 Rwy'n fydda'n edrych yn meddwl mewn i'r mynd i'r pysymologi. Felly mae'r ffordd wedi gweithio'r meddwl mewn i'r pysymologi. Meddwl a'r mynd i'r fydda'r ffordd yn mynd i'r rhai. Mae'n gweithio'n gwestiynau o'r ffordd o'r holl o'r amdano. Mae'r meddwl mewn i'r pysymologi ar hynny. Mae'r mwy oedd yn meddwl mewn i'r pysymologi. no? Ontology is your, your ontology is your list of what exists. So who believes in ghosts? Couple of people. Okay well on your ontology you have ghosts. If you believe in God on your list of what exists you have God. If you don't believe in God on your list of what exists God doesn't feature and if you don't believe in ghosts ghosts won't feature on your list of what exists. But chairs probably would, lecturers probably would, necklaces things like that probably feature on your things list of things that exist. So metaphysics looks at what is there in the world and what is its nature because once you've postulated the existence of something or decided on the existence of something you have a further question to ask well what's it like? So for example I told you that Heraclitus postulated atoms more than 500 years BC. Well he didn't know what they were like except that by definition they were the unsplittables okay because an atom was as far as you can go an atom of water is as far as you can go sorry no I'll have the water down here please. I don't want them to drink it. That's all right thanks just stick it down on the floor there. Where was I? Water? Yeah exactly look here there are quite a few atoms of water on my finger but at some point you'll get down to something such that if you go below that it won't be water it'll be CO2 it'll be a molecule but it won't be water itself because you'll have gone too far for it to be water. So you postulate the existence of atoms for whatever reason it could be as a theoretical entity so some people postulate God as a theoretical entity how do we explain all this we need something like this let's call it God okay so how do we postulate this we need something unsplittable let's call it an atom and of course you might when you actually because once you've postulated the existence of something and you have some idea of what it's like you then want to find out more about it and you want to see if you're right to think it exists so for example the Higgs boson we have reason to think it exists we have various ideas of what it's like which I won't go into because I don't know enough about them um we believe in its existence enough to spend millions on this large Hadron Collider in Switzerland uh but when we actually find it if we actually find it then we're going to know more about it and that's what we're doing we've postulated it we've said this is on our list of things that exist at least as a hypothesis now we want to test that hypothesis and see whether it's true so metaphysics asks questions like what is the and what is its nature now obviously many of these questions are questions of science um so the Higgs boson does it exist what's it like these are questions for science but questions like causation what is causation does causation exist causation the relation between cause and effect that's not a question for science the scientist must assume that causation exists philosophers ask does it and what's the nature of causation could causation go backwards for example could there be a cause that happens after its effect um is causation a relation between events or between objects or between facts or what are the relator of the causal relation so these are all questions of metaphysics um epistemology on the other hand is the study of knowledge so there's a big difference between what is the case and what we know or can know to be the case there may be things that are the case that we'll never know and I've mentioned three consecutive sevens in the decimal expansion of pi before so what you know and what is the case you hope that what you if you know well actually if you know something it must be the case um but what you hope is that what you believe you know is actually the case but the study of what is the case and what you know to be the case are two different questions once to do with metaphysics the others to do with epistemology so epistemology looks at what can we know can we for example know that the sun will rise tomorrow do you remember when we were doing logic we looked at induction um can we know it well we don't know for certain must knowledge be certain knowledge or could it be the case that we know something that we don't know we know do you see what i mean what is knowledge like um so actually I should have put that here but what is knowledge what can we know and how can we know it so for example if there are moral values um we don't know it by sensory perception I never see right and wrong uh certainly not through my eyes or through uh tactile sense or or anything like that so there must be some other way how do we know that two plus two equals four again you don't see that that's the case how do you know that all swans are white I know they're not but let's pretend for a minute um how do you know that all ravens are black that's a better one um well let's forget I'll be no ones I know what you're like I could see you thinking that how do we know that given that if you if you're going to say that all ravens are white you're talking about all ravens even the ones that you've never seen even the ones that nobody has ever seen even the ones on mars if there are ravens on mars you're saying all ravens are black includes those ravens on mars well how can you know that do you see what I mean so there are two different questions as what is knowledge in the first place must we know that we know something or can we know something that we don't know that we know um what's it got to do with justification what's it got to do with belief etc and how can we know these things so that's the distinction between metaphysics metaphysics is to do with truth and what is the case and what's its nature epistemology is to do with knowledge justification belief and how we can know whatever it is that we do know so that's that's the main distinction let me just pour myself some h2o h2o what did I say earlier I said I suddenly remembered that I I heard myself saying something false well right okay let's look at ontology the study of what there is or what exists okay one question I said earlier that there are many things that questions of what is the case and what is its nature that are questions for science but questions like does god exist um in the god delusion if any of you have read it Richard Dawkins claims that this is a scientific hypothesis like any other well if that's true it must be possible to conduct experiments observations in order to determine the existence of god I have no idea what experiments or observations he has in mind but I actually don't think this is a question for science I think Dawkins is wrong to think this is a straightforward scientific hypothesis um I think this question for philosophy um there are evidence our reasons for thinking god exists to take the form of uh arguments rather than evidence or observations so for example the most obvious argument is is the one I used earlier god is a theoretical entity uh he's postulated to explain the existence of the universe okay