is an apple. Therefore, the attribution per se, as a semantic or a functional relation, does not make Mary conscious of an apple, while a state of being the subject of awareness does. C: a narrative center. Mary’s biography frequently and consistently refers to one and the same character named Mary, which is therefore a narrative center of the biography. Of course, written biographies are not in and by themselves conscious, nor do they entail consciousness or “subjecthood” in their narrative centers or authors.

consciousness… and is as much a thing or object as any G-type star or grain of salt”. Here the underlying philosophical position is the “naturalized Cartesianism” (Strawson, 1994) that couples materialism with the belief in real existence of conscious mental phenomena. Strawson (1997) is, however, cautious about using the term “entity”: his main reason to believe in the self appears to be the subjective feeling, or the sense of self, rather than the logical necessity for any conscious experience to have a subject (the one who has the experience). In contrast, the mainstream position with respect to the self in modern cognitive psychology and philosophy of mind continues the line of Hume (1739/1965) and James (1890/1950) up to extreme nihilism. For example, Dennett (1991) attempts to "reduce" the self as the subject of experience to the center of narrative gravity. Blackmore (2000, 2002) follows and radically expands this view, claiming that both the self and consciousness with all of its

contents are mere illusions. A similar concept is expressed by Metzinger (2003): “No such things as selves exist in the world… for ontological purposes, ‘self’ can therefore be substituted by PSM (phenomenal self-model). However, this first reading of the concept of ‘being no one’ is only an answer to a crude traditional metaphysics of selfhood, and I think as such it is a rather trivial one.” Again, the logical necessity for a subject of conscious experience is completely ignored (an act moreover called “trivial”). In our view, this general trend in the contemporary literature amounts to denying certain basic psychological and philosophical concepts a legitimate scientific status: a position known as eliminative materialism (Churchland, 1988). The two main positions taken by modern philosophers with respect to the self, i.e., that (a) the conscious self is an illusion, or that (b) it is a “thing” that cannot be reduced to physical properties of any sort, both derive from the

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empiricist traditions. There are, however, philosophical approaches deviating from these traditions. One of these, known as “downward causation”, relates to the possibility of emergent mental properties (e.g., ‘emergent interactionism’; Sperry, 1969). According to this position, a given state of consciousness is chosen among a series of conscious states made possible by the nervous system at a certain moment. The decisive point in this choice lies on the higher, psychic level. It is the previous states which determine or select which one of the possible states of consciousness should be realized (hence the interactionism). Although some of these ideas may resonate with the discussion in the present work, we have to stress that we base our study on empirical data and on objectively derived facts and logic. The modern neuroscientific picture of the brain as a dynamical system sheds no light on the origin of many mental properties associated with it, including the subject-self, free will (Wegner, 2002), qualia, and consciousness. Perhaps the most popular scientific view, among those who do not reject these issues as irrelevant to science, can be broadly characterized by the doctrine that the mental supervenes on the physical (e.g., Kim, 1999). According to the supervenience principle, things which are physically indistinguishable are mentally indistinguishable. In other words, given all physical facts, one could in principle tell all mental facts. Stated differently, each mental feature is entailed by a particular physical feature (e.g., a certain pattern of neuronal firing in such-and-such brain areas entails given subjective feelings). For short, in the text below we call this determining physical feature the substratum of the mental feature (although the term "correlate" could be acceptable too, traditionally it has more narrow semantics involving an objective measurement). Chalmers (1996) accepts the general supervenience doctrine, adding that the supervenience principle should be taken in the local, weak, functionalist sense, with the following meaning. (i) “Local” means that the principle works for a given physical object or a given part of the world taken separately, not just for the entire world as a whole. (ii) “Weak” means that the supervenience relation implies merely a correlation rather than a logical necessity. One of the supporting arguments for this view is the logical possibility of zombies objectively indistinguishable from us, yet lacking conscious experience (a notion not to be confused with zombie states as psychological conditions). It follows that, in general, experience is a metaphysical property, which is not reducible to physical properties of its substratum, or any physical features at all (property dualism). This circumstance has been well captured by a set of philosophical arguments, from Leibniz’s mill (1714/1840) to Nagel’s bat (1974), Block’s absent qualia (1978), and Searle’s Chinese Room

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(1980). As Chalmers argues, the existence of subjective experience cannot in principle result from any physical law, and therefore it must be postulated based on intuition. (iii) “Functionalist” means that mental states do not critically depend on the specific physical nature of the substratum (e.g., brain tissue versus silicon chips). On the contrary, the principle of organizational invariance is all that matters for instantiation of mental properties. This principle is based on Shannon’s (1948) concept of information, which disregards semantics, or meaning of the information: the substratum is viewed in this case as a pattern of causal interactions abstracted from the instantiating medium. This claim is supported by strong arguments, including “fading qualia” and “dancing qualia” (Chalmers, 1995). In this respect it is worth mentioning that recent experiments with rewiring visual pathways to auditory cortex in ferrets (Sur, 2002) suggest that the choice of the medium objectively does not matter. Chalmers (1996) only tangentially addresses the problems of the subject-self concept, focusing instead on the analysis of experience per se. The question therefore remains open as to whether the supervenience doctrine could be extended in order to accommodate the subject of experience, the self. Is a scientific self-concept possible, and, if yes, what sort of a concept can it be? We address this question in the present work with the following strategy. We start by analyzing the view of the self as an illusion and show its logical inconsistency. Then we formulate an entity-self concept in a manner consistent with the supervenience doctrine and based on intuition. We further analyze this concept ontologically using a thought experiment. This is done, first, in an third-person philosophical framework (which leads to a failure), and second, in a first-person framework. Then we revert to an epistemological analysis of the self-concept and derive general cognitive-psychological implications. THE SELF AS AN ILLUSION Intuitively, it is hard to accept that the subject of experience is an illusion, because our life, all of our experiences, the perception of everything that we can possibly perceive in the world is for us nothing but the being of our own self. The assertion “I am” may even appear intuitively more convincing than the other, famous Cartesian “I think, therefore, I am”, or any logical or pseudological argument in general. Yet it is reasonable to ask: does logic support the intuition that the self is not an illusion? The answer is “Yes”, as we argue in the following paragraph (c.f., Evans, 1970). To be specific, we are going to show that the concept of “illusory self” contradicts the existence of natural, subjectively experienced states of immediate self-awareness.

