Transparency, phenomenal concepts and a posteriori physicalism
Bénédicte Veillet
It seems that concepts too—like propositional attitudes, perceptual experiences, or even
whole minds—are sometimes said to be transparent. The metaphor must be appealing; it
certainly finds itself applied often enough though that’s certainly not to say that the
notion of transparency at play throughout is the same. Here then is a first approximation
of what is supposed to make a concept transparent according to a recent characterization:
when deployed by a thinker, the transparent concept “reveals the nature of its referent”
(Goff 2011, 194). The notion of conceptual transparency raises a number of (more or less
general) questions; first, naturally, are questions about how to make sense of the idea that
a concept might reveal the nature of its referent—what is meant by ‘revealed’, and what
makes this revelation one that is about the nature of its referent? And there are further
questions about what concepts (if any) might plausibly be transparent, and what their
transparency might entail.
I have two goals in the paper, then. The first is to examine the notion of conceptual
transparency and to show that it is rather difficult to get a clear sense of what it involves
(section 1). The second is to examine how the metaphor is actually used to draw
significant conclusions about our phenomenal experience. The stakes seem high:
phenomenal concepts are supposed to be quite intuitively transparent; and yet their
transparency is supposed to entail the falsity of a posteriori physicalism.1 The use of the
transparency metaphor, especially in Goff (2011), is supposed to help provide a more
compelling intuitive version of that argument. In section 2, I argue that Goff’s
transparency argument fails which suggests that it’s not clear how useful considerations
about transparency of phenomenal concepts turn out to be.
1
See Goff 2011, Nida-Rümelin 2007, Levine 2007.
1
1. Making sense of conceptual transparency
1.1. An initial characterization
I propose to take Goff (2011) at our starting point, for the simple reason that he provides
a rather detailed discussion of the notion(s) of conceptual transparency. Goff’s very first
characterization of transparency is expressed in terms of its opposite, opacity. A
transparent concept is one that is not opaque, and a concept C of property P is opaque “iff
C reveals nothing of what it is (or what it would be) for an object to have” property P
(2011, 192). I take it that means that a concept C (of property P) will be transparent iff,
by contrast, C reveals something of what it is (or would be) for an object to have P.
Now there is not supposed to be anything mysterious about concepts revealing
something; the point is that a concept reveals something about its referent iff possessing
that concept will allow the thinker who possesses it to know a priori at least some of
what it takes (or might take) for an object (or property) to fall under that concept. As
Chalmers puts it “possessing the [transparent] concept puts one in a position to know
what its referent is”, or at the very least, to know what some properties of the referent
are.2 Consider, to illustrate, the concept being a friend.3 A thinker who possesses the
concept being a friend will thereby be in a position to know that for something to fall
under it, that it would have to be a person, say, and someone the thinker cares about.4 We
could then say that the concept being a friend “reveals” to the thinker something about
what it takes to fall under the concept; in other words, it is transparent. To contrast, we
can imagine (with Goff) a situation in which he is asked to think about the property his
friend Kev is thinking about without being told anything else about it. And so Goff thinks
of that property by tokening the following concept being the property that Kev is thinking
about now (rigidly designated). There is a sense in which Goff tokening of that concept
reveals nothing about what it take for something to actually be that property. Goff “has
no idea what its nature is” (193), it could be anything at all—and so his concept is opaque
2
Chalmers, powerpoint presentation “From the Aufban to the Canberra Plan”, Slide 18.
This is a recurrent example of a plausibly transparent concept (see Chalmers, Goff 2011, Diaz-Leon
2013).
4
I’ll assume this is right, despite concerns about Facebook friends and man’s best friend.
3
2
rather than transparent.
1.2. A spectrum
This initial characterization is one that Goff ends up refining quite a bit. What we end up
with is actually a spectrum along which concepts range from transparent to translucent, to
mildly opaque, to radically opaque.
1.2.1 Transparent and Translucent
The first elucidating contrast is between transparent and translucent concepts. A
translucent concept, we’re told, is one that “reveals part (but not all) of the nature of its
referent” (Goff 2011, 194); a fully transparent concept, by contrast, reveals all of the
nature of its referent. In other words, it now seems that a concept C (of property P) is
transparent iff C puts its thinker in a position to know everything of what it is (or would
be) for an object to have P; and a concept C is translucent iff it puts its thinker in a
position to know something (but not everything) of what it is (or would be) for an object
to have P.
