CSE 719: Computational Theories of Consciousness, Fall 2009 ======================================================================== Jackson quotes (for bib info, see online bibliography) ======================================================================== Three versions of the "Knowledge Argument", a.k.a. the Mary thought experiment: 1. From Jackson 1982 ------------------------------------------------------------------------ "...the thesis of Physicalism[:] that all (correct) information is physical information [where physical information is the information we have from "the physical, chemical and biological sciences...and also for information that automaticlly comes along with it"] (p.127) "Mary is a brilliant scientist who is, for whatever reason, forced to investigate the world from a black and white room via a black and white television monitor. She specialises in the neurophysiology of vision and acquires, let us suppose, all the physical information there is to obtain about what goes on when we see ripe tomatoes, or the sky, and use terms like 'red', 'blue', and so on. She discovers, for example, just which wave-length combinations from the sky stimulate the retina, and exactly how this produces via the central nervous system the contraction of the vocal chords and expulsion of air from the lungs that results in the uttering of the sentence 'The sky is blue'. (It can hardly be denied that it is in principle possible to obtain all this physical information from black and white television, otherwise the Open University would of necessity need to use colour television.) "What will happen when Mary is released from her black and white room or is given a colour television monitor? Will she learn anything or not? It seems just obvious that she will learn something about the world and our visual experience of it. But then it is inescapable that her previous knowledge was incomplete. But she had all the physical information. Ergo there is more to have than that, and Physicalism is false." (p.130) 2. From Jackson 1986 ------------------------------------------------------------------------ "Mary is confined to a black-and-white room, is educated through black-and-white books and through lect relayed on black-and-white television. In this way she learns everything there is to know about the physical nature of the world. She knows all the physical facts about us and our environment, in a wide sense of 'physical' which includes everything in *completed* physics, chemistry, and neurophysiology, and all there is to know about the causal and relational facts consequent upon all this, including of course functional roles. If physicalism is true, she knows all there is to know. For to suppose otherwise is to suppose that there is more to know than every physical fact, and that is just what physicalism denies. ... "It seems, however, that Mary does not know all there is to know. For when she is let out of the black-and-white room or given a color television, she will learn what it is like to see something red, say. This is rightly described as *learning*--she will not say 'ho, hum.' Hence, physicalism is false." (p. 291) 3. From Jackson 2003 ------------------------------------------------------------------------ a) "The epistemic intuition that founds the knowledge argument is that you cannot deduce from purely physical information about us and our world, all there is to know about the nature of our world because you cannot deduce how things look to us, especially in regard to colour. (p.1) "A brilliant scientist, Mary, is confined in a black and white room without windows. She herself is painted white all over and dressed in black. All her information about the world and its workings comes from black and white sources like books without coloured pictures and black and white television. She is, despite these artificial restrictions, extraordinarily knowledgeable about the physical nature of our world, including the neurophysiology of human beings and sentient creatures in general, and how their neurophysiology underpins their interactions with their surroundings. Can she in principle deduce from all this physical information, what it is like to see, say, red? "There is a strong intuition that she cannot. This intuition is reinforced by reflecting on what would happen should she be released from her room. Assuming that there is nothing wrong with her colour vision despite its lack of exercise during her incarceration, she would learn what it is like to see red, and it is plausible that this would be learning something about the nature of our world, including especially the nature of the colour experiences subjects enjoy. From this it would follow that she did not know beforehand all there was to know about our world." (pp.2-3) b) Jackson's recantation: "The epistemic intuition is that it is impossible to deduce what it is like to sense red from the physical account of our world. In particular, Mary in her room will not be able to do it. I have argued that if what it is like means all the properties of seeing red, it is possible in principle to deduce them all. That follows from representationalism, [ROUGHLY, EXPERIENCE "REPRESENTS"...] and the appearance to the contrary arises from the conflation of intensional properties [...& THE INTENSIONAL OBJECT OF REPRESENTATION HAS ONLY "INTENSIONAL" PROPERTIES...] with instantiated ones. ... (p.18) [SO, A RED SQUARE THAT I AM THINKING OF IS NOT AN INSTANCE OF A RED THING--RED IS AN INTENSIONAL PROPERTY OF IT, NOT AN INSTANTIATED ONE] "So what is the before and after story about Mary? If feel [I.E., QUALIA] is a matter of immediacy [ROUGHLY, "TRANSPARENCY" OF REPRESENTATION], inextricability ["you cannot prise the colour bit from the shape bit of a visual experience."], and richness ["Visual experience represents how things are here and now in terms of colour, shape, location, extension, orientation and motion" (p.24)] of representational content, and if the state plays the right kind of functional role, the difference is that, after her release, Mary has representational states with all those properties. If she makes the mistake of conflating intensional properties with instantiated properties, she will think that she has learnt something new about how things are, but she'll be wrong. Rather, she is in a new kind of representational state from those she was in before. And what is it to know what it is like to be in that kind of state? Presumably, it is to be able to recognise, remember and imagine the state." (p.27)