Physicalism

Physicalism

Overview
Physicalism is a philosophical position holding that everything which exists is no more extensive than its physical properties; that is, that there are no kinds of things other than physical things. The term was coined by Otto Neurath
Otto Neurath
Otto Neurath was an Austrian philosopher of science, sociologist, and political economist...

 in a series of early twentieth century essays on the subject, in which he wrote:
"According to physicalism, the language of physics is the universal language of science and, consequently, any knowledge can be brought back to the statements on the physical objects."


In contemporary philosophy
Contemporary philosophy
Contemporary philosophy is the present period in the history of Western philosophy beginning at the end of the 19th century with the professionalization of the discipline and the rise of analytic and continental philosophy....

, physicalism is most frequently associated with the mind-body problem in philosophy of mind
Philosophy of mind
Philosophy of mind is a branch of philosophy that studies the nature of the mind, mental events, mental functions, mental properties, consciousness and their relationship to the physical body, particularly the brain. The mind-body problem, i.e...

, regarding which physicalism holds that all that has been ascribed to "mind" is more correctly ascribed to "brain" or the activity of the brain.
Discussion
Ask a question about 'Physicalism'
Start a new discussion about 'Physicalism'
Answer questions from other users
Full Discussion Forum
 
Unanswered Questions
Encyclopedia
Physicalism is a philosophical position holding that everything which exists is no more extensive than its physical properties; that is, that there are no kinds of things other than physical things. The term was coined by Otto Neurath
Otto Neurath
Otto Neurath was an Austrian philosopher of science, sociologist, and political economist...

 in a series of early twentieth century essays on the subject, in which he wrote:
"According to physicalism, the language of physics is the universal language of science and, consequently, any knowledge can be brought back to the statements on the physical objects."


In contemporary philosophy
Contemporary philosophy
Contemporary philosophy is the present period in the history of Western philosophy beginning at the end of the 19th century with the professionalization of the discipline and the rise of analytic and continental philosophy....

, physicalism is most frequently associated with the mind-body problem in philosophy of mind
Philosophy of mind
Philosophy of mind is a branch of philosophy that studies the nature of the mind, mental events, mental functions, mental properties, consciousness and their relationship to the physical body, particularly the brain. The mind-body problem, i.e...

, regarding which physicalism holds that all that has been ascribed to "mind" is more correctly ascribed to "brain" or the activity of the brain. Physicalism is also called "materialism
Materialism
In philosophy, the theory of materialism holds that the only thing that exists is matter; that all things are composed of material and all phenomena are the result of material interactions. In other words, matter is the only substance...

", but the term "physicalism" is preferable because it has evolved with the physical science
Physical science
Physical science is an encompassing term for the branches of natural science and science that study non-living systems, in contrast to the life sciences...

s to incorporate far more sophisticated notions of physicality than matter, for example wave/particle relationships and non-material forces produced by particles.
The related position of methodological naturalism says that philosophy and science should at least operate under the assumptions of natural sciences (and thus physicalism).

The ontology of physicalism ultimately includes whatever is described by physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...

 — not just matter
Matter
Matter is a general term for the substance of which all physical objects consist. Typically, matter includes atoms and other particles which have mass. A common way of defining matter is as anything that has mass and occupies volume...

 but energy
Energy
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...

, space
Space
Space is the boundless, three-dimensional extent in which objects and events occur and have relative position and direction. Physical space is often conceived in three linear dimensions, although modern physicists usually consider it, with time, to be part of a boundless four-dimensional continuum...

, time
Time
Time is a part of the measuring system used to sequence events, to compare the durations of events and the intervals between them, and to quantify rates of change such as the motions of objects....

, physical forces, structure
Structure
Structure is a fundamental, tangible or intangible notion referring to the recognition, observation, nature, and permanence of patterns and relationships of entities. This notion may itself be an object, such as a built structure, or an attribute, such as the structure of society...

, physical processes, information
Physical information
In physics, physical information refers generally to the information that is contained in a physical system. Its usage in quantum mechanics In physics, physical information refers generally to the information that is contained in a physical system. Its usage in quantum mechanics In physics,...

