TheInfoList

In
philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about Metaphysics, existence, reason, Epistemology, knowledge, Ethics, values, Philosophy of mind, mind, and Philosophy of language, language. Such questio ...

, supervenience refers to a relation between sets of properties or sets of facts. X is said to supervene on Y if and only if some difference in Y is necessary for any difference in X to be possible. Here are some examples: * Whether there is a table in the living room supervenes on the positions of molecules in the living room. * The truth value of (A) supervenes on the truth value of (¬A). * Molecular properties supervene on atomic properties. * One's moral character supervenes on one's action(s). These are examples of supervenience because in each case the truth values of some propositions cannot vary unless the truth values of some other propositions vary. Supervenience is of interest to philosophers because it differs from other nearby relations, for example
entailment Logical consequence (also entailment) is a fundamental concept Concepts are defined as abstract ideas A mental representation (or cognitive representation), in philosophy of mind Philosophy of mind is a branch of philosophy that studies th ...
. Some philosophers believe it possible for some A to supervene on some B without being entailed by B. In such cases it may seem puzzling why A should supervene on B and equivalently why changes in A should require changes in B. Two important applications of supervenience involve cases like this. One of these is the supervenience of mental properties (like the sensation of pain) on physical properties (like the firing of 'pain neurons'). A second is the supervenience of normative facts (facts about how things ought to be) on natural facts (facts about how things are). These applications are elaborated below. But an illustrative note bears adding here. It is sometimes claimed that what is at issue in these problems is the supervenience claim itself. For example, it has been claimed that what is at issue with respect to the mind-body problem is whether mental phenomena do in fact supervene on physical phenomena. This is incorrect. It is by and large agreed that some form of supervenience holds in these cases: Pain happens when the appropriate neurons fire. The disagreement is over why this is so. Materialists claim that we observe supervenience because the neural phenomena entail the mental phenomena, while dualists deny this. The dualist's challenge is to explain supervenience without entailment. The problem is similar with respect to the supervenience of normative facts on natural facts. Discussing the '' is-ought problem'' it is agreed that facts about how persons ought to act are not entailed by natural facts but cannot vary unless natural facts vary, and this rigid binding without entailment might seem puzzling. The possibility of "supervenience without entailment" or "supervenience without reduction" is contested territory among philosophers.

# History

Supervenience, which means literally "coming or occurring as something novel, additional, or unexpected",Horgan, Terry (1993) "From supervenience to superdupervenience: meeting the demands of a material world." ''Mind.'' 102: 555-86. from "super," meaning on, above, or additional, and "venire," meaning to come in Latin, shows occurrences in the
Oxford English Dictionary The ''Oxford English Dictionary'' (''OED'') is the principal historical dictionary A historical dictionary or dictionary on historical principles is a dictionary which deals not only with the latterday meanings of words but also the historica ...
dating back to 1844. Its systematic use in philosophy is considered to have begun in early 20th-century
meta-ethics In metaphilosophy Metaphilosophy, sometimes called the philosophy of philosophy, is "the investigation of the nature of philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about reason, Meta ...
and
emergentism In philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about Metaphysics, existence, reason, Epistemology, knowledge, Ethics, values, Philosophy of mind, mind, and Philosophy of language, langua ...
. As
G.E. Moore George Edward Moore (4 November 1873 – 24 October 1958) was an English philosopher who, along with Bertrand Russell Bertrand Arthur William Russell, 3rd Earl Russell (18 May 1872 – 2 February 1970) was a British polymath A polyma ...
wrote in 1922, "if a given thing possesses any kind of intrinsic value in a certain degree, then... anything ''exactly like it'', must, under all circumstances, possess it in exactly the same degree". This usage also carried over into the work of R. M. Hare. For discussion of the emergentist roots of supervenience se
Stanford Encyclopedia of Philosophy: Supervenience
In the 1970s, Donald Davidson was the first to use the term to describe a broadly physicalist (and non-reductive) approach to the philosophy of mind, called ''
anomalous monismAnomalous monism is a philosophical Philosophy (from , ) is the study of general and fundamental questions, such as those about existence Existence is the ability of an entity to interact with physical or mental reality Reality is the sum ...

