In Defense of the Phenomenal Concept Strategy
Several different anti-physicalist arguments have been proposed during the last two decades that start from a premise about an epistemic or conceptual gap between physical and phenomenal descriptions[1] and conclude – on a priori grounds – that physicalism is false.[2] Physicalists have come up with various different strategies to counter these arguments. The most promising physicalist line of defense, in my view, is based on the idea that the epistemic and conceptual gaps between phenomenal and physical descriptions – which these anti-physicalist arguments take as their starting point to argue for the non-physical nature of phenomenal properties – can be explained by appeal to the nature of phenomenal concepts rather than the nature of non-physical phenomenal properties. Phenomenal concepts, on this proposal, involve unique cognitive mechanisms, but none that could not be fully physically implemented. If this project is successful, it amounts to a powerful reply to the anti-physicalist arguments. I will call this project – following Stoljar (2005) – the Phenomenal Concept Strategy (PCS).
David Chalmers (2007) has presented a Master Argument to show that the PCS – not just this or that version of it, but any version of it – fails; the basic idea is that there are a priori reasons to deny the possibility of the kind of phenomenal concepts this strategy requires, i.e., physicalistically respectable concepts that at the same time explain our epistemic situation[3] with respect to qualia. Chalmers argues that the phenomenal concepts posited by such theories are either not physicalistically explicable, or they cannot explain our epistemic situation with regard to qualia. If he is correct then the PCS defense of physicalism fails. However, here I argue that it is his Master Argument that fails. My claim is his argument does not provide any new reasons to reject the PCS. I also argue that, although the PCS is successful in showing that the physicalist is not rationally compelled to give up physicalism in the light of the anti-physicalist arguments, the anti-physicalist is not rationally compelled to give up the anti-physicalist argument in the light of the PCS either. There is a symmetry between the two positions as far as a priori considerations are concerned.
I. Physicalism and
the gaps
The debate between
physicalism and anti-physicalism is a debate about fundamental ontology.
According to physicalism, the world’s fundamental ontology is physical.[4] It is
not easy to say exactly what makes fundamental entities and properties
“physical.” But this isn’t a problem since it suffices for our discussion that
physicalism is understood as requiring that fundamental
physical properties and entities and micro-systems composed of them are
“non-mental.” So if physicalism is true then micro-systems (e.g. individual
molecules) do not possess intentionality or phenomenal consciousness (or proto
intentionality and phenomenality).
(Phys) "T□ (P É T).[7]
If
there are mental truths – for example, that Mary knows what it is like to see
red – that are not necessitated by the complete physical description then
physicalism is false since there would
then be entities or properties whose existence and/or instantiations are not
entailed by the complete physical description (including the
fundamental physical laws) of our world.
The anti-physicalist arguments start from a premise
that there is an epistemic gap between P and
Q[8].
Chalmers’ Zombie Argument (Chalmers 1996, forthcoming), e.g., starts with the
premise that there is a gap between our conception of P and our conception of Q. He
claims that zombies – i.e., creatures that are our physical duplicates but lack
some or all of our phenomenal experiences – are conceivable, i.e., that P&~Q is conceivable.[9] But if we can thus conceive of P&~Q then there is a gap between conceiving of P and conceiving of Q.[10]
Phenomenal descriptions are
supposedly different in this way from descriptions involving concepts like
WATER and even name concepts like
Anti-physicalists go on arguing that these epistemic gaps, together with some plausible – putatively a priori – principles imply that there is an ontological gap between the physical and the phenomenal, i.e., that physicalism is false. Chalmers, e.g., claims that it is a priori that if P&~Q is conceivable then P&~Q is possible. From this, and the conceivability of zombies he concludes that physicalism is false.
The Zombie Argument
1) P&~Q is conceivable. [11]
2) If P&~Q is conceivable then P&~Q is metaphysically possible.
3) If P&~Q is metaphysically possible then physicalism is false.
