flex-introphil-Week 3 - Minds, Brains and Computers-Handout - Philosophy of Mind, Large Format.pdf

Dr. J.S.Lavelle, University of EdinburghMOOC Introduction to the Philosophy of Mind (January 2013)

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Introduction to the Philosophy of MindIntroductionPart one: Theories of Mindi. Cartesian dualismii. Identity theoriesiii. FunctionalismPart two: Mind as Computeriv. Turing machinesv. Searles Chinese Room argumentConclusions

IntroductionWhat is it to have a mind? Were certain that anyone reading thishandout has a mind. But what are the special properties we considerminded beings to have, and are these properties shared by other animals,or even infants? In this lecture I introduce some of the approachescontemporary philosophers have taken to the question of what it is tohave a mind.Some terminology: I will use the term mental state to refer to anymental phenomenon, e.g. thoughts, emotions, sensations. So the thoughtthat beaver dams are cool, and the joy I feel when I see beavers building adam are examples of mental states that I can have.Further readingClark, A. (2001).Mindware. Oxford University Press. (Introduction andchapter 1)


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i. Cartesian (or Substance) DualismCartesian dualism is the idea that the mind is made of a fundamentallydifferent substance to the body. The mind is made of immaterial stuffand the body is made of material stuff.Material substances

Have extension. Extension = occupies a certain amount of space.Immaterial substances

Do not have extensionAccording to Cartesian dualism, minds are made of immaterial thinkingsubstance which does not occupy a place in space. The part of me thatthinks exists independently of the body.

>> To find out more about how Descartes argued for this position,see Appendix 1.Princess Elizabeth of Bohemia & the problem of causationPrincess Elizabeth of Bohemia was one of Descartes pupils. She pointedout that physical things can only be changed by interaction with otherphysical things. If the mind is immaterial (i.e. not physical) then how canit instigate changes in the body, which are physical? It is clear that mindscause behaviours it is my desire for juice that causes me to walk to thefridge but how can this be on Descartes position? She challengedDescartes to

[Explain] how the mind of a human being, being only a thinkingsubstance, can determine the bodily spirits in producing bodilyactions. For it appears that all determination of movement isproduced by the pushing of the thing being moved, by the mannerin which it is pushed by that which moves it, or else by thequalification and figure of the surface of the latter. Contact isrequired for the first two conditions, and extension for the third.[But] you entirely exclude the latter from the notion you have of thesoul, and the former seems incompatible with an immaterial thing.


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Princess Elizabeth of Bohemia, 1643. Cited Kim (2006, 41 -2)Descartes faces the problem of explaining how minds can cause bodies tomove if they are made of substances which do not occupy a place in space.Similarly, he will also need to explain how physical substances that weingest can affect our minds, as is the case with hallucinogens.Further readingDescartes 2nd and 6th Meditations. Many editions available.ii. Identity theoryPhysicalism is the view that all that exists is physical stuff, that is, stuffwhich has extension. Therefore, whatever our explanation of mentalphenomena is, it cant go around citing immaterial stuff! This gets aroundthe problem of causation, because if mental phenomena consist inphysical stuff, just like our bodies, then they can interact with our bodiesto cause various behaviours.On one view of physicalism mental phenomena, like thoughts andemotions etc., are identical with certain physical phenomena, e.g. acocktail of chemicals in our heads. This is known as the identity theory.The identity theory of physicalism with regards to mental states claimsthat having a mental state consists in being in a particular physical state.For example, being in pain is identical to your C-fibres firing and there isnothing else to it than that. Identity theory is a reductive account ofmental states: it is reducing them to physical processes.There are two ways of spelling out the identity theory, which rely on thetoken/type distinction.The token/type distinctionHow many dogs were at Crufts last year?This question could be interpreted in two ways. The questioner might beasking about how many types of dogs (i.e. breeds) were at Crufts last year,and the answer would be around 300. Alternatively, she could be askingabout how many individual dogs were at Crufts last year, in which case


