Metaphysics is the branch of philosophy that
examines the fundamental nature of reality,
including the relationship between mind and
matter, between substance and attribute, and
between possibility and actuality. The word
"metaphysics" comes from two Greek words that,
together, literally mean "after or behind
or among [the study of] the natural". It has
been suggested that the term might have been
coined by a first century CE editor who assembled
various small selections of Aristotle’s
works into the treatise we now know by the
name Metaphysics (ta meta ta phusika, 'after
the Physics ', another of Aristotle's works).Metaphysics
studies questions related to what it is for
something to exist and what types of existence
there are. Metaphysics seeks to answer, in
an abstract and fully general manner, the
questions:
What is there?
What is it like?Topics of metaphysical investigation
include existence, objects and their properties,
space and time, cause and effect, and possibility.
== Epistemological foundation ==
Metaphysics study which is conducted using
deduction from that which is known a priori.
Like foundational mathematics (which is sometimes
considered a special case of metaphysics applied
to the existence of number), it tries to give
a coherent account of the structure of the
world, capable of explaining our everyday
and scientific perception of the world, and
being free from contradictions. In mathematics,
there are many different ways to define numbers;
similarly in metaphysics there are many different
ways to define objects, properties, concepts,
and other entities which are claimed to make
up the world. While metaphysics may, as a
special case, study the entities postulated
by fundamental science such as atoms and superstrings,
its core topic is the set of categories such
as object, property and causality which those
scientific theories assume. For example: claiming
that "electrons have charge" is a scientific
theory; while exploring what it means for
electrons to be (or at least, to be perceived
as) "objects", charge to be a "property",
and for both to exist in a topological entity
called "space" is the task of metaphysics.
There are two broad stances about what is
"the world" studied by metaphysics. The strong,
classical view assumes that the objects studied
by metaphysics exist independently of any
observer, so that the subject is the most
fundamental of all sciences. The weak, modern
view assumes that the objects studied by metaphysics
exist inside the mind of an observer, so the
subject becomes a form of introspection and
conceptual analysis. Some philosophers, notably
Kant, discuss both of these "worlds" and what
can be inferred about each one. Some philosophers,
such as the logical positivists, and many
scientists, reject the strong view of metaphysics
as meaningless and unverifiable. Others reply
that this criticism also applies to any type
of knowledge, including hard science, which
claims to describe anything other than the
contents of human perception, and thus that
the world of perception is the objective world
in some sense. Metaphysics itself usually
assumes that some stance has been taken on
these questions and that it may proceed independently
of the choice—the question of which stance
to take belongs instead to another branch
of philosophy, epistemology.
== Central questions ==
=== 
Ontology (Being) ===
Ontology is the philosophical study of the
nature of being, becoming, existence or reality,
as well as the basic categories of being and
their relations. Traditionally listed as the
core of metaphysics, ontology often deals
with questions concerning what entities exist
or may be said to exist and how such entities
may be grouped, related within a hierarchy,
and subdivided according to similarities and
differences.
=== Identity and change ===
Identity is a fundamental metaphysical issue.
Metaphysicians investigating identity are
tasked with the question of what, exactly,
it means for something to be identical to
itself, or — more controversially — to
something else. Issues of identity arise in
the context of time: what does it mean for
something to be itself across two moments
in time? How do we account for this? Another
question of identity arises when we ask what
our criteria ought to be for determining identity?
And how does the reality of identity interface
with linguistic expressions?
The metaphysical positions one takes on identity
have far-reaching implications on issues such
as the mind-body problem, personal identity,
ethics, and law.
The ancient Greeks took extreme positions
on the nature of change. Parmenides denied
change altogether, while Heraclitus argued
that change was ubiquitous: "[Y]ou cannot
step into the same river twice."
Identity, sometimes called Numerical Identity,
is the relation that a "thing" bears to itself,
and which no "thing" bears to anything other
than itself (cf. sameness).
A modern philosopher who made a lasting impact
on the philosophy of identity was Leibniz,
whose Law of the Indiscernibility of Identicals
is still in wide use today. It states that
if some object x is identical to some object
y, then any property that x has, y will have
as well.
