Supervenience and OntologyAuthor(s): Daniel BonevacSource: American Philosophical Quarterly, Vol. 25, No. 1 (Jan., 1988), pp. 37-47Published by: University of Illinois Press on behalf of North American PhilosophicalPublicationsStable URL: http://www.jstor.org/stable/20014221Accessed: 03/05/2010 01:54
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American Philosophical Quarterly Volume 25, Number 1, January 1988
SUPERVENIENCE AND ONTOLOGY
Daniel Bonevac
TN matters of science and ontology, the logical -
-empiricists had their hearts in the right place, but were confused about the details. Or so much
current wisdom has it. We can say, with many
contemporary philosophers, that the empiricists were correct to emphasize the ontological unity of
science and the primacy of physics, but wrong to
rely on reduction as the only way to establish
intertheoretic relationships. We can sympathize with the physicalist impulses motivating construc
tionalist programs such as Carnap's without sanc?
tioning those particular means of construction.
Indeed, we can easily yearn to keep the logical
empiricists' ontologically parsimonious conclu?
sions without committing ourselves to the drudgery of outlining the logical structure of the world. But
how?
Supervenience seems to provide an ideal answer.
The concept of supervenience relates closely to our
ordinary idea of dependence. Indeed, its advocates
take supervenience to be a precise expression of
our intuitive notions of dependence and determin?
ation.1 Generally, one realm?of properties, facts, events, sentences, or models?supervenes on
another just in case the latter determines the former;
just in case, that is, the constitution of the former
realm is a function of the constitution of the latter.
Sociology supervenes on psychology, for example, if the psychological facts, taken together, determine
the sociological facts. And our ordinary macro
level discourse supervenes on microphysics if
macro-level circumstances depend on, or are func?
tions of, microphysical circumstances. Superveni? ence thus gives us a way to explicate the primacy of physics and the unity of science. We can say that all the sciences supervene, ultimately, on
physics. That is to say, the physical facts determine
all scientific facts. Or, as Geoffrey Hellman and
Frank Thompson put it in their principle of the
physical determination of truths,". . . all the truths
stateable in the language of mathematical physics
fix all the truths stateable in any language whatsoever."2 Without completing a single reduc?
tion, then, we can advocate a thoroughgoing
physicalism that seems immune to the objections that have plagued "type-" and "token-" identity theories.
In this paper I will try to shed some light on the
legitimacy of the hope for an ontological but non
reductionist unity of science. As it stands, super? venience is rather vague; as I'll point out in a
moment, however, there is no shortage of more
determinate formulations. But most of these formu?
lations, construed ontologically, seem to resist
logical?i. e., model-theoretic?analysis. They face, I'll argue, some serious problems. The first is a dilemma, the "supervenience dilemma," which
confronts the advocate of the ontological utility of
supervenience with a choice between a notion that in fact lacks ontological significance, bearing little
relation to the intuitive arguments and ontological intuitions used to support it, and a notion incapable of interpreting the relevant discourses in reasonable
ways. The second is epistemological. Suppose that economics supervenes on physics. Why? How?
What is the nature of the dependence relation? How could we possibly be in a position to establish it? This puzzle pertains to many accounts of super? venience.3 In this paper I'll formulate an account of supervenience solving these problems. In the
end, I shall argue, supervenience, though not equi? valent to reduction, does rely on reduction in the sense that we should analyze it in terms of re?
duction. If this is correct, then the ontological appli? cations of the two notions stand or fall together.
Supervenience does not allow us to achieve the
logical empiricists' ontic aims without doing some
hard reductive work.
I
Donald Davidson characterizes the superveni? ence of the mental on the physical by saying that
37
38 AMERICAN PHILOSOPHICAL QUARTERLY
"... there cannot be two events exactly alike in
all physical respects but differing in some mental
respect," or, equivalently, "that an object cannot
alter in some mental respect without altering in
some physical respect."4 Jaegwon Kim similarly calls one family of properties "supervenient" on
another such family when "two things alike with
respect to the second must be alike with respect to
the first."5 More explicitly, Kim writes, "A family of properties M is supervenient upon a family of
properties N with respect to a domain D just in case for any two objects in the domain D if they
diverge in the family M then necessarily they
diverge in the family N; that is to say, for any x
and y in D if x and y are indiscernible with respect to the properties in the family N, then necessarily
x and y are indiscernible with respect to the prop? erties in M."6 John Haugeland calls two possible
worlds discernible with a language L if some sen?
tence of L is true in only one of the worlds, and
stipulates, where K and L are languages and W is
a set of worlds, that "K weakly supervenes on L
(relative to W) just in case any two worlds in W
discernible with K are discernible with L."7 Finally, Paul Teller articulates a useful general schema, of
which each of the above is an instance: 'Truths of kind S supervene upon/are determined by truths of kind P if and only if any two cases which agree as
to truths of kind P also agree as to truths of kind
S."8 All these accounts fit the pattern:
F supervenes on G, relative to D, iff VxVy eD(x =Gy -> x =Fy).
