Philosophy of mind is a branch of philosophy
that studies the ontology, nature, and relationship
of the mind to the body. The mind–body problem
is a paradigm issue in philosophy of mind,
although other issues are addressed, such
as the hard problem of consciousness, and
the nature of particular mental states. Aspects
of the mind that are studied include mental
events, mental functions, mental properties,
consciousness, the ontology of the mind, the
nature of thought, and the relationship of
the mind to the body.
Dualism and monism are the two central schools
of thought on the mind–body problem, although
nuanced views have arisen that do not fit
one or the other category neatly. Dualism
finds its entry into Western philosophy thanks
to René Descartes in the 17th century. Substance
dualists like Descartes argue that the mind
is an independently existing substance, whereas
property dualists maintain that the mind is
a group of independent properties that emerge
from and cannot be reduced to the brain, but
that it is not a distinct substance.Monism
is the position that mind and body are not
ontologically distinct entities (independent
substances). This view was first advocated
in Western philosophy by Parmenides in the
5th century BCE and was later espoused by
the 17th century rationalist Baruch Spinoza.
Physicalists argue that only entities postulated
by physical theory exist, and that mental
processes will eventually be explained in
terms of these entities as physical theory
continues to evolve. Physicalists maintain
various positions on the prospects of reducing
mental properties to physical properties (many
of whom adopt compatible forms of property
dualism), and the ontological status of such
mental properties remains unclear. Idealists
maintain that the mind is all that exists
and that the external world is either mental
itself, or an illusion created by the mind.
Neutral monists such as Ernst Mach and William
James argue that events in the world can be
thought of as either mental (psychological)
or physical depending on the network of relationships
into which they enter, and dual-aspect monists
such as Spinoza adhere to the position that
there is some other, neutral substance, and
that both matter and mind are properties of
this unknown substance. The most common monisms
in the 20th and 21st centuries have all been
variations of physicalism; these positions
include behaviorism, the type identity theory,
anomalous monism and functionalism.Most modern
philosophers of mind adopt either a reductive
physicalist or non-reductive physicalist position,
maintaining in their different ways that the
mind is not something separate from the body.
These approaches have been particularly influential
in the sciences, especially in the fields
of sociobiology, computer science (specifically,
artificial intelligence), evolutionary psychology
and the various neurosciences. Reductive physicalists
assert that all mental states and properties
will eventually be explained by scientific
accounts of physiological processes and states.
Non-reductive physicalists argue that although
the mind is not a separate substance, mental
properties supervene on physical properties,
or that the predicates and vocabulary used
in mental descriptions and explanations are
indispensable, and cannot be reduced to the
language and lower-level explanations of physical
science. Continued neuroscientific progress
has helped to clarify some of these issues;
however, they are far from being resolved.
Modern philosophers of mind continue to ask
how the subjective qualities and the intentionality
of mental states and properties can be explained
in naturalistic terms.
== Mind–body problem ==
The mind–body problem concerns the explanation
of the relationship that exists between minds,
or mental processes, and bodily states or
processes. The main aim of philosophers working
in this area is to determine the nature of
the mind and mental states/processes, and
how—or even if—minds are affected by and
can affect the body.
Our perceptual experiences depend on stimuli
that arrive at our various sensory organs
from the external world, and these stimuli
cause changes in our mental states, ultimately
causing us to feel a sensation, which may
be pleasant or unpleasant. Someone's desire
for a slice of pizza, for example, will tend
to cause that person to move his or her body
in a specific manner and in a specific direction
to obtain what he or she wants. The question,
then, is how it can be possible for conscious
experiences to arise out of a lump of gray
matter endowed with nothing but electrochemical
properties.A related problem is how someone's
propositional attitudes (e.g. beliefs and
desires) cause that individual's neurons to
fire and muscles to contract. These comprise
some of the puzzles that have confronted epistemologists
and philosophers of mind from at least the
time of René Descartes.
== Dualist solutions to the mind–body problem
==
Dualism is a set of views about the relationship
between mind and matter (or body). It begins
with the claim that mental phenomena are,
in some respects, non-physical. One of the
earliest known formulations of mind–body
dualism was expressed in the eastern Sankhya
and Yoga schools of Hindu philosophy (c. 650
BCE), which divided the world into purusha
(mind/spirit) and prakriti (material substance).
Specifically, the Yoga Sutra of Patanjali
presents an analytical approach to the nature
of the mind.
In Western Philosophy, the earliest discussions
of dualist ideas are in the writings of Plato
who maintained that humans' "intelligence"
(a faculty of the mind or soul) could not
be identified with, or explained in terms
of, their physical body. However, the best-known
version of dualism is due to René Descartes
(1641), and holds that the mind is a non-extended,
non-physical substance, a "res cogitans".
Descartes was the first to clearly identify
the mind with consciousness and self-awareness,
and to distinguish this from the brain, which
was the seat of intelligence. He was therefore
the first to formulate the mind–body problem
in the form in which it still exists today.