, state
State (computer science)
In computer science and automata theory, a state is a unique configuration of information in a program or machine. It is a concept that occasionally extends into some forms of systems programming such as lexers and parsers....

, etc. Because it claims that only physical things exist, physicalism is generally a form of ontological monism.

Reductive and non-reductive physicalism


Physicalism can be reductive or non-reductive; reductionism
Reductionism
Reductionism can mean either an approach to understanding the nature of complex things by reducing them to the interactions of their parts, or to simpler or more fundamental things or a philosophical position that a complex system is nothing but the sum of its parts, and that an account of it can...

 is a concept regarding the relationship between the parts of an object and the whole.
There are several important concepts relevant to the distinction between the types of physicalism.

Supervenience



Supervenience
Supervenience
In philosophy, supervenience is a kind of dependency relationship. For example, mental states might depend on physical brain states. This dependency is typically held to obtain between sets of properties. A classic example is that mental states of pain supervene on 'C-fibers firing'...

 is a concept with broad applicability throughout philosophy that has particular importance to physicalism. It describes the relationship between the fundamental objects of physical reality and those of everyday experience as well as those of a more abstract social nature. Subtle differences in the interpretation of the supervenience concept underscore different schools of thought within physicalism.

Supervenience can be seen as the relationship between a higher level and lower level of existence where the higher level is dependent on the lower level. One level supervenes on another when there can only be a change at the higher level if there is also a change at the lower level. (e.g., a set of properties A supervenes upon a set of properties B when there cannot be an A difference without a B difference). The debate about this notion as regards physicalism is to what extent mental phenomena exist independently of their (supposed) fundamental lowest level - the physical.

Supervenience establishes such a relationship between the mental and the physical, that any change in the mental is caused
Causality
Causality is the relationship between an event and a second event , where the second event is understood as a consequence of the first....

 by a change in the physical. Just as a shadow is dependent upon the position of the object causing it, is the mental dependent upon the physical. Physicalism thus implies (through modal realism
Modal realism
Modal realism is the view, notably propounded by David Kellogg Lewis, that all possible worlds are as real as the actual world. It is based on the following tenets: possible worlds exist; possible worlds are not different in kind from the actual world; possible worlds are irreducible entities; the...

) that:
No two worlds could be identical in every physical respect yet differ in some other respect.


The corresponding conclusion about the mental would be as follows:
No two beings, or things could be identical in every physical respect yet differ in some mental respect.


Another description of supervenience does away with levels altogether and rather pictures reality as a matrix or mosaic, upon which we imply different patterns (the old levels) but emphasising that all patterns are variations of the same implicit reality.

However, supervenience alone is not sufficient to establish the basis of physicalism. It is possible that mental or other non-physical states supervene upon the physical. As this allows for the possibility that the mind is causally inefficacious and only contingently related to the physical, supervenience physicalism is compatible with epiphenomenalism
Epiphenomenalism
In philosophy of mind, epiphenomenalism, also known as Type-E Dualism, is a view that "mental" states do not have any influence on "physical" states.-Background:...

. However, when supervenience physicalism and token physicalism are combined, minimal physicalism is met, as will be detailed in the following sections.

Token and type theories



The type/token distinction is easily illustrated by way of example. In the phrase "yellow is yellow is yellow is yellow", there are only two types of words ("yellow" and "is") but there are seven tokens (four of one and three of the other). The thesis of type physicalism consists in the idea that mental event types (e.g., pain in all individual organisms of all species at all times) are, at least contingently, identical with specific event types in the brain (e.g., C-fibre firings in all individual organisms of all species and at all times).

If Type Physicalism is true then mental state M1 would be identical to brain state B1. This would imply that a specific mental state of pain, for example, would perfectly correlate to a specific brain state in all organisms at all times. However, some qualify this by saying that some mental states are not always reduced to only one specific brain state (see Putnam
Hilary Putnam
Hilary Whitehall Putnam is an American philosopher, mathematician and computer scientist, who has been a central figure in analytic philosophy since the 1960s, especially in philosophy of mind, philosophy of language, philosophy of mathematics, and philosophy of science...

's multiple realizability
Multiple realizability
Multiple realizability, in philosophy of mind, is the thesis that the same mental property, state, or event can be implemented by different physical properties, states or events...

