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Transcript of Explanatory gap
Saul Kripke Joseph Levine pain = Sensation of pain the way it appears to us, i.e. some transparent liquid, i.e. water
phenomenon, i.e. two hydroxy groups, one oxygen group, i.e. H₂0 Step from conceivability to metaphysical possibility "Type-B physicalist" "Against physicalism" Critics:
Main consraint (i.e. belief in qualia) only of subjective nature. Pain is defined by itself either true or false, i.e. no tautology
might be false in some possible world
For me it's a bit weired that Levine is called a Typ-B physicalist because he wants to point out problems of materialism in his paper. He only claims that materialism cannot fully explain everything.
Mental state = Physical state ; e.g. Pain = C-fibre firing
Theoretical identity statements (e.g. water = H2O) are fully explanatory nothing crucial is missing for making sense out of it. Psycho-physical identity statements are not! causal role explains some important aspects
Function not explainable qualitative character how it feels why it should feel the way it does Qualia physical properties can hardly 'fit' the phenomenal properties. it what we identify with it g a p There is this subjective feeling that pain is something special! Phenomenon First of all:
How to close the gap?
What is sufficient for a full explanation?
What kind of explanations leave no gap? Why does qualia then demand explanation? There is a process that is describable in terms of the fundamental physical magnitudes (e.g. gravity constant) which can explain all phenomenons which cannot be described in terms of fundamental physical magnitudes (e.g. mental phenomena) in terms of occurrences of those. Water = H₂0 C-fibre firing = pain v ¬ pain Exemplary summary: Full explanation of phenomenal character? yes no Physical property without phenomenon conceivable? yes no Neuroscience: thought experiment Let's imagine some creatures which realize pain with the opening of valves and the inflation of cavities in the feet. (Remember Lewis: Mad pain and Martian pain.) There must be a full explanation of why C-fibre firing is pain.
Then we could generate a description of how a physical (or functional) state has to be like in order to feel just like human pain. It must be able to pinpoint what difference causes the different qualia in the Alien! Without closure of explanatory gap facts about the kind and the existence of phenomenal experiences of pain in physically/functionally different creatures are impossible! Conceivability Possibility When we imagine ¬ (water = H₂0) we mean ¬ ("the thing which behaves and looks like water" = H₂0) instead. We can distinguish between
Conceivability Possibility We know why water is a liquid,
why it sometimes gets hard under certain conditions. BUT! C-fibre firing = pain is epistemologically inaccessible because we can't properly describe other possible worlds with creatures feeling pain. while it could perhaps be a metaphysical fact! Materialism and Qualia: the explanatory gap Identity statements feel contingent. Psycho-physical identity statement OK! Contingency of theoretical identity statements can be explained away, i.e. there is a plausible reason why it feels contingent although it really isn't. 1 2 3 OK! OK! Contingency of psycho-physical identity statements cannot be explained away. Psycho-physical identity statements contingent are 4 It's conceivable that psycho-physical identity statements might be false in some other possible world. Metaphysical gap OK! 5 Epistemological gap Not OK! It's metaphysically possible that psycho-physical identity statements might be false in some other possible world. c-fibres fire pain / Knowledge c-fibres fire / pain Reality Significant
Difference Theoretical identity statement Functional state ≈ Physical state ; e.g. Heat = Motion of molecules versus Problem: physical Knowledge phenomenal knowledge physical property phenomenal property We cannot distinguish between the appearance and the phenomenon. Big threat for materialist! ¬ (A = B) "Kripke, I've got something which underlies the fact, that psycho-physical identity statements cannot be explained away: the explanatory gap!"
NOT! Argument in two sentences: Theoretical
identity statements Psycho-physical
identity statements 1. There is nothing in C-fibres which could explain the subjective pain-sensation everyone feels.
2. C-fibre firing without pain is conceivable. Function
Phenomenon causal role in interaction with environment Ouch!!! Water = H₂O C-fibre firing = pain Science vs. Qualia Example Example g a p g a p EEG, fMRI experiments discovered that there is some correlation of brain activity and pain sensation in humans. is 1. Atomaric structure can fully explain the phenomenal character of water.
2. It could not be anything else. All is explained by chemistry/physics. fully explainable with the help of science Neuroscience, i.e. physical properties can explain some functional/structural properties. screaming, jercking, moaning BUT ... What kind of explanations leave no explanatory gap? We feel pain because of c-fibre firing. Description of qualia is missing! A ball falls because of gravity.
Yet, it seems a bit odd because gravity is just a brute fact about the universe and hence appears arbitrary! vs. "Some facts of nature should just appear arbitrary to us and do not demand explanation."
seems fully explainable. Levine doesn't mention it clearly, but when the explanation only gounds on physical magnitudes, an identity statement is definitely fully explained. physical magnitude Explanation Physical/
state the way the state feels like when being in it. for Connection As materialist: Do I really have to close the explanatory gap? "I'll not tell you in this essay, but so much: Because of explanatory reductionism of materialism these arbitrary magnitudes don't arise in theories like psychology." Physical reductionism Defending the explanatory gap psycho-physicial identity statements are unknowable... Reminder: We know: Levine allows conceivability of false identity statements. Pain sensation Brain activity Correlation As rigid Materialists, can we tell whether an alien creature with a totally different physical constitution feels pain as humans do? ... even if they were metaphysical facts. No! We are in a disjunctive state! Dilemma i.e. pain = c-fibre firing v inflation of cavities v blabla v ... v ... Functionalism for the rescue? Inverted Qualia i.e. what plays the pain-role musn't be pain. Physicalist reductionism concerning particular kinds of qualia;
i.e. reduce this functional state to one physical state! all physical disjunctive states play the pain-role. Qualia Possible Solutions: Deny that psycho-physical identitiy statements are kind of contingent and eliminate belief in qualia
Accept the explanatory gap and that there is a jigsaw piece missing! Difference Qualia vs. Materialsm