________
4) Physicalism is false.[12]
The Phenomenal Concept Strategy is based on the core idea that the conceptual and epistemic gaps are due not to the nature of qualia but rather the nature of the concepts in terms of which we think about qualia. The key factor is that the explanation on offer is claimed to be compatible with physicalism. By providing a clear conception of how the key epistemic/conceptual facts can hold in a purely physicalistic world the physicalist can show that the a priori premise of the anti-physicalist arguments linking the epistemic gaps to ontological gaps is mistaken. The puzzling conceptual/epistemic facts themselves do not a priori require an anti-physicalist explanation. The Phenomenal Concept Strategy provides an alternative – physicalist – explanatory scheme for those facts.[13]
II. The Phenomenal Concept
Strategy
Phenomenal concepts have a
number of unique and puzzling features. The sense that there is something
special about phenomenal concepts is very closely tied up with features of the epistemic access they afford to qualia.
When we deploy phenomenal concepts introspectively to some phenomenally
conscious experience as it occurs, say a phenomenal experience of the color
blue, we are said to be acquainted
with our own conscious experiences. While philosophers have understood
‘acquaintance’ in various ways, it is generally taken to be a unique
epistemological relation that relates a person to her own mental states directly and, according to some, in a substantial way. I will understand “substantial” grasp of a property as
requiring the possession of a vivid mode of presentation[14]
of that property that strikes the thinker as essential to the property.
Such a relation has struck many philosophers as deeply puzzling. Accounts of phenomenal concepts either have to take the acquaintance relation as primitive, explain it in terms of psychological or physical/functional mechanisms, or acquaintance with our phenomenal experiences has to be denied. The version of the Phenomenal Concept Strategy I have developed (author’s article 2) - constitutional account of phenomenal concepts - accounts for these features in a way compatible with physicalism.
On the constitutional account there is an intimate relation between a phenomenal concept and its referent; the experience serves as its own mode of presentation. Unlike in the case of most concepts, e.g., the concept DOG, where it doesn’t matter exactly what neural configurations constitute a particular token of DOG as long as the requisite causal/informational relations between it and dogs hold, in the case of phenomenal concepts, e.g., the concept PAIN, constitution matters for reference, both in terms of how the reference is determined, and in terms of how the concept cognitively presents its reference. More precisely, on this view, every concept token applied to current experience is constituted by that token experience, and this fact is crucial in determining the reference of the concept. Not only is it the case that a token state that realizes a token concept also is a token of the referent, but it is because the concept is so constituted that it so refers. There are, of course, applications of phenomenal concepts that are, on this theory, not constituted by occurrent phenomenal states; e.g., applications of phenomenal concepts to one’s past or future experience, to other peoples’ experiences, etc. But the canonical, first person, present tense applications are always so constituted and these other applications are derivative on first person applications.[15]
If this account is true it would explain the puzzling aspects of our acquaintance with our own experience in a manner that doesn’t appeal to non-physicalistic metaphysics. I will argue that doing that also helps explain the epistemic gaps that the anti-physicalist arguments are based on – in a way compatible with physicalism.[16] First of all, the constitutional account explains how we can have a substantial grasp of phenomenal properties even while this grasp is direct, and unmediated by physical or functional modes of presentation. Because, on this account, in the canonical, first person, present tense applications of a phenomenal concept an instance of the property it refers to is literally (physically) present in the concept, there will be always something it is like to token the concept in those canonical applications.[17] Undergoing a token of the phenomenal property reveals something that seems essential about that property in a particularly vivid manner, namely, it reveals what it is like to have it. This means that phenomenal concepts provide a substantial grasp of the phenomenal properties they refer to. And because, according to the theory, tokens of phenomenal concepts present their referent as the property whose token they incorporate – and not via any functional or physical description – they will refer to phenomenal properties directly, as well as substantively.
The constitutional account can now be marshaled to account for the epistemic gaps that drive the conceivability arguments.
The conceivability of zombies is explained by the directness and substantiality of our phenomenal concepts which, under the constitutional account, is compatible with physicalism. The directness of phenomenal concepts follows, as we observed above, from the fact that the reference of a phenomenal concept is determined by how it is constituted and not by any description that is associated a priori with the concept. We can see that phenomenal concepts on the constitutive account work quite differently from other non-physical concepts.[18] Their directness ensures that the zombie-scenario cannot be ruled out a priori, and their substantiality ensures that zombies are also conceivable. This explanation is perfectly compatible with a physicalist – as well as a dualist – metaphysics.