=== Arguments for dualism ===
The most frequently used argument in favor
of dualism appeals to the common-sense intuition
that conscious experience is distinct from
inanimate matter. If asked what the mind is,
the average person would usually respond by
identifying it with their self, their personality,
their soul, or some other such entity. They
would almost certainly deny that the mind
simply is the brain, or vice versa, finding
the idea that there is just one ontological
entity at play to be too mechanistic, or simply
unintelligible. Many modern philosophers of
mind think that these intuitions are misleading
and that we should use our critical faculties,
along with empirical evidence from the sciences,
to examine these assumptions to determine
whether there is any real basis to them.Another
important argument in favor of dualism is
that the mental and the physical seem to have
quite different, and perhaps irreconcilable,
properties. Mental events have a subjective
quality, whereas physical events do not. So,
for example, one can reasonably ask what a
burnt finger feels like, or what a blue sky
looks like, or what nice music sounds like
to a person. But it is meaningless, or at
least odd, to ask what a surge in the uptake
of glutamate in the dorsolateral portion of
the prefrontal cortex feels like.
Philosophers of mind call the subjective aspects
of mental events "qualia" or "raw feels".
There is something that it is like to feel
pain, to see a familiar shade of blue, and
so on. There are qualia involved in these
mental events that seem particularly difficult
to reduce to anything physical. David Chalmers
explains this argument by stating that we
could conceivably know all the objective information
about something, such as the brain states
and wavelengths of light involved with seeing
the color red, but still not know something
fundamental about the situation – what it
is like to see the color red.If consciousness
(the mind) can exist independently of physical
reality (the brain), one must explain how
physical memories are created concerning consciousness.
Dualism must therefore explain how consciousness
affects physical reality. One possible explanation
is that of a miracle, proposed by Arnold Geulincx
and Nicolas Malebranche, where all mind–body
interactions require the direct intervention
of God.
Another possible argument that has been proposed
by C. S. Lewis is the Argument from Reason:
if, as monism implies, all of our thoughts
are the effects of physical causes, then we
have no reason for assuming that they are
also the consequent of a reasonable ground.
Knowledge, however, is apprehended by reasoning
from ground to consequent. Therefore, if monism
is correct, there would be no way of knowing
this—or anything else—we could not even
suppose it, except by a fluke.
The zombie argument is based on a thought
experiment proposed by Todd Moody, and developed
by David Chalmers in his book The Conscious
Mind. The basic idea is that one can imagine
one's body, and therefore conceive the existence
of one's body, without any conscious states
being associated with this body. Chalmers'
argument is that it seems possible that such
a being could exist because all that is needed
is that all and only the things that the physical
sciences describe about a zombie must be true
of it. Since none of the concepts involved
in these sciences make reference to consciousness
or other mental phenomena, and any physical
entity can be by definition described scientifically
via physics, the move from conceivability
to possibility is not such a large one. Others
such as Dennett have argued that the notion
of a philosophical zombie is an incoherent,
or unlikely, concept. It has been argued under
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. This argument
has been expressed by Dennett who argues that
"Zombies think they are conscious, think they
have qualia, think they suffer pains—they
are just 'wrong' (according to this lamentable
tradition) in ways that neither they nor we
could ever discover!"
See also the problem of other minds.
=== Interactionist dualism ===
Interactionist dualism, or simply interactionism,
is the particular form of dualism first espoused
by Descartes in the Meditations. In the 20th
century, its major defenders have been Karl
Popper and John Carew Eccles. It is the view
that mental states, such as beliefs and desires,
causally interact with physical states.Descartes'
famous argument for this position can be summarized
as follows: Seth has a clear and distinct
idea of his mind as a thinking thing that
has no spatial extension (i.e., it cannot
be measured in terms of length, weight, height,
and so on). He also has a clear and distinct
idea of his body as something that is spatially
extended, subject to quantification and not
able to think. It follows that mind and body
are not identical because they have radically
different properties.At the same time, however,
it is clear that Seth's mental states (desires,
beliefs, etc.) have causal effects on his
body and vice versa: A child touches a hot
stove (physical event) which causes pain (mental
event) and makes her yell (physical event),
this in turn provokes a sense of fear and
protectiveness in the caregiver (mental event),
and so on.
Descartes' argument crucially depends on the
premise that what Seth believes to be "clear
and distinct" ideas in his mind are necessarily
true. Many contemporary philosophers doubt
this. For example, Joseph Agassi suggests
that several scientific discoveries made since
the early 20th century have undermined the
idea of privileged access to one's own ideas.
Freud claimed that a psychologically-trained
observer can understand a person's unconscious
motivations better than the person himself
does. Duhem has shown that a philosopher of
science can know a person's methods of discovery
better than that person herself does, while
Malinowski has shown that an anthropologist
can know a person's customs and habits better
than the person whose customs and habits they
are. He also asserts that modern psychological
experiments that cause people to see things
that are not there provide grounds for rejecting
Descartes' argument, because scientists can
describe a person's perceptions better than
the person herself can.
=== Other forms of dualism ===
==== 
Psychophysical parallelism ====
Psychophysical parallelism, or simply parallelism,
is the view that mind and body, while having
distinct ontological statuses, do not causally
influence one another. Instead, they run along
parallel paths (mind events causally interact
with mind events and brain events causally
interact with brain events) and only seem
to influence each other. This view was most
prominently defended by Gottfried Leibniz.
Although Leibniz was an ontological monist
who believed that only one type of substance,
the monad, exists in the universe, and that
everything is reducible to it, he nonetheless
maintained that there was an important distinction
between "the mental" and "the physical" in
terms of causation. He held that God had arranged
things in advance so that minds and bodies
would be in harmony with each other. This
is known as the doctrine of pre-established
harmony.
==== Occasionalism ====
Occasionalism is the view espoused by Nicholas
Malebranche as well as Islamic philosophers
such as Abu Hamid Muhammad ibn Muhammad al-Ghazali
that asserts that all supposedly causal relations
between physical events, or between physical
and mental events, are not really causal at
all. While body and mind are different substances,
causes (whether mental or physical) are related
to their effects by an act of God's intervention
on each specific occasion.
