\'\'What Experience Teaches Us\' Summary; David Lewis PDF

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A summary of David Lewis' reply to Frank Jackson's 'Knowledge Argument'...

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David Lewis’ Ability Hypothesis

Experience as the Best Teacher If you want to know what some new experience is like you can learn it by having that experience. You cannot learn it by being told about the experience. However, Lewis denies this proves anything about the metaphysics of mind/limits of science. Example: Skunks and Vegemite If you have not smelled a skunk, then you don’t know what it’s like, and won’t unless you smell it for yourself. Lewis has never tasted vegemite, so does not know what it’s like to taste vegemite. Lessons on chemical composition of skunk scent/vegemite, physiology of nostrils/taste-buds. Neurophysiology of sensory nerves/brain won’t help… Lewis also uses the example of Mary and Nagel’s bat. In latter case, we can never become bat-like enough to have the experiences of a bat. However… Experience is the best way of coming to know what an experience is like. Can we say it’s the only possible way – probably not. Change that takes place in you when have experience and come to know what its’ like – maybe same change could be produced by precise neurosurgery/magic? Could science lessons equally cause the same change? It’s a contingent truth that experience is the best teacher about what a new experience is like, but we do have good reason to think it’s true. Still, maybe some way of giving the lessons hasn’t yet been invented and some way of taking them in not yet practised. Consider sight reading – musicians can read score and know what it would be like to hear the music. New music not entirely new, a rearrangement of lots of smaller old experiences… might turn out to be the case for new smells and new tastes, even for sonar sense experience… We can say that we have no faculty for knowing on the basis of mere science lessons what some ‘new enough’ experience would be like… but how new is new enough? Three Ways to Miss the Point 1. Literalist – ‘know what it’s like’ taken to mean ‘know what it resembles’… Could be told smell of skunk resembles smell of burning rubber. Mary probably knows a lot about colour resemblances – about which colours are called similar by subjects, which ones are conflated with memory, etc. But this is not what ‘know what it’s like’ means. Certainly resemblance can be helpful, if you already know what the comparison is like. Mary knows enough perhaps to place each colour experience precisely in a network of resemblance, despite never knowing what any node of a network is like… We could do the same for bat experiences, perhaps. But still, won’t tell us what an experience is like. 2. Know what it’s like = know what experiences I would have? E.g. don’t know what it would be like to drive a steam locomotive fast on a cold stormy night…

Why can’t just be told what experiences you would have? Just need a way to refer to them – in terms of causes (‘experience one has upon tasting substance of x and y chemical composition’); or in terms of effects; or in terms of physical states of nervous system that mediate between ncauses and effects (e.g. exp. One has when nerves fire in such and such a pattern). Mary can refer to colour-experiences in all of these ways, so should be easy to tell her what experiences people have on seeing the colours. In fact you’d be telling her what she knows already. If Mary knows exp. Of seeing green = experience associated with particular pattern of nerve firings, she knows the right kind of unobvious identity, so knows what the experience one has on seeing green. But since Mary does know what experiences she’d have if she saw colours but doesn’t know whati t would be like, so this can’t be the right understanding of ‘know what it’s like’. Only know what driving locomotive would be like because I already know what each constitutive experience is like. 3. Until Mary sees green it will never be true that she’s seeing green – irreducibly egocentric knowledge. Only those of whom egocentric proposition is true can know it, and only at times when it’s true of them; so a proposition Mary can’t know ‘til she sees colour, which will coincide with the moment when she’ll first know what it’s like to see colour. So is this why exp. The best teacher, as a necessary consequence of the logic of egocentric knowledge? No: two separate phenomena…Mary will probably stop knowing what it’s like to see green after she stops knowing the egocentric proposition, as she must stop knowing it as soon as sh stops seeing green. Equally, if we switched the focus to ‘has seen green’, she’d still know this even if forgot what exp. Was like. Secondly might come to know what it’s like to see green even w/o knowing egocentric proposition: at first may only have known she was seeing some colour or other, finding out what some colourexperience or other is like, w/o being able to put a name to it. Thirdly, egocentric might have demands nothing to do with exp. – Mary can’t know she’s turning 50 til she does, but this does not involve some special experience. So gaining e-centric knowledge that one is in some situation only when one is in it does not equal finding out what an experience is like only when one has that experience. Does the following work better? One knows what is the X, by knowing that the X is the Y, where the identity isn’t particularly obvious. The ‘Y’ might be an E-description… so knowledge that X Is the Y might be irreducibly E-centric knowledge, which cannot be had until it is true of you that the X is the Y. So to gain unobvious identity concerning taste of vegemite – comes true that the taste is the one I’m having at this very moment, which would come true at the very moment I tasted it. But most cases of gaining unobvious E-centric identity don’t result in finding out what an experience is like… e.g. I plan to taste vegemite on Thursday at 12pm; Wednesday ifi watch the clock I gain unobvious E-centric knowledge that taste of V-mite is taste I’ll be having in exactly 24 hours. So have a knew way of knowing the taste of vegemite, apparently…! Hypothesis of Phenomenal Information Tempting to say that physical info does not help Mary: hypothesis that in addition to physical information, there’s also irreducibly different kind: phenomenal information.