Though these characterizations of supervenience have much in common, there are also striking differences. Davidson speaks of events being alike
or unlike in various "respects"; Kim speaks of
things being indiscernible or diverging in a family of properties. Haugeland thinks in terms of worlds
discernible or indiscernible with languages, and
Teller, generalizing, thinks in terms of "cases"
agreeing or disagreeing "as to truths."
I assume that an adequate account of superveni? ence should admit of logical, specifically model
theoretic, analysis. I want to characterize a concept that is clear and precise enough to be logically useful. By this criterion, "respects," "events,"
"facts," and even "truths" do not fare very well.
Suppose, for example, that we adopt a type-free semantics for truth, nominalization or attitudes such as knowledge and belief.9 We might begin with a
partial structure M0 for some unproblematic portion of the language, and then apply a function F which
augments and revises M0. We continue applying F
until, at some transfinite ordinal 7, we reach a
fixed point: F(My) = My. Such a construction
tempts us to ask philosophical questions. Under what circumstances might truth in our entire lan?
guage supervene on truth in that portion not con?
taining the predicate true? Under what cir? cumstances might truths about abstract entities
supervene on truths about concrete entities? Under
what circumstances would "higher-order" attitude attributions supervene on "first-order" attributions?
It's hard to see how we could even begin to answer
these questions without significantly sharpening our analysis of supervenience.
Clearly, to devise a logically workable notion
of supervenience, it is necessary to make some
decisions. First, supervenience is a dyadic relation, but on what set? What constitutes the relation's
field? In terms of the above schema, what appro?
priate values for'F' and 'G'? "Respects"? Sets of
properties? Languages? "Truths"? Facts? Second,
saying that one realm supervenes on another amounts to saying that the first is a function of the
second; whenever the arguments are identical, the
values will be identical. Or, more accurately in this
context, whenever the arguments are indiscernible
in a given respect, the values will be too. But what are the relevant arguments and values? That is, what are appropriate values for V and y in the
schema? For the sake of convenience, I'll refer to
these arguments and values as "points." So we can
ask: what are supervenience's points? Events?
Things? Worlds? "Cases"? It is not obvious that
any general schema that can cover all these options will retain much content. Third, do we need a par? ameter such as 75'?
We can perhaps look to approaches to reduction
for help, since reduction should be a particular kind
of supervenience relationship. Reduction, most
naturally, relates two theories, we can construe
theories, in turn, as sets of sentences in some par? ticular language that are closed under logical con?
sequence, or, more generally, as classes of models
SUPERVENIENCE AND ONTOLOGY 39
of some particular similarity types. Taken either
way, the concept of a theory is exact enough to
admit logical analysis. I shall understand superveni? ence, therefore, as a relation between theories. This
is very close to Teller's answer, "Truths," to the
intuitive answer, "Facts," and, for reasons that will soon become clear, to Haugeland's answer, "Lan?
guages." Certainly it is the answer most applicable to the ontological issues concerning type-free lan?
guages discussed a moment ago. Usually, I will
talk about first-order theories, though much of what
follows applies more generally.
Thinking of theories as supervenience's relata
may seem to obscure or even run afoul of an impor? tant distinction. We can speak of particular theories, perhaps, as standing in supervenience relations. Thus, we might say that Mendelian gene? tics supervenes on contemporary biochemistry, or
that Freudian psychology supervens on a
behavioristic theory of op?rant conditioning, which
in turn supervenes on contemporary neurophysiol ogy. We might call these assertions of name-brand
supervenience.10 Theories clearly constitute the
field of name-brand supervenience. Most assertions of supervenience, however, have
a sharply different character. We may say that the
mental supervenes on the physical, that chemistry supervenes on physics, or that psychology super? venes on neurophysiology, without having any spe? cific theories of these realms in mind. I'll refer to these as assertions of generic supervenience. By definition, they concern not particular sets of state?
ments but entire realms of discourse. It may seem most natural to represent generic supervenience claims as relating, not theories, but languages.
I maintain, however, that even generic super? venience relates theories, considered abstractly as
model classes. If we say that chemistry supervenes on physics, for example, we mean that the physical facts, taken together, determine the chemical facts.
We can paraphrase this as saying that what is true
in the language of physics determines what is true in the language of chemistry. But I think we should
understand this in turn as asserting that the reali? zation of any possible physical state of affairs
uniquely determines the realization of a possible chemical state of affairs. If so, then the appropriate relata are collections of possible states of affairs
of certain kinds. The formal representation of a
possible state of affairs is a model structure. Even
in cases of generic supervenience, therefore, we
can think of classes of models as constituting the
field of the relation.
Indeed, a conception of supervenience as relating classes of structures includes a conception relating
languages as a special case. To say that chemistry supervenes on physics is to say, in my view, that
there is a functional relation between physically
possible physical structures and physically possible chemical structures. The classes of models being related are the class of physically possible structures
of some language for physics and the class of phys?
ically possible structures of a language for chemis?
try. But my account requires only that the relata
be classes of model structures. If we think of the
classes being related as classes of all logically pos? sible structures of certain kinds, we are thinking of supervenience as holding between languages, since we can identify a language with the class of all structures of a given similarity type.
