Dictionary Definition
supervene v : take place as an additional or
unexpected development
User Contributed Dictionary
English
Verb
See also
- (philosophy): Wikipedia's entry on Supervenience
Extensive Definition
In philosophy, supervenience is
a kind of dependency relationship, typically held to obtain between
sets of properties.
According to one standard definition, a set of properties A
supervenes on a set of properties B, if and only if any two objects
x and y which share all properties in B (are "B-indiscernible") must also
share all properties in A (are "A-indiscernible"). That is,
A-properties supervene on B-properties if being B-indiscernible
implies being
A-indiscernible. The properties in B are called the base properties
(or sometimes subjacent or subvenient properties), and the
properties in A are called the supervenient properties.
Equivalently, if two things differ in their supervenient properties
then they must differ in their base properties. To give a somewhat
simplified example, if psychological properties supervene on
physical properties, then any two persons who are physically
indistinguishable must also be psychologically indistinguishable;
or equivalently, any two persons who are psychologically different
(e.g., having different thoughts), must be physically different as
well. Importantly, the reverse does not follow (supervenience is
not symmetric): even if being the same physically implies being the
same psychologically, two persons can be the same psychologically
yet different physically: that is, psychological properties can be
multiply
realized in physical properties.
Supervenience has traditionally been used to
describe relationships between sets of properties in a manner which
does not imply a strong reductive
relationship. For example, many hold that economic properties
supervene on physical properties, in that if two worlds
were exactly the same physically, they would also be the same
economically. However, this does not entail that economics can be
reduced in any straightforward way to physics. Thus, supervenience
allows one to hold that "high-level phenonema" (like those of
economics, psychology, or aesthetics) depend, ultimately, on
physics, without assuming that one can study those high-level
phenomena using means appropriate to physics.
History
Supervenience, which means literally "coming or
occurring as something novel, additional, or unexpected"
In subsequent years Terry
Horgan, David Lewis,
and especially Jaegwon Kim
formalized the concept and began applying it to numerous issues in
the philosophy of mind. This raised numerous questions about how
various formulations relate to one another, how adequate the
formulation is to various philosophical tasks (in particular, the
task of formulating physicalism), and whether it
avoids or entails reductionism.
Definitions
In the contemporary literature, there are two
primary (and non-equivalent) formulations of supervenience (for
both definitions let A and B be sets of properties).
- A-properties supervene on B-properties if and only if all
things that are B-indiscernible are A-indiscernible. Formally:
- \forall x \forall y (\forall X_ (Xx \leftrightarrow Xy) \rightarrow \forall Y_ (Yx \leftrightarrow Yy))
- A-properties supervene on B-properties if and only if anything
that has an A-property has some B-property such that anything that
has that B-property also has that A-property. Formally:
- \forall x \forall X_ (Xx \rightarrow \exists Y_ (Yx \and \forall y (Xy \rightarrow Yy)))
For example, if one lets A be a set of mental
properties, B be a set of physical properties, and chooses a
domain
of discourse consisting of persons, then (1) says that any two
persons who are physically indiscernible are mentally
indiscernible, and (2) says that any person who has a mental
property has some physical property such that any person with that
physical property has that mental property.
Some points of clarification. First, the
definitions above involve quantification over properties and hence
higher
order logic. Second, in (1), expressions of the form (\forall X
(Xx \leftrightarrow Xy)) capture the concept of sharing all
properties, or being indiscernible with respect
to a set of properties. Thus, (1) can be understood more
intuitively as the claim that all objects that are indiscernible
with respect to a base set of properties are indiscernibile with
respect to a supervenient set of properties, or, as it is also
sometimes said, that B-twins are A-twins. Finally, supervenience
claims typically involve some modal force, however, the way that
modal
force is specified depends on which more specific variety of
supervenience one decides upon (see below).
(1) and (2) are sometimes called "schemata",
because they do not correspond to actual supervenience relations
until the sets of properties A and B, the domain
of entities to which those properties apply, and a modal force have
been specified. For modal forms of supervenience, the modal
strength of the relation is usually taken to be a parameter (that
is, the possible worlds appealed to may be physically possible,
logically possible, etc.). Also, note that in the early literature
properties were not always central, and there remain some who
prefer to frame the relation in terms of predicates,
facts, or entities instead, for
example.