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Is “I” an illusion? (Or, “am I an illusion?”) If “I” is an illusion, then who is having this illusion? The notion of an illusion presupposes a subject: an observer or a believer who is suffering from the illusion. Who is this subject? The answer that this subject is another illusion does not solve the problem, because it raises the same question again (“who, then, is the subject of that illusion?”), thus leading to an infinite regress. The answer that the subject is the same illusion does not lead to a solution either: the word “illusion” means a perceptional error or a false belief, thus implying that the object of illusion (the very illusory feature) does not exist. Since in any sense of the word “existence” (real, imaginary, etc.) a thing cannot definitely exist and not exist at the same time, the object and the subject of one and the same illusion logically cannot be one and the same thing. In a mental state of self-awareness, an instance of the self S is aware of itself (i.e., of the very same instance S). Therefore, S is at the same time the object and the subject of this mental state, and we conclude that this mental state logically cannot be an illusion. Thus the concept of the self viewed as an illusion proves to be logically flawed. It might be worth mentioning here that the requirement for a subject of an illusion might appear as a metaphysical holdover from natural language. Philosophers have given this argument: thinking happens only in living things, machines are not living things, therefore machines cannot think. The claim that conscious experiences require a subject might be no better founded than that thought requires life. Grammatically, a subject is required if we report a conscious experience, but this may be no more significant than the fact that when we want to report that rain is occurring we have to say ‘it is raining’ – this does not imply that there is some metaphysical subject of weather states. Nonetheless, we hold that, while it is possible to produce verbal introspective reports without consciousness (in a machine or in a human zombie state), it is not possible to be conscious without being a subject, i.e., without being a self. Grammatically, both English sentences, “I am conscious” and “it is raining”, require a subject; however, logically, the concept of rain does not imply a subject who “rains”, while the concept of consciousness does. Our argument does not rely on natural language or any linguistic feature. Nevertheless, the linguistic tautology and contradiction of “the self calling itself an illusion” could be taken as a complementary point to the argument presented above. Similarly, the logic of the existence of the subject-self as a reality is unaffected by Lichtenberg’s (1793/1994) criticism of the Cartesian “cogito”: according to Lichtenberg, Descartes was only entitled to the claim ‘Thought occurs’, not the claim: ‘I am thinking’. While, again, this is correct from a linguistic point of view (given certain semantics of

‘I’), we do not infer the self from the existence of thoughts per se. As explained above, a mental state of S with the content “I am”, in which “I” refers to S, logically cannot be conceived as an illusion, and therefore, given this state as a datum accessible to human experience, S cannot be an illusory feature. Thus, if I really believe that I am (i.e., the foregoing mental state is instantiated in my brain), then, indeed, I am (i.e., my self exists). This conclusion is by no means trivial (e.g., Metzinger, 2003; see also Ascoli, 1999a). In particular, the next section addresses the question of the existence of such mental states. Assuming for the moment that the above mental states indeed exist, we have established that, at every moment of conscious life in which the subject is self-aware, there is a non-illusory self, the possessor of experiences (a logical subject). Nevertheless, there seems to be no guarantee that one and the same self persists through time: the instance of the self we proved not to be an illusion is momentary and has no time extent. The subject of all ‘my’ remote experiences could still be an illusion. For example, a false memory could have been implanted in my brain under hypnosis, or, in principle, my body could have been destroyed five minutes ago, and substituted by an identical duplicate in the same environment, with all the same memories. If it is presumed that the self cannot survive this process (we shall return to this topic below), then this subject would probably think that it had a persisting and continuous, longterm existence. Setting aside externalist interpretations of this version of the swampman argument (Dretske, 1995; Tye, 2004), it appears that this subjective feeling could be illusory. This logic, however, fails at a sufficiently short time scale. Indeed, every elementary instance of conscious experience is extended over time. On the one hand, experiments have established that an elementary conscious act (e.g., a volition to move a finger; Libet et al., 1979; Libet, 1985) has objective representations in the brain that are distributed in time at the scale of hundreds of milliseconds. On the other hand, the subjective perception of time is itself “smeared” approximately at the same time scale, and cannot “resolve” two arbitrarily close moments, similarly to the inability of a naked eye to resolve two dots separated by a micron. Perception of time never goes down to nanoseconds: two consecutive nanoseconds of conscious mental life in a human subject belong to one and the same temporal instance of conscious experience. The associated instance of the self only makes sense as one instance of the self extended over time, not as two or more consecutive instances of zero duration. Therefore, the self as the subject of experience possesses a finite temporal extent. While brain tissue could in principle be destroyed and replaced

Ontology and epistemology of the self

with a duplicate every nanosecond, the subject-self could not, for there is no known conscious experience or mental state in general that can be defined or understood as lasting for a time interval that short. Similarly, the concept of tsunami wave makes sense at the scale of miles of open water, but not referred to a single water molecule. We conclude that the claim that the self as the subject of conscious experience is not an illusion must hold for a finite time interval. In the next section we shall consider the question of how long this time interval is. Here we point out that, in general, one should be careful when considering time in connection with the self (c.f., Husserl, 1905/1990; Lemmon and Moore, 2001). The subjectivity of the self implies the lack of a simple relation between time perceived subjectively (“subjective time”, or the proper time of the self) and physical time, i.e., the timing of physiological events supporting the process of perception in the brain (Libet et al., 1979; Libet, 1985). These two concepts of time belong to different frameworks: the first-person perspective of the subject and the objective view of the world. It is not surprising that they cannot be perfectly mapped onto each other at a small time scale. We assume, however, that subjective time and physical time are unambiguously related at a large time scale. THE SELF AS

WE KNOW IT

In this section we proceed to formulate a selfconcept, step by step, by building assumptions and axioms based on intuition and relying on a framework that was initially developed by Chalmers (1996) for the description of consciousness. Here by "intuition" we refer to immediate, vivid and distinct experiences, as opposed to guesses about general facts of the world. In the previous section we assumed one’s immediate belief in his/her own existence, and ruled out a possibility that the subject of this belief could be an illusion. We now question that assumption: is there sufficient evidence for immediate, vivid and distinct beliefs in one’s own existence, i.e., beliefs in existence of the believer taken in the very same instance when (s)he has this belief? Based on intuition, we postulate (the “zeroth” axiom) a positive answer: vivid and distinct experiences of this sort exist and are, in fact, very common. Therefore, we disagree with Blackmore (2002), who proposes that there are no vivid and distinct experiences in general (as well as consciousness and the self in particular). While self-evident to most of us, this postulate may be hard to accept as a scientific axiom, similarly to any subjective inference from private, first-person data that is not supported by objective material evidence. It may be equally difficult to “prove” the existence of the world (Grossmann,

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1992), yet this circumstance does not prevent us from living in (and scientifically investigating) the world. In the words of Chalmers (1996): “…I cannot prove that consciousness exists. We know about consciousness more directly than we know about anything else, so ‘proof’ is inappropriate. The best I can do is provide arguments wherever possible, while rebutting arguments from the other side. There is no denying that this involves an appeal to intuition at some point; but all arguments involve intuition somewhere, and I have tried to be clear about the intuitions involved in mine”. A similar statement applies to the existence of the experience of being oneself. We cannot prove or disprove it; therefore, we postulate it based on intuition. Note that, instead of immediately postulating the existence of the self, we claim that it suffices to postulate the experience of immediate self-awareness, to then logically deduce the existence of the self. The rationale for this longer step is that it may be easier for a modern scientist to accept the reality of a mental state than the reality of the self. Immediate vivid experiences of mental states may also be more familiar than direct vivid “experiences of self”. It may be useful to compare this position with alternative points of view, which are popular in the current philosophical literature. The mainstream positions in cognitive philosophy and psychology are most commonly rooted in the third-personperspective. This encourages the claim that there are only experiences (or mental states), and no self (e.g., Metzinger, 2003). However, as discussed above, this claim becomes hard to defend if the self is meant as the subject of experience. Indeed, if there were such “subjectless” states, how would anybody know about them? From the point of view of a subject, two types of mental states can in fact be distinguished: those that the subject does not possess (e.g., mental states in the brains of other people and, possibly, some states in the subject’s own brain, which may not be consciously accessible), and the subject’s own present, immediate, vivid and distinct experiences. The main difference between these two kinds of mental states, i.e. the relation to their subject, may not be obvious for a third-person observer, e.g. a scientist studying the subject, but is clear for the subjects themselves. This distinction is also tangentially expressed by Rosenthal (2003): “Suppose that one is in some mental state – one has, say, a thought or desire or emotion – but one is in no way whatever aware of being in that state. It will then subjectively seem to one as though one is not in any such state. But a state that one seems subjectively not to be in is plainly not a conscious state. So it’s a necessary condition for a state to be

