A romp through the philosophy of the mind -- Marianne Talbot (1/5)

okay right this first session we're going to be talking about identity theory and why it won't work so first I'll be telling you what identity theory is in session two we're going to be talking about non reductive physicalism so I'll have to explain that to you because first you need to know what reductive physicalism is before you can understand non reductive and then i'm going to look at if physicalism won't work what is the alternative and of course at the moment you're thinking well of course physicalism is going to work so that's not a problem and in the fourth session I'm going to be looking at are we asking the wrong question and session five is entirely for you and you'll be asking me questions I'll probably be doing a lot of talking but but the impetus will come from you okay so let's go straight into session one which is identity theory and why it won't work and what I'm in to do is I'm going to look at the context in which the identity theory was postulated so you know why identity theory was attractive at that time I'm going to look at what identity theory is why it's attractive generally what the arguments are for it and finally I'm going to look at why we shouldn't accept identity theory so that's the outline of what I'm going to do let's get straight on and do it okay looking at the context of identity theory you might recognize this chap if not you might have heard of him Rene Descartes in the mid 1600s and right up until the early 1900s and his theory Cartesian dualism was the in theory of mind Cartesian dualism holds that there's a real distinction between mental states and physical States and actually this was a very serious distinction because he actually thought they were different substances that the physical world is a substance like this whereas the mental world is a completely different sub students interesting question and but he thought they can't be identical because they're essential properties are utterly different so okay we're going to look at hasn't meant the so the properties of the mental and the properties the physical according to Descartes are completely different well okay let's think about that let's just look Descartes believed that the essence of the mind the essence of mind in other words the properties essential to the mind were various forms of thinking okay so what do you think various forms of thinking might be can you think of different forms of thinking different ways in which you might think or different thoughts that you might have different sorts of thoughts sorry certainly problem-solving would involve thinking wouldn't it yes yes emotions whether emotions or thoughts I'm less sure about that I would have thought that they the essence of emotions might be to have some quality so to love someone there's something it's like isn't it isn't there to love someone there's something big angry there's something it's like to be angry and philosophers call that those states have some sort of quality or qualia there's something that it feels like to have them deduction is a different way of thinking that's right rather than a different sort of thought but imagination would be one way of thinking actually for Descartes that was a bit of a technical term he wouldn't have thought imagination was a matter for the mind at all but I'm going to put that on one side because I can see why you think it is and and I don't think we need to go into it and you're thinking of different contents of thought and several of you are and that that's perfectly reasonable planning you're another one who's thinking of the same sort of thing intending would we one sort of thoughts went it's so when you intend to do something that's a very specific sort of thoughts you're having vision wishing rational thought and all thought is rational and it really is yes I'll come back to that in a minute you might be surprised by that but actually let me quickly explain and the fact is that he right you can be irrational in your thinking but irrationality is a failure within the house of reason you can't be irrational unless you can be rational so this table for example can't be rational at all can it and it can't be rational either sure ative thinking you wouldn't say that was thinking their intuition and I'd like to put on one side for a minute again we'll come back to that maybe okay that that's quite enough I think we're in fact I think is very good we're doing very well where's a pen um right okay I now want to think we've we've got our feelings in for what the mind is like what what sort of thing are in the mind I'm going to make a distinction here between the physical realm and the mental realm okay can you all see this there is that better okay this is the mental this is the physical and we're going to look at things we're going to look at properties and we're going to look at relations you probably can't read that but it doesn't matter I'll tell you what it is if you forget and okay so the things in the mind we've looked at intentions we've looked at thoughts generally what else did we look at we looked at wishes hopes and we looked at emotions so things like anger and fear and love and so on we might look at sensations like pain etc okay give me some things that you think of as physical what sort of thing do you think of as physical a table yeah rather obviously physical tables matter is physicality so I won't put that in a star I think we'll put it yeah sorry physical people well can I say human bodies human bodies are certainly physical whether people are is will leave out for a minute what else is physical feelings feeling did you say and what we usually think of feeling is mental don't mate here or what rock boiled hard like sorry like here we feel ear but can't see it an ear if air ah air is physical yes okay it is sensations on that side so pain and tickles well okay if I kick you and I wouldn't dream of taking you Susie but if I kicked you and I would cause damage to your tissue and you would feel pain we usually consider the tissue damage as physical but the pain is mental and it's the pain that's the sensation you feel you say you feel the tissue damage but actually what you feel is the pain caused by the tissue damage so some people who have had a leg amputated will continue to feel pain but they'll even continue to fill it in their leg but as they have no leg that this isn't the case so we know it isn't the case okay anything else that's physical can we have a few more molecule uh well all these things are made up of molecules molecules are certainly physical but I'm thinking of more straightforward things like pens I mean molecules we can certainly put in their pens thank you who said that go to the top of the class David Partridge I just learned his name okay those are some things some of which are mental some of which are physical but what about properties of these things let's start with the evening easy ones give me some properties of physical things hardness okay what did you say entity density okay shape weight and yeah well it's shapes that can be a apprehension is a mental thing not a physical thing isn't it so this this give me something Square somebody well actually don't bother there's something blue will do okay so this chair is blue and I apprehend its blueness I perceive that it's blue the perception is a mental state the blueness of the chair is a physical state okay thank you well done color is a physical property yeah anything else extension solidity extension means solidity so if there's something physical it'll take up space won't it in some form or other it'll be three-dimensional even err is is a three-dimensional in that you can't if it's there you can't go into it the same place temperature yeah that's an interesting one actually I forgot to point extension in temperature is an interesting one because and there's the temperature of the table say or the radiator and there's the feeling of heat when I touch it do you see what I mean so there's the feeling of heat but but the temperature of the radiator okay what about properties of the mind so what sort of properties the thoughts