Of course, for the constitutional account to work, some of its details have to be worked out, in particular, the idea that constitution plays a role in determining reference in the case of phenomenal concepts. Whether this can be fully done still remains to be seen.[19] For the purposes of rebutting the conceivability arguments – and Chalmers Master Argument – it is enough if such an account cannot be ruled out on a priori grounds.
The anti-physicalist arguments aim to show, on a priori grounds, that physicalism is false. They can be reformulated to show that physicalism can be ruled out a priori in a world in which phenomenal consciousness exists. For example, the a priori version of the Zombie Argument runs like this:
The Zombiea priori Argument
1) It is a priori that P&~Q is conceivable.
2) It is a priori that If P&~Q is conceivable then P&~Q is metaphysically possible.
3) It is a priori that if Q and P&~Q is metaphysically possible then physicalism is false.[20]
________
4) It is a priori that if Q then Physicalism is false.
In sum, the anti-physicalist arguments can be reformulated to show – not just that physicalism is false but – that a purely physical world where phenomenal experience occurs is inconceivable. To counter these arguments, it is enough for the proponent of the PCS to show that such a world is conceivable. Let’s call creatures that that inhabit a purely physical world but enjoy phenomenal states illuminati.[21] The PCS will succeed if it can help establish that illuminati are conceivable. According to the PCS, both zombies and illuminati are conceivable because of our direct, vivid grasp of phenomenal states in introspection. Furthermore, and crucially, the PCS helps establish the conceivability of illuminati by providing a conceivable explanation of the epistemic gaps that arise in the illuminati world in terms compatible with physicalism.
III. Chalmers’ criticism of the Phenomenal
Concept Strategy
David Chalmers’ (2007) Master Argument claims to establish that there are a priori reasons to rule out the possibility of an account of phenomenal concepts that physicalistically explains the epistemic gaps between P and Q. He argues that phenomenal concepts are either not physicalistically explicable, or they “cannot explain our epistemic situation” with regard to qualia. To get this conclusion, Chalmers argues for the following two premises, providing the physicalist with a dilemma.
If P&~C is conceivable, then C is not physically explicable.
If P&~C is not conceivable, then C cannot explain[22] our epistemic situation.
where C stands for the claim that we possess phenomenal concepts with the relevant key feature (e.g., being constituted by an instance of the referent) posited by a physicalist account of phenomenal concepts.
There are two issues that need clarification before evaluating the argument. One is the question of what vocabulary C should be couched in; the other is what is meant by “epistemic situation” in the argument. We will get to each of these issues in turn.
The content and conceptualization of C
Conceivability, in all its varieties, is a conceptual matter and so the evaluation of Chalmers’ premises will depend on what conceptualization of C we have in mind. According to the physicalist, C can be conceptualized not only using phenomenal language (CPhen) but, alternatively, it can be conceptualized using physical language (CPhys). Of course, if physicalism is right, there are many possible non-phenomenal, “physical” conceptualizations of the same phenomenon (e.g., C might be formulated as having concepts that are constituted by the same perceptual or sensory states that they refer to; or as being in a certain neuro-physiological, chemical, quantum-mechanical, etc., state). However, the issue of multiple possible physical conceptualizations of C will not make a difference in our discussion, as we will see shortly.
Using this apparatus, we get the following four premises:
1Phen) If P&~CPhen is conceivable, then CPhen is not physically explicable.
1Phys) If P&~CPhys is conceivable, then CPhys is not physically explicable.
2Phen) If P&~CPhen is not conceivable, then CPhen cannot explain our epistemic situation.
2Phys) If P&~CPhys is not conceivable, then CPhys cannot explain our epistemic situation.