It is worth emphasizing that the initial characterization of transparency (mentioned in the
subsection just above) is not equivalent to the notion of transparency we have here; the
initial characterization is in in fact much weaker since it requires merely that a concept
reveal something about its referent to be transparent whereas it now requires that a
concept reveal everything about its referent. The initial notion—call it weak
transparency—really seems to encompass both the second notion—call it strong
transparency—and the notion of translucency. And notice, too, that our initial plausible
example of a weakly transparent concept is quite unlikely to be strongly transparent.
After all, it is far from obvious that possessing the concept of being a friend allows a
thinker to know everything of what it would take to be a friend.5 But insofar as
possessing that concept plausibly enables a thinker to know something about the nature of
the referent, the concept will count as translucent. Examples of concepts that are
transparent in the strong sense are interestingly harder to come by. Goff mentions the
5
Tye (2009) argues that it is in fact possible to use the concept being a friend deferentially—if that’s right
the concept is certainly not strongly transparent, though it may well be translucent.
3
concept being spherical in Euclidian geometry; but when it comes down to it he claims
only to “know a priori at least something of what it is for an object to be spherical in
Euclidean geometry, i.e. I know it’s for that object to have all points on its surface
equidistant from its centre” (193 emphasis mine). This leaves open the possibility that the
concept will turn out to be translucent.6 Maybe the most plausible examples of strongly
transparent concepts are those involving explicit compositionality, like the concept being
H2O, or being a red car. Possessing the concept being H2O plausibly puts one in the
position to know everything of what it would take to fall under the concept’s referent: it
would take being made up of two atoms of hydrogen and one atom of oxygen, period.7
1.2.2. Mildly and radically opaque
Now it turns out that what we’ve said so far about strong transparency and of
translucency are still not quite specific enough, as Goff’s discussion of the “opaque” end
of the spectrum suggest. An opaque concept, it seems, can fall into either of two opaque
categories. It can turn out to be mildly opaque, just in case it “does not reveal essential
properties of the referent, but does reveal accidental features of the referent which
uniquely identify it in the actual world”; or it can be radically opaque, iff it “reveals
neither essential nor accidental properties of its referent” (194)–or at least no accidental
properties of the referent that uniquely identify it in the actual world.
Mildly opaque concepts are supposed to be fairly familiar: a concept like being water
would qualify since it is plausible to say that it does not reveal essential properties of its
referent stuff (that it is H2O) but reveals accidental features of it that are supposed to
uniquely identify it (that it is the stuff in lakes and rivers). And concepts used
referentially might qualify as well; I may not know any of the essential properties of the
referent of being arthritis, but possessing the concept might still put me in a position to
know at least some of its (accidental) properties. Examples of radically opaque concepts
6
It also suggests that there may be cases in which we will be genuinely unsure about whether a concept is
transparent or translucent.
7
Papineau suggests something like this. He writes: “No doubt there are ways of thinking of things that
make certain essential properties a priori knowable. But I take such a priori knowledge to derive from
(possibly implicit) compositionality in the relevant modes of thinking” (2006, 102).
4
are less forthcoming; Goff in fact admits that it is possible for someone to deny that there
are radically opaque concepts.8 But still he believes there are plausible examples of such
a concept: he imagines a situation in which he meets a guy Bob at a party and forms a
recognitional concept on the basis of the meeting. When he wakes up the next day, Goff
has forgotten Bob’s name and lost all unique ways of identifying him; still if he were to
think of him using the recognitional concept he first tokened the night before (provided
he can), he would be deploying a radically opaque concept (see Goff, 196 fn11).