have so like you say that pen is hard or that table weighs a lot or that chair is blue when you say that belief is that belief is frightening okay I'm going to put frightening in because I want to think about it credible did somebody say if it's a belief it would I mean credible means believable doesn't it that a belief is a believable hmm whoops we usually think of rigidity over here actually because rigidity is a physical state isn't it so what do you mean when you say that a belief is yes we do say that don't we and what is rigid thinking because we don't mean it's rigid like that do we that's stuck in what-what-what is it finished let's come back to that because I think we can come back to that intensity a belief can be intense there's something much simpler things beliefs can be what about true don't don't we think of beliefs is true or false in photic yes and we're thinking of properties of thoughts at the moment we're not thinking logical okay well put logical in there actually I won't forget put logical in there and I'll tell you why in a minute sorry calm okay serene okay round you're it's very interesting you're going for a lot of interesting things you'd obviously all make good creative writers here I'm going to put justified in and because we think of thoughts is more or less justified don't we so so you wouldn't say of a chair that it could be justified or of a glass that it could be justified but thoughts can be justified can't they so it's that belief of yours justified or not and there certainly is always verbal they may be always verbalize a ball but but there's certainly not always verbal because I daresay you have thoughts to which you don't give voice I do every now and again and so truth and falsehood my mind um I think compelling could be on the list but I suspect that compelling actually means justified what makes the thought compelling and what is it for a thought to be compelling um and by that you mean true okay I'll tell you what let's move on to two relations because rational relations come in the relations section so physical things can be causally related can't they so a pens rolling off the table can oh sorry my pushing the pen can be causally related to the pens falling off the table causal relations there are temporal relations in the physical world one event is before another there are also temporal relations in the mental world and there are also causal relations in mental worlds one thought can cause another but but notice with thoughts that's often a malfunction of a thought what you want with thoughts is the rational relation between them you want one thought to be a reason for another if one thought causes another and well let's look at wishful thinking here my desire for something that my husband isn't having an affair for example and causes my belief that he isn't having an affair now notice that there isn't any rational relation between that desire and that belief there's simply a causal relation and that's a malfunction in mind isn't it we don't think that the desire is a good reason for the belief at all so there is causation in the mind but let's put a question mark there just to show that perhaps we wish there weren't we want it to be rational rather than causal and so those of you who say thoughts are logical and yes indeed thoughts are enter into logical relations with each other so if you say if the dog barked sorry if the dog saw a stranger it would have barked the dog saw a stranger it barks yes they are you see you're all rational people you can immediately see what you can deduce from the two beliefs that I talked about and that's because your beliefs are rationally related to each other and you're they enter into logical really you can logically deduce one belief from two other beliefs but there aren't any rational relations in the physical world other this this pen doesn't entail anything the way that the two beliefs I just gave you entailed the conclusion you came up with you can't get two physical things that are consistent with each other whereas you can have two beliefs that are consistent with each other so to be consistent is to for two beliefs to be true oh sorry such that they can be true together well given that tables can't be true and pens can't be true how can you say that the pen is consistent with the table you can say that the belief that the pen is black is consistent with the tables being under the pen for example but those are beliefs you're talking about not tables and pens and oil and water aren't consistent now what do you mean by consistent here it's a natural relationship sort of sue buyers work where things can go together that's what but that's where as rigid was a metaphor a physical metaphor for thoughts consistent is a mental metaphor for physical substances and oil and water are inconsistent aren't they rather than consistent yes I thought you mean that they don't mix yeah these are a similarity between the men well what is inconsistency mean in the rational realm let me tell you it means two for two beliefs to be inconsistent it means that they can't both be true together and they can't both be false together okay they can't both be true and they can't both be false so if one is true the other is false and if the other is true the one is false see what I mean that's what it means in the in the mental realm but if you put it in the physical world you can see where the metaphor comes from can't you but there's one like dancers one table in the room yeah and then I say can you speak up so everyone can hear then I say a few moments later at home there was left table in the room and was that other circle yep quite regardless now okay what Bob said is if I say there's one table in the room and then later on he says there's two tables in the room and those two facts he says are inconsistent what what's he got wrong can anyone say sorry Bob I apologize I know you can take it hang on I love this I love this because it's such an easy one to deal with I'm going to run out of firm flipchart here which is going to be very frustrating and Bob said if I say there are two tables in the room and then I say actually can I make it properly inconsistent there is only one table in the room okay these two facts are inconsistent okay is that what you said Bob okay and what do what does statements like that Express if you say there are two tables in the room what are you expressing your belief that there are two tables in the room right if you say there's only one table in the room what are you expressing your belief that there's one table in the room is the belief there are two tables in the room inconsistent with there is only one table in the room yep those two beliefs are inconsistent therefore the two statements are inconsistent the facts I only inconsistence by extension if you see what I mean those two facts couldn't both obtain do it could couldn't both be true your belief that there's one table in the room and that there are two tables in the room do you see there are different levels there's the level of I'm gonna run out of no I'm not there's a whole other one there okay there's the level of this plum thumb is still suffering from the accident I have accident in which I broke my thumb and that was over a year ago and I still can't turn pages and there's the level of the world if we like there's the level of thought and there's the level of language so there's the property of redness there's the thought the concept if you like is red and then there's the word is red that's a predicate okay you can say red has three letters you can't say of that of the concept because concepts don't have letters and you can't say that of the color because colors don't have letters either you with me okay and this you can say it's the color but you can't say have a concept that it is a color it isn't it's a concept and you can't say have a word that it is a color either do you see what I mean these three levels have to be kept separate in your thinking the whole time because if you slide from thinking I'm thinking I'm saying this and you get confused between what it is you're saying and what it is you're saying is of or between the world that