''. As he said in 1970, "supervenience might be taken to mean that there cannot be two events alike in all physical respects but differing in some mental respects, or that an object cannot alter in some mental respects without altering in some physical respects."Davidson, Donald (1970) "Mental Events." Reprinted in ''Essays on Actions and Events''. Oxford: Clarendon Press In subsequent years Terence ("Terry") Horgan,
David LewisDavid or Dave Lewis may refer to: Academics *A. David Lewis (born 1977), American comic writer and scholar of religion and literature *David Lewis (academic) (born 1960), English scholar of development *David Lewis (lawyer) ( – 1584), Welsh ...
, and especially
Jaegwon Kim Jaegwon Kim (September 12, 1934 – November 27, 2019) was a Korean-American Korean Americans () are Americans of Koreans, Korean ancestry (predominantly from South Korea (99%), with a very small minority from North Korea, Koreans in China, ...
formalized the concept and began applying it to many 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 In philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about Metaphysics, existence, reason, Epistemology, knowledge, Ethics, values, Philosophy of mind, mind, and Philosophy of language, languag ...
), and whether it avoids or entails
reductionism Reductionism is any of several related Philosophy, philosophical ideas regarding the associations between Phenomenon, phenomena, which can be described in terms of other simpler or more fundamental phenomena. It is also described as an intellectu ...
.

# 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). (1) A-properties supervene on B-properties if and only if all things that are B-indiscernible are A-indiscernible. Formally: *$\forall x \forall y \left(\forall X_ \left(Xx \leftrightarrow Xy\right) \rightarrow \forall Y_ \left(Yx \leftrightarrow Yy\right)\right)$ (2) 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: *$\forall x \forall X_ \left(Xx \rightarrow \exists Y_ \left(Yx \land \forall y \left(Yy \rightarrow Xy\right)\right)\right)$ For example, if one lets A be a set of mental properties, lets B be a set of physical properties, and chooses a
domain of discourse In the formal sciences Formal science is a branch of science studying formal language disciplines concerned with formal systems, such as logic Logic is an interdisciplinary field which studies truth and reasoning Reason is the capacity ...
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 In mathematics Mathematics (from Greek: ) includes the study of such topics as numbers ( and ), formulas and related structures (), shapes and spaces in which they are contained (), and quantities and their changes ( and ). There is no gener ...
. Second, in (1), expressions of the form $\left(\forall X \left(Xx \leftrightarrow Xy\right)\right)$ 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 indiscernible 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 Domain may refer to: Mathematics *Domain of a function In mathematics, the domain of a Function (mathematics), function is the Set (mathematics), set of inputs accepted by the function. It is sometimes denoted by \operatorname(f), where is th ...
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,
fact A fact is something that is true True most commonly refers to truth Truth is the property of being in accord with fact or reality.Merriam-Webster's Online Dictionarytruth 2005 In everyday language, truth is typically ascribed to things ...
s, or
entities Entity may refer to: Computing * Character entity reference, replacement text for a character in HTML or XML * Entity class, a thing of interest within an entity–relationship model or diagram * SGML entity, a primitive data type in Standard Gen ...