This discussion of opaque concepts brings out an interesting fact about the spectrum
more generally. The explicit mention of essential properties of (mildly and radically)
opaque concepts suggests that the key to spelling out what transparency is really about in
terms of essential properties. We said earlier that a strongly transparent concept reveals
all of the nature of the referent, and it now seems like the way to understand this mention
of the nature of the referent is in terms of essential properties. Strongly transparent
concepts, then, are those that reveal all of their referents’ essential properties; translucent
concepts reveal some but not all of a referents’ essential properties; opaque concepts
(whether mild or radical) reveal none of a concept’s essential properties. In other words,
it now seems that a concept C (of property P) is narrowly transparent iff C puts its thinker
in a position to know everything essential of what it is (or would be) for an object to have
P; and a concept C is translucent iff it puts its thinker in a position to know something
(but not everything) essential of what it is (or would be) for an object to have P; a
concept C is mildly opaque iff it puts its thinker in a position to know something uniquely
identifying but nothing essential of what it is (or would be) for an object to have P; a
concept C is radically opaque iff it puts its thinker in a position to know nothing uniquely
identifying and nothing essential of what it is (or would be) for an object to have P.
Now that we have the whole spectrum characterized, it is worth re-emphasizing how they
differ from Goff’s own initial notions of both transparency and opacity. The initial claim
about opacity was that a concept is opaque when the concept “reveals nothing of what it
is (or what it would be) for an object” to fall under it (2011, 192 emphasis mine). But
notice that this is stronger than what Goff ends up saying of even radically opaque
8
He interprets Chalmers (1996, 2002) as making that claim.
5
concepts. A radically opaque concept is one that reveals no essential properties of the
referent and no (uniquely identifying) accidental properties of it—but that is not to say
that the concept reveals nothing or no property of the referent at all. Think back to Goff’s
example of a radically opaque concept, the concept he uses to think about Bob, one of the
guys he met at the party. Notice that even that concept reveals something about its
referent—that he is some guy Goff met at the party. What is supposed to make this a
radically opaque concept is that this is not enough to uniquely identify Bob as opposed to,
say, Andrew, Bryan or Brad. A radically opaque concept, it seems, may fail to be opaque
in the initial sense; it may fail to be a fully opaque concept as we might say.9 It may be,
however, that a fully opaque concept will be radically opaque as well: if we grant that
being the property that Kev is thinking about is supposed to reveal nothing about the
referent property, then certainly it will reveal no essential or uniquely identifying
accidental property of it.
And this makes even clearer the fact that our initial, weak characterization of a
transparent concept—as simply a concept that reveals something (as opposed to nothing)
about its referent—is very weak indeed. It’s not just that strongly transparent concept and
translucent concepts are transparent in the weak sense. Mildly opaque concepts too are
weakly transparent since they reveal something about their referents, even though that
something is not anything essential; and some of the concepts that Goff ends up calling
radically opaque (the recognitional concept of Bob from his own example) will turn out
to be transparent in that very weak sense (it reveals that the referent is a person, or
someone Goff met at the party). One upshot is that the initial weak notion of transparency
may be much less interesting than it might have seemed at first. To draw that initial
contrast between weakly transparent and fully opaque concepts seemed to be getting at
something worthwhile; and claiming that a concept was transparent, as opposed to
opaque, seemed as though it was making a substantive claim about it, one that could have
interesting implications. But given how unusual it is to get oneself to think about a
9
The fact that when Goff does not use the concept of being a property that Kev is thinking about as an
example of a radically opaque concepts (and that despite the fact that he’s used that example earlier in the
paper) suggests that he thinks of radically opaque concepts as revealing something about their referents.
6
property without getting to know anything at all about it,10 it would seem that none of the
concepts we normally use will turn out to be fully opaque. If that’s right, to say that a
particular concept (of type of concept) is weakly transparent (i.e. not fully opaque) is
saying something much less substantive (and distinctive) about it11; and it is not obvious
what of interest the weak transparency of certain (kinds of) concepts can entail.
1.3. An alternative characterization
Diaz-Leon (2013) provides her own characterization of “what it means to say that a
concept reveals something (or everything) of what it is for an object to have the
corresponding property.” (2013, 12) Here is what she has to say:
(*) “A concept C reveals (something of) what it takes for C to be satisfied iff
possession of concept C enables the subject to know an application conditional of
the following form: ‘if x is P, then x is C’ (or ‘if x is C, then x is P’)” (12)
Notice, first, that this looks like Diaz-Leon is about to provide a characterization of weak
transparency (a concept reveals something of what it takes…). And it certainly is true that
(*) does not amount to strong transparency: possessing a translucent concept like being a
friend would satisfy (*) and enable the thinker to know an application conditional of the
form mentioned:
(1) If x is a friend, then x is a person.