you picture and your picture of the world it's very easy to get confused do you see what I mean we're trying to keep these three levels separate and what bob was doing there was sliding from what he could say and in doing so express his beliefs and to what he was saying it about it's not the facts that are inconsistent or the sentences that express them both of the sentences are true that maybe yeah I because they're saying I believe yeah I'm sorry the to save them again what are the two sentences one person said Bob said there's berries there is a table one both would be leeks times dare one doesn't each of them would be expressing their beliefs it would be true of Bob that he believed whatever it was he said he believed it would be true off Colin that he believed whatever it was he said he believed whether their beliefs are true is a completely different question isn't it because and if we say let's move the surface I can use this one as well if I can reach it actually build could you put that over there for me make it easier thank you and what's your name Mary good I can spell that Mary believes Mary Ann is wearing red okay notice there's a sentence embedded within another sentence yep okay so there's the embedding sentence which is Mary believes that Mary Ann's wearing red and there's the embedded sentence Mary Ann is wearing red now I think that that's probably true and that's probably true as well we'll call this skirt red didn't know quibbles about maroon or anything like that but could that be true in that false yeah Mary could have a false belief could they both be false yes I might have put my yellow skirt on today could now I've forgotten which way around I need to go and could that be true and that false yeah you see the the truth value of the what's true about Mary's belief differs quite independently about what whether Mary believes is true I got my syntax mix-up there but you can see where I was going one more question then we're moving on you said that my boss said there is a table in the room that was his belief no he was expressing his belief in a sentence so I mean I think the table only exists by this probably no no no no no if I said that I can a much better argument for it yeah so currently the the table is in the room the fact the table the tables being in the room makes true the sentence the table is in the room and it makes true the belief the sentences in the room for that reason we call it a fact we might say the fact that the table is in the room makes it true that this the statement the table is in the room etc but we have to distinguish the fact that makes true the statement and the belief that's what's important to keep separate here okay let's let's move on I need more pens and let's move back to where we were going here because we haven't even got on to identity theory yet and okay I'm going to add in here we we had all sorts of other things threatening compelling which I believe was a sort of justification and so on what I want to point out is how very varied oh there's something we've left out here bill you did say spatial didn't you well I read your thoughts then and the cup at the glass rather is on top of the table the water is in the glass the glass is in between Mary and me okay so in this physical world their spatial relations but do you have those in the mental world can we say that a desire is on top of a belief know we might scent metaphorically but that's what would mean it was metaphorical what about one belief being in between another we could say that couldn't we bowed mean temporally in between wouldn't we we wouldn't mean spatially in between beliefs don't seem to occupy space they don't seem to enter into spatial relations what I'm getting at here is why Descartes thought that the mind was quite different from the body he would look and you'd say well hang on believe the thing about beliefs is they can be true they can be justified and they can enter into rational relations with each other tables can't be true they can't be justified either they can't enter into rational relations with each other and pens can be hard pens can be weighty pens can be black but beliefs can't be hard weighty or black the thing about mental states and physical states is they have completely different properties from each other and we haven't actually mentioned qualia here but qualia the feeling of awful feeling of pain or the pleasant feeling I get when I look at Susie's jacket red happens to be my favorite color etc what it feels like to be in love what it feels like to be angry these are not physical properties this table doesn't feel these things it's true that we are human bodies which are physical and we feel those things which is quite interesting but all what Descartes thought that meant is that the thing about human beings is that they are persons when a human body is occupied by a saw is housed by a human mind then you get the intermingling of the mind and the body and that is what a person is so that's why when somebody said persons here I put human bodies rather than persons because persons are a mingling of the mind and the body according to Descartes okay so that's why Descartes thought the mind and body were completely different distinct now let's move on and it seems obvious that if two states differ in their properties than they can't be identical to each other can they i mean if two things are going to be the very same thing they've got to have the same property as haven't they they can't have different properties so as long as we believed that mental states and physical states differed with respect to their properties indeed they're essential properties we also believed that they had to be states of two different kinds and this is where dualism came from the idea that mental states physical states have completely different properties therefore they can't be the same thing one question David then I want to move on well a thought is extended in time isn't it a thought can take a while to come although actually I'm not I think a process of thought is extended in time rather than thought itself but why does that mean it has to be extended in space if you think space and time one thing I then you would have to say it was it centered in space but we don't usually think of thoughts as being extended in space we can't say a thought is six inches long can we not in ordinary world anyway well let's we're going to look at identity theory now so let's let's look at it and okay so that's when I was going to do what I've already done so we'll move on from that and okay there's undoubtedly a problem with the belief that mental states are not physical states because if mental states are not physical which is what Descartes said and which is what everyone believed on the strengths of his argument for so many years but how could they interact with physical states if they are not themselves physical states difficult problem that and and in the twentieth century it started to become intolerable because we think of physics as causally closed in other words if any physical event occurs it will have been caused by another physical event there can't be a cause of a physical event that itself falls outside physics that's what we think and if that's true then either mental events are physical events or mental events don't causally interact with physical events well yes they do if I throw my pen at you you'll duck and when you see it's coming seeing the red of the traffic light causes me to put my foot on the brake when I have a headache I might take an aspirin and that will do away with the pain of my headache my thought that there's water in the glass causes me to take a drink I mean we think that mentally interacts with physical all the time so we don't want to get rid of the idea that mental and physical events causally interact with each other but then how can we can't it continue claiming that mental events are not physical that's the thought so I'm going to look at one of the theories there were several theories before identity theory you might have heard of behaviorism behaviorism says that mental states are behavioral patterns so for example the having a pain is