# Varieties of supervenience

Beginning in the 1980s, inspired largely by
Jaegwon Kim Jaegwon Kim (September 12, 1934 – November 27, 2019) was a Korean-American Korean Americans () are Americans of Koreans, Korean ancestry (predominantly from South Korea (99%), with a very small minority from North Korea, Koreans in China, ...
's work, philosophers proposed many varieties of supervenience, which
David LewisDavid or Dave Lewis may refer to: Academics *A. David Lewis (born 1977), American comic writer and scholar of religion and literature *David Lewis (academic) (born 1960), English scholar of development *David Lewis (lawyer) ( – 1584), Welsh ...
called the "unlovely proliferation".Lewis, David (1986) ''
On the Plurality of Worlds ''On the Plurality of Worlds'' (1986) is a book by the philosopher A philosopher is someone who practices philosophy. The term ''philosopher'' comes from the grc, φιλόσοφος, , translit=philosophos, meaning 'lover of wisdom'. The c ...
''. Oxford: Oxford University Press.
These varieties are based both on (1) and (2) above, but because (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 actual 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 Value or values may refer to: * Value (ethics) In ethics Ethics or moral philosophy is a branch of philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about Metaphysics, existence, reason, E ...
of a physical object to an
agent Agent may refer to: Espionage, investigation, and law *, spies or intelligence officers * Law of agency, laws involving a person authorized to act on behalf of another ** Agent of record, a person with a contractual agreement with an insuran ...
is sometimes held to be supervenient upon the physical properties of the object. In
aesthetics Aesthetics, or esthetics (), is a branch of philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about Metaphysics, existence, reason, Epistemology, knowledge, Ethics, values, Philosophy of m ...

, the
beauty Beauty is commonly described as a feature of objects that makes these objects pleasurable to perceive. Such objects include landscapes, sunsets, humans and works of art. Beauty, together with art and taste, is the main subject of aesthetics ...

of La Grande Jatte might supervene on the physical composition of the painting (the specific
molecules A molecule is an electrically Electricity is the set of physical phenomena associated with the presence and motion Image:Leaving Yongsan Station.jpg, 300px, Motion involves a change in position In physics, motion is the phenomenon ...

that make up the painting), the artistic composition of the painting (in this case,
dots Dots or The Dots may refer to: *Dots (candy) Dots, or Mason Dots (trademarked DOTS), is a brand of gumdrop, gum drops marketed by Tootsie Roll Industries, which claims that "since its 1945 launch," the candy has become "America's...#1 selling gum ...
), the figures and forms of the painted image, or the painted canvas as a whole. In
ethics Ethics or moral philosophy is a branch of philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about Metaphysics, existence, reason, Epistemology, knowledge, Ethics, values, Philosophy of mind, ...

, the goodness of an act of
charity Charity may refer to: Giving * Charitable organization or charity, a non-profit organization whose primary objectives are philanthropy and social well-being of persons * Charity (practice), the practice of being benevolent, giving and sharing * Ch ...
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 spatiotemporal entities that constituted it, the deaths it caused, or the natural disaster itself. The claim that moral properties are supervenient upon non-moral properties is called moral supervenience.

## Mental properties

In
philosophy of mind Philosophy of mind is a branch of philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about Metaphysics, existence, reason, Epistemology, knowledge, Ethics, values, Philosophy of mind, mind, a ...

, 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 John Haugeland (; March 13, 1945 – June 23, 2010) was a professor of philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about reason, Metaphysics, existence, Epistemology, knowledge, Ethic ...
, 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 referenceA direct reference theory (also called referentialism or referential realism)Andrea Bianchi (2012) ''Two ways of being a (direct) referentialist'', in Joseph Almog, Paolo Leonardi, ''Having in Mind: The Philosophy of Keith Donnellan''p. 79/ref> is a ...
theories, and
semantic externalism In the philosophy of language In analytic philosophy Analytic philosophy is a branch and tradition of philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about reason, Metaphysics, exist ...
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 as a series of durationless moments that lie between the physical past and the physical future is known as presentism.