Put formally, it states
∀
x
∀
y
(
x
=
y
→
∀
P
(
P
(
x
)
↔
P
(
y
)
)
)
{\displaystyle \forall x\;\forall y\;(x=y\rightarrow
\forall P\;(P(x)\leftrightarrow P(y)))}
However, it seems, too, that objects can change
over time. If one were to look at a tree one
day, and the tree later lost a leaf, it would
seem that one could still be looking at that
same tree. Two rival theories to account for
the relationship between change and identity
are perdurantism, which treats the tree as
a series of tree-stages, and endurantism,
which maintains that the organism—the same
tree—is present at every stage in its history.
=== Space and time ===
Objects appear to us in space and time, while
abstract entities such as classes, properties,
and relations do not. What then is meant by
space and time such that it can serve this
function as a ground for objects? Are space
and time entities themselves, of some form,
or must they exist prior to other entities?
How exactly can they be defined? For example,
if time is defined as a "rate of change" then
must there always be something changing in
order for time to exist?
=== Causality ===
Classical philosophy recognized a number of
causes, including teleological future causes.
In special relativity and quantum field theory
the notions of space, time and causality become
tangled together, with temporal orders of
causations becoming dependent on who is observing
them. The laws of physics are symmetrical
in time, so could equally well be used to
describe time as running backwards. Why then
do we perceive it as flowing in one direction,
the arrow of time, and as containing causation
flowing in the same direction?
Causality is linked by most philosophers to
the concept of counterfactuals. To say that
A caused B means that if A had not happened
then B would not have happened.
Causality is usually required as a foundation
for philosophy of science, if science aims
to understand causes and effects and make
predictions about them.
=== Necessity and possibility ===
Metaphysicians investigate questions about
the ways the world could have been. David
Lewis, in On the Plurality of Worlds, endorsed
a view called Concrete Modal realism, according
to which facts about how things could have
been are made true by other concrete worlds,
just as in ours, in which things are different.
Other philosophers, such as Gottfried Leibniz,
have dealt with the idea of possible worlds
as well. The idea of necessity is that any
necessary fact is true across all possible
worlds. A possible fact is true in some possible
world, even if not in the actual world. For
example, it is possible that cats could have
had two tails, or that any particular apple
could have not existed. By contrast, certain
propositions seem necessarily true, such as
analytic propositions, e.g., "All bachelors
are unmarried." The particular example of
analytic truth being necessary is not universally
held among philosophers. A less controversial
view might be that self-identity is necessary,
as it seems fundamentally incoherent to claim
that for any x, it is not identical to itself;
this is known as the law of identity, a putative
"first principle". Aristotle describes the
principle of non-contradiction, "It is impossible
that the same quality should both belong and
not belong to the same thing ... This is the
most certain of all principles ... Wherefore
they who demonstrate refer to this as an ultimate
opinion. For it is by nature the source of
all the other axioms."
== 
Peripheral questions ==
What is "central" and "peripheral" to metaphysics
has varied over time and schools; however
contemporary analytic philosophy as taught
in USA and UK universities generally regards
the above as "central" and the following as
"applications" or "peripheral" topics; or
in some cases as distinct subjects which have
grown out of and depend upon metaphysics:
=== Cosmology and cosmogony ===
Metaphysical cosmology is the branch of metaphysics
that deals with the world as the totality
of all phenomena in space and time. Historically,
it formed a major part of the subject alongside
Ontology, though its role is more peripheral
in contemporary philosophy. It has had a broad
scope, and in many cases was founded in religion.
The ancient Greeks drew no distinction between
this use and their model for the cosmos. However,
in modern times it addresses questions about
the Universe which are beyond the scope of
the physical sciences. It is distinguished
from religious cosmology in that it approaches
these questions using philosophical methods
(e.g. dialectics).
Cosmogony deals specifically with the origin
of the universe. Modern metaphysical cosmology
and cosmogony try to address questions such
as:
What is the origin of the Universe? What is
its first cause? Is its existence necessary?
(see monism, pantheism, emanationism and creationism)
What are the ultimate material components
of the Universe? (see mechanism, dynamism,
hylomorphism, atomism)
What is the ultimate reason for the existence
of the Universe? Does the cosmos have a purpose?
(see teleology)
=== Mind and matter ===
Accounting for the existence of mind in a
world otherwise composed of matter is a metaphysical
problem which is so large and important as
to have become a specialized subject of study
in its own right, philosophy of mind.