engaging in avoidance behavior or saying ow or something like that but that was very quickly discredited because we think of pain is what causes behavioral patterns of pain don't be rather than what is the behavioral pattern and but this is identity theory of mind and I would be prepared to bet that 50 at least 50% of people in this room actually I secretly think that as at least 99 percent of people in this room probably holds an identity theory but I'm now going to tell you why it's wrong these first I'm going to tell you what it is and the aim of the identity theorist is to discover empirical evidence for bridge laws now a bridge law and there are different sorts of law there are bridge laws and there are causal laws a bridge law says that all X F is and and a causal law says for all X and it is caused by G of X sort of thing um if and only if so abridge law is actually a statement of identity it says that all F so G ok all in this case I've got all pains are identical see fiber firing or all believing x' P are identical to activations of neural state N or something like that and the idea is that you're reducing the mental to the physical you can use these bridge laws so for every mental predicate is an intention is a pain is a feeling of love is this nothing the other you can correlate it with a physical predicate in such a way that you can say the mental state is the physical state they are one in the same state you see this in the newspapers all the time they say love is oxytocin activation or something like that or the belief that P and we get I mean you'll see I think will go and I just want to say here that I'm talking about non reductive physicalism later so identity theory is reductive physicalism because it uses these bridge laws to reduce the mental to the physical and the idea is that anything you could say about mental states you could translate if you like into physical statements by means of these bridge laws so if all pains are the same thing as a sefa if there's no pain that isn't a c fiber firing anything you could say using the word pain you could also say using the word c fiber firing if you like they are ontologically the same thing and and it's important to note here that the notion of identity being used is that of numerical identity not qualitative identity what do I mean by that if we say two dresses are identical we mean that the dresses are alike in their qualities don't we but there's still two dresses these dresses are qualitatively identical okay but when we say that Hesperus is identical to phosphorus we mean that the planet named by the name Hesperus is the very same planet as that named by phosphorus they're both the planet Venus and here it is so when we're talking here about numerical identity we're talking here about qualitative identity and when we're talking about psychophysical identity theory we're also talking about numerical identity so two dresses are qualitatively identical Hesperus is numerically identical to phosphorus an identity Theory believes that mental state types like pains as pain as a type of mental state is identical numerically to physical tape state types such as see fiber firing or in the case of the belief that P neural state n one question what to go surfing since I'm sorry can we have some numerical attention but with not presently and also you probably can poison one team and what we're not talking about yet whether numerically identical things could have qualitatively different properties all I want to do at the moment is distinguish numerical identity from qualitative identity any other questions about this distinction that I'm making here which is actually very important for understanding correlation but that's not this is that claim being made is is that it's a much stronger claim than a claim that the mental states are correlated with physical states the claim is that mental states are the very same thing as so it's a hugely strong claim you're quite right to distinguish the claim a and B are correlated from a is that as numerically identical to B because there's a to collect different claims something no definitely not numerically just stronger no qualitative identical is more than kind of like it it would have to be identical in its qualities but not the very same thing so again going back to the two dresses these two dresses are identical in various causes not all their qualities because they're not in the same place etc which gives you a hint for where we're going these they they're qualitatively identical but they're not dress is missing would make them not they're not the same dresses there are different dresses yeah if you have two things they cannot be the same thing can they bridge law well actually if you wait I think I'll answer that question so okay are you happy with the difference between quality was that another question back nope okay let's move on so identity theories the claim that mental state types like pains are identical to physical state types like see fibers or beliefs that pee are identical to neural state N okay I'm get that's what identity theory is and if you'll think you're happy with what it is I'm going to go on to why we might believe it and later on why we might not believe it yes just the individual is the sight to see um this is useless because this is fitting Jesus and I can't even yes I can I can turn this over bill could you help actually no don't worry because I can do it myself by the look of it efficiency way or what now all I need is pens that work then I'd be fine I forgot what I'm about to ask ok um is a pain ok there's a mental predicate this is the relation and all these are members of that relation or if you prefer this is the class of pains and these are all members of the class of pains you with me ok then if you have is a C fiber firing ok you would also the class of pains would be exactly the same thing as the class of C fiber firing so every token that is a pain is a C fiber firing and every token that is a C fiber firing is a pain that's what the identity theorist is claiming does that make sense 1 than 2 I'll talk about that in a minute I haven't said why we might believe it yet at the moment all I've said is this is what the theory is ok I promise I'll go into that so I will answer that question another word consciousness is a property of mental states so or a type if you like of mental states so anyone who is who has mental states is usually thought will be thought of in somebody who is conscious what is it you're conscious of your beliefs your desires your hopes your fears your pains your sensations okay let's let's look at why identity theories attractive okay here's the first reason and some of our behaviors seem straightforwardly to be a function of events in our environment if I what's your name wearing the purple t-shirt yep Julie if I throw my Pennock Julie she'll Doug if I throw it hard enough and she sees it coming she'll Doug and that seemed her ducking seems to be straightforwardly a function of the fact that my pens coming towards her and others are explicable only on the assumption that they're a function of the way the world appears to us so imagine that I'm drinking my water as you've seen me do several times and then I put it here and it crashes to the floor okay how would you explain that it was vodka says Alan hero fun he's so mean giving away my secrets say okay can I put that a little little I would consider it more precisely but I'm putting words in your mouth so you can tell me if I'm wrong and I put it there because I believed the table was there yeah okay so it was my false belief that caused me to put it down so if I put it there you don't even notice it because why did Marian put the cup there because the tables there and but if I put it here you move from explaining my behavior in terms of the world to explaining by behavior in the terms of the way the world appear to me do you see what I mean you you move from thinking about the world that we picture to our picture of the world or in this case my picture of the world and we often do that when things go wrong so you believe you've left your coat on the hook at the beginning of the party and