Gain physical info – narrow down physical possibilities, maybe all down to one, but leave range of phenomenal open. Conversely, what it’s like to learn an exp. = acquiring phenomenal information, whereby possibilities previously open are eliminated. (Analogy with point on x-y plane… all x info still leaves open possibilities about y). Phenomenal information (if hypothesis of phenomenal information is true) is information about a certain feature of experience. If the hypothesis is false, then there’s still experience, but no information about experience is phenomenal info. So in saying information about exp. Is phenomenal info, one presupposes the hypothesis. So, if the hypothesis is false and materialism is true, there is still information about ‘raw feels’, ‘ways to feel’, and ‘what it’s like’ etc, but this is physical information, and can be conveyed in lessons.

The Knowledge Argument If KA worked it would refute the bare minimum common to all materialist theories. Minimal materialism a supervenience thesis that implies that any two possibilities that are the same physically will be the same simpliciter, which KA denies by suggesting that phenomenal information eliminates additional possibilities. But materialism a contingent truth – so there might be two possibilities alike physically but no simpliciter. Our world is not a world in which this is the case. So restricted supervenience thesis – within class of worlds incl. actual world there’s no difference w/o physical. Relevant class of worlds is those that have nothing wholly alien to this world. No wholly different kinds of things/fundamental properties. KA still refutes restricted thesis: could be a possibility only eliminated by phenomenal info, but lacks nothing alien to this world. Or eliminated possibility does have some X alien to this world – then phenomenal info. has revealed info that X not present : reveals presence of something hitherto unknown, but not alien from actuality (as inadequately represented by materialism). If phenomenal info. might eliminate possibilities impoverished by comparison w/ actuality, a counterexample to Sthesis. Lewis concludes that KA does work if we grant the hypothesis of phenomenal information – so he denies the hypothesis. Strangeness of the Hypothesis Opposed to more than just materialism. Also contra parapsychology (science of all non-physical things, properties, causal processes etc we might need to explain the things we do). Mary may study all of this as well as the physical information, but still won’t know what colour is like. E.g. learning about the aura of vegemite. If there is phenomenal information, it’s independent of every kind of information that could be used in lessons for the inexperienced. It is meant to eliminate possibilities that any amount of lessons leave open. Additionally, Lewis holds that information is treated by the hypothesis in terms of the elimination of possibilities: it excludes various alternatives. But phenomenal information resists this treatment:

when I don’t know what it’s like to experience something, I cannot present to myself a range of alternative possibilities, because I cannot imagine what it is or is not like. So can’t even pose the question PI is designed to answer (is it this way or that) – alternatives unthinkable before, and also after, except for the one that turns out to be actualised… Odd enough to be questionable… Epiphenomena Also strange that PI is isolated from all other kinds of info. Has no explanatory role in explaining why we talk about the phenomenal aspect of the world. Mary doesn’t do the new things she does upon seeing colour because she knows what it’s like to see colour: if phenomenal aspect absent, or aspect she gained had been different, her actions would have been the same. Cannot deny that phenomenal aspect of the world is epiphenomenal without contradicting the truths of physics. Ability Hypothesis Having a new experience = gaining abilities to remember and imagine, as well as recognitional abilities. ‘Knowing what an experience is like under a description’ – ability to remember or imagine an experience, while also knowing the E-centric proposition that what one is then imagining is the experience of x and y description. Maybe knowing what it’s like to taste vegemite really means ‘knowing what it’s like to taste vegemite under the description ‘tasting vegemite’’, and then knowing would involve ability and information. But Lewis denies this – makes sense for someone to say ‘I know this experience well and have known what it’s like, but only today have I found out that it’s the experience of tasting Vegemite’. (Déjà vu a good example?). As well as gaining ability to remember, also gain ability to imagine related experiences – might e.g. be able to imagine tasting vegemite ice cream. Ability hypothesis states that these abilities just are knowing what it’s like: explains why lessons won’t teach you. Lessons impart information, and ability is something else – knowledge-that doesn’t automatically provide know-how. If AH correct, phenomenal information an illusion. Objection: we gain abilities because we gain phenomenal information. Experiences leave traces in people that enable us to do things – traces = representations that bear info about their causes. But Lewis responds that these traces don’t represent special phenomenal facts. Causal basis for abilities may indeed be a special kind of representation of some kind of information – but just need to deny that it represents special info about a special subject matter. Might represent the details of the stimuli, details of the inner state produced, etc… =...