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conscious that one be aware, or conscious, of being in that state”. It is then further explained that this second, higher-order state of awareness may not be conscious (Rosenthal, 2003). The framework we are presenting in this work is, in a sense, simpler than Rosenthal’s higher-order thought theory. If the subject, the self, is experiencing a conscious mental state, this in and by itself means that this subject is aware of the experiential content. This condition is exactly what this conscious mental state consists of. No higher-order thought or an additional state of awareness about self being in this state is logically necessary. For example, the subject-self who has a conscious experience may not be aware of self at all and, in particular, of self being in this state, and still have the experience. Although higher-order thoughts play in Rosenthal’s framework a similar functional role as the subject in our framework, we do not view the subject as a thought, but rather as a thing (c.f., Strawson, 1997), particular characteristics of which are different from those of thoughts (see also Searle, 1983). Accepting the existence of the self, the subject, leads to a problematic situation. The only thing that the self knows directly, and the only environment within which the self can be found as an element of the world, is its own subjective reality, i.e. the first-person experience viewed from its own firstperson perspective. Therefore, regardless of how sophisticated future measurement tools might grow, an individual’s self and its immediate conscious experience will be always directly observable by that individual’s self only: the self is epistemologically subjective (Searle, 1998). At the same time, any valid empirical scientific study must be objective, e.g., consistent with a thirdperson perspective. Nevertheless, together with Searle we believe that an objective, empirical analysis of the self and consciousness is possible: here epistemology should not be confused with ontology. There may exist ontologically objective facts about selves, that is, facts about their phenomenal existence and other natural properties, which do not depend on who is observing these facts. One of the goals of the present work is to establish facts of this category. In this sense, we can use our intuition (limited to vivid and distinct experiences, as explained above) to learn about the self-concept “built into” human minds and about its subjective properties (see also Ascoli, 1999a). In order to proceed in the analysis of ontologically objective facts about subjective selves, certain assumptions need to be made about the relations between the objective physical world and everyone’s subjective, private self. Following Chalmers (1996), we select the local, weak, functionalist supervenience principle (see above) as the basic philosophical framework. Therefore, we

assume a definite supervenience relation understood as a unique, fixed mapping from the set of all possible physical conditions in a particular human brain (or another object with equivalent functional organization) to the set of possible instances of the self and its mental states. To summarize, we postulate that the self, meant as the subject of conscious experience, can be granted status of non-illusory mental entity that supervenes on a particular physical object (e.g., a human brain). Understood in this sense, the self should not be confused with its physical substratum, i.e., the minimal part or feature of the physical reality that entails it (i.e., on which it supervenes). The substratum of the self is a collection of (possibly highly abstract) objective, physiological brain characteristics that uniquely determine the given instance of the self with all of its mental properties via the supervenience relation (i.e., neural correlates of the self). These mental properties include the immediate subjective conscious experience, the subject-object relation of the self to its experience (“subjecthood”, attitude, etc.), and the context in which the experience occurs, i.e. the mental perspective, specified by the individuality of the subject, a precise moment of subjective time (see above), a location in space, etc. The next step is to add dynamics and temporal continuity to this picture. As explained in the previous section, mental states and the associated instances of the self have a finite extent in time and overlap with each other on the temporal axis (c.f., Strawson, 1997). In order to clarify this issue from a first-person perspective, we again rely on intuition. At every moment of conscious mental life, the self-subject is not just aware of one moment of time, but also of motion, including changes in the external world, changes in its mind, and the very time flow. Consecutive, overlapping instances of the self form a continuous sequence in time (underlying the subject’s stream of consciousness) that appears as a line at a sufficiently large time scale during wake states. The continuity of all subjective experiences is perceived along this line. The temporal extent and natural overlap of instances of the self, together with their functional interrelationships, induce a topology on the set of instances of one’s self taken at different moments of time. This allows one to connect each instance to its (unique) predecessor, and thus to track the entire time evolution of the self, representing it by a continuous trajectory in subjective space-time at a sufficiently large time scale. The associated stream of consciousness (i.e., the sequence of experiences associated with the sequence of instances of my self) is stored as episodic memory and remains generally available for later retrieval. From a first-person perspective, the only world that one knows directly is the subjective world, not the world that is commonly called ‘objective reality’. In this subjective world, only one subject

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of experience is immediately known and accessible. This self is distinct from “other” subjects, whose existence can only be guessed, but never know directly (and could therefore be illusory). The same line of reasoning applies to other instances of one’s own self taken from the past and from the future: it can only be guessed that they are (were, will be) real, not illusory. The subject, however, has direct access to its autobiographical memories, and in this sense it is “closer” to its self in the past than to somebody else, whose memories cannot be accessed directly. After accepting the principles of existence, supervenience, and continuity, something essential is still missing in the present framework. Everything that can be objectively learned about consciousness, from behavioral actions and introspective reports to membrane voltages and synaptic efficacies, can be described with a mathematical model. Therefore, in principle it can be simulated in a computer or a dynamical system in general. However, if there were an implementation of this sort, it might not be the same self or an extension of the same self, but a different self (Kurzweil, 2005). Here we are talking about a numerically rather than qualitatively distinct self. The logical possibility of numerous selves, possibly possessing qualitatively identical experiences, follows from the “epistemic” asymmetry of the methods of learning about oneself and about another, external implementation (Chalmers, 1996). This epistemic asymmetry is in turn the consequence of a personally obvious fact: “I just happened to be this person, and not that”. If asked (in a hypothetical scenario), most people would strongly refuse to “trade” their self (including all feelings, memories, values, skills, habits, etc.) with that of a different person they hated and did not respect. Some people would entertain the possibility to be “transplanted” into someone whose life they “liked”. Yet, from an objective standpoint, this “self-transplant” would make no difference in the world whatsoever. On the one hand, as persuasively argued by Parfit (1984), nothing more can be derived from the fact of personal identity than can be derived from the continuity of selfawareness, episodic memory and the like. On the other hand, this conclusion holds in a third-person perspective only, in which any scientific analysis eventually has to be couched. Nevertheless, as stated above, the latter circumstance does not prevent us from using the first-person-perspective data, e.g., intuition, in this analysis. Based on intuition, we take the subjective self to be discrete and countable. A state of being one half or any fraction of oneself appears to be simply impossible to imagine (even when consciousness is on a verge of disappearance). Similarly, one cannot imagine being in a state of “multiplicity”: if several selves were simultaneously present in a single individual (e.g., multiple personality disorder), a given subject would still be one of them, with no