then you go to get it at the end of the party and it's not there I thought I left my coat here you'll say immediately going from I left my coat here too I thought I left my coat here do you see what I mean the the error shifts you back because something has gone wrong if your belief had been true you would never have even noticed that you had a belief but because it's false your push back into thinking about your beliefs about the world rather than the world about which you have beliefs you'll see what I mean so and we need to appear to appeal to beliefs and when something goes wrong ok but hypothesis how do you explain this well and inside our heads there's something that causes me to put my glass down on the table ok so the belief that the table is there now sometimes that belief is true the table is there in case you don't eat no SID sometimes that belief is false and you do notice it but inside my head there's one in the same neural state that's causing the action in both on both occasions on one occasion the world isn't willing and on the other occasion the world is and but there's something in my head that is both the it is the case that P and the it appears to be the case that P state do you see what I mean and so if you go much they hold it there and somebody moved it my belief would still be well okay right here I come and move up and I put my coat here and in the meantime bill moves my coat go on just just do it with it okay so I continue to believe that my coat is there don't I and then I go round and ah now I might express I could say I believe I left my coat there which would be a true belief or I believed my coat was there or is there which would be a false belief so so it doesn't now he's going through my pockets did so do see what I mean as long as you get the the content of the belief right you can track it through but it doesn't matter how you do it if the belief is false and you so you believe something's true and it turns out to be false you'll be immediately pushed back into I'm going to draw you another picture this is why I need so many flip charts and this is okay here's the world that we picture and here's our picture of the world and usually we're conscious only of that we go through the world and we're conscious of tables and pens and watches and curtains and things like that we don't ever think about this lot but then something goes wrong and we suddenly think oh I thought my coat was there and actually what you are here is in your constructing a picture of your picture of the world aren't you so instead of thinking that your coat is on the hanger you're thinking my belief that the coat is on the hanger is false see what I mean so here you've got coat on hanger and here you've got belief coat is on hanger is false so here's the object and here's the predicate subject rather and here's the predicate and here's the subject and here's the predicate completely different and here what have you got here can you ever tell me well actually no don't bother about that it's just getting too complicated I can see I can see cans of worms coming out at coming up in front of me um but do you see why we would think that there's something in my head that is the same whether my belief is true or not and so it looks as if and beliefs are in the head we think and what we know what goes on inside the head now Descartes actually Descartes would have known - there are neural states that activate in response to environmental stimuli and that causally impact on our behavior so my putting the glass down there's going to be a neural state causally implicated in the production of that behavior whether that behavior is based on a true belief that the tables there or based on a false belief that the tables there see what I mean obviously beliefs are in the head I obviously there and obviously they're in neural states there is a neural state in there that is both the sorry that is the belief that the glass the belief that the table is there and whether the belief is false or true or not is something to do with the world nothing to do with what's going on inside my head because inside my head it looks the same to me whether the belief is true or false doesn't it think about hallucinations okay that's the first reason second reason what we've we've looked at this reason but not as a reason we dearly want to think of the mental as causally efficacious we want to think that it's the fact that we love our partner that caused us to marry him her well we want to think that it's because the glass is full that I put it to my lips and take a drink and so on but because we think of physics as causally closed in other words physical events don't just pop out of the physical and pop back in again and we think that everything that causes a physical event causally interacts with a physical event must itself be physical given this if mental states are not physical states it makes mental state causation look problematic but if mental states are physical which is what the identity theory says no problem of course they can cause causally interact with physical states no problem so three that's sorry that was two three Occam's razor of which you may have heard and tells us that we shouldn't multiply entities unnecessarily we should we should take theories if we have two possible theories both of which would explain a phenomenon then we should take the simplest theory rather than the more complicated one because there's no reason to take the more complicated one if both of them explain it then so dualism will explain psychophysical in wealth actually dualism doesn't explain psychophysical interaction but physicalism i reductive physicalism of this kind does explain causal interaction and what's more it's on two logically more parsimonious that was a good word wasn't it and so reducing the mental to the physical immediately halves the numbers of entities that we've got to admit into our ontology ontology forint I should have said is our list of what exists so if you believe in ghosts then on your list of what exists you have ghosts you admit ghosts into your ontology so if we say that mental states so we have an ontology that says okay there are ghosts and pens and tables and mental states and physical states or neuro signal states and we just said that these two are the same thing so our ontology is immediately looking much neater get rid of a whole class of entities say that they're the same as the other class oh look a fourth reason okay the fourth reason and it's that science and and this is the one that this is the reason why you are all identity theorists in my my guess is that you're all identity who's science appears to have already found correlations of precisely the thought the sort that would expect if mental states are physical states and if mental states are physical states then you don't get a mental state sorry you don't get a pain without a see fiber firing you don't get see fiber firing without pain and science has come up with this this according to neuroscience news these are thoughts you can see on this functional magnetic resonance imaging scan and here you've got pain and here you've got empathy so this person is actually feeling pain this person is merely empathizing with somebody else who's feeling pain so here you've got the so called mirror neurons sorry there's a forest of hands that went up then bridge laws go further than correlations that's right bridge laws say that a is identical to B and but what what is your evidence is saying that a is identical to B often not always that they have properties in common what what else might you and correlations are quite in science correlations are a very good thing to point to I mean it's certainly the case you wouldn't get identity without correlation but you're absolutely right to think that correlation isn't sufficient for identity that that would be evidence for identity but actually most in science judging from the newspapers which is a very bad way to judge science you would think that finding a correlation is sufficient for finding an identity and actually reading a lot of papers by various people you would think that many scientists also think