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.