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direct access to experiences of the others. While most human beings are ready to accept the existence of other subjects, no one can directly experience mental states other than his/her own. Therefore, any attempt to “count” oneself would return a result of “one”. This should not be confused with the ability to be aware of two simultaneous mental states of one’s own, even if they are logically and informationally disconnected, such as an abstract conception of the number 5 and a sensation of red. For example, one can imagine consuming a red tomato and at the same time planning the five working days. In fact, most experiences are of this sort: e.g., simultaneously walking in a garden, hearing birds, seeing a cherry tree, remembering yesterday’s party, smelling the scent of grass, looking up at the sun, and dreaming about the future. Although not all of these experiences are necessarily causally disconnected, some of them in principle can be. Different, possibly disconnected experiences often belong to different cognitive modalities, and are instantiated in different parts of the brain. Why then is it impossible to have experiences entailed by two substrata that are permanently disconnected from each other, such as two separate brains? The self simply appears to be confined within its substratum. Based on the above intuitions, we postulate confinement of the self: i.e., permanent binding of the self to its substratum (limited under realistic circumstances to one particular brain or part of it). The rationale can be now reformulated for a “thirdperson-perspective viewer”. Given the intuitively derived fact of existence of a subjective world with the self in it, there are many possibilities for its realization associated with one and the same instance of objective reality, all entailed by supervenience. For example, an alternative subjective world can be imagined with somebody else (rather than the previously selected subject) being “the self”. Accepting the local supervenience relation together with the reality of the intuitive, first-person-perspective, subjective world leads to one conclusion: the simultaneous co-existence of all subjective worlds entailed by the physical reality together (the alternative idea of rejecting the supervenience principle will be considered later). Therefore, we must assume that there are at least as many subjects as there are conscious people: each subject residing in its own subjective world, all worlds being equally real, each of the subjects being a discrete entity. This corresponds to one unified world with multiple subjects in it, each with its own experiences, with all these subjects and the associated experiences being separable, “impenetrable” by each other, distinguishable from each other, and countable. The combined result is summarized below. The characterization is obviously not complete, but it reflects mental properties intuitively attributed to the self that are crucial in the present analysis.

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Essential Self-concept Axioms 1. Existence. The self exists as a mental entity possessing a certain set of mental properties, including “subjecthood” and conscious experience. The self is the subject with respect to its conscious experience. 2. Continuity. The self evolves continuously in time, and can only have one definite past. More exactly, each given instance of the self, except a newborn self, has one definite predecessor. Each instance of the self of a given individual is characterized by its unique proper subjective time. 3. Supervenience. Each instance of a self has a substratum, which can be conceived as a specific functional organization (i.e., a pattern of causal relations) instantiated in a physical medium or object, such as the brain. The substratum entails the self with all its mental properties. Each particular physical state of the substratum entails a particular mental state of the self. This implies the following (see also Kim, 1998). i. There can be no instances of a self not associated with any substratum. ii. Two selves cannot share the same substratum. iii. The continuous existence of the self critically depends on the continuous existence of its substratum. iv. The birth (emergence) and the death (vanishing) of the self are necessarily bound to the corresponding events in the physical substratum. v. The self may only have direct access to the information available in the substratum, including the current state of consciousness, memories of personal experiences, personal system of values, general knowledge about the world, skills, habits, etc. 4. Localization and confinement. The self is localized in a definite context, as determined by its substratum, including spatial and temporal coordinates. All parts of the substratum must be physically, causally, or functionally connected to each other: e.g., the substratum cannot be distributed among functionally disconnected physical objects (under normal conditions this implies that the substratum is limited to one brain, and cannot include two or more brains). The self is permanently bound to its substratum: e.g., it cannot “jump” from one substratum to another (no “self transplant” is allowed). The set of properties listed in the last axiom (4) can be expressed in the following alternative format. Any instance of a self can be symbolically labeled as “I”, meaning a distinction of this self from all other selves in the world, a distinction that may go beyond any qualitative difference in properties of individual selves (e.g., if there are qualitatively identical selves). Once a single instance is labeled, this label (“I”) can be unambiguously tracked back in time, since we

assume that every instance of the self has a unique predecessor (except a newborn self). Thus there can be no multiple instances of the self labeled “I” with the same proper time, and all selves in any finite part of the world can be labeled one by one, and therefore counted. Below we analyze these axioms in the context of a thought experiment, considering two versions of the self-concept: from the third-person and firstperson perspective. The first version corresponds to Chalmers’ (1994a, 1994b) nonreductive functionalism, plus an assumption that the subjectself is an entity. We show that this version of the self-concept leads to a contradiction. The second version takes the perspective of only one of the subjective worlds, with the unique subject-self in it. This version appears to be internally consistent through the analysis of the thought experiment. THE MIRROR QUEST: A THOUGHT EXPERIMENT Imagine that on Planet X archaeologists found a large, framed, two-sided mirror. The reflecting surface was so perfect, that they decided to send the mirror to a secret laboratory for further investigation. Physicists who studied the mirror discovered that it was not an ordinary mirror, but a new, sophisticated kind of a singularity in space and time connecting two kinds of matter: X-matter (their own, the only previously known kind) and Ymatter (a kind previously unknown to Xphysicists). The two sorts of matter physically occupied the same space, but did not interact with each other. Otherwise they were not different from each other in any respect, and each of them formed its own world: “X-universe” and “Y-universe”. In order to avoid confusions, we need to clarify that here by “X-universe” and “Y-universe” we are referring to one and the same Universe, one and the same space-time continuum, with two different sorts of matter in it. Specifically, in this Universe, each X-particle has exactly one Y-counterpart, and vice versa. We further assume that the two counterpart worlds are identical copies of each other and exactly coincide in space and time, yet do not have any effect on each other (except via the mirror, as specified below). This assumption is not as implausible as it may first appear: similar hypotheses were recently discussed in astrophysics in relation to the hidden mass problem (Mohapatra and Teplitz, 2000; Foot and Silagadze, 2001; Dolgov, 2002); however, in order to avoid unnecessary complications, here we do not consider astronomical distances and do not take gravity into account. Also for the sake of simplicity, we limit the analysis to a classical world, without quantum effects. Probably even stronger mirror-quest-like arguments could be given from within the quantum-mechanical framework (c.f., Everett, 1957), although their

Ontology and epistemology of the self

rigorous analysis would be burdened by as of yet unresolved controversies on the philosophical interpretation of quantum mechanics. Returning to the mirror, X-scientists discovered that the singularity was impenetrable to all known elementary particles. The mirror simply repelled particles, like an ideal reflecting surface, with one additional rule: each reflected photon changed its kind from X to Y, and vice versa (that is, in addition to reversing its circular polarization, as with any ordinary mirror). Thus, light emitted from the X-world was reflected by the mirror into the Yworld, where it was received as ordinary Y-light (Figure 2). This was impossible to notice visually, because the two universes were absolutely identical. This perfect XY symmetry of the Universe appeared to be the product of chance: there was no symmetry-stabilizing mechanism. As a result, any counterpart physical objects in the two worlds, including people, were indistinguishable from each other, and so were thoughts and feelings in each “pair” of persons: at least, this is what Xscientists thought. A few years later, X-physicists predicted a new kind of elementary particles and designed a blaster that could generate a beam of them. To their surprise, when the blaster was built and tested, the beam failed to interact with any matter, except for live human brain tissue, in which case it proved to