==== Property dualism ====
Property dualism is the view that the world
is constituted of just one kind of substance
– the physical kind – and there exist
two distinct kinds of properties: physical
properties and mental properties. In other
words, it is the view that non-physical, mental
properties (such as beliefs, desires and emotions)
inhere in some physical bodies (at least,
brains). How mental and physical properties
relate causally depends on the variety of
property dualism in question, and is not always
a clear issue. Sub-varieties of property dualism
include:
Emergent materialism asserts that when matter
is organized in the appropriate way (i.e.
in the way that living human bodies are organized),
mental properties emerge in a way not fully
accountable for by physical laws. These emergent
properties have an independent ontological
status and cannot be reduced to, or explained
in terms of, the physical substrate from which
they emerge. They are dependent on the physical
properties from which they emerge, but opinions
vary as to the coherence of top–down causation,
i.e. the causal effectiveness of such properties.
A form of emergent materialism has been espoused
by David Chalmers and the concept has undergone
something of a renaissance in recent years,
but it was already suggested in the 19th century
by William James.
Epiphenomenalism is a doctrine first formulated
by Thomas Henry Huxley. It consists of the
view that mental phenomena are causally ineffectual,
where one or more mental states do not have
any influence on physical states or mental
phenomena are the effects, but not the causes,
of physical phenomena. Physical events can
cause other physical events and physical events
can cause mental events, but mental events
cannot cause anything, since they are just
causally inert by-products (i.e. epiphenomena)
of the physical world. This view has been
defended most strongly in recent times by
Frank Jackson.
Non-reductive physicalism is the view that
mental properties form a separate ontological
class to physical properties: mental states
(such as qualia) are not reducible to physical
states. The ontological stance towards qualia
in the case of non-reductive physicalism does
not imply that qualia are causally inert;
this is what distinguishes it from epiphenomenalism.
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. Superficially, it seems to be a form
of property dualism, since it regards everything
as having both mental and physical properties.
However, some panpsychists say that mechanical
behaviour is derived from the primitive mentality
of atoms and molecules—as are sophisticated
mentality and organic behaviour, the difference
being attributed to the presence or absence
of complex structure in a compound object.
So long as the reduction of non-mental properties
to mental ones is in place, panpsychism is
not a (strong) form of property dualism; otherwise
it is.
==== Dual aspect theory ====
Dual aspect theory or dual-aspect monism is
the view that the mental and the physical
are two aspects of, or perspectives on, the
same substance. (Thus it is a mixed position,
which is monistic in some respects). In modern
philosophical writings, the theory's relationship
to neutral monism has become somewhat ill-defined,
but one proffered distinction says that whereas
neutral monism allows the context of a given
group of neutral elements and the relationships
into which they enter to determine whether
the group can be thought of as mental, physical,
both, or neither, dual-aspect theory suggests
that the mental and the physical are manifestations
(or aspects) of some underlying substance,
entity or process that is itself neither mental
nor physical as normally understood. Various
formulations of dual-aspect monism also require
the mental and the physical to be complementary,
mutually irreducible and perhaps inseparable
(though distinct).
==== Experiential dualism ====
This is a philosophy of mind that regards
the degrees of freedom between mental and
physical well-being as not necessarily synonymous
thus implying an experiential dualism between
body and mind. An example of these disparate
degrees of freedom is given by Allan Wallace
who notes that it is "experientially apparent
that one may be physically uncomfortable—for
instance, while engaging in a strenuous physical
workout—while mentally cheerful; conversely,
one may be mentally distraught while experiencing
physical comfort". Experiential dualism notes
that our subjective experience of merely seeing
something in the physical world seems qualitatively
different than mental processes like grief
that comes from losing a loved one. This philosophy
also is a proponent of causal dualism which
is defined as the dual ability for mental
states and physical states to affect one another.
Mental states can cause changes in physical
states and vice versa.
However, unlike cartesian dualism or some
other systems, experiential dualism does not
posit two fundamental substances in reality:
mind and matter. Rather, experiential dualism
is to be understood as a conceptual framework
that gives credence to the qualitative difference
between the experience of mental and physical
states. Experiential dualism is accepted as
the conceptual framework of Madhyamaka Buddhism.
Madhayamaka Buddhism goes even further, finding
fault with the monist view of physicalist
philosophies of mind as well in that these
generally posit matter and energy as the fundamental
substance of reality. Nonetheless, this does
not imply that the cartesian dualist view
is correct, rather Madhyamaka regards as error
any affirming view of a fundamental substance
to reality.In denying the independent self-existence
of all the phenomena that make up the world
of our experience, the Madhyamaka view departs
from both the substance dualism of Descartes
and the substance monism—namely, physicalism—that
is characteristic of modern science. The physicalism
propounded by many contemporary scientists
seems to assert that the real world is composed
of physical things-in-themselves, while all
mental phenomena are regarded as mere appearances,
devoid of any reality in and of themselves.
Much is made of this difference between appearances
and reality.