If supervenience is a functional relation between
theories, then what are the appropriate arguments and values of the function? What are the appropriate
"points?" I think Haugeland and Teller are on the
right track here: worlds, or "cases," seem to reflect the modality in our intuitive sense that if, for exam?
ple, the biological supervenes on the physical, then
the world could not differ biologically without also
differing physically. Nevertheless, worlds them? selves lack explicit logical or mathematical struc? ture. The most straightforward formal representa? tion of a world, of course, is a model structure.
Consequently, I shall let model structures serve as
the points in the definition of supervenience. So far, then, we have something like this: a
theory 71 supervenes on a theory 72 if and only if any two model structures that are 71 -discernible are also 72-discernible:
71 supervenes on 72 iff, for any model structures M and M', M =T2 1 M' -> M =71 1 M'.
This sounds promising. In fact, however, this brief
provisional definition raises more questions than it answers. If we make language parameters explicit, this becomes obvious. A theory 71, in language
LI, supervenes on a theory 72, in L2, just in case
40 AMERICAN PHILOSOPHICAL QUARTERLY
any two models (in what similarity type?) that are
71-discernible are also 72-discernible. It is not clear
what class of models we should be considering here. Nor is it obvious what 7-discernibility, the
discernibility of models with respect to a theory, can mean. If the models and the theory occupy the same similarity type, then explicating this notion seems simple enough, following Haugeland's lead:
two models can be discernible with respect to 7
only if some sentence in 7's language is true in
only one of the models. If the models and the theory
occupy different similarity types, however, this makes no sense.
II
Hellman and Thompson have proposed an
analysis purporting to solve this problem. Recall
that Haugeland, speaking of worlds rather than
models, says that two worlds are discernible with
language L if some sentence of L is true in only one of the worlds. L-indiscernible worlds agree on
the sentences of L; they are elementarily equivalent on L. Hellman and Thompson too use elementary
equivalence to explicate indiscernibility. But, as
I've indicated in the last section, a serious problem remains: we need to make sense of the notion of
models, in some similarity type, being elementarily
equivalent relative to another, perhaps completely
disjoint, language. Hellman and Thompson take the class of relevant
models as a subset of the models in a similarity
type large enough to include the types of the
theories involved. The problem then reduces to that
of understanding elementary equivalence relative
to a sublanguage. But this amounts to the elemen?
tary equivalence of their reducts to the sublanguage. Hellman and Thompson's account, however,
doesn't solve the problem I've mentioned in a very
satisfying way when the domains of the theories
concerned differ. To see how serious this problem is, we need to consider some metaphysical intui?
tions underlying appeals to supervenience.
Thinking as materialists, we might naturally tend
to take the language of physics as basic, as "carving
reality at its joints." We think of reality as intrin?
sically partitioned into physically characterizable
units. The same reality, of course, can be recarved
along other lines; the same essentially physical material, however, is being recarved. So it seems
reasonable to identify models as those of the lan?
guage of physics which also interpret some addi?
tional vocabulary. The metaphor of carving seems important to any
ontological conception of supervenience. Two
theories linked by supervenience carve the world
in different ways. Without committing ourselves to the fundamental character of either mode of indi
viduation, we can compare the modes, finding one
less fundamental, perhaps even parasitic, on
another. But neither theory need give us any
ontological insight into the way the world is; neither
needs to "carve reality at its joints." To quote
Haugeland:
[T]he individuals, or "tokens," of which our sentences are true are just as "relative" to the level of description as are the kinds or "types" into which those sentences sort them. The world does not come metaphysically individuated, any more than it comes metaphysically categorized, prior to and independent of any specific description resources . . .
(p. 101).
Thus, in general, we should think of the theories
involved as imposing their own ideology and
ontology on the world. Supervenience relates two
ways of individuating the world. As Robert Kraut
points out, "the intuitive picture we get is that there
is some kind of neutral material ("the world") which serves as a model of both 71 and 72" (p. 24). It
appears, then, that we want the models of our def?
inition to be neutral, in some way, between the
languages of 71 and 72. The obvious way to
accomplish this is to let those models occupy a
different, disjoint similarity type. This brings us back to our problem: how can we
interpret the theories at hand in these models? We
have to give them a determinate similarity type, but we must then examine them for elementary
equivalence relative to totally different similarity
types. This problem is not an artifact of dealing with supervenience model-theoretically; it arises on any account. To phrase it in terms of possible worlds: we think of the worlds as made up of neutral
stuff, but yet as determining truth values of sen?
tences in some particular languages. How is this
possible?
SUPERVENIENCE AND ONTOLOGY 41
One conceivable solution is tie one or both lan?
guages down to the structure of reality, either by
sanctioning one of them with ontological perspicac?
ity, or by introducing abstract entities?properties,
propositions, facts or whatever?for the languages to share.111 don't believe that accounts employing abstract entities for this purpose can succeed, for
Quinean reasons, but the point is too large to argue here.