that's the simplest argument it's the argument that people have used uh from the beginning of time um other people use different arguments for example the moral argument you don't need god to explain the existence of the physical world but how come there exist people like us who are capable of rationality who reason who have free will who make choices uh and in particular make moral choices people like us who value things who see right and wrong good and bad beautiful and ugly and things like that um physics can't see right and wrong good or bad etc uh this is not the sort of thing that physics or or any physical science can investigate um but you might think that god is the explanation for the existence of things like that or you might deny that you might say no you don't need god to explain right and wrong you can easily explain right and wrong by appeal to evolutionary biology so altruism is a question of um either kin support uh or if I scratch your back you'll scratch mine etc so if you look at dorkin's chapter I think it's four but I may be wrong about that he offers four or five arguments for how you can explain morality without god so does god exist lots of different arguments for the existence of god lots of different rejections of those arguments lots of different comebacks on those rejections and philosophers are going to have a job for at least a couple of hundred years I think I think the god's illusion is far from the final word on it um but there are other questions like that that's a biggie obviously but there are other beings do moral values exist is there right and wrong does right it's a really a property of an actions being right or wrong or can we reduce the idea of being right to something um some people would say natural like um happiness so the utilitarians want to reduce happiness to the sorry reduce right and wrong to the idea of the greatest happiness of the greatest number so there's no more to right or wrong than and how many people you make happy by an action that you do now what you're doing there is you're reducing one thing to another thing so here's something we don't understand right and wrong and we think that it needs an explanation and we're tempted to postulate god for it maybe um but on the other hand if if we can say well actually we don't have an explanation for that but there's actually no more to that than this in particular combinations um and we do have an explanation for this or at least this is something for which we can think that there'd be a much easier explanation than god so on the grounds of occam's razor um given two explanations both of which work you always go for the simpler one if you can explain happiness and you can reduce morality to happiness then you haven't got a problem with morality you don't need to postulate god see what i mean so um you might i mean some people try and reduce the idea of god to um i mean actually Dawkins again does this uh he thinks that god is the idea we all want for security for a father figure something to to rely on um so he's reducing god to that um the utilitarians try and reduce moral values to uh happiness cant on the other hand isn't a reductionist he thinks right and wrong exist that the moral law exists in and of itself and that it's quite different from anything else so if you remember last week for cant a moral action is an action that's carried out because of reverence for the moral law it can't be said to be anything else it can't be said to be something that just as a matter of fact produces the greatest happiness of the greatest number and reverence for the moral law says cant is not something you can reduce to anything else something easier to understand another example of this would be mental states i don't i thought i was going to come to mental states but i see it's not on there so i'll put it in anyway do mental states exist well what are mental states well mental states divide into two there are the so-called propositional attitudes so attitudes to propositions things like beliefs you can't have a belief unless it's a belief about something can you so i believe that um an is wearing sort of maroon that maroon right there you are i believe an's wearing maroon i believe when anna's got a necklace on somebody's got a lovely pink jumper on just in front of anna future sort of color um okay all of those beliefs have a content but there are other propositions propositional attitudes so i can have a desire towards the same content desire is a different attitude but i could have the desire that anna's wearing a necklace or i could wish that um anna is wearing is all the same names isn't it is wearing maroon i could also intend that anna's wearing maroon i could i could set out to make sure she wears maroon today because i want to use her as a an example so these are lots of different attitudes to contents and you can get the same attitude and different contents and the same uh content and different attitudes so that's one type of mental state the so-called propositional attitudes the other type is the so-called qualitative states so um when i looked at this lady's lovely future colored cardigan um i have a certain experience okay there's something that it's like for me to see that cardigan there's something that it's like for me to see these chairs there's something it's like for me to be in pain or to feel a tickle or something like that and these are qualitative states they're states that have a quality to them um so i'm sure you can do your own rough and ready distinction now into states that have a certain raw feel to them and states that are attitudes to propositions why do we think these exist well how could i possibly explain your behaviour without citing desires beliefs intentions hopes fears you know why did she suddenly get up and leave the room um answer because she suddenly realised it was the wrong lecture she suddenly realised it was the wrong lecture so she had a belief about what the right lecture was she suddenly came to believe that this was the wrong lecture so she formed an intention to leave the room so in order to explain your behaviour i postulate all sorts of beliefs and desires but here's another little story um woodlice um why do woodlice congregate under rocks and things tell me it's dark why why do woodlice congregate where it's dark because they want to be safe or something like that okay and they and they believe it's safe under rocks okay you're a bit reluctant to attribute beliefs are you well don't give my story away okay yep absolutely okay when we first see a woodlice and certainly if we're speaking to a child or something like that we we would use belief desire psychology to explain woodlice behaviour because that's what comes very easily to us so woodlice believe that it's safe under rocks and they want to be safe so they intend to go under rocks as a matter of fact the correct explanation of woodlice behaviour is that they embody a mechanism such that when it's dry around them they move and they move in a speed that's determined by how dry it is around them and as it gets damper they they come to a halt and incidentally they move in whatever direction they happen to be pointed they don't sort of turned around and make for that rock if they're standing in that direction there's a rock over there they'll go for that