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the answer would be around 3,000. In the second case, philosopherswould say she is asking about how many dog tokens there were at Crufts.If I were looking at two Bassett hounds, we would say that I was looking attwo tokens of the same type: I am looking at one type of dog (namely, theBassett hound type) and two instances of that type, referred to as tokens.This matters for our discussion because when an identity theorist saysthat mental phenomena are identical with physical phenomena, we wantto know whether she thinks:

a) That types of mental phenomena (e.g. the type feeling sad, or thetype feeling happy) are identical with types of physical phenomena(e.g. that feeling sad can be reduced a particular chemical cocktail).This is known as type- identity theory. 1Or

b) That instances, or tokens, of mental phenomena are identical withphysical phenomena. On this view, you can just claim that thehappy feeling I had yesterday at 15:10 was identical with a physicalstate. This is known as token- identity theory.

Type- identity theory claims that for every type of mental phenomenon(feeling sad; feeling happy; wanting something or hating something) thereis a corresponding physical state. So pains are identical with C-fibreactivation2: my pain is identical with my C-fibres activation, and your painis identical with your C-fibres activation; my pain now is identical with C-fibre activation and my pain yesterday lunch time was also identical withthe activity of my C-fibres.By contrast, token-identity theorists say that my pain yesterday wasdefinitely identical with a physical state. And my pain today is definitelyidentical with a physical state. And your pain is identical with a physicalstate. But these physical states might all be different: the first might beneuron 24 firing, whilst the second is neuron 408 firing. All the token-1 Strictly speaking type-type identity theory because it says types of mentalphenomena are identical with types of physical phenomena.2 Philosophers love to talk about C-fibres as being identical with pain. But, really, weknow that the neural correlates of pain are much more complicated. We also likediscussing pain a lot, which gives a worrying insight into the profession.


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identity theorist is committed to is that every mental phenomenon isidentical with some physical phenomenon.Type- identity theory offers a stronger research program. It says that typesof physical states, e.g. a surge in endorphins, are identical with types ofmental state, e.g. feeling happy, and that this is the case for all humans.A problem for type- identity theoryHilary Putnam, in his 1967 paper The Nature of Mental States raised thefollowing objection to type-identity theory, arguing that it is too narrow.Imagine that we find the cocktail of chemicals which we are certain istype-identical to the mental state of feeling pain. Putnam says that allweve done is find out the identity relation between pain and its physicalrealisation in humans. Lets say, for the sake of argument, that octopusbrains are made up of totally different chemicals to human brains, butthat we have good reason to believe that these critters feel pain, e.g. theywithdraw from hot stimuli, they engage in avoidance behaviour aroundthose stimuli, we see a spike in their brain activity when they touch hotthings. Do we want to deny them pain because their brains are made upof different stuff to ours? Of course not, says Putnam.Multiple realisabilityThe key point for Putnam is that mental states are multiply realisable.This just means that any mental state, e.g. the mental state of wanting apet beaver, can be instantiated in a variety of different physical systems.It could be in a physical system made out of H2O and other chemicals(like us) or a system made out of something totally different, like thechemicals in an octopus brain.To take a different example: in our society, money is made of bits of paperand metal. But in other societies shells are used to trade with, and thevalue of various things is measured in terms of how many shells they areworth. In other societies still livestock serve the function that metal andpaper serve in our society. But cows, shells and bits of paper and metalare all recognisable as currency in virtue of them all playing a particularrole (being traded for other objects, and being a unit of value). Currency


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is thusmultiply realisable: there are lots of different things that arecurrency in different cultures, but they all share a common role.iii. FunctionalismPutnams insight had a considerable impact on contemporary philosophyof mind. He was saying that rather than thinking about mentalphenomena in terms of what they might be made of physically (becausethis leads to all sorts of problems when it comes to non-humans) weshould be thinking about them in terms of what they do. This led to thefunctionalist account of mental states. Functionalists claim that trying togive an account of mental states in terms of what theyre made of is liketrying to explain what a chair is in terms of what its made of. Whatmakes something a chair is whether that thing can function as a chair: canit support you sitting on it; does it have support for your back; does itraise your sitting position up from the ground? Chairs can be made of lotsof different things, and look completely different, but what makes themidentifiable as chairs is the job that they do.Putnams big claim was that we should identify mental states not by whattheyre made of, but by what they do. And what mental states do is theyare caused by sensory stimuli and current mental states and causebehaviour and new mental states.