## Computational properties

There are several examples of supervenience to be found in
computer network A computer network is a set of computer A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations automatically. Modern computers can perform generic sets of operati ...
ing. 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 An Internet service provider (ISP) is an organization that provides a myriad of services for accessing, using, or participating in the Internet The Internet (or internet) is the global system of interconnected computer networks that ...
'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 The Open Systems Interconnection model (OSI model) is a that characterises and standardises the communication functions of a or computing system without regard to its underlying internal structure and technology. Its goal is the interoperabil ...

of computer networking supervenes on the layers below it. 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 The term glyph is used in typography Typography is the art and technique of arranging type to make written language A written language is the representation of a spoken or gestural language A language is a structured system o ...
, which in turn supervenes on the ink deposition on the paper.

## Biological properties

In biological systems
phenotype In genetics Genetics is a branch of biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular inter ...

can be said to supervene on
genotype The genotype of an organism is its complete set of genetic material. Genotype can also be used to refer to the or variants an individual carries in a particular gene or genetic location. The number of alleles an individual can have in a specific ...
. This is because any genotype encodes a finite set of unique phenotypes, but any given phenotype is not produced by a finite set of genotypes. Innumerable examples of
convergent evolution Convergent evolution is the independent evolution Evolution is change in the heritable Heredity, also called inheritance or biological inheritance, is the passing on of Phenotypic trait, traits from parents to their offspring; eit ...
can be used to support this claim. Throughout nature, convergent evolution produces incredibly similar phenotypes from a diverse set of taxa with fundamentally different genotypes underpinning the phenotypes. One example is evolution on islands which is a remarkably predictable example of convergent evolution where the same phenotypes consistently evolve for the same reasons. Organisms released from predation tend to become larger, while organisms limited by food tend to become smaller. Yet there are almost infinite numbers of genetic changes that might lead to changes in body size. Another example of convergent evolution is the loss of sight that almost universally occurs in cave fish living in lightless pools. Eyes are expensive, and in lightless cave pools there is little reason for fish to have eyes. Yet, despite the remarkably consistent convergent evolution producing sightless cave fish, the genetics that produce the loss of sight phenotype is different nearly every time. This is because phenotype supervenes on genotype.

# 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 ''Epiphenomenal 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; they envisioned a possible world (a world that could possibly exist) ''W'' which 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. The possibility of such a world should be compatible with physicalism as this is a property of the actual world; but a supervenience-based definition of physicalism would imply that such a world could not exist, because it differs from the actual world with respect to a mental property, but is physically identical. A typical response to this objection is Frank Jackson's; he adjusted the supervenience-based definition of 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. is physically identical) of ''W'' is a duplicate of ''W simpliciter.''" This avoids the problem because the "ectoplasm" world is not a minimal physical duplicate, so its identity with the actual world need not follow.

## The lone ammonium molecule problem

The ''lone ammonium molecule problem'' provides a problem for Jackson's solution to ''epiphenomenal ectoplasm''. It was proposed by
Jaegwon Kim Jaegwon Kim (September 12, 1934 – November 27, 2019) was a Korean-American Korean Americans () are Americans of Koreans, Korean ancestry (predominantly from South Korea (99%), with a very small minority from North Korea, Koreans in China, ...
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 ammonium 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 from those 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

Suppose that the supervenience thesis for physicalism is stated as a nomological constraint, rather than a metaphysical one; this avoids any objection based on the thesis ruling out metaphysical possibilities which a physicalist would leave open. But the thesis would not rule out the metaphysical possibility of philosophical zombies, although their impossibility is a clear consequence of physicalism.

## Problem of necessary beings

The ''problem of necessary beings'' was proposed by Jackson in 1998, in which he stated that the existence of a non-physical necessary being (in all possible worlds) would prove physicalism false. However, physicalism allows for the existence of necessary beings, because any minimal physical duplicate would have the same necessary being as the actual world. This however is
paradox A paradox is a logically self-contradictory statement or a statement that runs contrary to one's expectation. It is a statement that, despite apparently valid reasoning from true premises, leads to a seemingly self-contradictory or a logically u ...

ical, based on the fact that physicalism both permits and prevents the existence of such beings.