). That is, the same mental state can be produced from many different physical brain states. Token physicalism only states that for every particular occurrence, there is a physical particular with which it is identical. Therefore, while the mental state of pain or happiness is not type-identical to any one specific brain state, it is still physical and identical to a particular brain state. It may be helpful to understand that we often use different sets of vocabulary to describe an identical thing, which arise out of different disciplines. For example, a particular color, say, yellow, is a term that is identical to a particular light wavelength within the visible electro-magnetic spectrum. In this case to describe the actual color yellow and to describe the same as a wavelength, is an example of a type-type identity for they are the same thing.

N.B. Though popular, and useful, modern colour science has discredited the view that any colour is identical with any single wavelength. In fact mutilple realizability reigns here as well - any colour has infinite metamers - physical spectral reflectance distributions which can produces indistinguishable colour experiences in the subject. Thus token identity holds between colours and physical/brain states at best.

Reductive physicalism


All types of reductive physicalism are grounded in the idea that everything in the world can actually be reduced analytically to its fundamental physical, or material, basis. This is one reason why "physicalism" is often used interchangeably with the word "materialism." Both terms (in these instances) hold that all organic and inorganic processes can be explained by reference to the laws of nature. The general success of physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...

 in explaining a large range of phenomena in terms of a few of these basic natural laws; such as gravity, electricity, composition of mass, has assisted this belief.

The physicalist variation discussed above (Type Physicalism aka Identity Theory) is ontologically reductionist, as it reduces mental states and processes into physical states and processes.

Reductive physicalism is compatible with eliminativism - the view that psychological states do not exist at all.

Type physicalism



Type physicalism (also known as Type Identity Theory, Type-Type theory or just Identity Theory) is the theory, in the philosophy of mind
Philosophy of mind
Philosophy of mind is a branch of philosophy that studies the nature of the mind, mental events, mental functions, mental properties, consciousness and their relationship to the physical body, particularly the brain. The mind-body problem, i.e...

, which asserts that mental event
Mental event
A mental event is a particular occurrence of something going on in the mind or mind substitute. It can be a thought, a dream, a feeling, a realization, or any other mental activity. Mental events are not limited to human thought but can be associated with animal and artificial intelligence as...

s are type-identical to the physical events in the brain with which they are correlated
Correlation
In statistics, dependence refers to any statistical relationship between two random variables or two sets of data. Correlation refers to any of a broad class of statistical relationships involving dependence....

. In other words, that mental states or properties are neurological states or properties. It is called type identity in order to distinguish it from a similar but distinct theory called the token identity theory.

According to Ullin Place
Ullin Place
Ullin Place was a British philosopher and psychologist. Along with J. J. C. Smart, he developed the identity theory of mind. Place was born in Yorkshire and studied under Gilbert Ryle at Oxford University. There, he became acquainted with philosophy of mind in the logical behaviorist tradition,...

, one of the popularizers of the idea of type-identity in the 1950s and '60s, the idea of type-identical mind/body physicalism originated in the 1930s with the psychologist E. G. Boring and took nearly a quarter of a century to finally catch on and become accepted by the philosophical community. Boring, in a book entitled The Physical Dimensions of Consciousness (1933) wrote that:
The barrier to the acceptance of any such vision of the mind, according to Place, was that philosophers and logicians had not yet taken a substantial interest in questions of identity and referential identification in general. The dominant epistemology of the logical positivists
Logical positivism
Logical positivism is a philosophy that combines empiricism—the idea that observational evidence is indispensable for knowledge—with a version of rationalism incorporating mathematical and logico-linguistic constructs and deductions of epistemology.It may be considered as a type of analytic...

 at that time was phenomenalism
Phenomenalism
Phenomenalism is the view that physical objects do not exist as things in themselves but only as perceptual phenomena or sensory stimuli situated in time and in space...

, in the guise of the theory of sense-data. Indeed Boring himself subscribed to the phenomenalist creed, attempting to reconcile it with an identity theory and this resulted in a reductio ad absurdum
Reductio ad absurdum
In logic, proof by contradiction is a form of proof that establishes the truth or validity of a proposition by showing that the proposition's being false would imply a contradiction...

of the identity theory, since brain states would have turned out, on this analysis, to be identical to colors, shapes, tones and other sensory experiences.