Indeed, physicalism, or the idea that matter
is the only fundamental substance of reality,
is explicitly rejected by Buddhism.In the
Madhyamaka view, mental events are no more
or less real than physical events. In terms
of our common-sense experience, differences
of kind do exist between physical and mental
phenomena. While the former commonly have
mass, location, velocity, shape, size, and
numerous other physical attributes, these
are not generally characteristic of mental
phenomena. For example, we do not commonly
conceive of the feeling of affection for another
person as having mass or location. These physical
attributes are no more appropriate to other
mental events such as sadness, a recalled
image from one's childhood, the visual perception
of a rose, or consciousness of any sort. Mental
phenomena are, therefore, not regarded as
being physical, for the simple reason that
they lack many of the attributes that are
uniquely characteristic of physical phenomena.
Thus, Buddhism has never adopted the physicalist
principle that regards only physical things
as real.
== Monist solutions to the mind–body problem
==
In contrast to dualism, monism does not accept
any fundamental divisions. The fundamentally
disparate nature of reality has been central
to forms of eastern philosophies for over
two millennia. In Indian and Chinese philosophy,
monism is integral to how experience is understood.
Today, the most common forms of monism in
Western philosophy are physicalist. Physicalistic
monism asserts that the only existing substance
is physical, in some sense of that term to
be clarified by our best science. However,
a variety of formulations (see below) are
possible. Another form of monism, idealism,
states that the only existing substance is
mental. Although pure idealism, such as that
of George Berkeley, is uncommon in contemporary
Western philosophy, a more sophisticated variant
called panpsychism, according to which mental
experience and properties may be at the foundation
of physical experience and properties, has
been espoused by some philosophers such as
Alfred North Whitehead and David Ray Griffin.Phenomenalism
is the theory that representations (or sense
data) of external objects are all that exist.
Such a view was briefly adopted by Bertrand
Russell and many of the logical positivists
during the early 20th century. A third possibility
is to accept the existence of a basic substance
that is neither physical nor mental. The mental
and physical would then both be properties
of this neutral substance. Such a position
was adopted by Baruch Spinoza and was popularized
by Ernst Mach in the 19th century. This neutral
monism, as it is called, resembles property
dualism.
=== Physicalistic monisms ===
==== 
Behaviorism ====
Behaviorism dominated philosophy of mind for
much of the 20th century, especially the first
half. In psychology, behaviorism developed
as a reaction to the inadequacies of introspectionism.
Introspective reports on one's own interior
mental life are not subject to careful examination
for accuracy and cannot be used to form predictive
generalizations. Without generalizability
and the possibility of third-person examination,
the behaviorists argued, psychology cannot
be scientific. The way out, therefore, was
to eliminate the idea of an interior mental
life (and hence an ontologically independent
mind) altogether and focus instead on the
description of observable behavior.Parallel
to these developments in psychology, a philosophical
behaviorism (sometimes called logical behaviorism)
was developed. This is characterized by a
strong verificationism, which generally considers
unverifiable statements about interior mental
life pointless. For the behaviorist, mental
states are not interior states on which one
can make introspective reports. They are just
descriptions of behavior or dispositions to
behave in certain ways, made by third parties
to explain and predict another's behavior.Philosophical
behaviorism has fallen out of favor since
the latter half of the 20th century, coinciding
with the rise of cognitivism. Cognitivists
reject behaviorism due to several perceived
problems. For example, behaviorism could be
said to be counterintuitive when it maintains
that someone is talking about behavior in
the event that a person is experiencing a
painful headache.
==== Identity theory ====
Type physicalism (or type-identity theory)
was developed by John Smart and Ullin Place
as a direct reaction to the failure of behaviorism.
These philosophers reasoned that, if mental
states are something material, but not behavioral,
then mental states are probably identical
to internal states of the brain. In very simplified
terms: a mental state M is nothing other than
brain state B. The mental state "desire for
a cup of coffee" would thus be nothing more
than the "firing of certain neurons in certain
brain regions".
Despite its initial plausibility, the identity
theory faces a strong challenge in the form
of the thesis of multiple realizability, first
formulated by Hilary Putnam. For example,
not only humans, but many different species
of animals can experience pain. However, it
seems highly unlikely that all of these diverse
organisms with the same pain experience are
in the identical brain state. And if this
is the case, then pain cannot be identical
to a specific brain state. The identity theory
is thus empirically unfounded.On the other
hand, even granted the above, it does not
follow that identity theories of all types
must be abandoned. According to token identity
theories, the fact that a certain brain state
is connected with only one mental state of
a person does not have to mean that there
is an absolute correlation between types of
mental state and types of brain state. The
type–token distinction can be illustrated
by a simple example: the word "green" contains
four types of letters (g, r, e, n) with two
tokens (occurrences) of the letter e along
with one each of the others.
The idea of token identity is that only particular
occurrences of mental events are identical
with particular occurrences or tokenings of
physical events. Anomalous monism (see below)
and most other non-reductive physicalisms
are token-identity theories. Despite these
problems, there is a renewed interest in the
type identity theory today, primarily due
to the influence of Jaegwon Kim.
==== Functionalism ====
Functionalism was formulated by Hilary Putnam
and Jerry Fodor as a reaction to the inadequacies
of the identity theory. Putnam and Fodor saw
mental states in terms of an empirical computational
theory of the mind. At about the same time
or slightly after, D.M. Armstrong and David
Kellogg Lewis formulated a version of functionalism
that analyzed the mental concepts of folk
psychology in terms of functional roles. Finally,
Wittgenstein's idea of meaning as use led
to a version of functionalism as a theory
of meaning, further developed by Wilfrid Sellars
and Gilbert Harman. Another one, psychofunctionalism,
is an approach adopted by the naturalistic
philosophy of mind associated with Jerry Fodor
and Zenon Pylyshyn.
