Imagine that you and a duplicate of yourself are lying unconscious, next to each other, about to undergo a complete step-by-step exchange of bits of your bodies. It certainly seems that at no stage in this exchange of bits will you have thereby switched places with your duplicate. Yet it also seems that the end-result, with all the bits exchanged, will be essentially that of the two of you having switched places. Where will you awaken? I claim that one and (...) the same person possesses both bodies, occupies both places and will experience both awakenings, just as a person whose brain has been bisected must at once experience both of the unconnected fields of awareness, even though each of these will falsely appear to him as the entirety of his experience. I also claim that the more usual apparent boundaries of persons are as illusory as those in brain bisection; personal identity remains unchanged through any variation or multiplication of body or mind. In all conscious life there is only one person - I - whose existence depends merely on the presence of a quality that is inherent in all experience - its quality of being mine, the simple immediacy of it for whatever is having experience. One powerful argument for this is statistical: on the ordinary view of personhood it is an incredible coincidence for you (though not for others) that out of 200,000,000 sperm cells the very one required on each occasion for your future existence was first to the egg in each of the begettings of yourself and all your ancestors. The only view that does not make your existence incredible, and that is not therefore (from your perspective) an incredible view, is that any conscious being would necessarily have been you anyway. It is a consequence that self-interest should extend to all conscious organisms. (shrink)

Most people will agree that if my brain were made to have within it precisely the same pattern of activity that is in it now but through artificial means, as in its being fed all its stimulation through electrodes as it sits in a vat, an experience would result for me that would be subjectively indistinguishable from that I am now having. In ‘The Story of a Brain’ I ask whether the same subjective experience would be maintained in variations like (...) these: The hemispheres are in different vats but interacting with each other through radio transmission. Smaller chunks - and eventually the individual neurons - are interacting in this way. The hemispheres or the smaller chunks undergo internally the same pattern of activity but without interacting with each other. (shrink)

I critically examine Nietzsche’s argument in The Will to Power that all the detailed events of the world are repeating infinite times (on account of the merely finite possible arrangements of forces that constitute the world and the inevitability with which any arrangement of force must bring about its successors). Nietzsche celebrated this recurrence because of the power of belief in it to bring about a revaluation of values focused wholly on the value of one’s endlessly repeating life. Belief in (...) recurrence would bring joy to those who had achieved excellence in this life and crush those who had not. I point out, however, that this significance of recurrence must be spoiled by the consideration that within each of the long cycles of recurrence there would have to be, as well, countless variations of this life. And I consider the issue of personal identity within such recurrences. Is it the same person or merely resembling but distinct persons in the recurrences or the variations? If it is the same person in precise recurrences, should the subjectively identical experience be thought of as really additional for that person? (shrink)

This paper could be thought of as divided into two parts. In the first I show through a series of thought experiments that it is a mistake to think of one’s individual experience as necessarily belonging to only one particular place, time and organism. In repetitions across a universe large enough to host them, the particular experience that one finds oneself in, which can be individuated only by the detailed type that is the entirety of its momentary subjective content, would (...) exist equally in every occurrence of that type, much as a moment in the plot of a novel would exist equally in every copy of that novel. Each distinguishable subjective moment of experience is thus a ‘moment universal’. In the second part of the paper I draw from this the conclusion that there could not be any proper possessors of lines of experience - that there are no proper persons - no continuing subjects of consciousness and self-interest. About five years after writing this paper I came to see that the particular identity of an experience could not be confined by types of momentary subjective detail any more than it could be confined by particular places, times or organisms. All experience is equally here, now and mine and all conscious organisms are equally I. My argument for this crucial further development is presented in ‘One Self – The Logic of Experience’, Inquiry 33 (1991): pp. 39-68. (shrink)