The revival of interest in the work of Gottlob Frege
Gottlob Frege
Friedrich Ludwig Gottlob Frege was a German mathematician, logician and philosopher. He is considered to be one of the founders of modern logic, and made major contributions to the foundations of mathematics. He is generally considered to be the father of analytic philosophy, for his writings on...

 and his ideas of sense
Sense
Senses are physiological capacities of organisms that provide inputs for perception. The senses and their operation, classification, and theory are overlapping topics studied by a variety of fields, most notably neuroscience, cognitive psychology , and philosophy of perception...

 and reference
Reference
Reference is derived from Middle English referren, from Middle French rèférer, from Latin referre, "to carry back", formed from the prefix re- and ferre, "to bear"...

 on the part of Herbert Feigl
Herbert Feigl
Herbert Feigl was an Austrian philosopher and a member of the Vienna Circle.-Biography:The son of a weaver, Feigl was born in Reichenberg , Bohemia, and matriculated at the University of Vienna in 1922...

 and J.J.C. Smart, along with the discrediting of phenomenalism through the influence of the later Wittgenstein
Ludwig Wittgenstein
Ludwig Josef Johann Wittgenstein was an Austrian philosopher who worked primarily in logic, the philosophy of mathematics, the philosophy of mind, and the philosophy of language. He was professor in philosophy at the University of Cambridge from 1939 until 1947...

 and J.L. Austin, led to a more tolerant climate toward physicalistic and realist ideas. Logical behaviorism emerged as a serious contender to take the place of the Cartesian "ghost in the machine" and, although not lasting very long as a dominant position on the mind/body problem, its elimination of the whole realm of internal mental events was strongly influential in the formation and acceptance of the thesis of type identity.

Non-reductive physicalism


The earliest forms of physicalism, growing historically out of materialism, were reductionist. But after Donald Davidson
Donald Davidson (philosopher)
Donald Herbert Davidson was an American philosopher born in Springfield, Massachusetts, who served as Slusser Professor of Philosophy at the University of California, Berkeley from 1981 to 2003 after having also held teaching appointments at Stanford University, Rockefeller University, Princeton...

 introduced the concept of supervenience
Supervenience
In philosophy, supervenience is a kind of dependency relationship. For example, mental states might depend on physical brain states. This dependency is typically held to obtain between sets of properties. A classic example is that mental states of pain supervene on 'C-fibers firing'...

 to physicalism, non-reductionist physicalism became more popular.

Non-reductive physicalism is the idea that while mental states are caused by physical states they are not reducible to physical properties (i.e. of a different ontological class).

Nonreductive physicalism has been especially popular among philosophers of biology and some biologists, who argue that all biological facts are fixed by physical facts but that biological properties and regularities supervene on so many multiple realizations of macromolecular arrangements that the biological is not reducible to the physical. Prominent exponents of this view are Philip Kitcher and Elliot Sober. Alexander Rosenberg
Alexander Rosenberg
Alexander Rosenberg is an American philosopher, and the R. Taylor Cole Professor of Philosophy at Duke University.Rosenberg was educated at Stuyvesant High School, the City College of New York and Johns Hopkins University...

 introduced Davidson's notion to the debate in 1978 but thereafter argued against nonreductive physicalism in ways similar to Jaegwon Kim's.
There are several varieties of non-reductive physicalism; some of which are opposed to each other.

Supervenience physicalism


Supervenience physicalism (proposed by Donald Davidson) is a non-reductive physicalism, as mental events supervene (i.e., physical properties are mapped to mental properties) on physical events rather than mental events reducing to physical events. For example if we accept supervenience physicalism, the pain someone would feel if electrocuted would supervene on the firing
Action potential
In physiology, an action potential is a short-lasting event in which the electrical membrane potential of a cell rapidly rises and falls, following a consistent trajectory. Action potentials occur in several types of animal cells, called excitable cells, which include neurons, muscle cells, and...

 of their c-fibres. Whereas if we accept reductive physicalism, the pain would be those c-fibres firing.