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be instantaneously lethal (one can also assume that the beam did also interact with other organisms and non-living matter, and instantly killed humans as well as other animals, but that X-scientists failed to notice that, and believed that the beam selectively interacted with, and killed, humans only). In addition, beam particles had a finite life time, thereby limiting the range of the blaster to close distances (few meters) only. An important property was predicted to relate the beam to the recently discovered singularity: the beam would freely penetrate the mirror, when passing on it from one side. The same beam, however, would be reflected like ordinary light (with its kind reversed from X to Y), when passing the mirror from the other side. Similar rules were predicted for the “Yuniverse” (i.e., for the Y-beam), except that the mirror would "switch" its sides in this case. As a result, shooting the blaster at the mirror would be safe for the shooter in one of the two worlds, and lethal in the other (Figure 2). Which world would depend on the selected side of the mirror. And thus, the new particle was predicted to violate the fundamental symmetry of the Universe. Nevertheless, scientists were unable to determine which side of the mirror was “safe” for their world. After innumerable proposals and committees, the government of Planet X decided to break the symmetry of the world in order to make the Y-

Fig. 2 – Mirror Quest. The thick dashed line separates the two kinds of matter, and the mirror (rectangle) joins them. The symmetryviolating beam (solid line) passing on the mirror from the left side in Y-universe is reflected into the X-universe (i.e., X-kind beam) to the left. When passing on the mirror from the left side in X-universe, the beam goes through the mirror to the right, while staying in Xuniverse. When passing on the mirror from the right side in Y-universe, the beam goes through to the left and stays in the Y-universe. Finally, when passing on the mirror from the right side in X-universe, the beam gets reflected into the Y-universe to the right. Therefore, the left side is safe in Y universe, while the right side is safe in X-universe. In contrast, ordinary light (dotted lines) is always reflected to the opposite universe, to the same side of the mirror.

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universe more useful than just an identical copy. The plan was to hire a volunteer who would come to the mirror alone, carrying the blaster, and would shoot the “reflection”. If the volunteer shot from the safe side, the “reflection” (but not the volunteer) would die instantly. If the volunteer shot from the wrong side, then he would die, but would be remembered as the greatest hero of all times. In any case, the symmetry of the world would be broken forever. A government agent found, hired, and briefed a volunteer. The agent also told the volunteer which side of the mirror was safe, presenting it as a government secret. This information was a bluff: nobody knew at that time which side of the mirror was safe. If someone had known, the symmetry would have been broken, but the volunteer did not think about it. And so it happened: one cloudy morning on Planet X, the volunteer took the blaster and went to the mirror. What was on his mind? At the beginning he tried to reason along these lines. “From a scientific point of view, it makes no difference which side of the mirror I shoot from, because nothing essential will happen. Before the blast, the other world is practically not different from a true mirror reflection of this world. Therefore, there is in fact just one I with two identical copies in the entire combination of the two worlds. Immediately after the blast, there should be exactly one I again. Objectively speaking, this must be one and the same I in any case. The dead body can be disregarded, and, hopefully, I will forget about it soon.” But then, when the volunteer finally stood in front of the mirror and pointed the blaster at his reflection, he was thinking the following. “At this very moment I am a conscious self, possessing my free will, and this is I who happened to be here, now, in this body. What does this mean? Is there any difference between this situation and a situation when I am “there”? If the fact is that I am here and not there, then it has to be a metaphysical fact, irrelevant to any objective property of the world. However, from my internal first-person perspective, everything else is secondary with respect to who I am. By denying the fact that I am this, and not that person, and therefore that from my first-person perspective there is a fundamental difference between this and that person beyond all possible objective characteristics, I deny my own existence. In principle, one can develop a complete theory of my brain, explaining why it behaves the way it does, and even be able to simulate in a computer every detail of its dynamics, up to the last ion channel. What this theory would not explain though is that I happened to be this self, in this brain, and not there. If my subjective existence is something very fundamental, that needs no further explanation nor reduction to other facts, then, why did I happen to be confined here, in this person, looking from this perspective? Why does that

person, looking at me from the mirror, lack the quality of being me? Why am I somebody particular at all? But the fact is, I am. “So, it’s good that I know which side to shoot from. Because if I shot from the wrong side, I know what my experience would be after that: just nothing at all, and this will be it: the end. However, if I shoot from the safe side, I will stay as I am – and will become a hero in the new world. Or, should I sacrifice myself for my twin brother? Right now he is not a brother to me, he is just my identical copy. Look, I decide to move, and he just automatically repeats my movements. I don’t even think he has his own free will, because my will controls his behavior. In fact, it is going to be my will that will terminate his life…” On this thought, the volunteer rose the blaster, pulled the trigger, shot – and died. The singularity was instantaneously destabilized by the blast and, together with the mirror, vanished forever without a trace. The volunteer’s “reflection” survived, and the symmetry of the world was broken. THE SELF AS AN ENTITY People on Planet X thought that the volunteer died, but on Planet Y they believed that he was alive. Where is the truth? Did anybody die at all? If so, was it murder or suicide? How many persons died? If the substratum of the self is an informational unit that does not distinguish among X and Y matter, and the volunteer’s brain was instantaneously destroyed in the X-world, there is no informational difference between the world before and after the blast: there always only was one volunteer, and now he stayed alive in the Yworld. But what about other people? Each of them was individual before the blast, and then gradually became two different persons after the blast. Consider for example the volunteer’s girlfriend. Exactly when and how was her new self brought to existence? Nothing happened to her body at the immediate moment of the blast, because she was waiting far away from the mirror. The symmetry of her body was broken gradually, perhaps, hours after the blast, and this was impossible to notice by any means, because the two worlds were already disconnected. For other people, who did not know the volunteer and lived in the opposite hemisphere of the planet, the process of macroscopic separation of the two worlds could have taken months, years, or have never happened at all. To say that a new entity-self associated with each newly separated body should emerge at some moment in time (which moment?) in only one (which one?) of the two worlds, is hardly intuitive. Moreover, this interpretation contradicts axioms 3 and 4 applied to each world separately, because (a) there were no physical events in the brain that could be associated with the birth of a new self,

Ontology and epistemology of the self

and (b) the two worlds are essentially causally disconnected. Therefore, if we view selves as entities conforming to axioms 1-4, we must discard the above interpretation, together with the idea that informational difference per se uniquely determines the number of selves. We can more formally analyze the Mirror Quest story from the viewpoint of nonreductive functionalism (Chalmers, 1994a, 1994b, 1995, 1996). Chalmers’ principle of organizational invariance applied to implementations of consciousness can be briefly formulated as follows (Chalmers, 1996). (a) Consciousness arises in virtue of the functional organization of a physical system, meaning that whenever a physical system implements the functional organization of a conscious state, this state must be present. (b) An abstract functional organization is specified by (i) a number of abstract components, (ii) for each component, a number of different possible states, and (iii) a system of causal relations, specifying how the state of each component depends on previous states of all components plus the input to the system, and how the output depends on component states. The nature of components and the states is left unspecified. (c) A physical system P implements an abstract functional organization M, if and only if there is a mapping f from the set of internal states of P onto the set of states of M, such that every transition rule of P, when projected by f onto M, holds there according to the dynamical laws of P. In mathematical terms, the existence of a mental feature defined by an abstract functional organization M is equivalent to the existence of a homomorphism f : (States of P) → (States of M)