Substance dualism is a classical theory in
which mind and body are essentially different,
with the mind having some of the attributes
traditionally assigned to the soul, and which
creates an immediate conceptual puzzle about
how the two interact. Idealism postulates
that material objects do not exist unless
perceived and only as perceptions. Panpsychism
and panexperientialism, are property dualist
theories in which everything has or is a mind
rather than everything exists in a mind. Neutral
monism postulates that existence consists
of a single substance that in itself is neither
mental nor physical, but is capable of mental
and physical aspects or attributes – thus
it implies a dual-aspect theory. For the last
century, the dominant theories have been science-inspired
including materialistic monism, Type identity
theory, token identity theory, functionalism,
reductive physicalism, nonreductive physicalism,
eliminative materialism, anomalous monism,
property dualism, epiphenomenalism and emergence.
=== Determinism and free will ===
Determinism is the philosophical proposition
that every event, including human cognition,
decision and action, is causally determined
by an unbroken chain of prior occurrences.
It holds that nothing happens that has not
already been determined. The principal consequence
of the deterministic claim is that it poses
a challenge to the existence of free will.
The problem of free will is the problem of
whether rational agents exercise control over
their own actions and decisions. Addressing
this problem requires understanding the relation
between freedom and causation, and determining
whether the laws of nature are causally deterministic.
Some philosophers, known as Incompatibilists,
view determinism and free will as mutually
exclusive. If they believe in determinism,
they will therefore believe free will to be
an illusion, a position known as Hard Determinism.
Proponents range from Baruch Spinoza to Ted
Honderich. Henri Bergson defended free will
in his dissertation Time and Free Will from
1889.
Others, labeled Compatibilists (or "Soft Determinists"),
believe that the two ideas can be reconciled
coherently. Adherents of this view include
Thomas Hobbes and many modern philosophers
such as John Martin Fischer.
Incompatibilists who accept free will but
reject determinism are called Libertarians,
a term not to be confused with the political
sense. Robert Kane and Alvin Plantinga are
modern defenders of this theory.
=== Natural and social kinds ===
The earliest type of classification of social
construction traces back to Plato in his dialogue
Phaedrus where he claims that the biological
classification system seems to "carve nature
at the joints". In contrast, later philosophers
such as Michel Foucault and Jorge Luis Borges
have challenged the capacity of natural and
social classification. In his essay The Analytical
Language of John Wilkins, Borges makes us
imagine a certain encyclopedia where the animals
are divided into (a) those that belong to
the emperor; (b) embalmed ones; (c) those
that are trained;... and so forth, in order
to bring forward the ambiguity of natural
and social kinds. According to metaphysics
author Alyssa Ney: "the reason all this is
interesting is that there seems to be a metaphysical
difference between the Borgesian system and
Platos". The difference is not obvious but
one classification attempts to carve entities
up according to objective distinction while
the other does not. According to Quine this
notion is closely related to the notion of
similarity.
=== Number ===
There are different ways to set up the notion
of number in metaphysics theories. Platonist
theories postulate number as a fundamental
category itself. Others consider it to be
a property of an entity called a "group" comprising
other entities; or to be a relation held between
several groups of entities, such as "the number
four is the set of all sets of four things".
Many of the debates around universals are
applied to the study of number, and are of
particular importance due to its status as
a foundation for the philosophy of mathematics
and for mathematics itself.
=== Applied metaphysics ===
Although metaphysics as a philosophical enterprise
is highly hypothetical, it also has practical
application in most other branches of philosophy,
science, and now also information technology.
Such areas generally assume some basic ontology
(such as a system of objects, properties,
classes, and space time) as well as other
metaphysical stances on topics such as causality
and agency, then build their own particular
theories upon these.
In science, for example, some theories are
based on the ontological assumption of objects
with properties (such as electrons having
charge) while others may reject objects completely
(such as quantum field theories, where spread-out
"electronness" becomes a property of space
time rather than an object).