In fact, Diaz-Leon is explicit about the fact that the notion she is hoping to capture is
really a “notion of transparency/translucency” combined (2013, 11).
But it is interesting that Diaz-Leon does not explicitly mention essential properties—and
in fact she worries (briefly) that (*) might “not rule out that a concept might be mildly
opaque, because even mildly opaque concepts such as ‘water’ can provide a priori access
to some contingent properties of water, such as ‘being watery stuff.’” (12, fn10) If that’s
10
It takes a game to get there in which we decide to rigidify descriptions like being the property Kev is
thinking about.
11
Claiming that all concepts are weakly transparent (that weak transparency is a condition for concept
possession) would be to say something very substantive indeed; but these are not the types of claims that
the metaphor is typically used to make. Those tend to be contrastive; that a concept is transparent is
supposed to be a noteworthy fact about it—one that makes it unlike other concepts.
7
right, (*) becomes a characterization that encompasses strong transparency, translucency
and mild opacity. And actually, things might look even worse for (*); after all, it seems
that Goff’s radically opaque recognitional concept of Bob does put him in the position to
know an application conditional of the form Diaz-Leon mentions. Goff can think, at the
very least
(3) If x is that guy, then x is a person.
And if that’s right, then a concept can meet the criteria described by (*) and still be
radically opaque. (*) would seem to collapse back into an account of weak transparency.
Of course, it isn’t difficult to modify (*) to avoid these implications: Diaz-Leon can
simply require that the application conditional provide us with an essential property of
C’s referent12; mildly and radically opaque concepts, which by definition do not reveal a
referent’s essential properties, would not satisfy (*) while strongly transparent and
translucent concepts would. I will now use (*) to refer to the modified version of DiazLeon’s condition; it really is a shortcut for talking about concepts that are
transparent/translucent (or non-opaque).
The discussion of (*) brings out two further interesting facts about our categories. First:
the fact that it seems possible for Goff’s radically opaque concept to satisfy (*) allows us
to notice something quite unexpected about that example. And that is the fact that though
Goff is unable to uniquely identify Bob the day after the party (by his own admission he
meets lots of guys at parties), his recognitional concept of Bob does in fact put him in the
position to know one essential property of his concept’s referent, namely that it’s a
person. And this would seem to suggest that despite what we may have thought, this is
not in fact a plausible example of a radically opaque concept; in fact it seems that this
concept cannot even be mildly opaque since mildly opaque concepts, by stipulation, do
not reveal any of their referents’ essential properties either. What looked like a radically
opaque concept seems most plausibly now translucent.
Diaz-Leon’s characterization of transparency/translucency makes clearer a second fact,
12
Diaz-Leon herself does not dismiss these worries by modifying (*). In the context in which she is using
(*), it does not matter (she claims) that mildly opaque concepts satisfy (*).
8
namely that a concept’s transparency/translucency does not gives us “some mysterious a
priori insight into the nature of reality.” (Goff 2011, 193) Merely possessing a
transparent/translucent concept does not entail anything about the ontology of our world,
and this is because we “do not know a priori whether this concept is satisfied.” (2011,
193) It may turn out, then, that nothing in the world actually has the essential properties
that our transparent/translucent concepts reveal to us; being a friend may satisfy (*), yet
that fact alone does not entail the ontological existence of people who are friends. The
insight that transparent/translucent provides is indeed conditional—it reveals to us merely
what essential properties the referent of the transparent concept would have, were it to be
satisfied, so that if any x at all is a friend, then we know that x is a person.
1.2. Conclusion
Where does this leave us? If anything, the discussion shows that the notions of
transparency and opacity are more slippery than we might want them to be. What initially
seems like a rather straightforward metaphor turns out to be quite difficult to nail down.