one except they're not going for that one are they they're being pushed by the dryness now once you know that explanation have i got it right that's right i wasn't going to use technical terminology but they are okay so that's the proper explanation of woodlice behaviour once you know about kinesis like this you can explain the behaviour of any woodlice anywhere at all as long as it's a normal woodlice anywhere at all at any time once you know that belief desires have been made redundant haven't they you know why should you postulate woodlice beliefs now or woodlice desires in fact all their behaviour is explicable in terms of things like like kinesis they're not all kinesis but they're things like that what about your behaviour can i explain your behaviour well a lot of your behaviour i can explain if i chuck my chalk at you that shows how old i am doesn't it if i chuck my chalk at you you're going to duck um that's not a a desire or belief driven behaviour that's just a hardwired response to the fact you see something coming towards you if you put your hands on a hot plate do the same thing so a lot of your behaviour and that's just one if you hear an ambulance coming you'll move out of the way that's a classically conditioned response a lot of your behaviour doesn't need to be explained by appeal to beliefs and desires but much of it does and this is why we postulate beliefs and desires this is why we say that beliefs and desires exist but perhaps ethologists people who study animal behaviour are going to find out one day that we can explain all our behaviour in terms of brain states and it might be that we can um one time in the future we'll be able to saw off the skull of newborn babies and fit a perspex dome instead so that we don't have to go in for all this interpretation which we're actually not very good at is it um trying to find out what we're all going to do instead we can just look at somebody's brain and say ah okay i know what you're going to do perhaps we'll all wear woolly hats so we can surprise people or something like that but do you see if we can explain all our behaviour without appealing to beliefs and desires we'd no more have reason to think you had a mind than we do to think would lice do so again the question do mental states exist is a huge question lots of people try and reduce mental states to physical states and then explain physical states that's it's much easier to explain physical states than mental states but if you don't want to be a reductionist if you want to say you cannot reduce mental states to physical states and there are all sorts of reasons to think you can't um then you're going to have to postulate mental states you're going to have to postulate contents and qualia and the minute you do you're going to have problems with with functionalism with um physics being able ever to understand mental states and my goodness you might end up having to postulate god or something again or maybe not we don't know so again the question is what is this does it exist at all if it does exist can we reduce it to something else if we can't reduce it to something else what is its nature here's another one what about possibilities okay i might have been wearing jeans mightn't i okay that's a possibility but and what's more it's a possibility that's actual isn't it it's an actual possibility well what is a possibility what's the nature of a possibility it's not something that actually exists is it okay so maybe we've got to postulate a different sort of existence now there are things that actually exist and there are things that possibly exist and there are things that don't even possibly exist so there are square circles don't even possibly exist unicorns might they exist or not marianne's wearing jeans certainly is an existing possibility do you see what i mean you're you're now getting layers of existence different levels of existence well and that little kitten on the floor down there is it fat you're looked you understood what my words were don't you need to postulate a little kitten down there in order to give meaning to my words some people have thought that if you do then that little kitten exists but it doesn't exist like and does so you need again another layer of existence well well some people have said that it's all not really existence let's call it persistence instead but but the thing is you've got to say if you say that every in order for you to understand the meaning of that little kitten is fat there needs to be a concept of a kitten or or a kitten or something you know there's a kitten that gives meaning to the words but it's not an existing kitten like the kitten that some of you may have at home so it's a persisting kitten or or an imaginary kitten is another way of thinking about it but do imaginary kittens exist well do they in imagination there you are there's another way of thinking of it so it's existence different types of existence there's existence in the real world and there's existence in your imagination there's existence in novels i mean when it when it comes up this little kitten down here it could be black ginger or anything couldn't it i haven't told you anything about what it's like but we all know that Sherlock Holmes wore a deer stalker didn't we did he something like that wasn't it okay so they've got again different levels of existence we all know that unicorns have horns you know well there aren't any unicorns well how can unicorns have horns if there aren't any do you see anyway so do possibilities exist is is a really difficult one that's the sort of thing that leads people to postulate the existence of possible worlds and i think i've mentioned possible worlds to you before lots of people postulate possible worlds but they're not realists about possible worlds mathematicians logicians physicists many of them all all those disciplines postulate possible worlds not all people in those disciplines do but if you postulate possible worlds you can see possible worlds as reducing to possible situations in this world or you can see possible worlds as real and david lewis very famous philosopher postulated the reality of possible worlds and he said well i've never really heard a very good argument against them a look of blank astonishment doesn't count as a as an argument what about physical objects well you might say well obviously they exist you know how can i deny that that exists okay well let's do a cartesian thought experiment in fact let's do the cartesian thought experiment when i have some water day cart was interested in the fact that we know that some of our beliefs are false but in the very nature of things we don't know which those beliefs are you see what i mean i mean would you like to tell me for sure that all your beliefs are true right okay what about you no it isn't no no a lot of your beliefs are false i guarantee if you believe it you believe that it's true that doesn't make it true okay does it no i you believe it's true exactly but this this is the problem with beliefs every belief you have you believe it's true because that's what a belief is to to have the attitude of belief towards a particular content is is to assent to as philosophers would say that content so in believing that this chair is blue there's the content that chair is blue and i assent to it i say that is