I will argue, however, that endowing one of the
theories with ontological perspicacity yields too
narrow an account. It need not be the case that one
of the theories in the supervenience relation is fun?
damental in the way physics is. Suppose that we
are interested in the supervenience of sociology on
psychology, or of biology on chemistry, or, more
acutely, of economics on biology, or political sci?
ence on chemistry. In these cases it seems peculiar to say that the supervening science is simply carving
differently the essentially psychological or chem?
ical material. The problem here afflicts, not the
"carving" metaphor, but the idea that the "base"
theory or language is always, or even most often, to be taken as characterizing the basic material
which is being carved. It seems far more natural
to say that political science and chemistry both
carve the physical material, but differently, and
that the individuation chemistry offers is in some
sense more fundamental than that offered by polit? ical science. Thus, the general case of superveni? ence involves two theories or languages that carve
reality differently; the reality itself may be indi?
viduated intrinsically into the units of one of these, but it need not be. Typically, then, we can expect that the underlying reality is carved in some third
way or, perhaps, is not intrinsically carved at all.
Thus, we sometimes need to view the relevant
models as constructed from a similarity type dis?
joint from those of 71 and 72.
The carving metaphor underlying many appeals to supervenience clashes with some standard for?
mulations. Take the case of the supervenience of the mental on the physical. Hellman and
Thompson, in effect, delimit the relevant models as those which have both mental and physical vocabulary.12 But what can we say about the domains of these models? If they have two disjoint subdomains?the mental and the physical?then,
as Kraut points out, this violates the intuition "that
it is somehow the same world which is getting "carved up" differently by the two theories or lan?
guages" (p. 25). It also undermines an ontological
interpretation of supervenience. But it is not clear what the domains of the models
can look like. Either the union of the theories con?
cerned contains some unrestrictedly universally
quantified sentences or not. Suppose that it does.
Within the language of relativistic mechanics, for
example, we say things like
P = NV.
(That is, momentum is the product of inertial mass
and velocity.) This disguises a quantification over
point-masses or particles and times (or perhaps
points of space-time), so that it may be formulated more perspicuously as an unrestricted universal
quantification:
VxVt[P(x,t) =
N(x,t)V(x,t)].
Let's say that this is one of the physical truths on
which the physical reducts of our models agree. The reducts limit the original models to the vocab?
ulary of physics, but they retain the same domains.
So the models can count this sentence true only by
holding that everything in the domain satisfies the above relationship between momentum, inertial
mass and velocity. If our mental theory, however, concerns thoughts, beliefs, desires, and the like, then we seem to be committed to the intelligibility of speaking of the mass of thoughts, the velocity of desires, and so on. To avoid this, we must appa? rently exclude mental episodes from the domain.
But then it is hard to see how the model can interpret sentences that seem to be talking about mental
entities; perhaps the models will agree on the mental
vocabulary largely by making at least existential
assertions in that vocabulary false. To identify mental entities with physical entities, of course, would be to lose the purported advantages of super? venience over type- and token-identity theories.
To generalize the argument: suppose that Ml =
<D\, cpl> is a model of 71 andM2 = <D2, <p2>
is a model of 72. For the sake of simplicity, suppose that D\ and D2 are disjoint, as are the languages to 71 and 72. How can we find an appropriate
model M* = <D*, cp*> for 71 U 72? Hellman
42 AMERICAN PHILOSOPHICAL QUARTERLY
and Thompson restrict M* to the language of 71
and to the language of 72. Both restrictions have
domain D*. If 72, say, contains an unrestrictedly
universally quantified sentence, then we face a
problem. If we take D* to be Dl U D2, then some
universally quantified sentences may be false on
D* even though they are true on D2. So it might turn out that neither M* nor its restriction to the
language of 72 are models of 72. If we take D*
to be D2, then the universally quantified sentences
come out right. But the existentially quantified sen?
tences of 71, assuming there are such, can be saved
only by invoking type- or token-identities or,
perhaps, by artificial adjustments in 9*. Assuming that we are happy neither with artificialities nor
with identities, M* and its restriction to 71's lan?
guage may not be models of 71. Choosing sets
between D2 and D\ U D2, or otherwise related to
those sets, generates some combination of these
difficulties. So suppose, finally, that we take ?)*
to consist of neutral material; let D* be disjoint from both D\ and D2. Then, without identities, how can we evaluate sentences of 71 or 72 in M * ?