Varieties of supervenience
There are many varieties of supervenience proposed in the philosophical literature, thanks in part to what David Lewis called the "unlovely proliferation" which occurred beginning in the 1980s, inspired largely by Jaegwon Kim's work. These varieties are based both on (1) and (2) above, but since (1) is more common we shall focus on varieties of supervenience based on it.We can begin by distinguishing between local and
global supervenience:
- Local: For any two objects x and y, if x and y are base-indiscernible, they are supervenient-indiscernible.
For example, if mental states locally supervene
on brain states, then being in the same brain state entails being
in the same mental state.
- Global: For any two worlds w1 and w2, if w1 and w2 are base-indiscernible, they are supervenient-indiscernible.
For example, if psychological properties globally
supervene on physical properties, then any two worlds physically
the same will be psychologically the same. The value of global
supervenience is that it allows for supervenient properties to be
determined not by local properties of an individual thing alone,
but by some wider spatiotemporal distribution of things and
properties. For example, something's being a dollar bill depends
not only on the paper and the inks it is made out of, but also on a
widely dispersed variety of features of the world it
occupies.
Both local and global supervenience come in many
forms. Local supervenience comes in strong and weak
varieties:
- Weak: For any world w, and for any two objects x in w and y in w, if x and y are base-indiscernible, they are supervenient-indiscernible.
- Strong: For any worlds w1 and w2, and for any two objects x in w1 and y in w2, if x and y are base-indiscernible, they are supervenient-indiscernible.
The difference is essentially whether
correlations between base and supervenient properties hold within
worlds only, or across possible worlds. For example, if
psychological properties strongly locally supervene on physical
properties, then any two people physically the same, in any two
worlds, will also be psychologically the same. On the other hand,
if psychological properties only weakly locally supervene on
physical properties, then those correlations between base and
supervenient properties that hold in virtue of the supervenience
relation are maintained within each world, but can be different in
different worlds. For example, my physical duplicates in the actual
world will have the same thoughts as I have; but my physical
duplicates in other possible worlds may have different thoughts
than I have in the actual world.
There are also several kinds of global
supervenience relations, which were introduced to handle cases in
which worlds are the same at the base level and also at the
supervenient level, but where the ways the properties are connected
and distributed in the worlds differ. For example, it is consistent
with global mental–physical supervenience on the simple formulation
described above for two worlds to have the same number of people in
the same physical states, but for the mental states to be
distributed over those people in different ways (e.g. I have my
father's thoughts in the other world, and he has my thoughts). To
handle this, property-preserving isomorphisms (1-1 and onto
functions between the objects of two worlds, whereby an object in
one world has a property if and only if the object which that
function takes you to in the other world does) are used, and once
this is done, several varieties of global supervenience can be
defined.
Other varieties of supervenience include
multiple-domains supervenience and similarity-based
supervenience.
Examples of supervenient properties
Value properties
The value of a physical object to an agent is sometimes held to be supervenient upon the physical properties of the object. In aesthetics, the beauty of La Grande Jatte might supervene on the physical composition of the painting (the specific molecules that make up the painting), the artistic composition of the painting (in this case, dots), the figures and forms of the painted image, or the painted canvas as a whole. In ethics, the goodness of an act of charity might supervene on the physical properties of the agent, the mental state of the agent (his or her intention), or the external state of affairs itself. Similarly, the overall suffering caused by an earthquake might supervene on the spatio-temporal entities that constituted it, the deaths it caused, or the natural disaster itself.Mental properties
In philosophy of mind, many philosophers make the general claim that the mental supervenes on the physical. In its most recent form this position derives from the work of Donald Davidson, although in more rudimentary forms it had been advanced earlier by others. The claim can be taken in several senses, perhaps most simply in the sense that the mental properties of a person are supervenient on their physical properties. Then:- If two persons are indistinguishable in all of their physical properties, they must also be indistinguishable in all of their mental properties.
An alternative claim, advanced especially by
John
Haugeland, is a kind of weak local supervenience claim; or,
weaker still, mere global supervenience. The claim that mental
properties supervene globally on physical properties requires only
a quite modest commitment: any difference between two possible
worlds with respect to their instantiated mental properties entails
at least some difference in the physical properties instantiated in
those two worlds. Importantly, it does not require that the mental
properties of an individual person supervene only on that person's
physical state.
