Philosophy of Mind Matthew Soteriou

Functionalism and Qualia Critics of functionalist accounts of the mental often appeal to thought experiments in which two subjects are in mental states that are functionally equivalent. If we can make sense of the idea that what it is like for one subject is different from what it is like for the other subject, then functionalism does not exhaust an account of the mental. (e.g. absent qualia and inverted spectrum arguments).

Inverted Spectrum Cases E.g. couldn’t there be an individual satisfies the functional definition of our experience of red, but is experiencing green instead?

Absent Qualia Cases Couldn’t there be creatures functionally equivalent to normal humans whose mental states have no qualitative character at all?

Do such thought experiments succeed in showing that qualia exist? What are qualia supposed to be, anyway? Does the existence of qualia threaten physicalism as well as functionalism?

Lecture 5 Modal Arguments for Dualism

Descartes, Kripke, and more recently, Chalmers use modal arguments to ground non-physicalist conclusions. Claims about what is metaphysically possible are used to ground non-physicalist conclusions. Claims about what is conceivable are used to ground claims about what is metaphysically possible.

Descartes For Descartes, the conceivability of my disembodied existence is supposed to ground a claim about the metaphysical possibility of my disembodied existence. It is metaphysically possible for me to exist as disembodied intellect. So I am, as intellect, not identical with a material substance.

“These arguments are enough to show that the decay of the body does not imply the destruction of the mind, and are hence enough to give mortals the hope of an after-life…”

Current Conceivabalility Arguments The following kind of argument offered by Chalmers: (1) Let P be the conjunction of all physical truths about the universe, and Q an arbitrary phenomenal truth about the universe: (2) If it is metaphysically possible that P and not Q, then physicalism is false (3) If it is conceivable that P and not Q, it is metaphysically possible that P and not-Q (4) It is conceivable that P and not Q Physicalism is false

Premise 1: The metaphysical possibility of P and not Q is inconsistent with the claim that the mental supervenes on the physical.

Premise 2: Is conceivability a legitimate / reliable guide to metaphysical possibility?

Premise 3: Is P and not Q really conceivable? What is meant by conceivability here?

Kripke’s work has been used to explain why conceivability does not entail metaphysical possibility. Certain necessary truths can only be known a posteriori and not a priori – e.g. It’s necessarily true that water = H2O. Epistemic possibility does not entail metaphysical possibility.

However, although Kripke’s work has been used to undermine modal arguments for dualism, Kripke also attempts offers a modal argument against materialism. (Interpretive question: Is Kripke’s argument supposed to be targeting type-identity theories only, or materialism in general?)

A priori vs. a posteriori: This is an epistemological distinction. ‘5 + 7 = 12’ is true a priori, since its truth can be ascertained without empirical investigation, simply by reflecting on the meaning of the expressions involved. ‘Heat = the motion of molecules’, by contrast, is true a posteriori, since any attempt to ascertain its truth relies on empirical investigation.

Necessary vs. contingent. This is a metaphysical distinction. A statement that is necessarily true if there is no possible world in which it is false. It is contingently true if it is true in the actual world, but there are possible worlds in which it is false.

Rigid vs. Non-Rigid designators A rigid designator is a term that refers to the same thing in every possible world in which it refers. A non-rigid designator does not refer to same thing in every possible world in which it refers. Definite descriptions (e.g. ‘The head of the philosophy department at Warwick University’) are often treated as non-rigid designators.

The necessity of identity: Identity statements involving two rigid designators (e.g. ‘heat = the motion of molecules’) always express necessary truths. If a=b, then it is necessarily true that a=b – i.e. there is no possible world in which that claim is false.

If ‘water = H2O’ is true it is necessarily true. But its truth is something we discover a posteriori. One cannot tell a priori whether water = H2O, so one cannot tell a priori whether there are possible worlds which contain water but not H2O (and vice versa).

Kripke’s Modal Argument against Type-Identity (as reconstructed by Hill) (1) It appears to be possible for there to be pain without C-fibre stimulation. For we can easily imagine a disembodied person experiencing pain. (2) It appears to be possible for there to be C-fibre stimulation without pain. For we can imagine a zombie whose c-fibres are being stimulated. (3) If it seems that properties X and Y are separable, then unless this appearance can be explained away, they really are separable. (4) If X and Y are separable, they are not identical.

(5) Explanation of apparent, but not genuine, separability of heat and mean molecular motion. (6) Apparent separability of pain and C-fibre stimulation cannot be explained in the kind of way indicated in (5). (7) The paradigm described in (5) is the only model for explaining appearances of separability. (8) Being a pain is not identical to being a case of C- fibre stimulation.