the same they think quite clearly for example that you can measure action potentials and measure the time at which an action potential occurs before an action occurs and what you have measured is the intention with which the action was performed in other words the intention is the same thing as whatever the physical state I well I'm not saying anything at the moment all I know all I'm doing is putting the reasons for why we should believe in identity theory I was going to make the same point all science is done is it show the particular parts of the brain showing activity are correlated with some sensations when they have no theory for explaining my hat or so will you all stop learning my theory that you've all you're all identity theorists ok you may not be you're absolutely right what I'm doing is I'm giving I'm giving the reasons why you might believe in identity theory and why people did believe in identity theory what they believed was go back just quickly over the four reasons okay the first one there seems to be something the way the world piers and the way the words saris your belief that P whether it's true or false seems to be the same in respective for how you act so whether your belief is true or false is completely irrelevant to what you do and that's one reason for believing identity theory second reason for believing it we want to think of the mental as causally efficacious we can only do that apparently if the mental is the physical thirdly it's nice and parsimonious we can make life simpler if we say mental states and physical states and fourthly and this is the one that most people will cite when they say that they are identity theorists science has already found the correlations we'd expect if identity theory was true and we would expect these correlations if identity theory was true and what you're giving voice to is whether finding these correlations is a sufficient reason for thinking that the mental is identical and of course I sympathize we're not talking about things that they are exist but on no no both there is dynamic as each other the reason I'm bringing behavior into it is we think of both brain States and mental states as causally implicated in the production of behavior don't we so you none of you would want to deny that when I put my glass on the table there was something going on in my brain that was causally implicated and my putting the glass on the table I suspect you also wouldn't want to deny that there's my belief that I'm putting the glass on the table is causally implicated in my putting the glass on the table so in both cases behavior is what mentals the new of neural states and mental states explain that's why behavior came into it hey coach hey I didn't see before Descartes would have talked as much about behavior I mean I've only given you sort of five minute introduction to Descartes if you read him you would see eTools quite a lot about maybe yeah yeah okay um right I've done that and I've done that so we've got both philosophical and scientific reasons for embracing identity theory and what I'm going to look at now is why we should reject it why identity theory is false even though we've got all those reasons for believing it there are better reasons for rejecting it goodness I'm going to do Kripke in 20 minutes with questions from you all right identity theory was suggested in 1950s in the early 60s but in the early 70s it was blown out of the water by a logician called saul kripke and i think he looks like the nicest man you could ever hope to meet doesn't he it was one of the shortest lives theories ever in philosophy I am perhaps even slightly shortened behaviorism but here's why now get your thinking caps on because you're going to do some logic okay here's the argument premise one numerical identity is a logically necessary relation if a is numerically identical to B then a is numerically identical to B in every possible world okay I'll explain all this in a minute but let me just read it out premise two tells us that logic tells us that the relation between the mental and physical states isn't a logically necessary relation there may be a correlation but it's the correlation isn't a logically necessary relation and identity is the conclusion is that the relation between mental and physical states whatever else it might be isn't that of numerical identity now this argument is valid by that I mean if the premises are true the conclusion must be true okay if it's valid and it is believe me and the only way we can question it is by questioning one or other of the premises okay does everyone want to agree with me that this argument is a valid argument does anyone want to dispute that no what a shame but you're absolutely right it is a valid argument you can't dispute it so the only way we can question that conclusion is by questioning one or other premise of this argument so let's have a look at those now okay why should we believe premise one that logical that numerical identity is a logically necessary relation it's a law of logic that everything is numerically identical to itself it's the famous law of identity a equals a I don't know where I would go if you wanted to question that law no gone then Bob cuesta reading this I'm trying to understand it the example what then Krueger gives all running Cricky Cricky is that the evening star logical pistils is identical with phosphorus yeah I know what you're going into can I know all I want you to look at at the moment I am going to go into the objection you're looking at but you're jumping far too far ahead all I want at the moment does anyone want to question this law of logic the a is identical to itself that everything is identical to itself everything is numerically the same thing as itself Bob shut up right much as I love you this is not the moment yes as long as you're not going to question if something is a law of logic then it's true over every possible world no I don't really wouldn't think of GRU at this point so much so that I won't even explain what GRU is to everybody else who doesn't know yeah if we had an hour I might try and recreate your thought and see where you were going wrong but we don't have an hour no well exactly which is why we're just not going there so yet but do you accept that jolly good okay if you're quite right to do so and okay so we're going to so premise one is okay we're not going to question premise one because it's a law it's straightforward law of logic um well you can use less incendiary language by talking about all possibilities all possible situations you don't have to say all possible worlds so as long as you believe that there are I mean do you think it's possible that I was wearing jeans today no I could have been couldn't I exactly so there's a possible word philosophers might say there is a possible world in which I was wearing jeans and all we mean is that this world is such that there is a possible way it might have been which is I was wearing jeans so it possible world talk isn't really as arcane as it sounds unless you're Kripke in which case it is I know Lewis not quickly okay why should we believe premise two premise two is logic tells us that the relation between mental and physical states is not logically necessary relation well what do you think our reason for believing that is that the all the things we went through before when we were looking at Descartes we we thought okay um we'll hang on a second do we really believe that um if it's a C fiber it is pain so if we see somebody who's clearly in pain who hasn't got any C fibers but it's clearly impact well actually let's just move on to the next Oh this is an explanation for the last one Leibniz law the indiscernible ax T of identicals tells us that if a is numerically identical to B then any property that a has will also be a property that B has note we've got two relativize this at a time I mean I had properties when I was a baby that I don't have now and but if you relativize it to time if anything is identical to me then if I have a property that thing is going to have the same property isn't it how could it not if it's the same thing as me you I'm not going to talk about Cambridge