Our spectrum now includes strong transparency, translucency, mild opacity, radical
opacity, and full opacity. Weak transparency encompasses every category except for full
opacity. And (*) encompasses strong transparency and translucency. Now the question is
whether these notions can be put to interesting use.
2. The argument against a posteriori physicalism
As mentioned earlier, the transparency metaphor figures prominently in Goff’s argument
against a posteriori physicalism. The strong transparency or translucency of our
phenomenal concepts is claimed to have radical ontological implications: according to
Goff, the fact that phenomenal concepts are either strongly transparent or translucent is
incompatible with a posteriori physicalism. The argument is rather simple and can be
schematized as follows:
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1. Phenomenal concepts are either transparent or translucent.
2. If a posteriori physicalism is true, then phenomenal concepts are not either
transparent or translucent.
3. Therefore, a posteriori physicalism is not true.
My goal in this section is to examine this argument and argue against it. As we will see,
the discussion of this argument will raise still further questions about the distinctions we
drew in the first section; and its failure suggests that it’s not clear how useful
considerations about the transparency/translucency of phenomenal concepts actually turn
out to be.
2.1. Some preliminaries
For the purposes of this paper, I take phenomenal concepts to be, most minimally,
concepts that we token when we think introspectively about the phenomenology of our
experience qua phenomenal states or properties. The paradigmatic example of
phenomenal concepts are the ones the infamous Mary gets to token when she finally
leaves her black-and-white room and think “so that’s what it’s like to see
red/yellow/purple”: whichever constituent of her thought is the one she tokens based on
introspecting the phenomenal property of her red experience will be a phenomenal
concept.13 Of course, the thought is that we ordinary folk also get to token such
phenomenal concepts, when we think about the phenomenology of our pain, or of beer
tasting experiences, or of our feelings of anger or joy etc. I hope to leave aside here
questions about what other features these thought-constituents need to have in order to
count as full-fledged phenomenal concepts. Some have taken to deny that there are
phenomenal concepts, even when rather minimally construed (see Tye (2009); Ball
(2009)). But most minimally, for our purposes here, phenomenal concepts are simply the
constituents of our (Mary’s) beliefs about our own phenomenal experiences that pick out,
via introspection, the phenomenal properties of those experiences. And the claim here is
that these concepts (thought-constituents), whatever else may be true of them, are what
we are talking about; and it is their intuitive transparency or translucency that is supposed
13
This would count as a basic application of a phenomenal concept (see Balog 2009).
10
to be incompatible with a posteriori physicalism
2.1.The case for the transparency/translucency of phenomenal concepts.
The case for the transparency/translucency of phenomenal concepts is mostly driven by
intuition. According to Goff, “when I reflect carefully on the phenomenal concept of
pain, it seems to me that it is not opaque in this sense: at least something of what it is for
something to feel pain is knowable a priori.” (Goff 193) Later, again, he claims that we
have “significant armchair intuitions about our phenomenal concepts, i.e. that our concept
of the feeling of pain reveals something of what it is for something to feel pain.” (207
emphasis mine) And Diaz-Leon claims that what needs to be accounted for is “how
phenomenal concepts can reveal at least something of what it would take for the
corresponding phenomenal property to be instantiated.” (2013, 1, abstract, emphasis
mine)
Now the intuition as stated so far is not about strong transparency or even about
translucency; it looks merely like the intuition that phenomenal concepts are transparent
in the weak sense, that they reveal something about their referent. Of course the
charitable interpretation of these claims may require our adding ‘essential’ next to
‘something’, so that the point is really that our phenomenal concepts seem to reveal to us
something essential about their referents. And some writers are quite explicit that this is
what they find intuitive. Loar writes that phenomenal concepts’ relation to their referents
involves a “grasp of essence.” (1990, 305, emphasis mine) Balog thinks that “when one is
aware of a phenomenal state in the process of having it, something essential about it is
revealed, directly and incorrigibly – namely, what it is like to have it.” (2012, emphasis
mine) Nida-Rümelin, meanwhile, claims that phenomenal concepts allow us to grasp
phenomenal properties and that to “grasp a property is to understand what having that
property essentially consists in.” (2007, 307) So we can imagine a phenomenal concept,
say the concept C* that Mary tokens when she leaves her black-and-white room to pick
out the red phenomenal property P*. By possessing C* Mary is now in a position to know
something essential about what it would take for an experience to have property P*; it
would have to feel a particular way. Notice that putting it this way does not commit us to
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the claim that phenomenal concepts are strongly transparent—the claim that is not that
Mary is now in a position to know everything essential about what it would take for an
experience to have P*. But neither does it commit us to the claim that phenomenal
concepts are translucent—that Mary would be in a position to know something but not
everything about what it would take for an experience to have P*. Phenomenal concepts,
as far as the intuitions described here “reveal”, could turn out to be either.