(*)

preserving causal relations, such that f covers all states of M. Note that the homomorphism f is not necessarily an isomorphism: e.g., it is not required to be one-to-one. In addition, f does not have to relate all possible states of P to some meaningful states of M. Indeed, it would be otherwise difficult to speak about an implementation of a simple finite-state automaton (FSA) in a silicon-based computer. There are many possible states of silicon chips, including frozen, melted, shredded into tiny pieces, etc., not all of which correspond to meaningful states in FSA. Therefore, the mapping f is allowed to be partial; however, it must cover all possible states of M. The mapping f is not required to be unique: at least one is necessary, but two or more would do as well. Given these details, the above definition (a-c, *) does not explicitly specify how many instances of M should be considered implemented in P, provided M is implemented in P. The reason is that the principle of organizational invariance can

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guarantee qualitative, but not numerical identity. Two functionally equivalent systems must have the same conscious states, but not numerically identical conscious states. In general, counting all possible mappings cannot establish numerical identity. For instance, counting each possible mapping of a physical human body P onto an abstract functional organization of a person as a separate implementation would amount to considering a huge population of practically identical persons coexisting in one and the same body; moreover, the total number of these persons could be hard or impossible to define. In fact, given the complexity of the human brain and a robust cognitive model M describing a person, it is unlikely that there can be only one, causality-preserving mapping from the first to the second. For example, a given person (including M implemented in the brain) is not considered to change, if an arbitrarily selected single neuron k is removed or dies. Therefore, each state of M should be robust with respect to alteration of a state of a single neuron k. Thus, assuming an existing mapping f (*), we can define an equally acceptable mapping fk that only differs from f in that it does not distinguish among states of neuron k. Because f must nevertheless distinguish among states of the brain, fk ≠ f. Therefore, f is not unique (alternative mappings exist). Same arguments could be repeated with electrons instead of neurons, etc. In addition, as pointed out by Chalmers (1996), the exact choice of M is generally ambiguous (e.g., fine-grained versus coarse-grained). To avoid the ambiguity with counting persons, we accept as a definition of the number of implementations the following natural extension of (a-c, *). (d) Two independent functional organizations M' and M" are implemented simultaneously in a physical system P, if and only if there exists a causality-preserving homomorphism F: (some possible states of P) → → (all possible states of M' + M") = = (all possible states of M') ⊗ ⊗ (all possible states of M").

(**)

In other words, P maps on both M' and M" simultaneously and independently. This interpretation also holds when M' = M" = M are one and the same abstract model taken in one and the same current state. Before the blast, we presume that the brain of the volunteer viewed from any universe, X or Y, implements M, which is the abstract functional organization of the conscious state of the volunteer’s self. Calling the two copies of the volunteer VX and VY, M is mapped on by VX, by VY, and by their union VZ = VX + VY; therefore, each of the substrata VX, VY, and VZ has at least one self. In addition, VZ maps on M + M (some

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VZ states never realize in a symmetric world, but are still possible in principle, and have the “correct” causal relations with other states). Therefore, VZ has two selves, apparently, one of which is in VX and another is in VY. After the blast, only VY maps on M, i.e. there is one conscious self in VY. Locally to the Y-universe, there is no discontinuity of the state of this self at the moment of the blast. Thus, VY retains all of the volunteer's memories and awareness. Locally to the X-universe, there was one conscious self before the blast, and none after the blast; in addition, there was an objective event of physical destruction of the substratum (death). Globally, there were two selves before the blast and one after, i.e. one death took place. It remains to add the obvious, that is, it was a murder. This interpretation of the death of a volunteer, however, may encounter serious problems in other logically possible variations of the Mirror Quest. Let us introduce an interaction between the two sorts of matter X and Y. This new interaction (described by a parameter w) does not change any of the existing forces between and properties of the elementary particles within each world, and therefore is impossible to detect locally, as long as the worlds remain perfectly symmetric. When w = 0, there is no interaction: the two sorts of matter are absolutely independent, as in the original scenario. When w > 0, this interaction produces an attractive force between each two counterpart elementary particles of matter. Other (non-massive or noncounterpart) particles do not interact across the two worlds, independent of the value of w. The interacting particles attract each other at a distance, but do not exert any force on each other when they both are at one and the same location (the gluon interaction among quarks possesses a similar property, called asymptotic freedom). We assume that when w = 1, the interaction is infinite: the two counterpart particles within each pair exactly coincide in space at all times, so it is inappropriate to call them two particles rather than one. The X-Y symmetry is perfect and stable at all levels, microscopic and macroscopic. When w = 0.9, the interaction is still so strong that the X and Y counterparts of any particle are confined within a very short distance (similarly to the confinement of two quarks in a meson, or of three quarks in a nucleon). As a result, any macroscopic physical object cannot be physically separated into its X and Y components. The macroscopic X-Y symmetry still cannot be broken. We further assume that when w = 0.5, macroscopic objects can be separated, but this requires a threshold force; separated objects would experience significant perturbations of their dynamics caused by the attraction to their “shadowmatter” counterparts. Finally, when w = 0.1, the force necessary to separate two corresponding objects and the perturbations experienced by the separated objects are so weak that they can only be

detected with high-precision measuring devices and would not affect normal life. These perturbations vanish in the limit w → 0. If w = 0, the two worlds are effectively independent, as in the original Mirror Quest story. We have concluded in this case that there are two selves entailed by each pair of persons. The same interpretation holds with w = 0.1, based on (a-d) and (**). However, with w = 1, every pair of XYcounterpart particles is in effect one particle. In this case the world is only one, and (as on our Earth) there is no reason for considering two selves for each person. What happens with w = 0.9? Upon the shooting, the volunteer’s death causes the death of its counterpart, because each particle in the Y world is strongly bound to the corresponding particle in the X world. In this case the two universes remain forever symmetric at a macroscopic level, and it would still be inappropriate to treat them as two universes. There is only one functional and physical world, and it is impossible to discern the existence of the Y world from within the X world. Logically, we could even think of our own world as an X world, and any common mirror as a singularity to a Y world. In this case, based on (a-d) and (**), there is only one copy of each self in the Mirror Quest: maintaining that there are two selves corresponding to each XY person would be equivalent to considering three selves per person in our real world, one for each quark of every nucleon. We can now imagine an alternative logical possibility, in which the interaction parameter w oscillates between 0 and 1 in a perfectly XYsymmetric world. What happens to the selves in this world at any moment of time? If the period of oscillations is large (years), we conclude, as before, that each individual has two selves when w = 0, and only one self when w = 1. However, if w changes gradually between 0 and 1, Chalmers’ fading qualia argument (1996) applies: although it is logically possible to gradually tune w, it makes little intuitive sense to gradually tune the existence of the subject of experience. The problem becomes even more obvious if the period of w-oscillations shortens asymptotically toward zero. When the period is one nanosecond, creation and elimination of selves during each cycle is not an option for interpretation (see “The Self as an Illusion” above). A similarly ambiguous situation arises if the value of w is 1 at all times until one nanosecond before the blast. In that precise instant, w becomes zero and stays so forever after. While the two universes are strongly causally related up to the shooting, their symmetry gets broken by the blast, and one of the (potential?) substrata destroyed. Is somebody killed by the blast in this scenario? When did his conscious experience develop? The variations of the Mirror Quest thought experiment with changing w-interaction suggest that a choice should be made: either each pair of