If I desire to drink some stuff thinking it is hot chocolate when actually it is hot mud, my desire is not a real one - it’s mistaken or only apparent. This example illustrates how a desire must always depend on a belief about its object, a belief about what it is and what it’s like. But beliefs are correctable, so desires are correctable. This leads us directly to a very sweeping principle - that I only really desire what I (...) would be desiring with a perfect grasp of everything involved. If there’s something that I desire only because my grasp of it is less than perfect, then it is not something that I really desire. I have no real reason for wanting it, and it would not be in my real self-interest to get it. The hypothetical perfect grasp that defines a real desire would have to have a God-like reach into all the relevant realities in all their actuality and all their potential. And it would have to include perfectly within it all the desires of all those affected by what the grasp was of. Therefore what would be wanted in a perfect grasp would be a reconciliation of all the systems of desire contained within it - not as they happen to be but as they would be corrected by a perfect grasp. This reconciliation of systems of desire is that which morality requires. Therefore what I really want - my own fully-corrected self-interest - is precisely the same as the requirements of morality. This sameness explains and justifies morality’s categorical character and over-riding authority. (shrink)

This challenging paper presents an ingenious argument for a functionalist theory of mind. Part of the argument: My visual cortex at the back of my brain processes the stimulation to my eyes and then causes other parts of the brain - like the speech centre and the areas involved in thought and movement - to be properly responsive to vision. According to functionalism the whole mental character of vision - the whole of how things look - is fixed purely in (...) the pattern of responses to vision and not in any of the initial processing of vision in the visual cortex. That this functionalist theory of vision is true can be proved with alarming ease. Imagine that just the left side of my visual cortex is replaced by a gadget that has precisely the same input/output relationship to the rest of the brain as the left visual cortex had. According to any view but functionalism, the character of my vision on the right side of my visual field (normally processed by the left visual cortex) would change radically with this change in all the intrinsic properties involved in the visual cortex, with this preservation of nothing but its functional role in bringing about my responses to vision. But, say I, we have enough here to be sure that in such a case there could be no change in the character of my vision. For we know by the stipulation of sameness of output that my responses in speech, thought and movement to the right side of my visual field will be precisely the same as they would have been with the natural left visual cortex and will harmonise just as they would have done with my responses to the other side of my vision. But if half my vision had disappeared or changed I’d be speaking, thinking and acting like someone with problems on the right side of his vision. It is impossible to separate my responses to vision from the character of my vision. The character of my vision is logically determined by the pattern of responses - by nothing but the functional role of my vision. (shrink)

Many philosophical positions wholly undermine themselves because to possess the truth that they claim for themselves they would have to be false. These are the theories that in one way or another reject the meaningfulness or attainability of objective truth.

Imagine two urns, each with a thousand beads - in one all the beads are blue while in the other only one of the thousand is blue. If one of these urns is pushed forward (based on the toss of a fair coin) and the single bead then randomly drawn from it is blue, we must infer that it is a thousand times more probable that the urn pushed forward is the purely blue one. The hypothesis that this was instead (...) the urn with only one blue bead would require that the occurrence of the evidence, the blue bead being drawn, was something improbable - and it is improbable that something improbable is what has occurred. Next consider an example of only one urn with no prior description. By the same reasoning as above, if all the first beads randomly drawn are blue, it is becoming more and more probable that the beads in the urn are generally blue. (Otherwise something improbable would be happening in another colour not appearing; and what’s improbable is improbable.) It is therefore probable also that the next bead drawn will be blue. This is induction. As Hume would have said, we could not know a priori, given this evidence, that the next bead will be blue. But, as he overlooked, we can know a priori, given this evidence, that it is probable that the next bead will be blue. In neither urn example has the belief regarding the beads been formed as a Humean habit of expectation after many observations of beads. (In the first case there is only one observation. The second could be modified to have all the beads drawn out at once.) Rather the belief is a product of a priori reasoning about probability. Next imagine that a coin has been tossed a thousand times and landed heads every time. There was a fair and a loaded coin. According to the same reasoning, it is overwhelmingly more probable that the coin used was the loaded one. For that the fair coin had so landed is most improbable. The hypothesis that there is no external world makes the orderliness in my current experience improbable - much like getting all heads with a fair coin. (Uncaused sensation would most probably be chaotic.) The most probable hypothesis is that of things like those we believe in causing this orderliness - as the coin’s being loaded would have caused all heads. The hypothesis that my experience has been made to take this pattern by a Cartesian malicious demon or by scientists controlling my brain in a vat can only falsely seem to make the character of the experience probable by sneaking in an inherently improbable ad hoc specification that this sort of pattern of experience was that which they were aiming at producing - like an ad hoc specification that the fair coin was one that by chance landed heads all thousand times. We may thus reject such hypotheses as improbable. So this is the problem of induction solved and scepticism answered through a priori reasoning. (shrink)