I now turn to an assessment of these premises. Two of the premises, 1Phys and 2Phen are vacuously true by virtue of having a false antecedent. Let’s take 2Phen first:
2 Phen) If P&~ CPhen is not conceivable, then CPhen cannot explain our epistemic situation.
Anybody who accepts the conceivability of zombies (as I do), will have to accept the conceivability of “phenomenal concept zombies” (i.e., creatures that are physically identical with us but have no phenomenal concepts) under phenomenal conceptualizations of phenomenal states and phenomenal concepts, and so count 2Phen as vacuously true. How about 1Phys?
1Phys) If P&~CPhys is conceivable, then CPhys is not physically explicable.
If CPhys is given in fundamental physical language, 1Phys is vacuously true. Since both 1Phys and 2Phen has a false antecedent, and so are true only vacuously, neither of them can be used to argue against the PCS.
On the other hand, 1Phen and 2Phys have true antecedents, and their consequent appears damaging to the physicalist project, so the physicalist needs to address them seriously. I admit that 2Phys is non-vacuously true, and so that CPhys cannot explain our epistemic situation. I believe that C has to be cast in phenomenal terms for it to explain our epistemic situation, i.e., I think that only CPhen explains our epistemic situation. I also accept 1Phen and so that CPhen is not physically explicable. I will devote the last section of this paper to arguing that that this combination of views – that only CPhen can explain our epistemic situation, but CPhen is not physically explicable – is not a threat for physicalism.[23]
IV. In Defense of the
Phenomenal Concepts Strategy[24]
The notion of “explicability” involved in the claim that CPhen is not physically explicable is closely tied to conceivability – P&~ CPhen is conceivable. Chalmers argues like this:
Here…we are assuming nothing about the relationship between conceivability and possibility. It may be that creatures satisfying P&~C are metaphysically impossible. We are simply assuming a connection between conceivability and explanation. More precisely, we are assuming a connection between and a certain sort of reductive explanation, the sort that is relevant here: explanation that makes transparent why some high-level truth obtains, given that certain low-level truths obtain…..for now, I will take the connection between conceivability and explanation for granted. (pp. 174-5)
It seems for Chalmers the connection between conceivability and explanation is straightforwardly a priori. I will call the notion of explanation (at least partly)[25] captured by this claim perspicuous explanation.
It is important to notice that whether a fact A perspicuously explains a fact B might be dependent on the conceptualization of the facts in question. As far as the notion of perspicuous explanation is concerned, it is an open question whether it is possible for some facts A and B, and some conceptualizations of A A1 and A2 that B is perspicuously explained by A under conceptualization A1, but not under conceptualization A2 (the same considerations apply with respect to different conceptualizations of B as well). The physicalist thinks that this is exactly the situation with respect to the fact that C and the fact that P. P doesn’t perspicuously explain CPhen but it does perspicuously explain CPhys! And CPhen and CPhys, according to the physicalist, express the same fact. To rebut the anti-physicalist, the proponent of the PCS merely has to argue that this is conceivable. If it is conceivable then the fact that P doesn’t perspicuously explain CPhen doesn’t a priori entail that CPhen is not physical. Indeed, there is no a priori reason to rule this situation out – no a priori reason, that is, except the putatively a priori anti-physicalist principles. But the PCS explains why the anti-physicalist principles are mistaken. The Master Argument is thus answered.
However, the anti-physicalist might object that such a situation is indeed inconceivable since the lack of a perspicuous explanation does a priori entail an ontological gap between the facts involved. But this argument relies on the original principles that the PCS is designed to rebut.[26] Invoking them again – this time arguing that phenomenal concept facts do not metaphysically supervene on the physical – doesn’t add anything to the original anti-physicalist argument which concluded that phenomenal facts do not metaphysically supervene on the physical. On the constitutional account of phenomenal concepts, both explanatory gaps – the one involving P and Q, the other involving P and CPhen – arise in virtue of the peculiar nature of phenomenal concepts. As a consequence, invoking the anti-physicalist principles concerning the metaphysical status of phenomenal concepts doesn’t provide any additional reason to reject the PCS. But physicalism would remain puzzling and downright incomprehensible if a perspicuous physicalist explanation of these gaps themselves was not conceivable. Luckily, the PCS has just such an explanation. It has the next best thing to a perspicuous explanation of Q in terms of P, namely, it has a perspicuous explanation of why we can’t have one. The proponent of the PCS turns things around by showing that a purely physical world where the epistemic gaps are explained by the constitutional account is conceivable. She does this by arguing that there is no a priori reason to rule out the existence of a purely physical world where q=b, and where the constitutional account of phenomenal concepts holds.[27] By showing that it is conceivable that the epistemic gaps are explained purely physically, the PCS removes the sense that they require a dualist treatment. Such an explanation can be a priori discredited only on the assumption that the a priori principles linking epistemic gaps to ontological gaps are true; the very principles which the PCS is rebutting. From the physicalist point of view, deploying these principles in an argument against the PCS misses the point of the PCS and begs the question in the dualist’s favor. Chalmers’ Master Argument hasn’t succeeded in refuting the PCS.
