Presentation on theme: "Cognitive Computing 2013 Consciousness and Computations 7. NON REDUCTIVE FUNCTIONALISM (CHALMERS) Mark Bishop."— Presentation transcript:
Cognitive Computing 2013 Consciousness and Computations 7. NON REDUCTIVE FUNCTIONALISM (CHALMERS) Mark Bishop
01/04/2014(c) Bishop: Consciousness and Cognition2 Constraints on a theory of consciousness A theory of consciousness should, give the conditions under which physical processes give rise to consciousness, it should specify just what sort of experience is associated. And we would like the theory to explain how it arises, so that the emergence of consciousness seems intelligible rather than magical. Chalmers argues that, consciousness can only be understood within a non-reductionist science of the mind. As consciousness is merely naturally supervenient, notlogically supervenient, on the physical states of the brain.
01/04/2014(c) Bishop: Consciousness and Cognition3 Logical Supervenience If B-properties logically supervene on A-properties, then B-properties follow analytically from A-properties which thereby exhaustively explain those properties.... because a suitably well-informed and rational thinker could, merely from her knowledge of the A-properties together with her knowledge of any nomological entailments that hold between the A-properties and the B- properties, infer the B-properties. Another way of describing the logical supervenience of B-properties on A-properties is to say that if we know all the micro-properties of a physical system (A) and their relationships, we necessarily know the macro-properties (B). Consider flocking behaviour as a macro property of a colony of robots. … Full knowledge of all the robots control programs and the initial conditions of the environment that pertain allow us to predict the next moves of the robot (s) and observe that, under certain specific conditions, flocking is entailed.
01/04/2014(c) Bishop: Consciousness and Cognition4 On zombies and consciousness The logical possibility of zombies: A physical, functional, and psychological duplicate which nonetheless has no subjective phenomenal experience. The zombie can talk about the ineffable pink of a rose but never see it. The zombie twin thinks, perceives, reflects on its own internal mental states, deliberates between chocolate chip mint ice cream and strawberry ice cream, and is even perceptually aware of a mental state called headache when it eats his ice cream too quickly, yet it experiences nothing at all.. The fact that zombies are logically possible means that consciousness cannot logically supervene on the physical.
01/04/2014(c) Bishop: Consciousness and Cognition5 Natural Supervenience If B-properties naturally supervene on A-properties, then knowledge of A-properties does not fix B-properties.... we must add some extra natural, (pheno-physical), bridging laws to the supervenience base (A-properties) to fix the B-properties. For Chalmers, consciousness merely naturally supervenes on the physical. If correct, this presents a fundamental problem for any reductionist account of mind.
01/04/2014(c) Bishop: Consciousness and Cognition6 The Principle of Structural Coherence From Chalmers: An isomorphism between the structures of consciousness and awareness, constitutes the Principle of structural coherence. This principle reflects the central fact that even though cognitive processes do not conceptually entail facts about conscious experience, consciousness and cognition do not float free of one another but cohere in an intimate way.
01/04/2014(c) Bishop: Consciousness and Cognition7 The Principle of Organisational Invariance, (POI) Ontologically two kinds of property: Physical properties. Phenomenal properties. For Chalmers in our world, but not in every possible world, there are pheno-physical bridging laws between the physical and phenomenal. In our world any system with the right kind of functional organisation will be conscious: The POI: For any system with conscious experience, a system with the same fine grained functional organisation will have qualitatively the same phenomenal experience.
01/04/2014(c) Bishop: Consciousness and Cognition8 Evidence for the POI: fading qualia A hypothetical organism with 'absent qualia' has no phenomenal experience, (no qualia), whatsoever, although it might have a perfectly normal psychology. The Fading Qualia Argument defines a gradual replacement scenario, and it takes the form of a reductio on the assumption that absent qualia are naturally possible. We imagine replacing neurons (or whatever) in the conscious subject with the analogous components from a functional isomorph, (perhaps made of silicon, although it doesn't matter), ex hypothesi with absent qualia. If the silicon replacement units exhibit absent qualia, then the question becomes whether qualia gradually fade out [for the intermediate subjects] or disappear abruptly at some percentage of replacement; or undergo some ever more bizarre phenomenal shift.