Anomalous monism


Donald Davidson proposed anomalous monism
Anomalous monism
Anomalous monism is a philosophical thesis about the mind-body relationship. It was first proposed by Donald Davidson in his 1970 paper Mental events. The theory is twofold and states that mental events are identical with physical events, and that the mental is anomalous, i.e. under their mental...

 as a non-reductive physicalism.

Token physicalism


Token physicalism states "for every actual particular
Particular
In philosophy, particulars are concrete entities existing in space and time as opposed to abstractions. There are, however, theories of abstract particulars or tropes. For example, Socrates is a particular...

 (i.e., object, event or process) x, there is some physical particular y such that x=y". This does not entail nor is entailed by supervenience, although if supervenience is true, it does not necessarily rule out token physicalism. The difference between supervenience and token physicalism is simple; token physicalism states that for every mental particular there is a physical particular to which it is identical, while supervenience physicalism states that set A (e.g., mental properties) cannot change unless set B (e.g., physical properties) changes as well. (i.e., A supervenes on B). As the name suggests, this is a dualistic conception of reality that does not discount the option of physical properties also having non-supervened mental properties. Supervenience physicalism rules out this possibility.

Still, token physicalism presents at least two problems. It requires that for social, moral, and psychological particulars there must be a physical particular identical with them. Consider the Supreme Court of the United States. The Supreme Court exists, but according to token physicalism, there is a physical object that is identical to the Supreme Court. However, this physical particular does not necessarily exist in any conventional use of the word 'physical'. Supervenience escapes this problem as the social, moral, and psychological particulars are said to supervene on the physical particulars that compose them. Token physicalism does not capture reductive physicalism, i.e., that everything is physical. Simply because every particular has a physical property does not rule out the possibility that some particulars have non-supervenient mental properties.

Emergentism


Emergentism
Emergentism
In philosophy, emergentism is the belief in emergence, particularly as it involves consciousness and the philosophy of mind, and as it contrasts with reductionism. A property of a system is said to be emergent if it is in some sense more than the "sum" of the properties of the system's parts...

 is a theory which came to popularity in the early twentieth century. It is a form of non-reductive supervenience, but one where reality is considered to supervene in a manner more akin to layers, rather than patterns within a single layer, as per later physicalism. These layers are said to be genuinely novel from each other (i.e., the psychological vs. the physical), and is thus a type of dualism
Dualism
Dualism denotes a state of two parts. The term 'dualism' was originally coined to denote co-eternal binary opposition, a meaning that is preserved in metaphysical and philosophical duality discourse but has been diluted in general or common usages. Dualism can refer to moral dualism, Dualism (from...

. Physicalism is essentially monistic.

Epiphenomenalism


Epiphenomenalism isn't exactly a variety of non-reductive physicalism, but it is compatible with some forms of it.
Epiphenomenalism is about a one-way causal interaction; it sees mental states as being the byproducts of brain states; with mental states lacking any causal effects on brain states(some types of epiphenomenalism do allow that some mental states can cause other mental states).
It was initially an attempt to solve the problem posed by the question 'what is the causal factor, the brain state or the mental state?' in relation to substance dualism; however it is also relevant to the causal significance of qualia; and as such has implications for property dualists and some non-reductionist physicalist theories. According to epiphenomenalism, the physical (brain state) is the causal factor.

Exclusion principle


One argument is the exclusion principle, which states that if an event e causes event e*, then there is no event e# such that e# is non-supervenient on e and e# causes e*. This comes when one poses this scenario; One usually considers the desire to lift one’s arm a mental event, and the lifting of one's arm, a physical event. According to the exclusion principle, there must be an event that does not supervene on e while causing e*. This is interpreted as meaning, mental events supervene upon the physical. However, some philosophers accept epiphenomenalism
Epiphenomenalism
In philosophy of mind, epiphenomenalism, also known as Type-E Dualism, is a view that "mental" states do not have any influence on "physical" states.-Background:...

, which states mental events are caused by physical events, but physical events are not caused by mental events. However, If e# does not cause e, then there is no way to verify that e# exists. Yet, this debate has not been settled in the philosophical community.