true that's what a belief is but of course i may be wrong i may be colourblind or something like that well given the circumstances in this case i probably would say i know but the fact is let's not bother about that i was just offering that as a but but you have beliefs about a lot of things the question is you know that many of those beliefs are false but you don't know which they are and in the very nature of things anything that you believe you believe to be true because that's what truth is you cannot have a belief that you don't believe to be true but you do know that not all your beliefs are true well they can't became very interested in this and he said well what i'm going to do is i'm going to take myself away from the world in the world we have to assume that our beliefs are true because we have to act on them um so in believing that chairs blue if i'm looking for something to match it i'll go and look for something blue okay we have to act on our beliefs he's going to put himself away and think okay how do i know that my beliefs are true what is it that justifies me in believing that my beliefs are true um and he thought the method i'm going to use to do this um is to treat as if false any belief i can entertain the slightest doubt about so if the belief that i believe to be true could be false i'm going to put it on one side as if it really is false and by that means hope to find something that i can that is absolutely certain and from that maybe i can build up the rest of my knowledge so it's a bit like you know some of the apples in your baskets are rotten but you don't know which they are so you take each one out and any that's a little bruised you put on one side as being maybe that's rotten and you hope to be left with only the good apples in the basket so Descartes wanted to look at his beliefs and say if there's any about which i can entertain the slightest doubt i'm going to treat it as if false okay so he's not saying that his beliefs are false he's saying it's as if they're false for this so first he went down three levels of doubt um the first one was the argument from illusion okay the argument from illusion tells us that um well our senses have deceived us i expect all of you have been deceived by your senses sometimes you've got home that wonderful skirt that you thought would go so well with that blouse and you've got the colour wrong the lights in this shop were the wrong colour or something like that we've all been deceived by our senses at some time well if we've all been deceived by our senses at some time should we take all the beliefs that we base on our senses and put them in the doubting basket treat them as if they're false should we if our senses has deceived us should we treat all our sensory beliefs as false okay put your hands up if you think yes okay put your hand up if you think no okay now tell me why you think no why must there be that possibility well hang on we've got two lots of can'ts nose here there's what we're suggesting is that your senses have sometimes deceived you does that mean you can never be sure that your senses are not deceiving you now no you can't be sure so sometimes we do trust our senses don't we i mean as a matter of fact how do you know that your senses have deceived you well hang on you experiment you prove it how how do you do this through your senses through your senses give can you give me an example possibly not whoo yes yes good one okay um so your belief that it was heavy although that's actually not a sensory belief probably is it well yes because i you put so much anticipated no no but it's not a when you your belief that the frying pan was heavy yes you can't really look at a frying pan and tell it's going to be heavier maybe you can maybe you can let me give you Descartes own example because i think it's a it's a good one Descartes said if you put a stick in water and it looks bent okay you've got reason for thinking that the stick is bent you take it out of water woo it's straight you've got reason for thinking the stick straight well okay there are two possibilities maybe when you put the stick in water it bends it or maybe it just appears bent so how do you test this you put your hands in the water you feel the stick when it's underwater and low it's straight okay so you've now got two reasons for thinking the stick straight and only one but the thing is you couldn't even know that your senses were deceiving you unless you rely on your senses so all we got to hear from the argument from illusion is that we know that not all our sensory beliefs are true not all our sensory beliefs are true sometimes usually in unusual psycho optimal conditions or maybe not unusual but not perfect psycho physical conditions our sensory beliefs deceive us but you can't go from the universal possibility of illusion to the possibility of universal illusion would you like me to say that again no oh i like saying that would you like me to say it again thank you thank you you cannot go from the universal possibility of illusion to the possibility of universal illusion are you with me okay so all those who said no you're right we do know that our senses sometimes deceive us but that doesn't tell us that we we can put all our sensory beliefs into the doubting basket because we would never know that our senses deceive us unless we rely on our senses so that's the first argument second argument dickheart went to was the argument um uh from the demon the demon argument rather than the argument from the demon um the demon sorry dream and anyone who knows what they're talking about will know that i'm talking rubbish second one was the dream the argument from dreaming okay so you're sitting here you're in the fire your the lights are on everything's fine you're looking at your hands in front of you how can you doubt that your senses aren't deceiving you now are they but on the other hand says dickheart haven't you ever been in the situation where everything has seemed to you to be a certain way and then you've suddenly woken up and found it wasn't that way at all so it looks as if all the sensory evidence is in and yet you're still wrong your belief is false so you believe that the hand is in front of you it's exactly with you as it would be if your hand was in front of you but your hand's not in front of you as a matter of fact you're dreaming okay does that mean we should put all our sensory beliefs in the doubting basket put your hands up if you think yes put your hand up if you think no you're beginning to get this now aren't you why not uh man in white um or beigey sort of jumper sorry i've picked on you and you don't have to okay would anyone else like to answer what why can we not put all our sensory beliefs in the doubting basket now because we wake up and what does that tell us that we've been dreaming that we're not always asleep exactly that sometimes our beliefs are true sometimes when i've got my hand in front of me like that and i'm thinking my hands in front of me i am awake and the reason i know that is because if i didn't wake up i couldn't know i was dreaming so it's exactly the same structure of arguments as as in the first one but whereas we got rid of all sensory beliefs that have formed in in suboptimal psychophysical conditions here here we've got rid of a lot more haven't we why do