Presentation on theme: "Cognitive Computing 2012-2013 Consciousness and Computations: human and machine consciousness 1. CONSCIOUSNESS AS A BIOLOGICAL PHENOMENA (SEARLE) Mark."— Presentation transcript:
Cognitive Computing 2012-2013 Consciousness and Computations: human and machine consciousness 1. CONSCIOUSNESS AS A BIOLOGICAL PHENOMENA (SEARLE) Mark Bishop
01/04/2014(c) Bishop: Consciousness and Computations2 The problem of consciousness On revulsion: perhaps as a collective subconscious echo of the conclusion to Wittgensteins early 20 th century masterpiece of analytic philosophy (The Tractatus Logico-Philosophicus) … 7: What we cannot speak about we must pass over in silence. … for much of the twentieth century the pernicious influence of behaviourism led many scientists to consider that consciousnesswas not a proper subject for scientific enquiry.
01/04/2014(c) Bishop: Consciousness and Computations3 But what does talk ofconsciousness encompass? Phenomenal consciousness: The insistent shrillness of a babys cry. The smooth cooling flow of fresh spring water. Reflexive and Access consciousness: Access consciousness (cf. Ned Block): the phenomenon whereby information in our minds is accessible for verbal report. Reflexive consciousness: imagine two people, both of which are in pain, but only one of which has a thought about that pain. Both would have phenomenal states, but only the latter would have a state of reflexive consciousness (on the pain).. Meta consciousness: Worrying that I might be worrying too much about pain. Searle, The mystery of consciousness How to move from neuronal activity to conscious experience?
01/04/2014(c) Bishop: Consciousness and Computations4 Consciousness and brains If consciousness resides in the brain, to understand consciousness why dont we simply analyse the operation of the brain in much the same way as we analyse the operation of a cell? Brains are complex. 100 billion neurons all massively interconnected. Furthermore, a reductionist analysis of neurons appears to leave out the central aspect of consciousness … Phenomenology; what experience actually feels like!
01/04/2014(c) Bishop: Consciousness and Computations5 What is consciousness? Defining consciousness … In The Mystery of Consciousness John Searle opts for a simple common sense definition of consciousness … … those states of sentience and awareness that typically begin when we awake from a dreamless sleep and continue until we go to [a dreamless] sleep again, or fall into a coma or die otherwise become unconscious. Consciousness is a binary predicate (it is present or absent) but states of consciousness may themselves be graduated. E.g. consciousness may be: sleepy; drowsy; alert; demented; senile etc. Searle is not interested in delineating exactly how far the phylogenetic scale consciousness pertains: Humans – yes Cats (& dogs) – yes Fleas - ?? Amoeba -- ????
01/04/2014(c) Bishop: Consciousness and Computations6 Searle on dualism From Descartes there has been a hard delineation of all substance into res cogitans and res extensa. For Searle [in part] Dualism arose to help get the religious authorities off the scientists back.. Cf. Galileo. Famous twentieth century dualists include: John Eccles [Nobel Laureate] God attaches soul to foetus at around 3 weeks. Roger Penrose [often labelled a modern-day Platonist] Not just one world but three: physical; mental and abstract-objects.
01/04/2014(c) Bishop: Consciousness and Computations7 Do brain processes cause consciousness? If brain processes cause consciousness, then this seems to imply a dualism of cause and effect: with brain process as causes and conscious states as effects. But not all cause and effect relations are temporally ordered. Consider, a pivoted-rod that is moved-down on one side co-temporally rises-up on the other. For Searle low-level brain processes cause [emergent] consciousness but as an emergent state (or feature) of the brain not a separate [tacked-on] entity; Is this a solution to the mind-body problem? I.e. The problem remains that mental phenomena appear to be qualitatively and substantially different from the physical bodies on which they appear to depend.
01/04/2014(c) Bishop: Consciousness and Computations8 Public lives; private feelings How do publicly measurable brain processes cause [private] internal feelings? My pain has a certain quality that is available to me but not you. Does this preclude mind reading machines ?? Qualia (quale): the subjective feeling of conscious state(s) or event(s). Not clear how to relate qualia to neuronal activity c.f. Francisco Varelas Neuro-phenomenology project. Qualia as a specific object (form) of conscious experience. Qualia of colour well defined (though perhaps not for Alva Noe). Qualia of second order differential equations less so…
01/04/2014(c) Bishop: Consciousness and Computations9 The ubiquity of the computational metaphor Many people think of the brain as a [digital/ connectionist/ analog] computer. The mind is to the brain as software is to hardware. Strong AI (Searle) The mind is a computer executing a suitable program. Syntax and semantics (Searle) 1. Computers operate via syntactical rules. 2. Minds have content; human languages have semantics. 3. Syntax is not the same or sufficient for semantics, (via CRA). HENCE PROGRAMS ARE NOT MINDS!
01/04/2014(c) Bishop: Consciousness and Computations10 Misconceptions of the CRA Machines cannot think But humans are machines.... and humans can think ! Computers cannot think But humans are computers (they can compute).. 2 + 2 = 4.. and humans can think ! Searle on possible emergent consciousness in a computer: It may be that an emergent property of a computer is consciousness (in much the same way as another emergent property is its giving-off heat).... but this is not consciousness via the instantiation of a specific computer program, (I.e. Strong AI).
01/04/2014(c) Bishop: Consciousness and Computations11 Syntax is observer-relative The natural sciences typically deal with observer-independent phenomena: mass; charge etc. Whereas the social sciences typically deal with observer-relative phenomena: money; marriage; society. Computer syntax is fundamentally observer-relative; it is not an observer-independent phenomena, intrinsic to the physics of putative computational systems. I.e. What makes computer electronics behave syntactically is the, eye of the beholder, or user of the equipment. Consider the AND gate / OR gate dichotomy which is contingent upon the logical mapping used between physical voltage and a logical computational state.
Some computations can be observer independent … Consider a human computer consciously computing E.g. 2 + 2 = 4… … However in general computation - as performed by a PC – is observer dependent and as such computation is a mere judgment made by an observer (and/or user). Albeit such computational interpretation is certainly not arbitrary - much effort is spent into designing hardware such that it functions in a certain, computational, way - but equally it is not intrinsic to the physics of the machine! Compare a chess computer used to play chess and the same program used to control a series of coloured lights in an art exhibition. To paraphrase Wittgenstein, The meaning of a computation is in its use. 01/04/2014(c) Bishop: Consciousness and Computations12
01/04/2014(c) Bishop: Consciousness and Computations13 Brains and computers Is the brain a digital computer? No, because nothing can be intrinsically a digital computer; Because computation is always relative to the goals of an observer. Can you assign a computational interpretation to the brain? Searle, YES ! Penrose, NO !
01/04/2014(c) Bishop: Consciousness and Computations14 On physical brains For Searle, brains are biological machines. Consciousness is caused by neuronal process and is an emergent feature of the brain. i.e. It is causally explained by the behaviour of the elements of the system; but it is not a property of any individual elements. C.f. The behaviour of H 2 0 molecules explains liquidity but individual molecules of H 2 0 are not liquid.