The belief that tigers are dangerous is distinct from the desire to hug atiger in virtue of what that belief does. The desire to hug a tiger wouldcause me to rush towards the tiger with open arms, and it might becaused by the belief that tigers are harmless human-loving creatures.Whereas the belief that tigers are dangerous is caused by my previousknowledge that tigers eat people and that creatures with big teeth aredangerous, and causes running away behaviour as well as new mental


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states such as the dislike of the person who let the tiger into the room inthe first place. To make the contrast with type-identity clearer: on a type-identity view what makes the belief that tigers are dangerous distinct fromthe desire to hug a tiger is the different chemical cocktails which thosestates consist in. But functionalists say that this is wrong: what makeseach of these states distinct is their different functional roles. They mightalso be made of different chemicals, but thats by-the-by. The interestingdifference lies in what causes them and what they do.Part two: Mind as ComputerFunctionalism provides the segue to the next aspect of this lecture,namely, that it has become very popular to think about the mind asanalogous to a computer. Computers are information processingmachines: they take information of one kind, e.g. an electrical pulsecaused by the depression of a key, and turn it into information of anotherkind, e.g. displaying a number on a screen. And one could argue thatminds are also information processing machines: they take informationprovided by our senses and other mental states which we have, process itand produce new behaviours and mental states. We individuate mentalstates by the processes that they can engage in, processes which requirecertain starting conditions (particular mental states and sensations) andresult in end conditions in the form of new mental states and behaviours.The similarity goes further: what allows us to identify something as acomputer or a mind is what that thing does, and not what it is made of.In this next part of the lecture, well look at some of the consequences ofthe view that minds are computers.iv. Turing machinesComputers come in varying degrees of complexity. There is a computer inmy washing-machine which controls the various cycles. There are alsocomputers which can generate complex probabilistic models which weuse to predict all kinds of phenomena: weather cycles, biologicaldegradation, wave formations etc. If minds are computing machines,then how complex does an information-processing system need to bebefore it counts as a mind? In his landmark paper Computing Machinery


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and Intelligence (1950) Alan Turing (1912 1954) proposed the followingthought experiment as a response to this question.Turing asks us to imagine three people, a questioner and tworespondents, a man and a woman. The questioner is in a different roomto the respondents, and can communicate with them via an instantmessenger style set-up: the questioner types questions which appear onscreens in front of the responding man and woman, who in turn can typemessages back. The task set to the questioner is to determine which ofthe respondents, labelled only as X and Y, is the man, and which is thewoman. The mans task is to mislead the questioner into believing that heis the woman, and the womans task is to help the questioner.The next stage of the game is very similar, except that the man is replacedby a computer, and the questioners task is to determine which of therespondents is the human, and which is the computer. As before, thecomputers task is to mislead the questioner into believing it is thehuman, and the human-respondents task is to help the questioner.Turings hypothesis was this: if a computer can consistently fool theinterrogator into believing that it is a human, then the computer hasreached the level of functional complexity required for having a mind.(For a cinematic interpretation of the Turing Test, take a look at RidleyScotts Bladerunner ).There are, as ever, objections to the hypothesis. It might be possible, forexample, that a machine with an extremely large database with a powerfulsearch engine passes the test. Thus, when asked what 84 13 is, themachine whizzes to its set of files labelled possible subtraction sums,pulls out the file labelled 84 13 (perhaps it is nestled between the fileslabelled 84 14 and 84 12) and displays whatever it finds in that file.And it does the same for questions like do you prefer your martinisshaken or stirred or what are your views on Tarantino films? We wouldbe reluctant to label such a machine a thinking machine. This suggeststhat Turings test is not sufficient for finding thinking machines, becauseit does not take into account the internal structure of the machine. Thisexample is intended to show that the internal structure of a processingmachine matters when it comes to determining whether it is minded.