01/04/2014(c) Bishop: Consciousness and Cognition9 Fading qualia: the subjects response … Consider the subject is at the Riverside football stadium in Middlesbrough and is asked to report the colour of the Boro home strip … If fading qualia occur, the subject would continue to report red, (as ex-hypothesi the subject remains a functional isomorph of conscious system), although its internal phenomenal experience is fading, (e.g. it may now be tepid grey), in contradiction to the coherence principle … Or if abruptly changing qualia occur this would imply a privileged neuron with special phenomenal power. Chalmers' preferred response is that neither fading or suddenly changing qualia are acceptable possibilities … … and hence that the assumed claim - that a genuine functional isomorph could lack qualia - must be rejected.
01/04/2014(c) Bishop: Consciousness and Cognition10 Dancing Qualia The same fine grained functional organisational must cause the same phenomenal experience. Consider one system [A] with normal phenomenal experience. Consider a second [B] with inverted qualia. Wire in parallel, controlled by a switch, the set of colour function neurons in [A] and the corresponding set from [B]. As we flick the switch back and forth between [A] neurons and [B] neurons, phenomenal experience will switch, dance, between say phenomenal blue and phenomenal green, although brain function would remain the same; again, an event in contradiction to the coherence principle … Hence the Inverted Spectrum is not plausible and the same fine grained functional organisation must impute the same phenomenal experience.
01/04/2014(c) Bishop: Consciousness and Cognition11 Chalmers on Searles Chinese Room Argument (1) Imagine a set of Chinese demons locked in room. Each demon simulates a single neuron of a subject who is phenomenally perceiving red, via formal transforms on bits of paper. Via Chalmers fading and dancing qualia, the demon system and the Chinese speaker must be equally phenomenally conscious. Now we reduce the number of demons by doubling their work.
01/04/2014(c) Bishop: Consciousness and Cognition12 Chalmers on Searles Chinese Room Argument (2) Eventually we are left with one demon and lots of paper which, via Fading & Dancing Qualia arguments, obviously must still perceive red. This is the same situation as the Chinese Room hence, via dancing and fading qualia, the CRA system must be phenomenally conscious… In fact, Chalmers argues that the demon itself is effectively redundant …... it is simply the change in functional states with which we impute consciousness in this version of the Chinese Room.
01/04/2014(c) Bishop: Consciousness and Cognition13 Searle on Chalmers: are zombies logically consistent? Searle is sceptical of Chalmers core tenets; specifically on the logical possibility of Zombies. Searle argues that although it is logically consistent to imagine a zombie doppelganger with the same behaviour as himself and no mental life… Such a doppelganger would not be a molecule by molecule duplicate of himself. For Searle a molecule by molecule duplicate would be as conscious as Searle Because identical biology entails identical consciousness.
On flying pigs … Chalmers asserts that as consciousness only naturally supervenes on the physical, it need not be a concomitant physical feature of all possible worlds For Chalmers there is nothing logically inconsistent with imagining a molecular zombie doppelganger.. Hence consciousness is something in addition to the physical facts of the world. Searle retorts that if we imagine a world where the laws of nature are different then we are free to imagine flying pigs But as imagining flying pigs says nothing about real pigs flying, Searle asserts that Chalmers has produced a logical invalid argument… 01/04/2014(c) Bishop: Consciousness and Cognition14
In support of Zombies: the swamp man? See Donald Davidson, 1987, Knowing ones own mind; suppose Davidson goes hiking in the swamp and is struck and killed by a lightning bolt. At the same time, nearby in the swamp another lightning bolt spontaneously rearranges a bunch of molecules such that, entirely by coincidence, they take on exactly the same form that Davidsons body had at the moment of his untimely death. This being, whom Davidson terms Swampman, has, of course, a brain which is structurally identical to that which Davidson had, and will thus, presumably, behave exactly as Davidson would have. He will walk out of the swamp, return to Davidsons office at Berkeley, and write the same essays he would have written; he will interact like an amicable person with all of Davidson's friends and family, and so forth. 01/04/2014(c) Bishop: Consciousness and Cognition15