Argument from methodological naturalism


The argument from methodological naturalism has two premises. First, it is rational to form one's metaphysical beliefs based on the methods of natural science. Secondly, the metaphysical world view is one that is led to by the methods of natural science, which is physicalism. Thus, it is most likely that physicalism is true. One reply to this argument is to reject the second premise and state that one is not led to physicalism by the natural sciences. However, this does not seem to have much support. While there are other options when considering the nature of the world, panpsychism
Panpsychism
In philosophy, panpsychism is the view that all matter has a mental aspect, or, alternatively, all objects have a unified center of experience or point of view...

 in cognitive science, or vitalism
Vitalism
Vitalism, as defined by the Merriam-Webster dictionary, is#a doctrine that the functions of a living organism are due to a vital principle distinct from biochemical reactions...

 in biology, this is irrelevant. The argument merely states that physicalism is the most likely, not that other views are impossible.

Knowledge argument


Though there have been many objections to physicalism throughout its history, many of these arguments concern themselves with the apparent contradiction of the existence of qualia
Qualia
Qualia , singular "quale" , from a Latin word meaning for "what sort" or "what kind," is a term used in philosophy to refer to subjective conscious experiences as 'raw feels'. Examples of qualia are the pain of a headache, the taste of wine, the experience of taking a recreational drug, or the...

 in an entirely physical world. The most popular argument of this kind is the so-called knowledge argument as formulated by Frank Jackson
Frank Cameron Jackson
Frank Cameron Jackson is an Australian philosopher, currently Distinguished Professor and former Director of the Research School of Social Sciences at Australian National University. In 2007-2008, he also became a regular visiting professor of philosophy at Princeton University...

, titled Mary's room
Mary's room
Mary's room is a philosophical thought experiment proposed by Frank Jackson in his article "Epiphenomenal Qualia" and extended in "What Mary Didn't Know"...

.

The argument asks us to consider Mary, a young girl who has been forced to investigate the world from a black and white room via a black and white television monitor throughout her life. However, she is allowed access to a large number of books, containing all physical knowledge within them. During her time in the room, she eventually comes to know all of the physical facts about the world, including all of the physical facts about color. Now, to the physicalist, it would seem that this would entail Mary knowing everything about the world. However, once she is let out of her room and into the world, it becomes apparent that Mary does not know everything about the world, such as the feeling or experience of seeing color. If Mary did not have such knowledge, how can it be said that everything supervenes upon the physical?

Physicalist response


One way the physicalist may respond to this argument is through the ability hypothesis, developed by Lawrence Nemerow and David Lewis
David Kellogg Lewis
David Kellogg Lewis was an American philosopher. Lewis taught briefly at UCLA and then at Princeton from 1970 until his death. He is also closely associated with Australia, whose philosophical community he visited almost annually for more than thirty years...

. The ability hypothesis draws a distinction between propositional knowledge, such as 'Mary knows that the sky is typically blue during the day', and knowledge-how, such as 'Mary knows how to climb a mountain'. It then states that all that Mary gains from her experience is knowledge-how. This argument shows that while Mary does gain knowledge from her experience, it is not the propositional knowledge which would need to be obtained if the knowledge argument were to be logically sound.

Perhaps one could argue that the circumstances of Mary's room do not include all physical knowledge because it does not include particular wavelengths of light. In other words, for Mary to have the feeling or experience of seeing color, she must be exposed to color. Then because color is a wavelength of light, it too is physical knowledge, and thus must be included in the books that Mary has. She would therefore be exposed to these wavelengths of light while still in the room, and would thus have the feeling or experience of seeing color. But this response seems implausible since Mary is supposed to have all physical knowledge about color, including knowledge about wavelengths, etcetera. The force of the thought experiment is exactly that the "feeling" or "experience" of seeing color is something that cannot be reduced to physical facts or information.