you want to well it's a contrast isn't it um through this cycle of thinking they've woken up and then they wake up again right but but in order to know that they are like that they must have woken up well okay but but with you i'm quite sure you've had lucid dreams where you've had the dream and suddenly you've woken up and you've thought wow you know who could have believed that i was dreaming sometimes you can know your dream but it's the lucid dream that's that's good for this one but what have we lost here what's in the doubting basket now no instantly there's another thing i want you to notice that lots of people think i mean it's hell sheer hell being a philosopher as a party because that when people find out you're a philosopher they're going for little games like oh good tell me that this exists does this exist why and you say something and they say oh no it doesn't you know tell me how tell me how and they're playing a sort of skeptics game that's extremely irritating i hope none of you ever play it um dakehart found reasons for doubting everything he didn't just doubt he took beliefs he believed to be true and he looked for a reason to doubt them and it's only when he found a reason to doubt them that he put them on one side um so he wasn't just doubting um he wasn't playing the skeptics game he was actually looking for reasons to doubt so what what have we lost here what's in the doubting basket once you've got the argument from dreaming well no because when you are you know that sometimes your belief there's a hand in front of you is correct is true so you don't you don't lose that you do sometimes see your hand in front of you but what do you lose no no you no we're looking for certainty we're we're wanting to know what isn't certain as a result of this some things are left certain uh i mean it's left certain for example well okay i'm asking you that what is left certain that's when you are awake your dream your beliefs your sensory beliefs if they're formed in in optimal psychophysical conditions are true you still got no reason to doubt that it's just that um you can say that unless i know i'm awake i cannot know for sure that there is a hand in front of me okay do i know that i'm really awake answer no i don't because i could be having a lucid dream but i do know that hands exist and that i can see them and that chairs exist and that i can see them or if you don't like that because i can in in our dreams we sometimes put together things in strange ways um i can know that blue exists and that um so you can go to simple things horses horns whiteness things like that the simple things from which we build up complex things i know that they exist so we're losing something of the world here but we haven't lost the whole world yet um there's still an awful lot that we know i don't know anything to be true now but i do have reason to believe that it is true if i it is true sometimes i when i'm awake and i have these reasons to believe things but then we get down to the demon argument and at the demon argument dickheart says okay well i'm assuming aren't i that um these experiences that i have as of my hands and of blwness and so on i'm assuming that these experiences are actually caused by something outside myself um and that the experience that i have is a is a guide to the nature of the cause of these experiences so my experience of blwness as of a blue chair is causing me to think that that experience is being caused by a chair that's blue and you've got a problem here because in order to know that a causes b you've got to be here haven't you you've got to see a correlation between a and b in the same way to know that a resembles b you've got to be able to see both a and b but are we ever in this position with result with respect to our experiences and the causes of our experience never we're always here aren't we didn't leave enough room for my arrow um we experience the world if you like through our experiences we can never get outside our experiences to see what the world is like to see what's causing these experiences um so it could be that our experiences are caused by something completely other than we take them to be caused by so here's the demon sorry i know it looks like a cat but it's a demon okay the demon opens up a gap between our experiences themselves and the causes of those experiences and it actually says how do we even know these experiences are caused why aren't they just experiences one following the other following the other following the other and there's nothing out there at all and actually Descartes at that point says i can't do this i'm going to put the demon there because i can't i find it impossible to believe there's nothing other than my experiences um but i can think that there's some cause of my experiences which is completely other than i take it to be and some people have tried putting evil scientists in here um but that doesn't work because an evil scientist isn't magic um what you're trying to do the demon is just there because it's impossible to imagine that your experiences don't have causes at all so you're putting something there so that there is a cause but the cause is completely other than you take it to be um he didn't panic for that reason no he he just literally couldn't wrap his mind around the idea that there's nothing outside causing your experiences you try it it's really very difficult to to get yourself to the point where you understand that there might be no physical world at all your experiences could be exactly as there are as they are even though nothing else else exists so all there is is Ann's experiences as of Marianne giving a lecture in philosophy there's no Marianne there's no philosophy there's no lecture there's no blue chair but it does seem to me very similar to the sort that people have of is this experience all a half it's it's it is a frightening experience beyond that it's nothing beyond death it's nothing beyond death but it's nothing to do with god it it's yeah i didn't actually say about god i just said people worry that there is nothing after death okay but but this is a different thing because it's it's not worrying about exit uh that sort of thing it's but it is a worrying thought i mean we want our beliefs about the external world to be true don't we and yet what's happening is that we're discovering that what Descartes said was that uh actually once you've done this thought experiment you realise that um there's the world and there's your picture of the world okay all your beliefs that you've formed about the world and you go through the world updating your beliefs all the time um but once you've um retreated into your picture of your picture of the world which should be here but i ran out of room um the world actually becomes unnecessary because if all there was was this you couldn't ever get outside to see whether this is there or not so once you've pushed yourself back into a reflective position you see that uh the world that you picture is quite different from your picture of the world and that your picture of the world could be exactly as it is even though the world was completely different and that's the Cartesian thought experiment that's hyperbolical doubt at this point you've you've started the question of how can we know i mean we do take ourselves to know