"Social" branches of philosophy such as philosophy
of morality, aesthetics and philosophy of
religion (which in turn give rise to practical
subjects such as ethics, politics, law, and
art) all require metaphysical foundations,
which may be considered as branches or applications
of metaphysics. For example, they may postulate
the existence of basic entities such as value,
beauty, and God. Then they use these postulates
to make their own arguments about consequences
resulting from them. When philosophers in
these subjects make their foundations they
are doing applied metaphysics, and may draw
upon its core topics and methods to guide
them, including ontology and other core and
peripheral topics. As in science, the foundations
chosen will in turn depend on the underlying
ontology used, so philosophers in these subjects
may have to dig right down to the ontological
layer of metaphysics to find what is possible
for their theories. For example, a contradiction
obtained in a theory of God or Beauty might
be due to an assumption that it is an object
rather than some other kind of ontological
entity.
== Relationship of metaphysics and science
==
Prior to the modern history of science, scientific
questions were addressed as a part of natural
philosophy. Originally, the term "science"
(Latin scientia) simply meant "knowledge".
The scientific method, however, transformed
natural philosophy into an empirical activity
deriving from experiment, unlike the rest
of philosophy. By the end of the 18th century,
it had begun to be called "science" to distinguish
it from other branches of philosophy. Science
and philosophy have been considered separated
disciplines ever since. Thereafter, metaphysics
denoted philosophical enquiry of a non-empirical
character into the nature of existence.Metaphysics
continues asking "why" where science leaves
off. For example, any theory of fundamental
physics is based on some set of axioms, which
may postulate the existence of entities such
as atoms, particles, forces, charges, mass,
or fields. Stating such postulates is considered
to be the "end" of a science theory. Metaphysics
takes these postulates and explores what they
mean as human concepts. For example, do all
theories of physics require the existence
of space and time, objects, and properties?
Or can they be expressed using only objects,
or only properties? Do the objects have to
retain their identity over time or can they
change? If they change, then are they still
the same object? Can theories be reformulated
by converting properties or predicates (such
as "red") into entities (such as redness or
redness fields) or processes ('there is some
redding happening over there' appears in some
human languages in place of the use of properties).
Is the distinction between objects and properties
fundamental to the physical world or to our
perception of it?
Much recent work has been devoted to analyzing
the role of metaphysics in scientific theorizing.
Alexandre Koyré led this movement, declaring
in his book Metaphysics and Measurement, "It
is not by following experiment, but by outstripping
experiment, that the scientific mind makes
progress." That metaphysical propositions
can influence scientific theorizing is John
Watkins' most lasting contribution to philosophy.
Since 1957 "he showed the ways in which some
un-testable and hence, according to Popperian
ideas, non-empirical propositions can nevertheless
be influential in the development of properly
testable and hence scientific theories. These
profound results in applied elementary logic...represented
an important corrective to positivist teachings
about the meaninglessness of metaphysics and
of normative claims". Imre Lakatos maintained
that all scientific theories have a metaphysical
"hard core" essential for the generation of
hypotheses and theoretical assumptions. Thus,
according to Lakatos, "scientific changes
are connected with vast cataclysmic metaphysical
revolutions."An example from biology of Lakatos'
thesis: David Hull has argued that changes
in the ontological status of the species concept
have been central in the development of biological
thought from Aristotle through Cuvier, Lamarck,
and Darwin. Darwin's ignorance of metaphysics
made it more difficult for him to respond
to his critics because he could not readily
grasp the ways in which their underlying metaphysical
views differed from his own.In physics, new
metaphysical ideas have arisen in connection
with quantum mechanics, where subatomic particles
arguably do not have the same sort of individuality
as the particulars with which philosophy has
traditionally been concerned. Also, adherence
to a deterministic metaphysics in the face
of the challenge posed by the quantum-mechanical
uncertainty principle led physicists such
as Albert Einstein to propose alternative
theories that retained determinism. A.N. Whitehead
is famous for creating a process philosophy
metaphysics inspired by electromagnetism and
special relativity.In chemistry, Gilbert Newton
Lewis addressed the nature of motion, arguing
that an electron should not be said to move
when it has none of the properties of motion.Katherine
Hawley notes that the metaphysics even of
a widely accepted scientific theory may be
challenged if it can be argued that the metaphysical
presuppositions of the theory make no contribution
to its predictive success.
== Rejections of metaphysics ==
A number of individuals have suggested that
much or all of metaphysics should be rejected.
In the 16th century, Francis Bacon rejected
scholastic metaphysics, and argued strongly
for what is now called empiricism, being seen
later as the father of modern empirical science.