We might be able to escape this dilemma by
relativizing quantifiers, and treating the physical
theory as implicitly limited to a physical domain, and the mental theory as limited similarly. One
might even argue that all quantifiers are restricted
and, so, that this relativization is automatic. But
this separates the two domains, engendering the
difficulties I mentioned a moment ago. D* will
include two subsets that act as domains for 71 and
72; the ontology of M* will thus include those of
Ml andM2. Hellman and Thompson's formulation,
then, gives rise to a dilemma, which I'll call "the
supervenience dilemma." Either the models contain
disjoint domains, in which case the "carving"
metaphor makes no sense and the ontological interest of supervenience is limited, or the models
cannot simultaneously interpret the two vocabu?
laries in a reasonable way. We might avoid this problem by taking an Aris?
totelian approach to the relation of the mental to
the physical, denying that the domains of the
theories concerned are distinct. But the dilemma
will confront us every time the theories concerned
seem to have disjoint or even very different
domains. If we want to maintain that facts about
social institutions, for example, supervene on facts
about individuals, the domains of the theories
involved will be different: one will contain persons and perhaps things, while the other will contain
nations, corporations, universities, etc.13 The
nominalist may want to maintain that truths about
abstract entities supervene on truths about concreta.
Our ordinary discourse about macroscopic objects has as its domain the objects of our experience, such as tables and chairs, "cabbages and kings," but the domain of microphysics consists of elemen?
tary particles.
Ill
I don't want to deny that one can formulate a
precise definition of supervenience. Surely one
could say that a relation R between two classes of
models 71 and 72 is a supervenience relation from 71 to 72 just in case (1) if R(M\, M) and R(MV,
M) then Ml = Ml '
(any two manifestations of the
same base structure are elementarily equivalent);
(2) 72 CR[Tl] (every model of 72 is related to some model of 71); and (3) R respects the structures
of the theories in a weak sense?that is, R is pre? served under ultrapowers.14 It follows from the def?
inition that, if M2 s M2', R(M\, M2) and R(M\ ',
M2'), then Ml = Ml'. Thus, elementarily equiva? lent models of 72 relate to elementarily equivalent
models of 71. States of affairs that are indiscernible
in the language of 72 are also indiscernible in the
language of 71. This account is extremely general. Nothing here captures the carving metaphor, but
at least nothing conflicts with it. One could supple? ment this account with a rationale for attributing
ontological significance to such a relationship.
Alternatively, one could say that supervenience is
purely a determination relation, without any inherent ontological significance.15
Such approaches, however, do nothing to
illumine the epistemology of supervenience. They say nothing about the nature of the dependence relation or the possible sources of evidence for it.
This difficulty, too, assails analyses such as that
of Hellman and Thompson. On their account, two
theories or languages have a potentially interesting relation over some class of models a. But whether
the relation is actually interesting seems to depend
SUPERVENIENCE AND ONTOLOGY 43
on a. Hellman and Thompson provide no way of
developing or analyzing an appropriate class. Even
if the formal relationship holds, therefore, it is
extremely difficult to interpret. The formulation
appears to make Horgan's problems of "cosmic
hermeneutics" unsolvable.16 To put this another
way, Hellman and Thompson give us a way to
determine when one realm supervenes on another, relative to a domain parameter a. We would like to know when one domain supervenes on another,
simpliciter. Quantifying over the classes of models
makes no sense, so it appears that we can derive the conclusions we want only if we can pick out
the appropriate value of the parameter. But nothing in the account indicates how we can do this.
Under what sort of circumstances could we
accumulate evidence for, and eventually establish, a supervenience relation? Suppose that you, as a
jungle linguist, encounter a tribe that uses two com?
pletely different languages: one during the day, and
another at night. These languages share a logical vocabulary, but have disjoint nonlogical vocabu?
laries and disjoint ontologies. You, initially, speak neither language. After some investigation, you
begin to believe that the natives use the night lan?
guage strictly for recounting the day's events and,
occasionally, for telling stories about the activities of days gone by. It is a language of recollection.
Thus, you decide that what counts as true in the
night language depends on what is true, or has been
true, in the day language. In short, you decide that the night theory?the set of sentences the natives are willing to assert in the night language?super? venes on the day theory. How can you come to
that hypothesis? First, you must be able to learn the languages
in question, translating, at least initially, into your native language. This of course requires two trans?
lation manuals: one for the day language, another for the night language. Then, you must compare the translations of the theses the natives are willing to advance in these languages. Your idea that truth in the night language stems from truth in the day
language results from your observation that the translations of assertions the natives make in the
night language follow from the translations of asser? tions they make in the day language. If we can think of the natives as articulating two theories,
closed under logical consequence, then your con?
jecture amounts to the hypothesis that the image of the night theory under translation into your lan?
guage is a subset of the image of the day theory. To draw any conclusions regarding superveni?
ence, of course, you must understand what the day and night languages mean. You accomplish this by
way of translation into your own language. In trans?
lating, you try to carry truths into truths to whatever extent possible. Additionally, your translation will
generally try to preserve logical structure. As a
result, in translating the night and day theories,
you are constructing reductions of these theories? or closely related theories, linked to them through error correction, approximation, etc.?into your own theory, the set of sentences you are willing to
advocate. You explain what the objects of the night and day languages are by reducing those objects to the entities of your language. Interpretation in
the intuitive sense, as Quine has stressed, is
interpretation in the technical sense. To say what the objects of a theory are is to reduce that theory to some other.17
In making your translations, then, you are giving an account of the natives' ontology, learning that, so interpreted, the ontology of the day theory includes the ontology of the night theory. You thus find your supervenience hypothesis ontologically
interesting. If true, it means that, relative to your
interpretation, the night language has no indepen? dent ontology. The entities to which the night theory commits its advocates amount to a subset of the entities to which the day theory commits its advocates.