Argument from philosophical zombies



The zombie argument is a thought experiment
Thought experiment
A thought experiment or Gedankenexperiment considers some hypothesis, theory, or principle for the purpose of thinking through its consequences...

 that states "there is a possible world in which there exist zombies". Zombies are organisms that appear to have consciousness
Consciousness
Consciousness is a term that refers to the relationship between the mind and the world with which it interacts. It has been defined as: subjectivity, awareness, the ability to experience or to feel, wakefulness, having a sense of selfhood, and the executive control system of the mind...

 and qualia
Qualia
Qualia , singular "quale" , from a Latin word meaning for "what sort" or "what kind," is a term used in philosophy to refer to subjective conscious experiences as 'raw feels'. Examples of qualia are the pain of a headache, the taste of wine, the experience of taking a recreational drug, or the...

, but in reality do not. Also, in this case the zombies have to be identical copies of organisms in the actual or other possible world.

It has been argued under reductive physicalism, that one must either believe that anyone including oneself might be a zombie, or that no one can be a zombie - following from the assertion that one's own conviction about being (or not being) a zombie is a product of the physical world and is therefore no different from anyone else's. Daniel Dennett, a critic of the argument, remarks that "Zombie
Zombie
Zombie is a term used to denote an animated corpse brought back to life by mystical means such as witchcraft. The term is often figuratively applied to describe a hypnotized person bereft of consciousness and self-awareness, yet ambulant and able to respond to surrounding stimuli...

s thinkZ they are conscious, thinkZ they have qualia, thinkZ they suffer pains - they are just 'wrong' (according to this lamentable tradition), in ways that neither they nor we could ever discover!"

The possibility of zombies would also entail that mental states do not supervene upon physical states, a claim that the reductionist physicalist is committed to, and Australian Philosopher David Chalmers
David Chalmers
David John Chalmers is an Australian philosopher specializing in the area of philosophy of mind and philosophy of language, whose recent work concerns verbal disputes. He is Professor of Philosophy and Director of the Centre for Consciousness at the Australian National University...

 argues that the coherent conceivability of a zombie entails a metaphysical possibility. It has also been explained by arguing that the zombie argument rests on the concept of the nature of qualia
Qualia
Qualia , singular "quale" , from a Latin word meaning for "what sort" or "what kind," is a term used in philosophy to refer to subjective conscious experiences as 'raw feels'. Examples of qualia are the pain of a headache, the taste of wine, the experience of taking a recreational drug, or the...

. If certain non-physical properties exist which match our conception of qualia, then such non-physical properties would be qualia, and zombies would be conceivable and metaphysically possible. However, if there are no non-physical properties, then what we think of as qualia are the physical properties which perform the functional tasks of what we conceive of as qualia. In this scenario, zombies would not be metaphysically possible.

Physicalist response


Although it has been argued that zombies in an observed world are indistinguishable from the observer (and therefore non-existent) under the assumption of reductionist physicalism, it has also been argued that zombies are not conceivable. It has been claimed under reductive physicalism, that when a distinction is made in ones mind between a hypothetical zombie and oneself (assumed not to be a zombie), and noting that the concept of oneself under reductive physicalism may ever only correspond to physical reality, the concept of the hypothetical zombie can only be a subset of the concept of oneself and will in this nature also entail a deficit in observables (cognitive systems) thereby contradicting the original definition of a zombie. This argument has been expressed by Daniel Dennett
Daniel Dennett
Daniel Clement Dennett is an American philosopher, writer and cognitive scientist whose research centers on the philosophy of mind, philosophy of science and philosophy of biology, particularly as those fields relate to evolutionary biology and cognitive science. He is currently the Co-director of...

 who argues that, "when philosophers claim that zombies are conceivable, they invariably underestimate the task of conception (or imagination), and end up imagining something that violates their own definition". Dennett, in The Unimagined Preposterousness of Zombies (1995) compares consciousness to health
Health
Health is the level of functional or metabolic efficiency of a living being. In humans, it is the general condition of a person's mind, body and spirit, usually meaning to be free from illness, injury or pain...

.

Hempel's dilemma


Hempel's Dilemma attacks how physicalism is defined. One could either define the physical with respect to the entities stipulated by contemporary physics or with respect to some future complete physics. Both options seem problematic. In the first case, it seems reasonable to assume (based on the history of science) that current physical theories will very probably be refined by future scientific discoveries. Therefore, it is very likely that any definition of "the physical" based on the current state of physics would end up being ultimately false. If on the other hand, we define the notion of what is physical based some future idealized physics, we have not effectively defined anything at all because nobody knows what entities a future physical theory might postulate.