Ontology and epistemology of the self

persons in the XY world must always have one self or always two selves, unless one of them dies or is born due to local physical conditions. Both answers prove to be contradictory at some point, even if locally, within each (X or Y) world, the laws of physics and lives of people remain normal (e.g., scientists may not know about the w-interaction and the existence of XY counterparts). If, for example, we take the position that even in the original story (no w-interaction) each pair of persons had only one self before the blast, then we would have to accept that new selves are created at the moment of the shooting or soon after it nonlocally, for nothing unusual happens to the people's brains in each world locally. This would contradict the local supervenience principle. If, on the contrary, we claim that each pair of persons always has two selves, even though the two universes may be forever causally related by a strong w-interaction, then we contradict the principle of organizational invariance, in the form (a-d) and (**). In either case, we are facing a logical inconsistency of Axioms 1-4. We should emphasize that we are merely trying to count the total number of selves, without involving the notion of unique personal identity. This analysis suggests that counting selves may be impossible in an objective nonreductive-functionalist framework. As a potential objection to this conclusion, one could propose the possibility that a world as described above (and thus problems of this nature) could not exist due to some fundamental reasons. Yet, even if worlds like these are physically impossible, they could still be simulated in a computer. Assuming that, in principle, a human being can be simulated in a computer, according to the principle of organizational invariance this implementation should give rise to equivalent mental phenomena. One could still object that even computer simulations of such worlds are impossible to accomplish, due to unknown effects of the mental on the physical, but this would violate the logical closure of physical laws. THE SELF AS

THE

SUBJECT

We thus consider an alternative version of the self-concept by introducing a single modification to the set of axioms 1-4. As an amendment to axiom 3, we now additionally require that there can be at most one self in the world. The rest of subjects must be considered similarly to Chalmers’ zombies. To be precise, we specify nothing about their phenomenal states, but they can have no self whatsoever. Thus, in this section, we shall use the term “self”, referring to one individual self only: the “I” (a token-self concept). We then assume the local perspective of the observer with respect to the X-Y division in each particular scenario considered above. This perspective allows the continuous

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temporal tracking of the “I”, up to the eventual death. The reader may easily verify that this choice does not lead to logical contradictions in any of the situations considered above and for any of the observers’ perspective: in all cases, each subject either continues its existence or dies. We conclude that this position of “subjective nonreductive functionalism” may be a useful template for defining an ontological framework of the self. We propose that all observations, including subjective first-person introspection of own self, retrieval of personal memories, etc., must be consistent with the following. (i) The self-concept must be understood as the token-self concept: the “I”, the unique self in the world. It only makes sense from the subjective, first-person perspective of this “I”, and only as a concept applied to the current instance of the “I” or past instances of the “I”. (ii) The existence of the “I” in the first place, as a subject of experience, cannot be entailed by any physical laws or properties, thus violating the weak supervenience principle. The “I” must be postulated based on intuition as a fundamental element of Nature, thereby defining its unique firstperson perspective. (iii) The current instance of the “I”, plus Axioms 1-4 (including the amendment to Axiom 3) determine unambiguously the causal relations, time and location entailing all past instances of the “I” together with their mental properties. This can be done consistently in all logically possible situations, including models with multidimensional time and multiple time travels, etc. (iv) Selves other then “I”, as well as future and past instances of the “I” separated from the present “I” by discontinuities in the substratum (e.g., teleport; Parfit, 1984), should be treated within this framework as mere abstract constructs. Related possibilities are discussed by Chalmers (2003). What good is this framework for? From an ontological viewpoint, we have determined its consistency with our intuition about self. However, when the task is to understand how the human brain works, the ontology of the self is almost irrelevant. What really matters in this case is the epistemology of the self, which dictates how the self-concept should be implemented in the brain (see e.g., Ascoli, 2000). From this viewpoint, the concepts of self outlined above should be discussed as cognitive-psychological models. There are fewer logical restrictions in this case, because human mind can be based on false beliefs about the self and the world (Kant, 1781/1929). The choice of a concept of self based on false beliefs, or fundamental errors (Samsonovich and Nadel, 2005, in this issue, p. 669) seems probable, although it does not imply denial of the ontological selfconcept. The psychological, epistemological theory of a mental phenomenon is independent of whether or not the corresponding philosophical, ontological

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view is correct (Rey, 1983, 1985; Smith et al., 1984; Hampton, 1997). In order to analyze the self-concepts from an epistemological standpoint, we consider two approaches in studies of theory of mind (ToM: this notion refers not to a theory, but to a cognitive phenomenon, which is the ability of humans to understand other minds and the self) (Baron-Cohen, 1995; Bartsch and Wellman, 1995). According to “theory-theorists” (e.g., Gopnik, 1993; Carruthers, 1996), people detect and represent psychological states both in themselves and in others by making inferences from common-sense psychological concepts, which exist in people’s minds as a theory. In contrast, “simulationists” (e.g., Gordon, 1986; Heal, 1986; Goldman, 1989, 1993, 1995; Currie, 1995) assume that people use their own first-hand experience (via the same mechanisms used for the currently conscious state of the self) in order to understand other minds. In other words, people perform “mental simulation”. For example, in order to predict a future decision of an agent, the attributor must take the target's perspective, i.e. “pretend” to be in a certain mental state (Goldman, 1998). The contrast between the theory-theorist and simulationist approaches is traditionally casted as a dualist “either/or” argument. However, the philosophical position that we have developed here allows both models of ToM to coexist and complement each other. The framework of subjective nonreductive functionalism creates a unique status of the “I” and its first-person perspective. In this layout, the theory-theorist approach allows for reasoning about other selves from within the same, individual first-personperspective of the “I”, while the simulationist approach requires exploration of other mental perspectives by the “I”. In addition, it is believed that most, if not all of these exploratory mental simulations are performed unconsciously (Goldman, 1998), while the “I” evaluates the results from its first-person perspective. This strategy could results in the subjective feeling that people call “an intuitive understanding of another person”. We surmise that the same mechanism may underlie the subjective feelings of at least some emotions, such as appreciation of a joke. In spite of a substantial amount of empirical studies in psychology of humor (Lefcourt, 2001), no general theoretical model of the mechanisms underlying the sense of humor has yet been proposed. Combining this unified epistemological framework with the one-self philosophical template formulated at the end of the previous section, we suggest the following implication for cognitive psychology and neuroscience: researchers should look for substrata of the self, even though the humanlike self-concept may not be easy to reconcile with logic and objective reality. Regardless of the question of the existence of the self as an objective entity, the complex of beliefs about the self is a