Nevertheless, the situation will not look this way to the natives. From their perspective, the night and day languages are irreducible; they are as dif? ferent as, well, night and day. Moreover, they seem
to be making ontological commitments to two
totally different domains of objects. From your per?
spective, of course, this is because the two lan?
guages carve up the universe in different ways. One language, perhaps, seems on its own terms to
speak about ordinary things and their properties, while the other seems to speak of forces, energies, and events. The metaphor of carving manifests itself in your translation of the natives' individua tion apparatus. What they consider identity, you
44 AMERICAN PHILOSOPHICAL QUARTERLY
may count as mere qualitative similarity, so that
what the natives count as a single object may
become, in your eyes, a multiplicity. As Quine warns, a language's scheme of indi
viduation?its identity predicate and quantifica tional apparatus?suffers from indeterminacy. As
the scheme of individuation goes, so goes the ontol?
ogy; you can impute an ontology to the natives
only relative to your own linguistic resources. You
do this by fixing the natives' quantificational
apparatus relative to your own language. In the
process, the apparent identity predicates of the night and day languages become weaker equivalence relations?in fact relative identity relations?under
your translation.18 From your perspective, the
native languages describe the same reality, but
using different?in fact weaker?discriminative
resources.
The story I've been telling, I maintain, sheds
considerable light on the nature of supervenience as an ontological relationship. But the parable fails
to conform to the general picture in a few respects. Kraut charges that, in translating the native identity
predicates as relative identity predicates, you have
distorted the character of the natives' discourse (p.
30). And, indeed, it would be silly to ascribe to
the natives a discriminative ability that they in fact
lack. To return to our political science/chemistry
example for a moment, the ontology of political science would seem to consist of nations, voting blocs, persons, etc., while that of chemistry includes liquids, molecules, and ions. From the
perspective of physics, these are derivative entities,
composed in various ways of elementary physical
particles. But the political scientist does not distin?
guish between two voting blocs?say, Texas
Republicans today and tomorrow?that have the
same dispositions, interests, strength, and so on,
simply because they consist of different elementary
particles. Thus it would be absurd to claim that the
ontology of political science consists of elementary
particles. Similarly, it is absurd to claim that the
natives' ontologies are captured in the translations.
We can also object that the story succeeds only because your discriminative capacities are stronger than the natives'. If we were dealing with natural
languages, this would be unlikely. Worse, the
notion of supervenience merits interest partly
because it seems to salvage the ontological unity of science. But, if we take the background language of the jungle linguist to be a natural language such as English, we will quickly find that the discrimina?
tive capabilities of the special sciences far outstrip those of the jungle linguist. Moreover, if we do
try to interpret the theories involved in superveni? ence in such a background language, we will prob?
ably make no progress. If it were clear to us in
English that what we have to say about the mental
is simply a subset of what we have to say about
the physical, then the problems that make super? venience seem so attractive an idea would never
have arisen.
These objections point out that the jungle linguist
story fails to illumine an important dimension of
supervenience. The language we have in mind as
a background language is not a natural language such as English. In most of the examples I've dis?
cussed, it has been the language of physics. But
current physical theory remains plainly inadequate for the role. What we seem to want is the language of the ultimate physics. This language, by defini?
tion, would have at least the discriminative power of our current scientific theories. Furthermore, in
translating our current theories into this language, we might not be reflecting our own current
ontologies faithfully, but we would be interpreting those ontologies with an eye toward the relations
that actually obtain between realms we had thought
unbridgeable. The Peircean anti-realist can thus
think of the proper background language as the
language of the (or at least an) ideal scientific com?
munity; the realist can think of it as the language of God, which mirrors precisely the structure of
the universe.
So far I have allowed this portrait of superveni? ence to remain informal. To make it more precise, recall that we have yet to settle fully the questions of (1) the points of the supervenience relation and
(2) its parameters. The points will be models in
the similarity type of our background language; there will be a single parameter, which restricts
consideration to those models of the background
language satisfying the background theory. The
link between the models of the background theory and the languages of the theories standing in a
supervenience relation will be reduction, that is,
SUPERVENIENCE AND ONTOLOGY 45
interpretation. Finally, talk of indiscernibility
fades, since the interpretations of the theories will
occupy the same background language; it has been
incorporated into the notion of interpretation. My
characterization, then, becomes:
71 supervenes on 72 relative to a background theory 7 iff there are translation functions / and g such that
(1)/interprets 71 in 7, (2) g interprets 72 in 7, and
(3) the image of 71 under /is a subset of the image of 72 under g. (Symbolically, 71 supervenes on 72
relative to 7 iff there are functions / and g such that
(1) 71 *sf 7, (2) 72 ^g 7, and (3)/[71] ? g[72].)19
IV
At first glance, this characterization is startling. Gone are references to indiscernibility and elemen?
tary equivalence. Gone is the modality that Kim
builds in explicitly and that lurks in Haugeland's
quantification over worlds and Hellman and
Thompson's quantification over models.