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In addition to this concern, one might wonder if the Turing test is toolimited: surely there might be beings who cannot persuade the questionerthat they are human but who we nevertheless want to count as minded.The Turing test relies on language, and it sets very narrow criteria forminds, namely, that they must be like human minds. But it is not a verybig stretch of the imagination to conceive of aliens who appear to actintelligently but who would not be able to pass the Turing test.Further readingTuring, A. (1950). Computing Machinery and Intelligence. Mind, 59, 433 460. There are also lots of free versions of the paper available on-line, andit pops up in lots of philosophy of mind anthologies.v. John Searles Chinese RoomThe idea that the mind is a computing machine is certainly an attractiveone. However, there are problems with the view, and to finish Id like topoint to some of these using John Searles Chinese Room thoughtexperiment (1980). Searle asks us to imagine the following situation: youare in a sealed room whose walls lined with books containing Chinesesymbols. For the sake of the experiment, we shall assume that you do notunderstand any Chinese at all, in fact, you are so ignorant of Chinese thatyou do not even know that the patterns in the book are linguistic symbols.There is a slot leading into the room, through which occasionally comepieces of paper with patterns on. You have a code-book which contains aset of rules (written in English) which tells you what to do when particularpatterns are posted through the slot; usually this means going to one ofthe books in the library, opening it to a particular page, and copying thepattern you see there onto the piece of paper you have received, andposting it back out through the slot. The code-book covers all possiblecombinations of patterns that you might receive.Now lets suppose that outside of the room is a native speaker of Chinese.Unbeknownst to you, she is posting questions in Chinese through the slot,and you are giving her coherent answers to these questions. Althoughbelieves she is conversing with someone who understands Chinese, you


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actually do not understand any Chinese at all, you dont even know thatyou are engaged in a communicative act!Searle is pointing to a fundamental issue facing the view that the mind is acomputing machine. Computers work by processing symbols. Symbolshave syntactic and semantic properties. Their syntactic properties aretheir physical properties, e.g. shape. Their semantic properties are whatthe symbol means, or represents. Thus, if I were to say let be thesymbol for start dancing, then its syntactic properties are that it has fourright angles and four equilateral sides, and its semantic property is that itrepresents the instruction start dancing, and that in certain contextswhen we perceive this symbol we should start to dance.Calculators, computers, etc. are symbol manipulating machines. Butimportantly, they are only sensitive to the syntactic properties of symbols.We program machines with rules that operate on the syntactic structureof the symbols it receives. One rule might be If input A and input Bproduce output A&B. The computer can do this operation just bylooking at the physical structure of the shapes.The problem is that the computer does not know that it is manipulatingsymbols that have semantic content any more than the person insideSearles Chinese room knows she is manipulating Chinese characters.This leads to a fundamental issue with the claim that the mind is acomputing machine: what part of the machine understands the symbolsthat it is manipulating? With a computer it doesnt matter that themachines processing has nothing to do with the semantic content of thesymbols, because it is the humans who use the machine that have thisinformation, we are the ones who give meaning to those symbols. But ifthe mind is just a processor which operates on the syntactic properties ofsymbols, then how can it produce a being who can understand themeaning of the symbols? How can a mind think about dogs, when all itrecognises are the syntactic properties of that symbol? Where is theprogrammer who deciphers the meaning of all the symbols?


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The Chinese Room argument throws up all sorts of tricky questions,discussion of which we shall have to leave for another day. Ill leave youwith one last puzzle.


