Knowledge and Reality Scepticism Lecture four: Semantic Externalism Ema Sullivan-Bissett [email protected] www.emasullivan-bissett.com Feedback and Advice hour: Thursdays, 11:30, office A/101 (weeks 2–6) Semantic Externalism ‘[T]he meaning and reference of some of the words we use are not solely determined by the ideas we associate with them or by our internal physical state’ (Lau and Deutsch 2010). ‘[M]eanings just aren’t in the head’ (Putnam 1981: 19). Churchill and the Ant ‘An ant is crawling on a patch of sand. As it crawls, it traces a line in the sand. By pure chance the line that it traces curves and recrosses itself in such a way that it ends up looking like a recognizable caricature of Winston Churchill. Has the ant traced a picture of Winston Churchill, a picture that depicts Churchill?’ (Putnam 1981: 1). Similarity and Representation • Similarity is neither necessary nor sufficient for representation. • Not sufficient: – the ant’s trace which resembled Churchill did not represent Churchill. • Not necessary: – printed words and spoken words can represent without resembling. Intention and Representation • What is necessary for representation? • Intention. ‘Suppose the ant had seen Winston Churchill, and suppose that it had the intelligence and skill to draw a picture of him. Suppose that it produced the caricature intentionally. Then the line would have represented Churchill’ (Putnam 1981: 2). Mental Representation ‘Suppose there is a planet somewhere on which human beings have evolved (or been deposited by alien spacemen, or what have you). Suppose these humans, although otherwise like us, have never seen trees. Suppose one day a picture of a tree is accidentally dropped on their planet by a spaceship which passes on without having other contact with them. Imagine them puzzling over this picture. What in the world is this? All sorts of speculations occur to them: a building, a canopy, even an animal of some kind. But suppose they never come close to the truth’ (Putnam 1981: 3). Mental Representation ‘For us, the picture is a representation of a tree. For these humans the picture only represents a strange object, nature and function unknown. Suppose one of them has a mental image which is exactly like one of my mental images of a tree as a result of having seen the picture. His mental image is not a representation of a tree. It is only a representation of a strange object (whatever it is) that the mysterious picture represents’ (Putnam 1981: 3–4). Humans* do Represent Trees • We can be externalist about representation, and still claim that the humans* do represent a tree upon seeing/thinking about the picture. • We can say this because the right causal connection obtains (providing the tree drawing was produced by a human being, who had seen a tree). • ‘There is a causal chain from actual trees to the mental image even if it is a very strange one’ (Putnam 1981: 4). HUMANS TREE DRAWING TREE HUMANS* REPRESENTATION OF A TREE No they don’t! (If we change the example) • Remove the causal chain. • Now the ‘picture’ dropped onto the humans*’ planet is not a picture but ‘the accidental result of some spilled paints’ (Putnam 1981: 4). • Now the ‘picture’ of a tree is as much a picture of a tree as the ant’s ‘drawing’ is a drawing of Churchill (i.e., it isn’t!). • Now the humans* ‘would still have mental images qualitatively identical with my image of a tree, but they would not be images which represented a tree any more than anything else’ (Putnam 1981: 4). Words • Imagine a typed sentence featuring a description of trees: ‘trees are beautiful green delights’. • Now imagine that sentence was randomly produced by monkeys at a type writer, hitting keys for millions of years. • Now the token of ‘trees’ in ‘trees are beautiful green delights’ does not refer to trees. (Putnam 1981: 4). The Japanese ‘Speaker’ • Imagine a person memorized the monkeys’ words ‘trees are beautiful green delights’, translated into Japanese. • Through hypnosis, the person mistakenly thinks he understands the sentence. • ‘[I]f he couldn’t use the words in the right contexts, answer questions about what he ‘thought’, etc., then he didn’t understand them’ (Putnam 1981: 4). Compare: Turing’s (1950) Imitation Game • Interrogator, person, machine. • Separate the interrogator from the person and the machine. • The interrogator’s aim: determine which of the two respondents is the person, and which is the machine. • The person’s aim: help the interrogator correctly identify him (the person). • The machine’s ‘aim’: make the interrogator mistakenly conclude that it (the machine) is the person. John Searle’s (1990) Response The Turing Test for Reference • The Turing Test for reference is designed to determine if the interlocutor’s words refer. • Once again: we have a conversation and… ‘[I]f no problems arise, if the partner ‘passes’ in the sense of being indistinguishable from someone who is certified in advance to be speaking the same