Goff drives home the plausibility of claiming that phenomenal concepts are
transparent/translucent by pointing out that it rather counter-intuitive to think that the
concepts are opaque, either mildly, radically, or fully so. It is true, I take it, that we
wouldn’t want to say (as Goff nonetheless claims Papineau does) that phenomenal
concepts reveal nothing at all about their referents the way property that Kev is thinking
about revealed nothing at all about that property.14 We might not even want to claim that
phenomenal concepts are radically opaque; that they merely reveal to us some accidental
properties of our experience that wouldn’t yet allow us to uniquely identify their referent
properties. What then of the possibility that phenomenal concepts may be mildly opaque?
Goff dismisses it like this: “It is reasonably uncontroversial, for the reasons Kripke gives
in Naming and Necessity [1980: 144–55], that phenomenal concepts are not mildly
opaque.” (194) To deny that phenomenal concepts are mildly opaque by appealing to
Kripke’s argument seems to go beyond simple intuition, but Diaz-Leon is right that “most
advocates of a posteriori physicalism typically agree that phenomenal concepts are not
mildly opaque” (9, fn 6). So I will assume, for the time being, that our intuitions about
phenomenal concepts are strong enough, and that they indeed suggest that these concepts
are either transparent or translucent.
2.3. Implications for a posteriori physicalism
Why, then, think that the transparency/translucency of our phenomenal concepts entails
anything about a posteriori physicalism? A posteriori physicalism, after all, is a lovely
view—as Goff puts it, it “promises to give everything and take nothing” (2011, 191);
lovely indeed. It is a view according to which everything in the world is wholly
14
This is Goff’s argument against Papineau’s view and strikes me rather as evidence that Goff must have
gotten Papineau’s view wrong.
12
physical—including phenomenal properties—but according to which we nonetheless
have two distinct sets of concepts for thinking about these properties, either in terms of
what it’s like to have them (using phenomenal concepts) or in terms of their broadly
physical/functional structure (using physical/functional concepts).
Unfortunately the a posteriori physicalist, Goff claims, cannot possibly maintain that
phenomenal concepts are strongly transparent since strongly transparent concepts are
supposed to enable the person who thinks with them to know everything essential about
what it would take for something to fall under that concept. Now the a posteriori
physicalist may agree that phenomenal concept C* reveals something essential about its
referent property P*, namely what it feels like to have it; but she cannot claim that the
concept reveals everything because there is something else that the a posteriori
physicalist is committed to thinking is essential about the referent property of C*, namely
that it is identical with a particular physical/functional property. And so, the a posteriori
physicalist cannot possibly maintain that phenomenal concepts are transparent in the
strong sense.
Goff goes on to argue that it is impossible for the a posteriori physicalist to maintain that
phenomenal concepts are translucent as well. To say that phenomenal concepts are
translucent is to say that they reveal some of their referent’s essential properties but not
all. But to say that a phenomenal concept is translucent then would be to say that it
reveals to us one essential property of its referent (its essential feel), though the referent
in question turns out to have another essential property (its broadly physical structure).
And this, Goff notes, amounts to property dualism—the truth of which is
straightforwardly incompatible with a posteriori physicalism. And so a posteriori
physicalism is incompatible with our phenomenal concepts being either transparent or
translucent.
2.4. What translucent concepts reveal
The claim that a posteriori physicalism is incompatible with translucency seems to be
where things get a little tricky. To start with, it seems clear that the argument for the
incompatibility of a posteriori physicalism and the translucency of phenomenal concepts
13
goes by too quickly. The a posteriori physicalist would indeed never want to claim that a
phenomenal concept reveals one essential property (its feely one) of its referent even
though the referent turns out another essential property (its physical/functional one),
since according to the a posteriori physicalist these are one and the same property.