changes if you don't mind with a Cambridge change you were talking about Cambridge changes no okay I'm not going to talk about them right and liveness law tells us that if pain states are numerically identical to see fiber firings and beliefs that p2 neural state ends then any property possessed by a pain will also be a property possessed by a see fiber firing and any property possessed by a belief that P is also going to be a property possessed by neural state n can you see that you wouldn't want to question that would you this means that if pains are identical numerically identical see fiber firings and beliefs that P - neural States ends then there couldn't be anything with the property of being a pain that doesn't have the physical properties of being C fiber firing nor could there be anything this is a C fiber firing that isn't also a pain and ditto with neural state n so it would be simply impossible logically impossible for there to be a pain state that isn't a cff or a belief that pees that isn't a neural state n logically impossible stimulate fire and get to five and you can have the patient unconscious yes that actually is desirable you would have them babe it was oh yes I see what you mean okay but actually they're more if sorry that's interesting that there are more interesting ones here we go and we've got good empirical reason to believe even this is a world in which there are pains that are not see fiber firings do you believe dogs can have pains yeah well it dogs don't have C fibers in which case how can how let's end them maybe they do but if pains RC fiber firing then you cannot have a pain that isn't let me finish you can't have a pain that we could say that I'll come on to that in a minute the fact is do you agree with me that if we say pain is C fiber firing pain is numerically identical to C fiber firing so if you get a pain then you get a C fiber firing then you you cannot have a pain without C fiber do you accept that okay now we see immediately that this has got to be wrong because there are dogs that have pains but they don't have C fibers okay well well you know we can get round this surely we can relativize it we can say that pain is C fiber firing in a human being not in a dog okay is that what you want to say well let's don't sneer like that when you say empirical there's nothing wrong with empirical when you say the pain is a sieve i but that's not meant to be a logical thing it's meant to be it and in what's been empirically discovered and therefore it turns out for all pains or see fibers I mean that really is what scientists discovers I knew you're all it'll become logically necessary it can't become logically necessary if if pain it you are overestimating or are you under estimating I'd have to think about that the thing is the identity theory was as simple as you are now seeing that it was and seeing why it's wrong the identity theory says pain is see fiber firing the reason it can't be is because there's an empirical reason to think that there are pains that are not see fiber firings in the fact that there are dogs and other animals that have pains but don't have C fibers firing and also and if there was an alien emotion and who seemed to be intelligent who came along and said you know well how did you make this spaceship pretty we know good stuff this this goes very fast goes faster than mine huh oh my leg he says not leg he doesn't have legs my tentacle thank you oh and you think but he doesn't have C fibers can't be in pain would we think that no because C fibers have got nothing to do with what being a pain is the essential property of being a pain is that it feels awful the essential property of being a C fiber is that it has a particular shape or pattern of firing or whatever and we just do not believe that pains are numerically identical to C fiber firing so when we consider the properties peculiar to pains and beliefs the properties without which these states wouldn't be the states they are and these properties just aren't necessary to any particular state in the way that they're necessary to a mental state and it's simply a fact empirically established in the case of sensations like pain that mental mental states are multiple-- realizable in other words one in the same type of mental state can be correlated with different physical states okay so this might be a C fiber but this might be a D fiber and this might be something completely different neural state W and this might be a okay it's also a fact concept established by conceptual analysis ie logic and that we would attribute beliefs the P to an alien if doing so was the only way to make sense of his behavior and we would do this quite irrespective of his physical makeup wouldn't matter I mean we're wondering whether we should attribute beliefs to computers or beliefs computers don't have brains like ours if we think we even possibly could attribute beliefs to the computer it's not because they are physically identical to us and this shows us that identity theory is just a non-starter absolutely an on runner pains cannot be numerically identical with see fiber firing and beliefs that P can't be numerically identical with activations of neural state n therefore identity theory is false and I've now got 10 minutes to look at problems for this argument so I'm not going to take any questions I'm just going to take a drink ah okay and it's interesting to note by the way that Kripke's argument is an updated and logically grounded version of de cartes arguments it's exactly the same argument of steak hearts it's just based on a bit more logic des cartes was also based on logic but not quite as obviously and but here a that all happened rather quickly didn't it and we introduced identity theory everyone thought it was sounded like a lovely theory lots of good reasons for it but suddenly it's gone and surely there's something wrong with Kripke's argument given how attractive identity theory is okay let's see how we might object to it and here's your objection sir what's your name Leo okay even if we can't find bridge laws that are entirely general might and we find bridge laws as a species specific so we can't we can say we can't say pain is the same as C fiber firing but we can say human pain is identical to C fiber firing okay that would be okay so we just weakened the identity claim and thereby make it stronger okay response we'd still have the problem of unusual species members if somebody seemed from everything he said and did over time and after covert scrutiny of course if he seemed to be in pain and yet to Lac C fiber firing wouldn't we continue would we continue to insist he couldn't be in pain no we wouldn't we we would think he could be in pain we would be much more likely to go for the idea that the brain can be plastic that other brain states can take over the function of pain when for some reason the C fiber firings are knocked out and we also we wouldn't insist that our alien couldn't believe P or even that great apes couldn't believe P so does that strike you as a non sequitur it does me at the moment maybe I'm just not seeing anyway if it does ignore it I I probably had a reason for putting it there but it's okay so so we can't relativize it to species that's not going to work either the fact is if it's not an identity it's not an identity even relative to species well what do you mean by pain when you tip when your dog no let's forget your dog promotes or something the dog is behaving in the same way that I might behave if I had pain but if I know that that's caused by something different which I don't know whether they have you might not call it pain I might call it pain okay no bang on that would be a way of that would be okay the objection to identity theory is hang on the dogs not got C fibers but it is in pain response to that in defensive identity theory is the dog is not in pain no yeah but it's not in pain do people think that people have thought that way yeah Descartes actually believed dogs couldn't be in pain but for a slightly different reason ya know you could save identity theory if you like by denying that any any anything different from a human being can't be so only human