This weak global thesis is particularly important
in the light of direct
reference theories, and semantic
externalism with regard to the content both of words and (more
relevant to our concerns here) of thoughts. Imagine two persons who
are indistinguishable in their local physical properties. One has a
dog in front of his eyes and the other has a dog-image artificially
projected onto his retinae. It might be reasonable to say that the
former is in the mental state of seeing a dog (and of knowing that
he does so), whereas the latter is not in such a state of seeing a
dog (but falsely believes that he sees one).
There is also discussion among philosophers about
mental supervenience and our experience of duration. If all mental
properties supervene only upon some physical properties at
durationless moments, then it may be difficult to explain our
experience of duration. The philosophical belief that mental and
physical events exist at a series of durationless moments that lie
between the physical past and the physical future is known as
presentism, and is a form of belief in Galilean
relativity.
Computational properties
There are several applications of the theory of supervenience to be found in computer networking. For example, in a dial-up internet connection, the audio signal on a phone line transports IP packets between the user's computer and the Internet service provider's computer. In this case, the arrangement of bytes in that packet supervenes on the physical properties of the phone signal. More generally, each layer of the OSI Model of computer networking supervenes on the layers below it.These computer examples illustrate a general
principle: we can find supervenience wherever a message is conveyed
by a representational medium. When we see a letter "a" in a page of
print, for example, the meaning latin lowercase "a" supervenes on
the geometry of the boundary of the printed glyph, which in turn supervenes on
the ink deposition on the paper.
Arguments against supervenience-based formulations of physicalism
Although supervenience seems to be perfectly suited to explain the predictions of physicalism (i.e. the mental is dependent on the physical), there are four main problems with it. They are Ephiphenomenal ectoplasm, the lone ammonium molecule problem, modal status problem and the problem of necessary beings.Epiphenomenal ectoplasm
Epiphenomenal ectoplasm was proposed by Horgan
and Lewis in 1983, in which they stated, a possible world (a world
that could possibly exist) W is identical to our world in the
distribution of all mental and physical characteristics (i.e. they
are identical), except world W contains an experience called
epiphenomenal ectoplasm that does not causally interact with that
world. If supervenience physicalism is true, then such a world
could not exist because a physical duplicate of the actual world
(the world that is known to exist) could not possess an
epiphenomenal ectoplasm. This was rectified by Frank
Jackson, by adjusting the application of supervenience within
physicalism to state "Physicalism is true at a possible world W if
and only if any world which is a minimal physical duplicate (i.e.
identical) of W is a duplicate of W simpliciter."
The lone ammonia molecule problem
The lone ammonia molecule problem provides a
problem for Jackson's solution to epiphenomenal ectoplasm. It was
proposed by Jaegwon Kim
in 1993 when he stated that according to Jackson's idea of
supervenience, a possible world W was identical to the actual
world, except it possessed an extra ammonia molecule on one of
Saturn’s rings. This may not seem to provide much of a problem, but
because Jackson's solution refers only to minimal physical
duplicates, this allows for the mental properties of W to be vastly
different than in the actual world. If such a difference would
cause mental differences on Earth, it would not be consistent with
our understanding of physicalism.
Modal status problem
The modal status problem is only problematic if
one thinks of physicalism as a contingent
truth (i.e. not necessary),
because it is described in terms of modal notions (i.e. through
modal realism). The problem is presented when from the statement
"Minimal physical truths entail all truths", one derives the
statement "S (a statement that describes all minimal physical
truths) entails S* (a statement that describes the world)". This
statement is a necessary truth, and therefore supervenience
physicalism could not be contingent. The solution to this is to
accept the above statement not as the equivalent of physicalism,
but as an entailment of it.
Problem of necessary beings
The problem of necessary beings was proposed by
Jackson in 1998, in which he stated that a necessary being exists
in all possible worlds as a non-physical
entity, and therefore proves physicalism false. However,
physicalism allows for the existence of necessary beings, because
any minimal physical duplicate would have the same mental
properties as the actual world. This however is paradoxical, based on the fact
that physicalism both permits and prevents the existence of such
beings. However, the existence of necessary beings is paradoxical
in itself. They are both distinct from the physical world and
dependent upon it. This violates Hume's fork
which states, "there are no necessary connections between distinct
existences".
Notes
supervene in German: Supervenienz
supervene in Spanish: Superveniencia
supervene in Finnish: Supervenienssi
supervene in Japanese: 付随性
supervene in Chinese: 随附性