Chalmers (2007) charges that the explanatory scheme outlined above is circular. But there is nothing viciously circular about the explanation I sketched above. It is true, to rebut the anti-physicalist arguments, it is not enough to show, as the proponent of the PCS does, that illuminati are conceivable, modulo the anti-physicalist principles. She also has to assume that the anti-physicalist principles are false (and so do not make illuminati inconceivable). But on that assumption, the physicalist perspicuously explains why the anti-physicalist principles are mistaken. One cannot prove from outside the system that the physicalist assumption is right. But on that assumption, everything works out just fine. The physicalist can answer all the anti-physicalist arguments.[28]
Chalmers claims that, on this
scheme, no progress can be made by following the PCS since the issue of
whether the new gap – i.e., the one involving CPhen and P
– is compatible with physicalism can be
raised with the same force it was raised with respect to the original
explanatory gap. The ontological implications of the gap between CPhen and P have to be denied which comes much to
the same thing as denying the ontological implications of the original gap
between C and P. What Chalmers overlooks is that the PCS provides
a conceivable physicalistic explanation
of the conceptual/epistemic
gaps (including the new gap involving phenomenal concept descriptions) and
so of the intuitive appeal of the anti-physicalist principles – which amounts
to more than a mere denial.
In fact, and this is a key point, the anti-physicalist engages in the same kind of circular argumentation against the physicalist that he accuses the physicalist of doing. The anti-physicalist rebuts the physicalist arguments against the anti-physicalist by assuming that these principles are true. So upholding the anti-physicalist principles in the face of physicalist challenges requires an assumption of their truth.
The situation might be described as a stalemate. Each side can unseat the other side’s core assumption – if they are permitted to make their own core assumption. The anti-physicalist appeals to the anti-physicalist principles, the physicalist appeals to the conceivability of illuminati. Both can show that, once granted that one core assumption, their view is consistent and can rebut challenges from the other side. Neither side can, without begging the question against the opponent, show that the other’s position is untenable. Where you end up depends on what you take as your starting point. And, as far as I can see, neither side has a privileged start.
This is puzzling. One would have thought that when it comes to a priorities, like the anti-physicalist principles, and the conceivability of illuminati, there are a priori ways to justify or refute them.[29] However, the relevant a priorities – the anti-physicalist principles and the conceivability of illuminati – are, as we have seen, self-justificatory. I know of no principles outside the physicalist and anti-physicalist systems that could settle this issue by showing that either side is incoherent. What we have here is a puzzling symmetry between the two positions.
If there is a way to break the stalemate it is by comparing the two metaphysical/explanatory systems in which each position is embedded, as actual accounts of the world. As I have argued elsewhere (Author’s article 1) there is no good reason to think that empirical evidence can break the tie. The only way empirically equivalent scientific theories are can be compared with each other is by considerations of simplicity and overall explanatory strength. Both physicalism and dualism have their own accounts of metaphysical necessity, mental causation, meaning, the nature of physical properties and consciousness, and what fundamental laws exist.
This is not the place to adjudicate the issue. The conclusion that we can draw from the foregoing discussion of the PCS and Chalmers’ Master Argument is that there are no a priori reasons to decide between the two metaphysical frameworks – except considerations having to do with the overall simplicity and explanatoriness of the respective metaphysical frameworks.[30] This is where the ontology wars will be decided, if at all.