Moreover, the concept of reduction has invaded
the definition. Basically, the definition says that
71 supervenes on 72 just in case we will eventually be able to construct a reduction of both to an ideal
theory; the part of that theory we will need for the
reduction of 71 is smaller than the part we will
need for 72. This will hardly reassure those seeking a nonreductive but ontologically meaningful
relationship. But this characterization has most of the proper?
ties that supervenience has been alleged to have.
Before arguing for this claim in detail, I want to
make one minor revision to the above definition.
It is clear from the literature that supervenience is
a partial ordering. Any realm should of course
supervene on itself; once you have fixed the facts
of some kind, you have fixed them. Correspond?
ingly, my definition indicates that every theory
supervenes on itself, relative to any theory in which
it can be interpreted. But supervenience should also
be transitive. If we think of scientific disciplines or, more generally, of kinds of discourse as ordered
ontologically, with physics at the bottom, and each
discipline or discourse supervenient on those below
it, then the primacy of physics follows only if super? venience is transitive.
Clues of assumed transitivity are the words "ul?
timately" and "in principle," as in this passage from
Horgan:
[A]ll characteristics of individuals in our world, and not just mental characteristics, are strongly dependent upon physico-chemical characteristics, and ultimately upon microphysical characteristics.20
To say that a discipline, say, economics, super? venes ultimately on microphysics is to say that
there is a chain of disciplines such that economics
supervenes on the first, the first supervenes on the
second, and so on, and the nth supervenes on micro
physics. But this implies that economics itself
supervenes on microphysics just in case superveni? ence is transitive.
Unfortunately, as I've developed the notion thus
far, supervenience is not transitive. If 71 super? venes on 72, and 72 on 73, then there are interpre? tations of 71 and 72 in the background theory with
the right properties, and also interpretations of 72
and 73. But this does not guarantee a link between
71 and 73, since 72 may receive two very different
interpretations. Economics may supervene on
psychology when we interpret psychology
physicalistically in one way, and psychology may
supervene on biochemistry when we interpret it in
another. Our fable had us interpreting the theories
concerned all at once in terms of our background
language, but the definition as it stands makes no
such requirement. I shall therefore expand the definition to that of
a supervening series of theories:
71, . . . , Tn form a supervening series relative to 7
just in case there are interpretations/l, . . .
,fn inter?
preting 71, . . . , Tn, respectively, in 7 in such a way
that/l[71]?/2[72]? . . . Cfa[Tn].
We could now express Horgan's thesis as the
claim that every discourse occupies a supervening chain that terminates with microphysics. Further, it is now clear that, if 71, . . . , Tn form a super?
vening chain, so do 71 and Tn alone. We thus
maintain the intuition behind the transitivity
requirement. On the other hand, we cannot always combine
two chains 71, . . . , Tm and Tm, . . . , Tn to get
a new chain 71, . . . , Tn; the chains may hold
46 AMERICAN PHILOSOPHICAL QUARTERLY
only by virtue of two very different interpretations of Tm. Intuitively, this seems plausible.
Our amended definition, I contend, has all the
characteristics that its advocates have wanted super? venience to have. Kim regards supervenience as a
"natural generalization" of the concept of reduc?
tion.21 Indeed, he takes care to show that, on his
account, reduction entails supervenience.22 Super? venience, as I've defined it above, does generalize the concept of reduction; 71 reduces to 72 just in
case 71 is supervenient on 72 relative to 72 (or any
supertheory of 72). In general, however, super? venience does not entail reducibility. To see this, let 71 and 72 be Haugeland's loop and arrow
theories.
My definition also makes sense of talk of indis?
cernibility: if objects are indiscernible in 72's lang?
uage, they can't diverge in the language of 71,
assuming that they belong to the domain of that
language at all. This additional condition, far from
being a shortcoming, makes intuitive sense. Kim, for instance, talks about two people in precisely the
same physical state also being in the same mental
state. But, supposing that only sentient beings are
in the domain of the mental state theory, what are
we to say about two electrons in the same physical state? My characterization refrains from forcing us
to assign them the same or, indeed, any mental
state.
The definition also makes it clear that fixing the
72 facts fixes the 71 facts: every model of the image of 72 is a model of the image of 71. This not only
explicates talk of determination and indiscernibility across possible worlds but makes clear a sense in
which those notions are too weak. After all, the
advocate of the ontological significance of super
venience wants to claim not merely that the phys? ical determines the mental, say, but that the phys? ical is all that there is; the mental, in the end, is
just the physical. That is what my characterization
yields: a model of the physical, thoroughly under?
stood, would be a model of the mental. Viewed in
the light of an ideal theory, or, if you prefer, in the
light of reality, the ontology of the supervening
theory is subsumed in the ontology of the base
theory.