Physicalist response


A scientifically minded physicalist may, following Andrew Melnyk, accept the first horn of the dilemma; that is, a physicalist could live with the idea that the current definition of physicalism may very likely end up being false as long as he believes the proposition is more plausible than any currently formulated rival proposition, such as dualism. Melnyk maintains that this is precisely the attitude most scientists hold towards current scientific theories anyway. For example, a defender of evolution may well accept that the current formulation of evolutionary theory is likely to be revised in the future, but she defends evolution because she believes current evolutionary theory is more likely than any current rival idea, such as Creationism. Thus, Melnyk's rebuttal, stated very crudely, is that one should define physicalism in relation to current physics, and hold a similar attitude towards its truth as most scientists hold towards the truth of currently accepted scientific theories.

Jaegwon Kim's argument against non-reductivism


Kim
Jaegwon Kim
Jaegwon Kim is a Korean American philosopher currently working at Brown University. He is best known for his work on mental causation and the mind-body problem. Key themes in his work include: a rejection of Cartesian metaphysics, the limitations of strict psychophysical identity, supervenience,...

 proposed that one cannot be a physicalist and a non-reductivist. Physicalism, according to Kim, has a principle of causal closure according to which every physical event is fully accountable in terms of physical causes. Claims that bodily movements are caused by the preceding state of the body and decisions/intentions are overdetermined. In other words, if the preceding state of the body is both necessary and sufficient, additional conditions are irrelevant.

Kim
Jaegwon Kim
Jaegwon Kim is a Korean American philosopher currently working at Brown University. He is best known for his work on mental causation and the mind-body problem. Key themes in his work include: a rejection of Cartesian metaphysics, the limitations of strict psychophysical identity, supervenience,...

 also attributes to physicalism the principle of causal exclusion according to which if one event has a sufficient cause at one time, no other event can be the cause. This then poses a problem for mental causation if one believes in the supervenience thesis of physicalism.

A priori and a posteriori physicalism


Physicalism is then further divided depending on whether it can be known a priori or a posteriori
A priori and a posteriori (philosophy)
The terms a priori and a posteriori are used in philosophy to distinguish two types of knowledge, justifications or arguments...

 that: If physicalism is true, S is the statement that describes the entire physical nature of the world collectively, and S* is the statement that describes the entire nature of the world, then S entails S*.

A priori physicalism holds that the above can be known without observation, i.e., independently from experience. Originally, it was assumed that physicalism was a priori, until Kripke argued in Naming and Necessity
Naming and Necessity
Naming and Necessity is a book by the philosopher Saul Kripke that was first published in 1980 and deals with the debates of proper nouns in the philosophy of language. The book is based on a transcript of three lectures given at Princeton University in 1970...

for the existence of necessary a posteriori truths.
However, an underexplored approach is that of Helmuth Plessner
Helmuth Plessner
Helmuth Plessner was a German philosopher and sociologist, and a primary advocate of "philosophical anthropology" .He was Chairman from 1953-1959 of the Deutsche Gesellschaft für Soziologie....

, whose idea of a material a priori based in our biology and environmental interactions is only now being recognized as relevant to a hermeneutics of nature, for example, in the works of Petran Kokelkoren.

A posteriori physicalism holds physicalism as a necessary truth known a posteriori, i.e., known through empirical observation. There are two main interpretations of a posteriori physicalism which exist today. One is that a posteriori truth can be reached a priori by contingent a posteriori truths. The other holds that there are a posteriori truths that are taken from non-contingent (i.e., necessary) truths. A problem arises when the former is combined with "S entails S*", leading to a contradiction. This view remains controversial within analytic philosophy.

See also


  • Monism
    Monism
    Monism is any philosophical view which holds that there is unity in a given field of inquiry. Accordingly, some philosophers may hold that the universe is one rather than dualistic or pluralistic...

  • Ontological pluralism
  • Presentism
    Presentism (philosophy of time)
    Saint Augustine proposed that the present is a knife edge between the past and the future and could not contain any extended period of time. This seems evident because, if the present is extended, it must have separate parts - but these must be simultaneous if they are truly part of the present...


External links