Is there a difference between Davidson and Swampman? Certainly Davidson holds that there is a difference between himself and the Swampman (even though no one would notice it). Athough Swampman will appear to recognise Davidsons friends, it is impossible for him to actually recognise them as he has never seen them before; Swampman has no causal history. This leads Davidson to deny that the Swampmans utterances can genuinely be construed as referring to anything in particular. 01/04/2014(c) Bishop: Consciousness and Cognition16
On recognising boxes … Suppose that at some point the previous day Davidson had looked across to a gold box on a shelf where, unknown to him, there was another, visually identical gold box hidden behind it. Though externally identical, the first box holds a chocolate; the second is empty. When Davidson makes the assertion about the gold box I saw yesterday, we take him to be referring to the one that he did in fact see (which does in fact secretly contain a chocolate). Counterfactually, had the boxes been arranged in the other order when Davidson looked across at the shelf yesterday we would understand Davidson to be referring to the other (empty) gold box, because in judging the reference of a word we take into account the causal history of its user. Yet in both cases, as the boxes are identical, Davidson and counterfactual Davidsons internal molecular state will be the same; hence, Davidson argues, molecular state alone is not enough to fix the meaning of someones words. 01/04/2014(c) Bishop: Consciousness and Cognition17 Counterfactual Davidsons brain state is the same Davidson brain state as examines gold box
On causal history … The Swampman has no causal history - it is in the same molecular state as both the actual Davidson and the counter-factual Davidson [whose utterances referred to different boxes] - as a result the Swampmans utterance, the gold box I saw yesterday, could refer to either box. In principle, Davidson tells us, the above indeterminacies can be extended to any degree we like: the fact that the Swampman happens to be molecularly identical to Davidson does not change the fact that he could have arrived at that state by any one of countless histories, each of which would demand we interpret him differently. Thus Davidson asserts that until the Swampman has begun interacting with and using language among the objects of the real world, we can have no grounds to attributing any meanings or thoughts to him at all. 01/04/2014(c) Bishop: Consciousness and Cognition18
Is the Swampman in support of Chalmers Zombies? On the one hand, the Swampman argument is believed to merely demonstrate that Swampmans utterances and thoughts do not mean anything, (and do not refer to anything in particular). On this view, Swampman's subjectivity and consciousness are considered to be unchanged. Alternatively others have argued that this lack of a causal history renders incoherent the notion that Swampman could have a mind at all… … Which in turn raises the question of whether he is, in fact, a person or a zombie. NB. Interestingly Davidson calls Swampman it rather than he. In the context of Chalmers molecule-by-molecule Zombie duplicates, the second interpretation of the Swampman argument lends some support to Chalmers claim that there can be Zombies which lack a conscious mind. 01/04/2014(c) Bishop: Consciousness and Cognition19
01/04/2014(c) Bishop: Consciousness and Cognition20 Other critics of Chalmers (1) Chalmers work attempts to, take consciousness seriously, but is not without its critics … The POI implies panpsychism. Explored in Bishop, (2002), Dancing with Pixies, orCounterfactuals Cant count. What level of functional equivalence needed for Fading & Dancing Qualia? Duplication or simulation? (Searle) Is functional equivalence possible/computable without duplication? (Penrose)
01/04/2014(c) Bishop: Consciousness and Cognition21 Other critics of Chalmers (2) Panpsychofunctionalism, (Max Velmans, Perspective, 1998) If consciousness of given sorts is invariably associated with functioning of given sorts then: All forms of functioning are associated with some kinds of experiences. The experience of consciousness is contingent on function not embodiment. But functionality is observer relative … Does the statue on my mantelpiece experience something different when it functions as: art; a door stop; incense holder? Or must it experience all possible states simultaneously?
01/04/2014(c) Bishop: Consciousness and Cognition22 Other critics of Chalmers (3) Equivocation in Dancing Qualia, (Heuveln, Dietrich & Michiharuoshima, Minds and Machines, 1998) Does the Dancing Qualia argument describe one conscious system with homunculus or two? When flicking the switch we could generate two individuals each experiencing their own phenomenology … … Easier to see by running Dancing Qualia Argument and switching between whole brains!