My argument suggests that supervenience can
play the purely negative role of defeating anti
materialist arguments based on type- and token
identities. They can even stand in supervenience relations in my sense without type- or token
identities. The use of relative identity relations
means that we do not need token identities; the
entities in the domains of 71 and 72 may not appear at all as individuals in the domain of 7. And, since
supervenience is weaker than reduction, we don't
need type-identities either. The concept of super? venience thus accomplishes what many of its
materialist advocates have claimed.
To play any positive ontological role, however,
supervenience must rely on reduction. If we view
the background theory as an advanced or ideal state
of the supervenience base theory, then we can say that supervenience, construed ontologically, is
simply reducibility in the long run. If we are physi calists, we would naturally construe both the base
theory and the ideal background theory as the ulti?
mate physics. In that case, however, supervenience on physics and reducibility to physics are equiva? lent. One cannot establish physicalism as a positive thesis by anything less than reduction.
The University of Texas
Received April 15, 1987
NOTES
1. Jaegwon Kim, "Causality, Identity, and Supervenience in the Mind-Body Problem," Midwest Studies in Philosophy, vol. 4
(1979), pp. 31-50; see pp. 43-44.
2. Geoffrey Hellman and Frank Thompson, "Physicalist Materialism," Nous, vol. 11 (1977), pp. 309-45, see p. 310.
3. Cf. Kim, "Supervenience and Nomological Incommensurables," American Philosophical Quarterly, vol. 15 (1978), pp.
149-56, see p. 154; "Psychophysical Supervenience," Philosophical Studies, vol. 41 (1982), pp. 51-70, see p. 68; Robert Kraut,
"The Third Dogma," presented at the Davidson conference, Rutgers University, April 1984, p. 25. Further references to Kraut
will be to this article.
SUPERVENIENCE AND ONTOLOGY 47
4. "Mental Events," in L. Foster and J. W. Swanson (eds.), Experience and Theory (Amherst: University of Massachusetts
Press, 1970), p. 88.
5. "Supervenience and Nomological Incommensurables," op. cit., p. 149.
6. "Causality, Identity, and Supervenience in the Mind-Body Problem," op. cit., p. 41.
7. "Weak Supervenience," American Philosophical Quarterly, vol. 19 (1982), pp. 93-103, see p. 97. Further references to
Haugeland will be to this article.
8. "A Poor Man's Guide to Supervenience and Determination," Southern Journal of Philosophy, vol. 22 Supplement, pp. 137-62,
see p. 145. Further references to Teller will be to this article.
9. See, for example, Saul Kripke, "Outline of a Theory of Truth," Journal of Philosophy, vol. 72 (1975), pp. 690-715; Anil
Gupta, "Truth and Paradox," Journal of Philosophical Logic, vol. 11 (1982), pp. 01-60; Hans Herzberger, "Naive Semantics and
the Liar Paradox," Journal of Philosophy, vol. 79 (1982), pp. 479-97; Solomon Feferman, "Toward Useful Type-free Theories
I," Journal of Symbolic Logic, vol. 49 (1984) pp. 75-111; Nicholas Asher and Hans Kamp, "The Knower's Paradox and Represen?
tational Theories of Attitudes," in Joseph Y. Halpern (ed.), Theoretical Aspects of Reasoning About Knowledge: Proceedings of
the 1986 Conference (Los Altos: Morgan Kaufmann, 1986), pp. 131-47.
10. Both this appellation and the distinction itself were suggested by Gerald Massey.
11. See Teller, p. 142.
12. See "Physicalist Materialism," pp. 310-11.
13. G. Currie, "Individualism and Global Supervenience," British Journal for the Philosophy of Science, vol. 35 (1984), pp.
345-58; see pp. 348-49.
14. This definition was suggested to me by Kenneth Manders.
15. Paul Teller, in comments on an earlier version of this paper, insisted that he never meant supervenience to have any direct
ontological significance, and maintained that Kim, Hellman and Thompson similarly had no ontological intentions. Certainly
Haugeland, Kraut and Horgan, however, have viewed supervenience as an ontological relationship. In any case, I am interested
here in exploring explicitly ontological versions of supervenience.
16. "Supervenience and Cosmic Hermeneutics," Southern Journal of Philosophy, vol. 22 Supplement (1983), pp. 19-38.
17. W. V. Quine, "Ontological Relativity," in Ontological Relativity and Other Essays (New York: Columbia University Press,
1969), pp. 26-68, see pp. 50-51.
18. See Peter Geach, "Identity," Review of Metaphysics, vol. 21 (1967), pp. 03-12.
19. A purely semantic definition would require developing a model-theoretic analysis of interpretability relations. For such a
development, see my "Model-theoretic Variants of Interpretability," forthcoming.
20. "Supervenience and Microphysics," Pacific Philosophical Quarterly, vol. 63 (1982), pp. 29-43; see p. 31.
21. "Causality, Identity, and Supervenience in the Mind-Body Problem," op. cit., pp. 43-44.
22. "Supervenience and Nomological Incommensurables," op. cit., p. 153.