beings can be in pain myself I wouldn't go for that but I it's not a perfectly good way of responding to quickly and saving so let me write it down so that you see I really mean this you can save identity theory by denying that things without C fibers can feel pain yeah you can definitely do that and that would save myself I would rather reject identity theory but if you want if you really want to keep identity theory you can do that instead yep no but you you yeah logically you could yeah absolutely I just I wouldn't want to how many other people would about something on them okay I mean I don't want to think that dogs and aliens whatever can't feel something which is distressing and awful but we don't have to call it the same thing no we could call it we could call it different things yeah okay let's move on I'm sorry I'm concerned that I'm only guess I haven't yet got to the most important objection which is this one and we might want to say that the law of identity doesn't always holds do you remember me we talked about a is a and I said you can't even question this well that's a very bad thing for a philosopher to say because of course you can question everything now take an identity statement the Maryanne Talbot is the director of studies in philosophy at oud C II is that a true identity statement okay and but it's true in this world but it doesn't hold in every world does it and there are worlds or possible situations if you prefer where Maryanne Talbot is not the director of studies in philosophy so you DCE ie any world where someone else got the job and then it wouldn't be true would it that Maryanne Tolbert is the director of studies in philosophy at oud see that's what no I might never have got the job it might never have been true that I I have but I might not have done there is a possible world in which I am NOT director of studies in philosophy so that's not the actual world in the actual world I am but in another possible world I might not be so as long as you accept that I'm Miriam might not be director of studies in philosophy you're accepting that this is not a necessary statement okay well then why shouldn't there be worlds in which pain isn't identical to cff even though in this world pain is see fiber firing okay why shouldn't there be why why shouldn't identity statements be contingent in the way the the one I'm looking at here is here's the response there are identity statements that are logically necessary that a contingent something's contingent if it's not logically sorry all of them are flanked by at least one non-rigid designator god is really tough to make you do this logic at this time of before your coffee's served okay a non rigid designator is a designator that names different things in different possible worlds and therefore can't track individuals across possible worlds and on a rigid designator I'll give you an illustration of that in a minute a rigid designator names the same thing in every possible world and can therefore track individuals across possible worlds okay if we ask could the director of studies in philosophy be anyone other than Maryanne the answer is clearly yes and what you do is you track me through other possible worlds don't you think is there another possible situation in which Mary Ann that person might not have been director of studies in philosophy is that what you do so you use my name to track me through different possible worlds don't you and the director of studies in philosophy is a designator but it's non rigid you can't use it to track the same person through different possible worlds because it names different people in different possible worlds that's it's a logical fact about designators that they work in these two different ways this one works simply by description so if I say with the gentlemen a yellow shirt please stand up yes yeah they're here there's a gentleman in the yellow shirt now that isn't a necessary description of David is it but it does happen to be a description that uniquely identifies him in this room okay so it's a designator I I got him by using it but it's not a designator that can track him across different possible worlds because I can say is possible situation which David isn't wearing yellow yes there is so David is a rigid designator but the man wearing the yellow shirt is not a rigid designator see the difference so if an identity statement is flanked by two rigid designators then it's necessarily true and if it's flanked by even one non rigid designator then it's contingently true so MT equals MT if this track is the same in every possible world and this names the same person in every possible world then if this person is that person in this world you can see that this is going to be this person in every possible world yeah whereas if you have M T equals D OS o UD e and this names a different person can you see that would be a contingent identity statement and that would be a necessary one so and if pain is a rigid designator and if C fiber firing is a rigid designator and if these two are rigid designators then Kripke's argument holds are you with me that's really very difficult to understand but you'll be able to track that through with with what I've given you here it fairly quick are there any are there any Bridget designates yes I don't think that already because you could have a different name oh okay and I could have a different name what would that mean say I was called Lucy Smith so there's a possible world in which Mary Ann told that is called Lucy Smith do you see what I mean as you're still tracking me through the worlds by using my name but you're looking at the world in which I was called Lucy Smith it's exactly the same so is called Lucy Smith is a non rigid designator whereas Lucy Smith would be a rigid designator you just use your intuitions to ask yourself whether words takes you through different possible worlds picking out the same thing so does the word pain in every possible world pick out something that feels awful could there be a world in which pain didn't feel awful no there's some people who like feeling awful right and I pain seems to be a rigid designator it seems to designate that horrible feeling which comes in many different forms as we know see fiber firing seems to rigidly designated do you remember my answer to - what if I was called Lucy Smith is Lucy Smith is called Lucy Smith is not a rigid designator is called pain isn't a rigid designator pain is a rigid designator okay let's carry on that's a really distant okay we can look are these words rigid designators you can question that okay I've suggested they are but but this is a way to get at crisp tripolis arguments do they name the very same thing in every in which that thing exists can you use these words to track states through different possible worlds if not you can diffuse Kripke's arguments so I've given you three ways three questions here such that if you aren't say yes to any of them and you can question Kripke you can also question Kripke in the way sorry what's your name penny wanted question no of course not no that would be to get your Venn diagrams mixed up yeah but but don't forget identity theory says that it's a biconditional it does say that everything that's the cff is a pain and everything that's a pain is a cff so debt identity theory challenging that because I was being challenged because say me adults they don't have Z purpose but they do not pay so all those things that they don't have see fibers but they might have something else which causes them a state which is as awful as hey well I do think it feels it up okay well if you're going to say that other species don't feel pain I think you probably do have to say that there are states that feel awful that are not pain yeah yeah yup if you want to question it you can answer any of these questions I'm just going to move on okay I'm going to eat into the next session a little bit you

Channel: University of Oxford

Views: 42,202

Rating: 4.8558559 out of 5

Keywords: Philosophy, Marianne Talbot, University of Oxford, Mind, Philosophy of Mind, Identity Theory

Id: NuoGvNSkS5Y

Length: 90min 45sec (5445 seconds)

Published: Wed Jan 23 2013