that there's an external world a physical world out there but what's our what possible justification could we have for this given that um all we can do is go and look for more experiences and our experiences are exactly what we we are asking are they caused by something and if so what i can't step outside my experience of course no scientific experiment is going to tell you the answer between are my experiences caused by an external world or are they caused by an evil demon there's no i can't go down and say oh is it a chair oh yes here we are it's a chair why can't i do that all i'm doing is giving myself more experiences aren't i i'm now having a tactile experience as well as a visual experience and there's an order tree one there as well but i mean they're only more experiences aren't they who are you hang on that i'm having another experience at this moment it's an order tree one there's um you know it's as of someone why people say did you see what i saw they do but no no hang on you haven't got yourself into hyperbolical doubt has she why hasn't she got into hyperbolical doubt yes it's she said no no she still thinks that i should think that she exists um i have lot i have very good reason to think i'm having experiences as of a female wearing maroon sitting in front of me who's speaking to me but these are just more of my experiences aren't i i can no more get outside my experiences to check whether an's really there and whether she's really telling me what i think she's telling me then i can to see whether the chair is there all i've got is more experiences so all i've got is more of this um here and i still haven't got this which is what i need so there's no point in looking for collaboration which is why there can't be any scientific um way of testing which hypothesis is true so here i have my experience the external world of those i can be certain okay i abs i'm absolutely sure now that i'm having experiences as of a lecture theatre etc what i want to know is are those experiences causing me to form beliefs that are true i there is a lecture theatre now notice the difference between i believe there's a lecture theatre and there is a lecture theatre okay the latter is metaphysics isn't it the former is postpistemology i can be certain of the former i can be certain of my own beliefs but i can't be certain that these beliefs are true can i and it's at this level of hyperbolical doubt at the third level of doubt that you start to wonder do physical objects exist at all interestingly Descartes thought that you could show that they did Descartes wasn't a skeptic lots of people think he was but in fact he wasn't he did this skeptical thought experiment in order to preempt skepticism he ended up believing in the existence of a physical world but he thought it was necessary to believe in god first he did that's right cogito ergo sum and the reason he did that can anyone think why he did that think here what i told you so far what's that that's right once you've got yourself back into your picture of your picture of the world and your inability to determine the existence of the world that you picture the only thing of which you can be certain is that you're thinking isn't it so here's my belief and let's the content of my belief is um the chair is blue i've got the attitude of belief towards that i've now got another attitude which is that of doubt towards that belief do you see what i mean you can't doubt your own beliefs without seeing that you have these beliefs and that's what Descartes says he said the very act of doubting makes me see that i believe and if i believe i exist i don't know what i am like but i exist because i exist as a thinking thing as a thing that thinks so i think therefore i am is because that once you've been in hyperbolical doubt that is the only certainty you have you actually have a few more about what you think but but you don't need to i think therefore i exist will encapsulate it rather neatly i think but you see you cannot doubt your own beliefs without seeing that you do believe something or other all you don't know is whether that belief is true however sometimes those are what sometimes those are true or or can be believed but if you i mean looking at evidence for example from physics about the nature of the universe about sort of wave particle forms about what the nature of the matter is all that kind of stuff what we're seeing is an extremely distorted view of reality looking at the evidence from psychology our perception is a highly flawed all our senses are highly flawed our brains are constantly filling in stuff that's around the edges and doing all kinds of fiddling about with what actually might or might not be out there so actually we know pretty much what we are experiencing much of it is an illusion um i'm afraid that in what you're saying you'll make it clear that you haven't got into hyperbolical doubt either um well in that case i don't understand what the nature of that is personally i think there is stuff out there but i don't think it is what we experience well we can but we can agree with all that and and accept i mean all daycuts asking is can we be certain that our experiences are being caused by anything secondly can we be certain that our experiences are a good guide to what there is now what you're saying is that the second we we know empirically that the answer to the second question is no but of course for him the most important question is the first one not the second one evidence coming out about sort of nature of consciousness in the cell which the implication is that that what we may perceive as being ourself is actually again quite illusory yes sure but i mean this is more grist to Descartes mill well i mean it's either irrelevant excuse me or or it's grist to Descartes mill i mean you can say you can add these in if you like to the argument from illusion but the argument from illusion is only the first step of Descartes argument and the step that really matters is this one and and that's the one that takes us to hyperbolical doubt and that's very definitely a philosophical or metaphysical question not an empirical one there's no way science can show us well there still is but the empiricism is nothing more than me testing out one experience against another which is a bit like testing out one newspaper against another it's not going to get you very far well doubting is a form of thinking well no you can't bring in other people no you can't you can't bring in other people at all the doubting is not what you're certain of by doubting is that you believe because in order to doubt the thing that you doubt is a belief of your own well exactly a belief is a thought it's a type of thought so you're you're doubting that you're thinking and in try you try and doubt whether you're thinking and you will become completely certain that you're thinking and so Descartes says isn't it strange because I would have thought that the world was far more presence to me than my own thoughts in fact my own thoughts have always seemed to be rather shadowy you know things that I'm not really certain of at all they're you know I can't hold them or see them or touch them or something but having done this I now see that my thoughts are far more certain to me than the external world which could be nothing so he you