REFERENCES
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Chalmers, D., (forthcoming in 2009), “The Two-Dimensional Argument Against Materialism”, in B. McLaughlin (ed.) The Oxford Handbook of the Philosophy of Mind.
Jackson, F., 1982, “Epiphenomenal Qualia”, Philosophical Quarterly 32: 127-36.
Jackson, F.,
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Kripke, S.,
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Levine, J, 2001. Purple Haze,
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Levine, J., 2007, “Phenomenal concepts and the materialist constraint”, in T Alter and S Walter (eds) Phenomenal Concepts and Phenomenal Knowledge: New Essays on Consciousness and physicalism, Oxford University Press.
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Nida-Rümelin, M., 2007, “Grasping Phenomenal Properties”, in T Alter and S Walter (eds) Phenomenal Concepts and Phenomenal Knowledge: New Essays on Consciousness and physicalism, Oxford University Press.
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[1] Phenomenal descriptions attribute phenomenal
properties (i.e. qualia) to experience
(and perhaps even to thought) in the sense of there being something it is
like to undergo an experience, something one can normally introspect, e.g.,
the feeling of my fingers flexing that (partly) characterizes my present bodily
sensation. I will assume throughout the paper that there are phenomenal
properties in this sense.
[2]
These arguments include, among others,
arguments based on conceivability considerations by Kripke (1972), Nagel
(1974), Bealer (1994), Chalmers (1996, and forthcoming), as well as the
Knowledge Argument of Jackson (1982), versions of the Property dualism Argument
in Robinson (1993), White (2007), and Nida-Rümelin (2007), and the Explanatory Gap Argument in Levine
(2001) and (2007).
[3] “Epistemic situation” is used by Chalmers in a
technical sense that I will explain later.
[4] Contemporary physicalists typically hold that the best account of that
ontology is provided by fundamental physics. Physics’ best hypotheses about
fundamental ontology is that it consists of elementary particles, strings
and/or fields occupying a space-time structure, and possessing a limited number
of quantitative properties (mass, charge, electromagnetic potential, and so
on). Physics also claims that there are only a few fundamental dynamical and
perhaps non-dynamical laws that govern the structure of space-time and the
evolution of its occupants.
[5] A positive phenomenal statement says that a
phenomenal property is instantiated; e.g., Joe
is feeling an itch. Negative truths, like There are no angels, and global statements, like Every gold cube has a volume smaller that
one cubic centimeter, are not metaphysically necessitated by the complete
physical truth about the world P
although they are necessitated by P
and a clause that says that P is the
whole fundamental truth. However, the phenomenal and physical truths we will be
interested in are all positive truths so I will ignore this complication for
the remainder of the paper.
[6] This formulation is based on Jackson’s (
[7]
" is a
substitutional quantifier, T is a statement variable for true positive
statements, ÿ is the metaphysical
necessity operator, and P is the complete fundamental physical truth, including the fundamental physical laws.
[8] P, again, is the full fundamental physical
description of the world, and Q is
any positive phenomenal truth, including the full positive phenomenal truth
about our world.
[9] A statement S is conceivable iff it cannot be ruled out a priori. Chalmers (2002) distinguishes between several different notions of conceivability, but, since these distinctions do not affect the arguments of this paper, I will stay with this basic definition.
[10] Some physicalists deny this. They think that
phenomenal concepts can be analyzed in terms of functional role or
representational character.
[11] P
is the complete fundamental physical description of the world, including the fundamental
physical laws, and Q is a positive phenomenal truth, e.g., that someone
is having a visual experience with a particular phenomenal character at a
particular time.
[12] Chalmers (forthcoming)
introduces some clarifications and emendations to this simple argument. None of
them plays a role in the arguments that follows so I am putting those to the
side.
[13] I will only directly
address the conceivability of zombies and the explanatory gap; but it can be
shown that the phenomenal concept strategy addresses all the other epistemic
gaps and so all the other anti-physicalist arguments based on the existence of
these gaps.