But that move won’t help, Goff thinks; because the a posteriori physicalist then seems
committed to claiming that a phenomenal concept, if translucent, would reveal
an aspect of that property. But, crucially, an aspect of a wholly physical state is
itself a physical state. Therefore, if the phenomenal concept of pain were
translucent, it would reveal that how pain feels involves a physical state (that
physical state being an aspect of the physical state which is the feeling of pain).
(Goff 2011, 197)
In other words, even if we grant that there is only one (ultimately physical) property, a
phenomenal concept like C*, if translucent, would put one in a position to know that in
order for something to fall C* it would have to be somehow physical.
But Goff, I now argue, misunderstands what translucency requires. To see why consider
the concept being H2O. This concept was used earlier as a plausible example of a strongly
transparent concept since possessing it plausibly reveals to us the (essential) fact that its
referent is something made up of two hydrogen atoms and one oxygen atom, period. To
use Diaz-Leon’s application conditional, possessing the concept being H2O puts someone
in a position to know
(4) If x is H2O, then x is made up of two hydrogen atoms and one oxygen atom.
But notice that the concept being H2O does not put us in a position to know further facts
about the properties found in the consequent of the conditional: the properties of being a
hydrogen atom and being an oxygen atom. After all, it may turn out that according to our
best ontology, the property of being made up of a hydrogen atom will be identical with
the property of being made up by a single positively charged proton and a single
negatively charged electron bound to the nucleus by the Culomb force, or with the
property of being made up of something with having atomic number 1. The essential
property revealed by the concept being H2O could then turn out to be identical with the
14
property of being made up of two objects with atomic number 1 and one object with
atomic number 8.
Now does the fact what it takes for an object to fall under the concept being H2O as stated
in (4) might be ontologically identical to the property just mentioned—and that the
concept being H2O does not put a thinker in a position to know that fact mean that the
concept being H2O was never strongly transparent in the first place? That it never truly
revealed everything essential about what it would take for an object to fall under the
concept? Notice that this raises more questions still about how to make sense of strong
transparency, but even if we assume that we now have reason to deny that the concept
being H2O is strongly transparent,15 it is hard to see how to deny that it is, at the very
least, translucent. The application conditional (4) reveals at the very least something
essential about what it takes for an object to be H2O; and the fact that it doesn’t put the
thinker in a position to know that its referent somehow involves protons or neutrons—i.e.
to token a (true) belief with the concepts being a proton or being a neutron as
constituents—does not make it any less translucent.
A posteriori physicalists can simply say the same about phenomenal concepts.16 Our
phenomenal conception of pain Cp reveals to us something essential about pain, namely
what it feels like to experience it (it feels painful). We can put this in the form of an
application conditional:
15
If considerations like these do lead us to deny that being H2O is strongly transparent, then it is not clear
that there will be very many (any) strongly transparent concepts—except perhaps for concepts of very
fundamental properties. If, on the other hand, we maintain that being H2O is still in an important sense
strongly transparent, then we might be able to say that phenomenal concepts are strongly transparent as
well. The fact that possessing Cp does not put us in a position to know that what it would take for
something to fall under Cp involves having certain physical/functional properties would not prevent C p from
counting as strongly transparent anymore than the fact that possessing being H2O does not put us in a
position to know that what it would take for something fall under it involves having a certain atomic
number or number of protons.
16
There may, of course, be important further differences between the two cases (the one involving being
H2O and Cp). So we can point out that the identity claim between the “two” properties in the H 2O case will
not leave on puzzling about how they could be identical, whether there is puzzlement galore when it comes
to identifying the “two” properties in the phenomenal case. But this is to point out that there is an
explanatory gap whose existence a posteriori physicalists ought to explain; and this is no longer about
transparency/translucency; and the goal here is merely to show an a posteriori physicalist could make sense
of how a phenomenal concept might be translucent not to account for the explanatory gap.