know he thinks he's gone from something or he's found something really surprising once you move from the perspective of picturing your world so I'm I'm thinking of the world that I picture not my picture of the world usually the only time I'm thinking of my picture of the world is when something's gone wrong you know I thought I hung my I hung my coat here okay I believed I hung my coat here I now have reason to believe it isn't there what's gone wrong so I've been pushed back into my picture of my picture of the world in order to question whether my belief is true or false but of course usually I come back almost immediately oh there it is and and so I immediately move back into my picture of the world looking at the world but what Descartes did is he he forced himself to stay here where what he was reflecting on was his picture of the world rather than the world that he pictured so he's looking at his beliefs and thinking are they true are they false are they justified are they not instead of looking at the chair and thinking is it blue is it hard is it okay do you see why people are out here not in here Ann isn't a belief my belief about Ann is a belief but Ann is here and Marianne's belief about Ann is what I am certain of but I'm certain of it until I doubt it and the minute I doubt it I can be certain of that belief but I can't be certain that it's true so whatever Ann says is is just more of my experiences Ann say that's right or I believe that Ann says it's blue and I know that my belief that Ann says it's true does not make it true that Ann says it's true and as I can you too will be able to do this when you become philosophers do you see what I mean once you understand what you're saying it becomes easy to say it although now I can't say it again but I'd have to get the flow of it back okay do you see why people are outside just a thought we have two houses and she thought we had one that was down the end of the road that came from preschool and one that came down the road from school my cat thinks we have two houses and I'm just wondering is it but she would have had no doubt about that belief and was it when she began to doubt the belief and then obviously then realized not quite that which we've only got the one house and is that almost the doubt of the belief makes it real well there's a very interesting between three and five children actually acquire the context the concept of a belief and until that point there's evidence to think that they don't properly form beliefs of their own but this there's an experiment that goes maxi the puppet whoever's it is who's looking after maxi I can't remember puts a chocolate in a box and then maxi goes out to play and the children are watching this and maxi's mum comes in takes the chocolate from the box and puts it into a cupboard or something like that then maxi comes in from playing and the children are asked where is maxi going to look for the chocolate now all the three-year-olds say in the cupboard because that's where they believe the chocolate is they know the chocolate is in the cupboard okay so that's where they think maxi'll look the five-year-olds will all say she'll look in the draw because they've understood the difference between appearance and reality okay the world can appear to you to be other than the way the world is and what your daughter did she she linked up her two beliefs and saw oh that house is that house but what she had really wasn't a belief in that sense hold was she yeah she she probably wasn't really having beliefs at that point yeah the thought is you don't really have a belief until you have the concept of belief because once it's only when you've got the concept of belief that you have the difference between appearance and reality and you see that beliefs can be either true or false so you can grasp the content concept of conditions of truth and falsehood and at that point you can really actually believe something whereas up until then it's just that you're just responding to a world because the world is you don't make any distinction between the world's being one way and it's appearing one way you don't see that those can come apart no no except i mean we'd call it one when we're speaking loosely but no okay right let's move on a bit because i mean we've we've been doing a lot of epistemology here under the heading of metaphysics but of course actually there's the metaphysics of epistemology just to confuse you because of course if you want to know the truth about knowledge then you're doing the metaphysics of knowledge and therefore the metaphysics of epistemology so we were looking at ontology before we got on to uh skepticism um but so we asked ourselves whether these things exist but we can then go on and ask well what are they like you know if we believe that god exists is he all these things um how can he be all these things because surely there's contradiction here isn't there if he's omnipotent he can do anything at all if he's omniscient he knows everything at all and if he's benevolent or good then how can he see the suffering in the world and not do something about it um so can god be all those things what about moral values if they exist are they absolute or relative do we all have our own moral values or is there a moral law that's objective and that exists for all of us um are there different possible worlds or only different possible states of this world and what's the difference between those two and what about physical objects are they independent of us or bundles of our ideas barkley uh bishop barkley thoughts that um skepticism was so threatening the idea that we couldn't be sure we had knowledge of the external world that what he thought is we had to build the external world from what we could be sure about so the only thing we can be sure about is our own experiences so what is the external world other than bundles of our own experiences now this may sound daft you know i mean there's more to an than my experience if i touch her she'll say ow or excuse me or something like that um but actually there again what have i got other than my own experiences auditory experiences etc so what barkley was saying was actually if you think of all your experiences and all your counterfactual experiences in other words if i came into this room at midnight that blue chair would still be there do you see that's a counterfactual experience i would still see that blue chair um there is no more to an object than our experiences or counterfactual experiences and actually you try and convince me that you have any reason to believe that the physical world exists that doesn't appeal to either an experience of yours or a counterfactual experience of yours and you'll fail counterfactual it is if i came into this room last night at midnight that's that's not true i didn't come into this room at midnight i was past the sleeping bed um but had i come into this room at midnight last night i would have seen that blue chair so and that's part of my reason for thinking that that blue chair exists independently of me is that it was here all the time it would still be here if i came back tomorrow but it might well exactly and so what barkley is saying is is that there is no reason i can give for believing that that chair exists that doesn't depend on either an actual experience