What all these different varieties of functionalism
share in common is the thesis that mental
states are characterized by their causal relations
with other mental states and with sensory
inputs and behavioral outputs. That is, functionalism
abstracts away from the details of the physical
implementation of a mental state by characterizing
it in terms of non-mental functional properties.
For example, a kidney is characterized scientifically
by its functional role in filtering blood
and maintaining certain chemical balances.
From this point of view, it does not really
matter whether the kidney be made up of organic
tissue, plastic nanotubes or silicon chips:
it is the role that it plays and its relations
to other organs that define it as a kidney.
==== Non-reductive physicalism ====
Non-reductionist philosophers hold firmly
to two essential convictions with regard to
mind–body relations: 1) Physicalism is true
and mental states must be physical states,
but 2) All reductionist proposals are unsatisfactory:
mental states cannot be reduced to behavior,
brain states or functional states. Hence,
the question arises whether there can still
be a non-reductive physicalism. Donald Davidson's
anomalous monism is an attempt to formulate
such a physicalism. He "thinks that when one
runs across what are traditionally seen as
absurdities of Reason, such as akrasia or
self-deception, the personal psychology framework
is not to be given up in favor of the subpersonal
one, but rather must be enlarged or extended
so that the rationality set out by the principle
of charity can be found elsewhere."Davidson
uses the thesis of supervenience: mental states
supervene on physical states, but are not
reducible to them. "Supervenience" therefore
describes a functional dependence: there can
be no change in the mental without some change
in the physical–causal reducibility between
the mental and physical without ontological
reducibility.Because non-reductive physicalist
theories attempt to both retain the ontological
distinction between mind and body and try
to solve the "surfeit of explanations puzzle"
in some way; critics often see this as a paradox
and point out the similarities to epiphenomenalism,
in that it is the brain that is seen as the
root "cause" not the mind, and the mind seems
to be rendered inert.
Epiphenomenalism regards one or more mental
states as the byproduct of physical brain
states, having no influence on physical states.
The interaction is one-way (solving the "surfeit
of explanations puzzle") but leaving us with
non-reducible mental states (as a byproduct
of brain states) – causally reducible, but
ontologically irreducible to physical states.
Pain would be seen by epiphenomenaliasts as
being caused by the brain state but as not
having effects on other brain states, though
it might have effects on other mental states
(i.e. cause distress).
==== Weak emergentism ====
Weak emergentism is a form of "non-reductive
physicalism" that involves a layered view
of nature, with the layers arranged in terms
of increasing complexity and each corresponding
to its own special science. Some philosophers
hold that emergent properties causally interact
with more fundamental levels, while others
maintain that higher-order properties simply
supervene over lower levels without direct
causal interaction. The latter group therefore
holds a less strict, or "weaker", definition
of emergentism, which can be rigorously stated
as follows: a property P of composite object
O is emergent if it is metaphysically impossible
for another object to lack property P if that
object is composed of parts with intrinsic
properties identical to those in O and has
those parts in an identical configuration.
Sometimes emergentists use the example of
water having a new property when Hydrogen
H and Oxygen O combine to form H2O (water).
In this example there "emerges" a new property
of a transparent liquid that would not have
been predicted by understanding hydrogen and
oxygen as gases. This is analogous to physical
properties of the brain giving rise to a mental
state. Emergentists try to solve the notorious
mind–body gap this way. One problem for
emergentism is the idea of "causal closure"
in the world that does not allow for a mind-to-body
causation.
==== Eliminative materialism ====
If one is a materialist and believes that
all aspects of our common-sense psychology
will find reduction to a mature cognitive
neuroscience, and that non-reductive materialism
is mistaken, then one can adopt a final, more
radical position: eliminative materialism.
There are several varieties of eliminative
materialism, but all maintain that our common-sense
"folk psychology" badly misrepresents the
nature of some aspect of cognition. Eliminativists
such as Patricia and Paul Churchland argue
that while folk psychology treats cognition
as fundamentally sentence-like, the non-linguistic
vector/matrix model of neural network theory
or connectionism will prove to be a much more
accurate account of how the brain works.The
Churchlands often invoke the fate of other,
erroneous popular theories and ontologies
that have arisen in the course of history.
For example, Ptolemaic astronomy served to
explain and roughly predict the motions of
the planets for centuries, but eventually
this model of the solar system was eliminated
in favor of the Copernican model. The Churchlands
believe the same eliminative fate awaits the
"sentence-cruncher" model of the mind in which
thought and behavior are the result of manipulating
sentence-like states called "propositional
attitudes".
== Mysterianism ==
Some philosophers take an epistemic approach
and argue that the mind–body problem is
currently unsolvable, and perhaps will always
remain unsolvable to human beings. This is
usually termed New mysterianism. Colin McGinn
holds that human beings are cognitively closed
in regards to their own minds. According to
McGinn human minds lack the concept-forming
procedures to fully grasp how mental properties
such as consciousness arise from their causal
basis. An example would be how an elephant
is cognitively closed in regards to particle
physics.
A more moderate conception has been expounded
by Thomas Nagel, which holds that the mind–body
problem is currently unsolvable at the present
stage of scientific development and that it
might take a future scientific paradigm shift
or revolution to bridge the explanatory gap.
Nagel posits that in the future a sort of
"objective phenomenology" might be able to
bridge the gap between subjective conscious
experience and its physical basis.