Premise (5): “Consider how the reference of the designators are determined; if these coincide only contingently, it is this fact that gives the original statement its illusion of contingency. In the case of heat and molecular motion, the way these two paradigms work out is simple. When someone says, inaccurately, that heat might have turned out not to be molecular motion, what is true in what he says is that someone could have sensed a phenomenon in the way that we sense heat [by means of its production of the sensation of heat, S] even though that phenomenon was not molecular motion.” (Kripke)

Premise (6): “Can something be said analogously to explain away the feeling that the identity of pain and c-fibre stimulation, if it is a scientific discovery, could have turned out otherwise? I do not see that such an analogy is possible. In the case of the apparent possibility that molecular motion might have existed in the absence of heat, what seemed really possible is that molecular motion should have existed without being felt as heat, that is, might have existed without producing the sensation S, the sensation of heat. Is it analogously possible that a stimulation of C- fibres should have existed without being felt as pain? If this is possible, then the stimulation of C-fibres can itself exist without pain, since for it to exist without being felt as pain is for it to exist without there being any pain.” (Kripke)

Christopher Hill attempts to defend type identity claims about pain by rejecting (7)

The Hill / Nagel explanation of the appearance of possibility: There are different types of imagination – we use sympathetic imagination in imagining presence / absence of mental events such as pain, and perceptual imagination in imagining absence / presence of brain processes. When we imagine the one without the other we splice together a situation sympathetically imagined and a situation perceptually imagined. The fact that we can do this without incoherence does not show that what we imagine is objectively possible. Our ability to do this is explained by the fact that there are two types of imagination that operate independently of one another.

Hill claims that general scepticism about our ability to obtain knowledge of modal facts is not entailed by his explanation. Because, (a) Claims about unreliability restricted to intuitions that have implications concerning a posteriori questions about matters of fact, and (b) It is not assumed that we are incapable of forming a posteriori modal intuitions that are correct, but only that our a posteriori intuitions tend to be incorrect when formed without being fully apprised of relevant empirical facts.

Hill’s assumptions about Kripke’s argt: Conceivability = appearance of possibility = imaginability. Other accounts of epistemic possibility – e.g. what cannot be ruled out a priori.

What kind of empirical information can rule out a non-identity claim? E.g. in the case of the claim ‘water is not identical to H20’, what sort of empirical information shows that claim to be false?

On some views, ‘water’ functions as a natural kind term, and this plays a role in explaining how one can come to discover empirically the identity in question. E.g. ‘water’ is not taken to refer to anything that has the superficial properties of water. Something counts as water only if it has the same underlying nature as water – it is a matter for scientific inquiry to discover what that is. Although the superficial properties of water fix the reference of the term ‘water’ for us, the term ‘water’ does not mean ‘anything that has such superficial properties. Compare the role of the sensation of heat in fixing the reference of the term ‘heat’.

What kind of non-identity claims cannot be ruled out a posteriori? Are there any? Are there any non-identity claims that cannot be ruled a priori or a posteriori? If there are, are these cases where epistemic possibility entails metaphysical possibility?

Returning to Chalmers’ argument: (1) Let P be the conjunction of all physical truths about the universe, and Q an arbitrary phenomenal truth about the universe: (2) If it is metaphysically possible that P and not Q, then physicalism is false (3) If it is conceivable that P and not Q, it is metaphysically possible that P and not-Q (4) It is conceivable that P and not Q Physicalism is false

One reading of conceivability: one cannot rule out a priori or a posteriori that P and not Q. Why can’t one rule out a posteriori that P and not Q? Because one cannot discover empirically that Q is identical to some physical condition? What would it take to discover empirically that Q is identical to some physical condition? Would co-variation of Q and that physical condition be sufficient?

Epiphenomenal Qualia? Note that the aspects of mind that Kripke and Chalmers appeal to in their arguments against physicalism are phenomenal, what-it’s-like qualities. Pain for David Lewis is a state the plays a certain kind of causal/functional role. Pain for Kripke is a sensation that has a phenomenal feel. Who is right about what pain is?

Could there be a state that played the functional role of pain without the phenomenal feel of pain? If so, would that state be pain? Could there be a state that had the feel of the sensation of pain but which didn’t play the functional role of pain? If so would that sensation be one of pain?

If one holds that a state cannot have the feel of the sensation of pain without playing the functional role of pain, does that mean denying that the phenomenal feel associated with pain is epiphenomenal?