of mine here it exists you know and you're having experiences of this chair now as well if you exist um or counterfactual ones if i came in tonight it would still be here i i would still see it that's true um but i would still uh okay but that that's if i had come in last night it would have been there yeah but i should be able to answer that and i can't because i'm tired um um what about bruises if somebody had moved it i wouldn't have seen it okay i might not be able to follow it but it's certainly true that i have reason to believe that this chair would have been here simply because it's tied to the floor um i mean that's not conclusive and that's not a very good response to what you're saying i've no reason to think it won't be and my what's more important to the you you try this as a thought experiment for yourself try and give yourself reason to believe that something that you believe exists exists okay so you believe this exists what are your reasons for believing it exists and see if you can find one that doesn't depend upon your own experiences either your actual experiences i can see it feel it touch it hear it or your counterfactual experiences if i was there then if i did this then if do you see what i mean then i would so you won't be able to do it barkley i was much cleverer than people think people tend to think that he thought of the external world as a ghostly sort of thing but he's just offering another explanation for our experiences and the fact that we go from these experiences to thinking there's an external world we do that immediately what why do we do this okay so so this is that's metaphysics then moving to epistemology what is knowledge okay do we have knowledge we've looked at that in some depth already do we have knowledge dickheart would say we can't claim to have knowledge of the external world unless we can get over his thought experiment which he thinks we can um what is knowledge though some people believe that it's okay well let me ask you this what what is knowledge we've been talking about knowledge for the last hour and a half or something but what is it that's very optimistic of him launching out like that good for you go on say for you what do you mean by gathered but we have knowledge of things that don't involve senses don't we two plus two equals four is not sensory knowledge so what is knowledge we collect it and put it in our brains how do you put something in your brain well actually you don't um i'm not sure you intentionally acquire knowledge anyway most of the time the knowledge you acquire isn't acquired intentionally it just um sorry what did somebody else say it's certainly acquired but what is it we acquire memories involved but there's a difference between memory and knowledge isn't there i mean in order to remember something that something has to have happened um memory is important but memory is different from knowledge it's not the same thing memory is essentially time related whereas knowledge isn't essentially time related it can be time related but it's not essentially so in the way that memory is yeah well and i mean there are different sorts of knowledge aren't there as well i mean i know how to ride a bike well i remember do i remember it well it's not propositional knowledge um okay let me tell you what one answer the classical answer to the question of what knowledge is is that it's justified true belief okay if you're going to have knowledge you must have a belief that belief must be justified and that belief must be true so um you believe or you you know that i'm wearing an aubergine dress don't you you all know that they have very good colour concepts here you have a belief that i'm wearing an aubergine dress do you yep okay is that belief justified how you can see it yeah okay you're justified in believing that and and let me tell you that it's true okay so you know i'm wearing an aubergine dress so that's the idea that so if a student comes to me and says well i Descartes said such and such and i say why do you think that and he says uh i don't know and i say okay well what follows from that belief and he says um i don't know uh and i said well why do you think that and he says uh don't know he doesn't know it does it does he you may have a belief about that um but it's and it what's more it may be a true belief but it's not justified therefore it doesn't count as knowledge he doesn't know it at all um if you don't have a belief about something you certainly can't know it but the other one and the one that most people get more worried about is that you cannot know something false if you cannot know that i'm wearing a yellow dress for example you can believe that you know something false but your belief that you know it is itself false are you with me so if you actually know something that thing must be true so maxi comes in from playing and she does she know that the chocolate is in the drawer no she believes she knows the chocolate is in the drawer but what she doesn't know is that her mum took it out and put it somewhere else so she has what she thinks is knowledge but it's not knowledge because it's not true she's got the belief she's justified in the belief but the belief isn't true therefore it cannot be counted as knowledge so you've got to again make that distinction between what you believe to be the case and what actually is the case because you can believe you know something that's false but you cannot actually know something false this is the crux of william morris's dictum only have in your house those things which you believe to be beautiful or which you know to be useful yes i'm not sure it's the crux of that but it certainly comes into it yes absolutely um yeah okay so um but here's a little problem for you getty a came up with this little problem it's called and it's been called ever since getty a problems um you have seen me driving a um a golf gti around oxford um you've come to believe that i own a golf gti as a matter of fact there is a golf gti that i own but it's in my garage and the one that you've seen me driving around belongs to a friend okay do you know that i own a golf gti i believe no sorry you believe that you know but do you know no you don't know why not it's not justified well it is justified no you've seen me driving around in it you're perfectly justified it is true i've got one in the garage no you don't know that you don't know but you don't know that's not the point why not but we do usually claim about um claim to have knowledge without having certainty don't we i mean you've seen me driving this car often um so you know you you think you're justified in claiming to know that i now i'll tell you what's happened here is the conditions that make your belief true i.e the car that's sitting in my garage that you've never seen me in come apart from the conditions that justify your belief the golf gti you've seen me driving around in and it's only if the conditions that make true your belief are the same as the conditions that justify your belief that you can have knowledge uh that what you have counts as knowledge so what gti showed is that it cannot be the case that knowledge is justified true belief justified true belief may be necessary for knowledge but it's not sufficient you need some other claim that makes it impossible for the truth conditions