== Linguistic criticism of the mind–body
problem ==
Each attempt to answer the mind–body problem
encounters substantial problems. Some philosophers
argue that this is because there is an underlying
conceptual confusion. These philosophers,
such as Ludwig Wittgenstein and his followers
in the tradition of linguistic criticism,
therefore reject the problem as illusory.
They argue that it is an error to ask how
mental and biological states fit together.
Rather it should simply be accepted that human
experience can be described in different ways—for
instance, in a mental and in a biological
vocabulary. Illusory problems arise if one
tries to describe the one in terms of the
other's vocabulary or if the mental vocabulary
is used in the wrong contexts. This is the
case, for instance, if one searches for mental
states of the brain. The brain is simply the
wrong context for the use of mental vocabulary—the
search for mental states of the brain is therefore
a category error or a sort of fallacy of reasoning.Today,
such a position is often adopted by interpreters
of Wittgenstein such as Peter Hacker. However,
Hilary Putnam, the originator of functionalism,
has also adopted the position that the mind–body
problem is an illusory problem which should
be dissolved according to the manner of Wittgenstein.
== Naturalism and its problems ==
The thesis of physicalism is that the mind
is part of the material (or physical) world.
Such a position faces the problem that the
mind has certain properties that no other
material thing seems to possess. Physicalism
must therefore explain how it is possible
that these properties can nonetheless emerge
from a material thing. The project of providing
such an explanation is often referred to as
the "naturalization of the mental". Some of
the crucial problems that this project attempts
to resolve include the existence of qualia
and the nature of intentionality.
=== Qualia ===
Many mental states seem to be experienced
subjectively in different ways by different
individuals. And it is characteristic of a
mental state that it has some experiential
quality, e.g. of pain, that it hurts. However,
the sensation of pain between two individuals
may not be identical, since no one has a perfect
way to measure how much something hurts or
of describing exactly how it feels to hurt.
Philosophers and scientists therefore ask
where these experiences come from. The existence
of cerebral events, in and of themselves,
cannot explain why they are accompanied by
these corresponding qualitative experiences.
The puzzle of why many cerebral processes
occur with an accompanying experiential aspect
in consciousness seems impossible to explain.Yet
it also seems to many that science will eventually
have to explain such experiences. This follows
from an assumption about the possibility of
reductive explanations. According to this
view, if an attempt can be successfully made
to explain a phenomenon reductively (e.g.,
water), then it can be explained why the phenomenon
has all of its properties (e.g., fluidity,
transparency). In the case of mental states,
this means that there needs to be an explanation
of why they have the property of being experienced
in a certain way.
The 20th-century German philosopher Martin
Heidegger criticized the ontological assumptions
underpinning such a reductive model, and claimed
that it was impossible to make sense of experience
in these terms. This is because, according
to Heidegger, the nature of our subjective
experience and its qualities is impossible
to understand in terms of Cartesian "substances"
that bear "properties". Another way to put
this is that the very concept of qualitative
experience is incoherent in terms of—or
is semantically incommensurable with the concept
of—substances that bear properties.This
problem of explaining introspective first-person
aspects of mental states and consciousness
in general in terms of third-person quantitative
neuroscience is called the explanatory gap.
There are several different views of the nature
of this gap among contemporary philosophers
of mind. David Chalmers and the early Frank
Jackson interpret the gap as ontological in
nature; that is, they maintain that qualia
can never be explained by science because
physicalism is false. There are two separate
categories involved and one cannot be reduced
to the other. An alternative view is taken
by philosophers such as Thomas Nagel and Colin
McGinn. According to them, the gap is epistemological
in nature. For Nagel, science is not yet able
to explain subjective experience because it
has not yet arrived at the level or kind of
knowledge that is required. We are not even
able to formulate the problem coherently.
For McGinn, on other hand, the problem is
one of permanent and inherent biological limitations.
We are not able to resolve the explanatory
gap because the realm of subjective experiences
is cognitively closed to us in the same manner
that quantum physics is cognitively closed
to elephants. Other philosophers liquidate
the gap as purely a semantic problem. This
semantic problem, of course, led to the famous
"Qualia Question", which is: Does Red cause
Redness?
=== Intentionality ===
Intentionality is the capacity of mental states
to be directed towards (about) or be in relation
with something in the external world. This
property of mental states entails that they
have contents and semantic referents and can
therefore be assigned truth values. When one
tries to reduce these states to natural processes
there arises a problem: natural processes
are not true or false, they simply happen.
It would not make any sense to say that a
natural process is true or false. But mental
ideas or judgments are true or false, so how
then can mental states (ideas or judgments)
be natural processes? The possibility of assigning
semantic value to ideas must mean that such
ideas are about facts. Thus, for example,
the idea that Herodotus was a historian refers
to Herodotus and to the fact that he was a
historian. If the fact is true, then the idea
is true; otherwise, it is false. But where
does this relation come from? In the brain,
there are only electrochemical processes and
these seem not to have anything to do with
Herodotus.
== Philosophy of perception ==
Philosophy of perception is concerned with
the nature of perceptual experience and the
status of perceptual objects, in particular
how perceptual experience relates to appearances
and beliefs about the world. The main contemporary
views within philosophy of perception include
naive realism, enactivism and representational
views.
== Philosophy of mind and science ==
Humans are corporeal beings and, as such,
they are subject to examination and description
by the natural sciences. Since mental processes
are intimately related to bodily processes,
the descriptions that the natural sciences
furnish of human beings play an important
role in the philosophy of mind. There are
many scientific disciplines that study processes
related to the mental. The list of such sciences
includes: biology, computer science, cognitive
science, cybernetics, linguistics, medicine,
pharmacology, and psychology.