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Representation is a three way relationWhat makes something a symbol or representation? We say thatsomething is a representation or symbol if it functions as one. When Imat the pub, I might use beer-mugs and coasters to represent a particularfootball formation on the table, and move them around to demonstratewhat happened in a game. The beer-mug is functioning to represent meon the football pitch.What we need to grasp here is that representation (including symbolicrepresentation) is a three way relation: X represents Y to Z; the beer-mugrepresents my position on the field to my friends. But when it comes tominds, its not clear what fills the place of Z: this neural activity representsa dog to ???ConclusionsThe aim of this lecture was to introduce some of the core topics incontemporary philosophy of mind. We began by looking at the merits ofphysicalism over Cartesian Dualism. We then turned to how thephysicalist position has played out, first through identity theories andthen through functionalism. Functionalist was the catalyst for thepopular move to start thinking of minds as computers, informationprocessing machines which operate on the syntactic structures ofsymbols. By thinking about our minds containing symbols which canrepresent states of affairs, we begin to address one of the fundamentalquestions in the philosophy of mind: how can thoughts be about things?We have not touched on how a symbol-crunching machine could possessconsciousness. Indeed, we have side-stepped the issue of consciousnessaltogether. That would be a topic for another day. We have also passedover the intricacies of these debates: each of these topics would bediscussed over two or three weeks in our undergraduate classes! Despitethis, I hope the MOOC has given you some insight into some of thepuzzles which have inspired, and continue to intrigue, philosophers ofmind.


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Further readingClark, A. (2001) Mindware: an introduction to the philosophy of cognitivescience O.U.P.Crane, T. (1995) The Mechanical Mind PenguinD. Hofstadter and D. C. Dennett (Eds.) The Minds I: Fantasies andReflections on Self and Soul Basic Books


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Appendix 1: The argument from doubtThere are several arguments which Descartes offers for his dualisticaccount of the mind, but the most famous is the argument from doubt(Discourse, second meditation):

1. I can doubt the existence of everything around me2. I cannot doubt the existence of my thoughts (my mind)3. Therefore, my mind must be made of something fundamentally

different from everything else around me.Descartes believed that this argument shows that the mind must be madeof a different substance to his body and other things found in the physicalworld. This is because it has a property which physical things do not: itsexistence cannot be doubted. To put it another way: I can imagine thatthe physical world does not exist, but it is impossible for me to imaginethat I dont exist because there has to be something which is doing theimagining! Hence the famous Cogito: I think therefore I am. In order tothink, there must be something which is doing the thinking (namely, me).There are significant problems with this argument. Most pressing, aspointed out by Leibniz (in his Philosophical Papers) and Arnauld (acontemporary of Descartes) the argument is revealing about the nature ofthe imagination (or doubt), but not necessarily about the nature of themind. Doubt is such that we cannot apply it to our own minds but thisdoes not tell us anything about the nature of the mind.An example might help here.3 Lets imagine that I am unaware that Dr.Jekyll is Mr. Hyde. I can imagine a scenario where Dr. Jekyll apprehendsMr. Hyde and leaves him in the custody of the police, going home to awarm supper whilst Mr. Hyde languishes in the cells cursing Jekyll. Yetthis imagining does not inform me of what is in fact possible. Rather, itreveals a limitation on my knowledge which cannot be appreciated frommy current perspective. It is perfectly logical to state that if two thingshave different properties then those two things distinct. But this doesnt

3 My thanks to Dr. Paul Sludds who thought of this example!


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hold once we throw psychological terms in there: If I believe two thingsto have different properties then they are distinct. This is because mybelief might not match on to how the world actually is. I believe that Dr.Jekyll has the property of being kind, and that Mr. Hyde lacks thisproperty (being a murdering psychopath), and I infer from this thatbecause Dr Jekyll has a property that Mr. Hyde lacks, they must bedistinct people. This believing, however, does not preclude the possibilitythat they are identical.

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