language, referring to the usual sorts of objects, etc., [we] conclude that the partner does refer to objects as we do’ (Putnam 1981: 9). • Is the Turing Test for Reference a definitive test for shared reference? No • ‘[I]t is not logically impossible […] that someone could pass the Turing Test for Reference and not be referring to anything’ (Putnam 1981: 10). • A machine programmed to produce English responses, with no sense organs or motor organs could pass the Turing Test for Reference. ‘[W]e cannot and should not attribute reference to such a device. It is true that the machine can discourse beautifully about, say, the scenery in New England. But it could not recognize an apple tree or an apple, a mountain or a cow, a field or a steeple, if it were in front of one. […] There is no more reason to regard the machine’s talk of apples as referring to real world apples than there is to regard the ant’s ‘drawing’ as referring to Winston Churchill’ (Putnam 1981: 10–11). Putnamian Brains in a Vat ‘Instead of having just one brain in a vat, we could imagine that all human beings […] are brains in a vat […] Perhaps there is no evil scientist, perhaps (though this is absurd) the universe just happens to consist of automatic machinery tending a vat full of brains and nervous systems’ (Putnam 1981: 6). Putnamian Brains in a Vat • Automatic machinery exists by cosmic chance or coincidence. • The machinery has no intelligent creator – all sentient beings are inside the vat. Wright’s Observation • The standard Brain in a Vat scenario is consistent with our beliefs about the external world being true—the alien/scientist tending the vat may not be a deceiver. Putnam’s story is inconsistent with almost everything I believe about the physical universe. So a sceptic’s argument using Putnam’s scenario is simpler (it doesn’t need to additional claim that the alien/scientist is a deceiver): ‘The standard brain-in-a-vat fantasy is, whereas Putnam’s is not, consistent with the truth of most of my beliefs about the material world. It may be that the purposes of the Evil Scientist do not require him to be a deceiver, and that most of the information I am fed is genuine. By contrast, Putnam’s version of a world wholly constituted by a group of brains-in-a-vat and that attendant automatic machinery is already inconsistent with almost everything I believe about the physical universe. This discloses a more substantial consequence of Putnam’s modifications to the standard story: an explicit sceptical argument built upon Putnam’s version can be significantly simpler’ (Wright 1992: 69–70). BREAK Putnamian Brains in a Vat ‘Instead of having just one brain in a vat, we could imagine that all human beings […] are brains in a vat […] Perhaps there is no evil scientist, perhaps (though this is absurd) the universe just happens to consist of automatic machinery tending a vat full of brains and nervous systems’ (Putnam 1981: 6). Putnamian Brains in a Vat • Let us suppose that the Putnamian brains in a vat story is true. If it were, could we, as envatted brains, say or think that this was the case? • No (even though the situation is a physically possible one, and one which is consistent with our experiences). • It cannot be true, because it is self-refuting. Self-Refuting Suppositions • Suppositions which if true, imply their own falsity. • ‘All general statements are false’ (Putnam 1981: 7). – ^ is a general statement. So if it is true, it is false. • ‘I do not exist’ (Putnam 1981: 8). – Entertaining of ^ makes it false. – For any ‘me’, if it is thought by me, or said by me, it is false. Putnamian Brains in a Vat and Self-Refutation ‘The supposition that we are brains in a vat has just this property. If we can consider whether it is true or false, then it is not true […] Hence it is not true’ (Putnam 1981: 8). Brains in Vats, ‘Trees’, and Trees • The word ‘tree’ as used by these brains in the vat are not connected to actual trees (run the counterfactual – they would still use the word ‘tree’ exactly as they do even if there were no actual trees outside of the vat!) • For us, the brains in vats’ words do represent trees (but qualitative similarity does not equal sameness of reference!) ‘[T]he brains in a vat are not thinking about real trees when they think ‘there is a tree in front of me’ because there is nothing by virtue of which their thought ‘tree’ represents actual trees’ (Putnam 1981: 13). Brains in Vats, ‘Trees’, and Trees • Possible referents for the brains in vats’ thoughts, utterances, or images of ‘trees’. – Trees in the image. – The electronic impulses that cause tree experiences. – The features of the program that are responsible for those electronic impulses. ‘These theories are not ruled out by what was just said, for there is a close causal connection between the use of the word ‘tree’ in vat-English and the presence of trees in the image, the present of electronic impulses of a certain kind, and the presence of certain features in the machine’s program’ (Putnam 1981: 14). ‘We are brains in vats’ • If the possible world in which the Putnamian brains in vats scenario is the actual world (i.e., if it really is the case), when we say ‘we are brains in vats’, that means something like – ‘We are brains in the image.’ – ‘We are brains in the electronic impulses that cause vat experiences.’ – ‘We are brains in the features of the program that are responsible for electronic impulses that cause vat experiences.’ ‘So if we are brains in a vat, then the sentence ‘We are brains in a vat’ says something false (if it says anything). In short, if we are brains in a vat, then “We are brains in a vat” is false’ (Putnam 1981: 15). Objections to Putnam’s Argument 1. Standard BiV Argument is Unscathed • Putnam’s argument doesn’t work against the standard brain-in-avat story in which an evil scientist is manipulating my brain. • If the scientist stimulates my brain to produce in me the experience of seeing a tree, in the same way that his own brain is stimulated when he sees a tree, I have sense impressions which are exactly like his veridical sense impressions. • This means that I really do represent a tree when my brain is stimulated in such a way as to produce in me the experience of seeing a tree, because my representation stands in a causal connection to real trees. TREE. REPRESENTATION OF A TREE Standard BiV Argument is Unscathed ‘Putnam's claims about reference, then, hold at best for worlds in which there is nothing other than brains in a vat and their automatic tenders […] So even if it follows from Putnam's remarks that it is not possible that I am in a vat of the latter sort, it does not follow that it is not possible that I am a brain in a vat of the standard sort. Hence Putnam's remarks have no force against a Cartesian skeptical argument built upon the (supposed) counterpossibility that I am a brain in a vat of the standard sort’ (Brueckner 1986: 151–2). 2. Recent Envatment Not Ruled Out • Putnam’s argument does not speak against the possibility that I am a recently envatted brain. • If I had been speaking English (as opposed to vatEnglish) up until the evil scientist took my brain, then my words will continue to refer even when I’m a brain in a vat (the right causal connections for reference are still in place). (Brueckner 2012). REPRESENTATION OF THE ROCKIES REPRESENTATION OF THE ROCKIES But… • The recent envatment scenario is not an ideal one for the sceptic to employ, since in such a scenario: ‘the pertinent skeptical argument leaves unscathed many of my knowledge-claims (such as that I was born in the USA, that I own a black cat,…) So the “recent envatment” scenario lacks the skeptical power of the Putnamian BIV scenario’ (Brueckner 2012). 3. Only Metalinguistic Knowledge Affected I am a brain in a vat. False. Because the brain is not ‘in a vat in the image’ (for example). Vat English I am a brain in a vat. False. Because she is not a brain in a vat. English 3. Only Metalinguistic Knowledge Affected • The sentence ‘I am a brain in a vat’ has different truth conditions in English and in vat-English, as such the sentence expresses different propositions in the two languages. • If I do not know whether I am speaking English or vat-English when I say ‘I am not a brain in a vat’, then I do not know what proposition is expressed by my utterance. • But all this allows me to claim is that ‘the metalinguistic knowledge that a certain sentence expresses a false proposition, rather than the objectlanguage knowledge that I am not a brain in a vat’. • But it is knowledge of the object-language kind which Putnam needs to refute scepticism. (Brueckner 1986: 166–7). 3. Only Metalinguistic Knowledge Affected I am a brain in a vat. Vat English I am a brain in a vat. English 3. Only Metalinguistic Knowledge Affected Next • Seminars: – Do the reading! – Come with at least one question per topic. • Assessment: – One 1500 word essay due noon on 10th November (Monday week seven). – Essay questions on the VLE. References Brueckner, Andrew 1986: ‘Brains in a Vat’. The Journal of Philosophy. Vol. 83, pp. 148–67. ----------------------------- 2012: ‘Scepticism and Content Externalism’. The Stanford Encyclopaedia of Philosophy, available online at http://plato.stanford.edu/entries/skepticism-content externalism/ Lau, Joe and Deutsch, Max 2010: ‘Externalism about Mental Content’. The Stanford Encyclopaedia of Philosophy, available online at http://plato.stanford.edu/entries/content externalism/ Putnam, Hilary 1981: ‘Brains in a Vat’ in his Reason, Truth and History. Cambridge: Cambridge University Press. Searle, John 1980: ‘Minds, Brains, and Programs’. Behavioral and Brain Sciences. Vol. 3, No. 3, pp. 417–24. Turing, Alan 1950: 'Computing Machinery and Intelligence'. Mind, Vol. 59, No. 236, pp. 433 –60. Wright, Crispin 1992: ‘On Putnam’s Proof that we are not Brains-In-A Vat’. Proceedings of the Aristotelian Society. Vol. 92, pp. 67–94.