My visual cortex at the back of my brain processes the stimulation to my eyes and then causes other parts of the brain - like the speech centre and the areas involved in thought and movement - to be properly responsive to vision. According to functionalism the whole mental character of vision - the whole of how things look - is fixed purely in the pattern of responses to vision and not in any of the initial processing of vision in (...) the visual cortex. That this functionalist theory of vision is true can be proved with alarming ease. Imagine that just the left side of my visual cortex is replaced by a gadget that has precisely the same input/output relationship to the rest of the brain as the left visual cortex had. According to any view but functionalism, the character of my vision on the right side of my visual field (normally processed by the left visual cortex) would change radically with this change in all the intrinsic properties involved in the visual cortex, with this preservation of nothing but its functional role in bringing about my responses to vision. But, say I, we have enough here to be sure that in such a case there could be no change in the character of my vision. For we know by the stipulation of sameness of output that my responses in speech, thought and movement to the right side of my visual field will be precisely the same as they would have been with the natural left visual cortex and will harmonise just as they would have done with my responses to the other side of my vision. But if half my vision had disappeared or changed I’d be speaking, thinking and acting like someone with problems on the right side of his vision. It is impossible to separate my responses to vision from the character of my vision. The character of my vision is logically determined by the pattern of responses - by nothing but the functional role of my vision. (shrink)

This article presents a paradox of inclusion, like Russell’s paradox but in a natural language.

It is argued that two observers with the same information may rightly disagree about the probability of an event that they are both observing. This is a correct way of describing the view of a lottery outcome from the perspective of a winner and from the perspective of an observer not connected with the winner - the outcome is improbable for the winner and not improbable for the unconnected observer. This claim is both argued for and extended by developing a (...) case in which a probabilistic inference is supported for one observer and not for another, though they relevantly differ only in perspective, not in any information that they have. It is pointed out, finally, that all probabilities are in this way dependent on perspective. (shrink)

For a while in this article it seems impossible to articulate a compelling reason for refraining from killing an innocent stranger with the press of a button when this would earn one a small prize and would be done with absolutely guaranteed immunity from any punishment or other harm (including even an instantaneous elimination of any chance of a guilty memory, achieved through hypnosis, and an ironclad commitment from God not to condemn the killing). After many failed attempts, a compelling (...) reason for not pushing the button is finally articulated. A distinction is demonstrated between merely apparent, mistaken desires and real desires. One might, for example, have merely an apparent, mistaken desire to be drinking the stuff in a mug of hot mud if one mistakenly believed that the stuff was hot chocolate. One would not really desire to be drinking that stuff. A desire, which must always be based on some belief about what its object is like, would always be open to correction along with the belief on which it depended. This realisation leads to the sweeping principle that one can only really desire what one would be desiring with a hypothetical perfect grasp of all that is involved. If one desires something only because of not fully grasping what that thing is, then one does not really desire it. What one really desires, then, regarding this stranger and pushing the button has to be what one would desire if fully experiencing, among other things, the entire value of the stranger's life from his own as well as every other angle along with the small value for oneself of the prize received on killing him. This equal concern for all is morality, and what is compelling in morality is that what it commands is what everyone really desires. (shrink)