=== Neurobiology ===
The theoretical background of biology, as
is the case with modern natural sciences in
general, is fundamentally materialistic. The
objects of study are, in the first place,
physical processes, which are considered to
be the foundations of mental activity and
behavior. The increasing success of biology
in the explanation of mental phenomena can
be seen by the absence of any empirical refutation
of its fundamental presupposition: "there
can be no change in the mental states of a
person without a change in brain states."Within
the field of neurobiology, there are many
subdisciplines that are concerned with the
relations between mental and physical states
and processes: Sensory neurophysiology investigates
the relation between the processes of perception
and stimulation. Cognitive neuroscience studies
the correlations between mental processes
and neural processes. Neuropsychology describes
the dependence of mental faculties on specific
anatomical regions of the brain. Lastly, evolutionary
biology studies the origins and development
of the human nervous system and, in as much
as this is the basis of the mind, also describes
the ontogenetic and phylogenetic development
of mental phenomena beginning from their most
primitive stages. Evolutionary biology furthermore
places tight constraints on any philosophical
theory of the mind, as the gene-based mechanism
of natural selection does not allow any giant
leaps in the development of neural complexity
or neural software but only incremental steps
over long time periods.
The methodological breakthroughs of the neurosciences,
in particular the introduction of high-tech
neuroimaging procedures, has propelled scientists
toward the elaboration of increasingly ambitious
research programs: one of the main goals is
to describe and comprehend the neural processes
which correspond to mental functions (see:
neural correlate). Several groups are inspired
by these advances.
=== Computer science ===
Computer science concerns itself with the
automatic processing of information (or at
least with physical systems of symbols to
which information is assigned) by means of
such things as computers. From the beginning,
computer programmers have been able to develop
programs that permit computers to carry out
tasks for which organic beings need a mind.
A simple example is multiplication. It is
not clear whether computers could be said
to have a mind. Could they, someday, come
to have what we call a mind? This question
has been propelled into the forefront of much
philosophical debate because of investigations
in the field of artificial intelligence (AI).
Within AI, it is common to distinguish between
a modest research program and a more ambitious
one: this distinction was coined by John Searle
in terms of a weak AI and strong AI. The exclusive
objective of "weak AI", according to Searle,
is the successful simulation of mental states,
with no attempt to make computers become conscious
or aware, etc. The objective of strong AI,
on the contrary, is a computer with consciousness
similar to that of human beings. The program
of strong AI goes back to one of the pioneers
of computation Alan Turing. As an answer to
the question "Can computers think?", he formulated
the famous Turing test. Turing believed that
a computer could be said to "think" when,
if placed in a room by itself next to another
room that contained a human being and with
the same questions being asked of both the
computer and the human being by a third party
human being, the computer's responses turned
out to be indistinguishable from those of
the human. Essentially, Turing's view of machine
intelligence followed the behaviourist model
of the mind—intelligence is as intelligence
does. The Turing test has received many criticisms,
among which the most famous is probably the
Chinese room thought experiment formulated
by Searle.The question about the possible
sensitivity (qualia) of computers or robots
still remains open. Some computer scientists
believe that the specialty of AI can still
make new contributions to the resolution of
the "mind–body problem". They suggest that
based on the reciprocal influences between
software and hardware that takes place in
all computers, it is possible that someday
theories can be discovered that help us to
understand the reciprocal influences between
the human mind and the brain (wetware).
=== Psychology ===
Psychology is the science that investigates
mental states directly. It uses generally
empirical methods to investigate concrete
mental states like joy, fear or obsessions.
Psychology investigates the laws that bind
these mental states to each other or with
inputs and outputs to the human organism.An
example of this is the psychology of perception.
Scientists working in this field have discovered
general principles of the perception of forms.
A law of the psychology of forms says that
objects that move in the same direction are
perceived as related to each other. This law
describes a relation between visual input
and mental perceptual states. However, it
does not suggest anything about the nature
of perceptual states. The laws discovered
by psychology are compatible with all the
answers to the mind–body problem already
described.
=== Cognitive science ===
Cognitive science is the interdisciplinary
scientific study of the mind and its processes.
It examines what cognition is, what it does,
and how it works. It includes research on
intelligence and behavior, especially focusing
on how information is represented, processed,
and transformed (in faculties such as perception,
language, memory, reasoning, and emotion)
within nervous systems (human or other animal)
and machines (e.g. computers). Cognitive science
consists of multiple research disciplines,
including psychology, artificial intelligence,
philosophy, neuroscience, linguistics, anthropology,
sociology, and education. It spans many levels
of analysis, from low-level learning and decision
mechanisms to high-level logic and planning;
from neural circuitry to modular brain organisation.
Rowlands argues that cognition is enactive,
embodied, embedded, affective and (potentially)
extended. The position is taken that the "classical
sandwich" of cognition sandwiched between
perception and action is artificial; cognition
has to be seen as a product of a strongly
coupled interaction that cannot be divided
this way.