functional unit that underlies most, if not all, acts of conscious cognition, and as such it must have a definite physical substratum in the brain. Here we do not refer to the superficial human beliefs about their selves and the self-concept in general, which may depend on many factors (religion, education, lifestyle, etc.), but rather the belief that lies beneath these factors, constituting the key element of the human brain blueprint. This implication raises a crucial question: is an empirical first-person science possible? The word “empirical” merely means “based on experience”; however, the term “empirical science” is traditionally understood in a more restricted sense: as a system of public facts derived from objective measurements. They are “objective” in the sense that they can be reliably reproduced, yielding consistent results, by independent researchers using similar paradigms. Thus, the term “objective” should be intended in the epistemological, not ontological connotation (in contrast, e.g., to the meaning of “objective reality”). Therefore, in principle, the notion of an objective measurement is applicable to the subjective analysis of first-person experiences. The fact that there is no known firstperson science beyond, perhaps, subjectiveidealistic philosophy, does not exclude the possibility that a practically useful first-person model could be in principle designed based on firstperson data. Nevertheless, given a complex cognitive paradigm, quantitative data analysis could be hard to accomplish inside the researcher’s own mind within one and the same first-person perspective. A major problem consists of the limited span of human working memory, and the short temporal duration of a mental state that is subjectively perceived as one instance of consciousness (Libet et al., 1979). In addition, the very attempt to look at the content of consciousness could immediately result in “jumping out” of the current first-person perspective, to a new, metacognitive first-person perspective. In other words, scientific conscious access may change the content of consciousness, altering the data. Despite these difficulties, we remain optimistic that this sort of science will eventually be developed, possibly with the aid of computers with the appropriate architecture (Samsonovich and Ascoli, 2002). CONCLUDING REMARKS In this work we emphasized the need to recognize the first person perspective in studies of the mind, counteracting the tendency in science to ignore both the observer and the intrincic relativity of subjective experience in the active construction of our models of reality. The initial question of the existence of the self was clarified in connection with natural, subjectively experienced states of immediate self-awareness, and the contradiction of the subject

Ontology and epistemology of the self

calling itself an illusion was illustrated. All science is founded on some initial axioms, and here, following Descartes (1637/1985), yet at a new level of analysis, we accepted the existence (as a reality) of the “I” and its first-person experience. Analysis of the Mirror Quest thought experiment and its variations demonstrated that treating the self as unique (the only one “I”), i.e. assuming the subjective perspective of the observer, is the only philosophical stance to avoid ontological inconsistency. The resulting one-self framework of subjective nonreductive functionalism yielded epistemological implications for neuroscientific and cognitive-psychological studies of the self, as well as suggestions for further developments towards a first-person science. The choice of nonreductive functionalism as the main basis of our analysis was not incidental. This view has the advantages of being practically compatible with both physicalism (which underlies most, if not all natural sciences) and mentalism (which underlies intuition), as well as being suitable for plausible operational definitions of consciousness. It respects the subjectivity of firstperson conscious experience, which is why it is not reductive and therefore not materialistic, but at the same time it is consistent with functionalism in all practical aspects. However, when applied objectively to the problem of the self, nonreductive functionalism critically fails to determine the number of conscious subjects. This happens in logically possible worlds that are locally indistinguishable from our world. Many alternative approaches to this problem do not share the positive features of nonreductive functionalism. For example, Dennett's nihilism (1991) does not logically discriminate between a conscious human being and a continuously running tape recorder. If the same circular tape is recorded over and over again, without erasing, converging multiple drafts could be found that are causally related to sensory input. Chalmers also seriously entertains more radical possibilities, considering that an electronic switch may have subjective experiences of its three possible states without necessarily qualifying as an agent or a person. According to Putnam (1988), assuming that consciousness is entailed by a substratum that can be implemented in a finite state automaton leads to the logical possibility of completely inanimate matter, such as a rock, being conscious (panpsychism). In our view, before granting a tape recorder, an electronic switch, or a rock status of subject of experience, it is important to understand what this subject of experience is conceptually. This includes understanding how it is functionally organized and implemented in the brain, and what it would take in principle to implement it in another system (Samsonovich and Ascoli, 2002). The question of which mental state (and self) substrata in the brain should or should not be considered conscious is neither new nor trivial: psychology offers double dissociation examples for

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virtually every conscious mental state associated with a specific cognitive paradigm involving awareness. Conditions may be found when (a) a cognitive function is performed, but the awareness of the associated mental state is absent (e.g., blindsight: Weiskrantz, 1997); and (b) a mental state persists, while its objective basis is apparently missing (e.g., the subjective feeling of self-unity in both split-brain personalities: Mark, 1996). Yet a general solution to these problems is not provided even by a detailed functional description of the brain in order to determine which substrata are associated with conscious and unconscious mental states, given a global operational criterion for consciousness. The critical question thus is: which functionalist concept relevant to mental states should play the central role in making the partition? We believe that the concept of self is the key to the answer (see also Ascoli, 1999b). Without the selfconcept, the partition does not come “for free” with any theory “explaining” what consciousness is. Examples include, but are not limited to, higherorder theories tangentially considered above (Rosenthal, 1996; VanGulick, 1988; Güzeldere, 1995), representationalism (Dretske, 1977), global workspace models (Baars, 1988), and views of consciousness as an activity-threshold phenomenon, or as associated with a special class of neurons and/or a special class of oscillations (Crick and Koch, 1990, 1998). As an alternative to all of these positions, we propose that a definitive functional aspect of a conscious mental state is that it belongs to a particular subject-self. Therefore, an acceptable practical answer to the question of what counts as a conscious state could be given based on the activity of the substratum of the self. Acknowledgments. We are grateful to Drs. Harold Morowitz and Rebecca Goldin for valuable discussions and for reviewing an earlier version of this manuscript. REFERENCES ASCOLI GA. Is it already time to give up on a science of consciousness? A commentary on mysterianism. Complexity, 5: 25-34, 1999a. ASCOLI GA. Neural patterns, abstraction, and the emergence of the Self. Noetic Journal, 2: 9-20, 1999b. ASCOLI GA. The complex link between neuroanatomy and consciousness. Complexity, 6: 20-26, 2000. BAARS BJ. A Cognitive Theory of Consciousness. Cambridge, UK: Cambridge University Press, 1988. BARTSCH K and WELLMAN HM. Children Talk about the Mind. New York: Oxford University Press, 1995. BERKELEY G. A Treatise Concerning the Principles of Human Knowledge. London: J. Tonson, 1710/1734. BLACKMORE S. The Meme Machine. Oxford, UK: Oxford University Press, 2000. BLACKMORE S. There is no stream of consciousness. Journal of Consciousness Studies, 9: 17-28, 2002. BLOCK N. Troubles with functionalism. In Savage CW (Ed), Perception and Cognition: Issues in the Foundation of Psychology. Minneapolis: University of Minnesota Press, 1978, pp. 261-325. CARRUTHERS P. Simulation and self-knowledge: A defense of theory-theory. In Carruthers P and Smith PK (Eds), Theories of Theories of Mind. Cambridge, UK: Cambridge University Press, 1996, pp. 22-38.

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