15
(5) If x is Cp, x feels painful.17
The fact that Cp does not put the person thinking with it in a position to know further
facts about the property mentioned in the consequent of this conditional—that the
property (feeling painful) is identical with a physical/functional property—need not make
it any less translucent. In other words, the fact that possessing Cp does not enable a
thinker to know that its referent involves physical/functional property—i.e. to token a
(true) belief with the concepts being physical or being functional as constituents—does
not make it any less translucent.
It may be that Goff was misled by the slipperiness of the word ‘reveal’. He says that “if
the phenomenal concept of pain were translucent, it would reveal that how pain feels
involves a physical state” (197). And there is a sense in which what he says sounds right,
since how pain feels just is a physical state, revealing something about how pain feels
will be revealing something about a physical state. The focus here, notice, is on the
property revealed. But the way we are supposed to spell out ‘reveal’ is in terms of what
possessing a concept puts thinkers in a position to know, namely in terms of a thinker’s
beliefs about the referent. The focus here then is on the concepts a thinker is enabled to
use to think about the property. Both phenomenal and physical concepts will reveal
something about a physical state, in that they both refer to a physical state; yet that is not
to say that the phenomenal concept will put the thinker who uses it in a position to know
or form a belief that the thing she is referring to is physical/functional—since forming a
belief like that would require being in a position to use the concepts being
17
Diaz-Leon worries that application conditionals like these are too trivial—and that if this is all a
phenomenal concept reveals about its referent, then one might object that it doesn’t truly count as revealing
anything. Diaz-Leon spends some time responding to this worry (2013, pgs 13-15), but the worry seems to
be more easily dismissed. First, if we all agree that phenomenal concepts are not fully opaque (that they are
not like the concept being the property Kev is thinking about), then phenomenal concepts will reveal
something no matter how hard it is to express what that is in a non-trivial way. Second, even dualists agree
that phenomenal concepts are (at the very least) translucent: that they reveal something essential about their
referents. So dualists too will have to claim that there should be application conditionals like (5). The
question can then be put to them: how would they express what phenomenal concepts reveal, if not by
using application conditionals like (5)? If (5) is deemed too trivial for C p to count as translucent, then it will
too trivial for Cp to be a translucent concept regardless of one’s metaphysical leanings—it will fail to be
translucent for dualists and a posteriori physicalists alike.
16
physical/functional.18
As far as I can tell, we have enough here to show that a posteriori physicalism is in fact
compatible with the translucency of phenomenal concepts. This is not to say that there
are no further worthwhile questions to ask about the ways in which a posteriori
physicalists appeal to phenomenal concepts, and the further assumptions they make about
these concepts.19 But at this juncture it does seem like there is any good reason to think
that the mere intuitive transparency/translucency of phenomenal concepts need pose any
problem for the a posteriori physicalism.
3. Conclusion
I had two main goals in the paper: to take examine at the notion(s) of transparency (and
related ones); and to evaluate Goff’s argument according to which the
transparency/translucency of phenomenal concepts was incompatible with a posteriori
physicalism. What the discussion suggests is, first, that it is rather difficult to get a clear
sense of what makes concept fall into our various categories; but second, and maybe
more importantly, that it’s clear that using the metaphor helps build a compelling
argument against a posteriori physicalism. Again, this is not to say that there are not
serious worries to have about a posteriori physicalism, but it may suggest that we would
better off focusing on them directly.
18
Diaz-Leon makes this point: that Goff’s reasoning is “conflating the distinction between concepts and
properties.” (2013, 5)
19
We may, for instance, wonder not merely how it is possible for phenomenal concepts to put us in the
position to know something essential about their referents, but how it possible for them to put us in the
position to know something essential and substantial/rich about the referent (for discussions of the
substantial nature of phenomenal knowledge see, for instance, Levine (2007), Levin (2007), Schroer
(2010)). It strikes me, at least at first glance, that these can possibly coming apart: Goff’s recognitional
concept (the one that picks out Bob, the guy he met at the party) does put him in a position to know
something essential about Bob (that he’s a person) but it’s not clear that it thereby puts him in a position to
know anything very substantial about Bob (remember that Goff had originally classified this concept as
radically opaque). Though of course this depends on what it takes to know something substantial.
17
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