== Philosophy of mind in the continental tradition
==
Most of the discussion in this article has
focused on one style or tradition of philosophy
in modern Western culture, usually called
analytic philosophy (sometimes described as
Anglo-American philosophy). Many other schools
of thought exist, however, which are sometimes
subsumed under the broad (and vague) label
of continental philosophy. In any case, though
topics and methods here are numerous, in relation
to the philosophy of mind the various schools
that fall under this label (phenomenology,
existentialism, etc.) can globally be seen
to differ from the analytic school in that
they focus less on language and logical analysis
alone but also take in other forms of understanding
human existence and experience. With reference
specifically to the discussion of the mind,
this tends to translate into attempts to grasp
the concepts of thought and perceptual experience
in some sense that does not merely involve
the analysis of linguistic forms.Immanuel
Kant's Critique of Pure Reason, first published
in 1781 and presented again with major revisions
in 1787, represents a significant intervention
into what will later become known as the philosophy
of mind. Kant's first critique is generally
recognized as among the most significant works
of modern philosophy in the West. Kant is
a figure whose influence is marked in both
continental and analytic/Anglo-American philosophy.
Kant's work develops an in-depth study of
transcendental consciousness, or the life
of the mind as conceived through universal
categories of consciousness.
In Georg Wilhelm Friedrich Hegel's Philosophy
of Mind (frequently translated as Philosophy
of Spirit or Geist), the third part of his
Encyclopedia of the Philosophical Sciences,
Hegel discusses three distinct types of mind:
the "subjective mind/spirit", the mind of
an individual; the "objective mind/spirit",
the mind of society and of the State; and
the "Absolute mind/spirit", the position of
religion, art, and philosophy. See also Hegel's
The Phenomenology of Spirit. Nonetheless,
Hegel's work differs radically from the style
of Anglo-American philosophy of mind.
In 1896, Henri Bergson made in Matter and
Memory "Essay on the relation of body and
spirit" a forceful case for the ontological
difference of body and mind by reducing the
problem to the more definite one of memory,
thus allowing for a solution built on the
empirical test case of aphasia.
In modern times, the two main schools that
have developed in response or opposition to
this Hegelian tradition are phenomenology
and existentialism. Phenomenology, founded
by Edmund Husserl, focuses on the contents
of the human mind (see noema) and how processes
shape our experiences. Existentialism, a school
of thought founded upon the work of Søren
Kierkegaard, focuses on Human predicament
and how people deal with the situation of
being alive. Existential-phenomenology represents
a major branch of continental philosophy (they
are not contradictory), rooted in the work
of Husserl but expressed in its fullest forms
in the work of Martin Heidegger, Jean-Paul
Sartre, Simone de Beauvoir and Maurice Merleau-Ponty.
See Heidegger's Being and Time, Merleau-Ponty's
Phenomenology of Perception, Sartre's Being
and Nothingness, and Simone de Beauvoir's
The Second Sex.
== Topics related to philosophy of mind ==
There are countless subjects that are affected
by the ideas developed in the philosophy of
mind. Clear examples of this are the nature
of death and its definitive character, the
nature of emotion, of perception and of memory.
Questions about what a person is and what
his or her identity consists of also have
much to do with the philosophy of mind. There
are two subjects that, in connection with
the philosophy of the mind, have aroused special
attention: free will and the self.
=== Free will ===
In the context of philosophy of mind, the
problem of free will takes on renewed intensity.
This is certainly the case, at least, for
materialistic determinists. According to this
position, natural laws completely determine
the course of the material world. Mental states,
and therefore the will as well, would be material
states, which means human behavior and decisions
would be completely determined by natural
laws. Some take this reasoning a step further:
people cannot determine by themselves what
they want and what they do. Consequently,
they are not free.This argumentation is rejected,
on the one hand, by the compatibilists. Those
who adopt this position suggest that the question
"Are we free?" can only be answered once we
have determined what the term "free" means.
The opposite of "free" is not "caused" but
"compelled" or "coerced". It is not appropriate
to identify freedom with indetermination.
A free act is one where the agent could have
done otherwise if it had chosen otherwise.
In this sense a person can be free even though
determinism is true. The most important compatibilist
in the history of the philosophy was David
Hume. More recently, this position is defended,
for example, by Daniel Dennett.On the other
hand, there are also many incompatibilists
who reject the argument because they believe
that the will is free in a stronger sense
called libertarianism. These philosophers
affirm the course of the world is either a)
not completely determined by natural law where
natural law is intercepted by physically independent
agency, b) determined by indeterministic natural
law only, or c) determined by indeterministic
natural law in line with the subjective effort
of physically non-reducible agency. Under
Libertarianism, the will does not have to
be deterministic and, therefore, it is potentially
free. Critics of the second proposition (b)
accuse the incompatibilists of using an incoherent
concept of freedom. They argue as follows:
if our will is not determined by anything,
then we desire what we desire by pure chance.
And if what we desire is purely accidental,
we are not free. So if our will is not determined
by anything, we are not free.
=== Self ===
The philosophy of mind also has important
consequences for the concept of "self". If
by "self" or "I" one refers to an essential,
immutable nucleus of the person, some modern
philosophers of mind, such as Daniel Dennett
believe that no such thing exists. According
to Dennett and other contemporaries, the self
is considered an illusion. The idea of a self
as an immutable essential nucleus derives
from the idea of an immaterial soul. Such
an idea is unacceptable to modern philosophers
with physicalist orientations and their general
skepticism of the concept of "self" as postulated
by David Hume, who could never catch himself
not doing, thinking or feeling anything. However,
in the light of empirical results from developmental
psychology, developmental biology and neuroscience,
the idea of an essential inconstant, material
nucleus—an integrated representational system
distributed over changing patterns of synaptic
connections—seems reasonable.
== See also ==
Philosophy of mind portal