[14] By “vivid” I mean something along the lines of what
David Kaplan called a “vivid name” (Kaplan 1968-1969). He introduced this
notion as part of an account of what it is to have de re knowledge of an individual or, as he says, to be “en rapport” with an individual.
[15] Such “indirect” applications of phenomenal concepts, in
my view, are conceptually linked with the “direct”, first person present tense
applications in some rather complicated way; for a more detailed account see
Author’s article 2.
[16] I argue elsewhere (Author’s
article 2) that all the other puzzling features of our epistemic relation to
our phenomenal experience – incorrigibility, asymmetric access, transparency,
fineness of grain, semantic stability, etc. – can be explained by the account
as well.
[17] Levine (2006, 2007) is critical of this approach. He argues that it is impossible to explain cognitive presence by physical presence.
[18] Nota bene: I am not denying that there are inferential links between thoughts involving direct phenomenal concepts that are individuative of them. I think it is quite plausible that there are conceptual links, even perhaps concept individuative conceptual links between direct phenomenal concepts such as we apply our own occurrent phenomenal experience on the one hand, and indirect phenomenal concepts such as we apply to other people’s phenomenal experiences, other mental concepts, and behavioral concepts, etc. on the other. My point is that to the extent that these are a priori they do not add up to conceptually sufficient conditions in terms of other mental concepts, functional, or behavioral concepts, etc. in other words, they are not of the sort that enables one to rule out a priori the zombie-scenario.
[19] For a proposal see Author’s article 2.
[20]
The Zombie Argument implicitly assumes that Q is true; I made this assumption
explicit for the purposes of the Zombiea
priori Argument.
[21] If physicalism is true,
then we, for example, are illuminati.
[22] What Chalmers has in mind here is, of course, constitutive,
rather than, say, causal, or teleological explanation.
[23] Chalmers, by contrast, thinks that accepting the claim that C is not physically explicable – under any conceptualization of C – would be the kiss of death for physicalism. In the light of this, he suggests that physicalists should cast C in non-phenomenal terms, to avoid having to assert the conceivability of P&~C and – via premise 1 – the consequent that C is not physically explicable. He holds out some hope for the physicalist to be able challenge 2 by offering both a special, topic neutral conceptualization of C and a topic-neutral characterization of our epistemic situation. I don’t think this can work for the physicalist; but since I don’t think accepting that C is not physically explicable is damaging to the physicalist project I’ll sidestep Chalmers’ suggestion. For a discussion of this issue see Author’s article 3.
[24] Papineau (2007) and Carruthers & Veillet
(2007) both offer interesting defenses of the PCS in the face of Chalmers’
Master Argument; they pursue rather different tacks from the one I am going to follow
in this section.
[25] These conditionals specify a conceptually
necessary (but perhaps not sufficient) condition on what Chalmers calls
“reductive” explanation. A full definition of reductive explanation is not
needed here anyway; all that is relevant, from the point of view of the
arguments in this paper, is the conceptually necessary conditions stated in the
conditionals.
[26] The principle at work
connects, on Chalmers’ account, a conceptual gap to an ontological gap. Another
version of the principle connects the explanatory gap to an ontological gap.
There are other – supposedly a priori – principles connecting some epistemic
gap with an ontological gap; but I am not going to discuss them here.
[27] Presumably, a full
explanation requires a general theory of concepts and representation, and an
account of mental processes. I will keep these out of consideration since these
things have to be in place for a full explanation irrespective of one’s
ontological views.
[28] Descartes used a similar overall argumentative
structure – the Cartesian Circle – as part of a strategy, ironically, to argue
for dualism.
[29] There are some instances of statements which if true
(false) must be a priori true (false)
but where we lack non question begging a priori ways of deciding the issue. For example, mathematical realists
typically think that Cantor’s Continuum Hypothesis is an instance. But the case
at hand seems as though it should be a priori decidable by us since it doesn’t
involve the complexity of the mathematical case.
[30] I am not going to decide
whether the terminology a priori properly
describes such considerations. Nothing rides on the terminology.