In the 18th century, David Hume took a strong
position, arguing that all genuine knowledge
involves either mathematics or matters of
fact and that metaphysics, which goes beyond
these, is worthless. He concludes his Enquiry
Concerning Human Understanding with the statement:
If we take in our hand any volume; of divinity
or school metaphysics, for instance; let us
ask, Does it contain any abstract reasoning
concerning quantity or number? No. Does it
contain any experimental reasoning concerning
matter of fact and existence? No. Commit it
then to the flames: for it can contain nothing
but sophistry and illusion.
Thirty-three years after Hume's Enquiry appeared,
Immanuel Kant published his Critique of Pure
Reason. Although he followed Hume in rejecting
much of previous metaphysics, he argued that
there was still room for some synthetic a
priori knowledge, concerned with matters of
fact yet obtainable independent of experience.
These included fundamental structures of space,
time, and causality. He also argued for the
freedom of the will and the existence of "things
in themselves", the ultimate (but unknowable)
objects of experience.
Wittgenstein introduced the concept that metaphysics
could be influenced by theories of aesthetics,
via logic, vis. a world composed of "atomical
facts".In the 1930s, A.J. Ayer and Rudolf
Carnap endorsed Hume's position; Carnap quoted
the passage above. They argued that metaphysical
statements are neither true nor false but
meaningless since, according to their verifiability
theory of meaning, a statement is meaningful
only if there can be empirical evidence for
or against it. Thus, while Ayer rejected the
monism of Spinoza, he avoided a commitment
to pluralism, the contrary position, by holding
both views to be without meaning. Carnap took
a similar line with the controversy over the
reality of the external world. While the logical
positivism movement is now considered dead,
(with a major proponent AJ Ayer admitting
in a TV interview that "it was a lot of fun
... but it was false") it has continued to
influence philosophy development.Arguing against
such rejections, the Scholastic philosopher
Edward Feser has observed that Hume's critique
of metaphysics, and specifically Hume's fork,
is "notoriously self-refuting". Feser argues
that Hume's fork itself is not a conceptual
truth and is not empirically testable.
Some living philosophers, such as Amie Thomasson,
have argued that many metaphysical questions
can be dissolved just by looking at the way
we use words; others, such as Ted Sider, have
argued that metaphysical questions are substantive,
and that we can make progress toward answering
them by comparing theories according to a
range of theoretical virtues inspired by the
sciences, such as simplicity and explanatory
power.
== Etymology ==
The word "metaphysics" derives from the Greek
words μετά (metá,"after") and φυσικά
(physiká, "physics"). It was first used as
the title for several of Aristotle's works,
because they were usually anthologized after
the works on physics in complete editions.
The prefix meta- ("after") indicates that
these works come "after" the chapters on physics.
However, Aristotle himself did not call the
subject of these books metaphysics: he referred
to it as "first philosophy." The editor of
Aristotle's works, Andronicus of Rhodes, is
thought to have placed the books on first
philosophy right after another work, Physics,
and called them τὰ μετὰ τὰ φυσικὰ
βιβλία (tà metà tà physikà biblía)
or "the books [that come] after the [books
on] physics".
However, once the name was given, the commentators
sought to find other reasons for its appropriateness.
For instance, Thomas Aquinas understood it
to refer to the chronological or pedagogical
order among our philosophical studies, so
that the "metaphysical sciences" would mean
"those that we study after having mastered
the sciences that deal with the physical world".
The term was misread by other medieval commentators,
who thought it meant "the science of what
is beyond the physical". Following this tradition,
the prefix meta- has more recently been prefixed
to the names of sciences to designate higher
sciences dealing with ulterior and more fundamental
problems: hence metamathematics, metaphysiology,
etc.A person who creates or develops metaphysical
theories is called a metaphysician.Common
parlance also uses the word "metaphysics"
for a different referent from that of the
present article, namely for beliefs in arbitrary
non-physical or magical entities. For example,
"Metaphysical healing" to refer to healing
by means of remedies that are magical rather
than scientific. This usage stemmed from the
various historical schools of speculative
metaphysics which operated by postulating
all manner of physical, mental and spiritual
entities as bases for particular metaphysical
systems. Metaphysics as a subject does not
preclude beliefs in such magical entities
but neither does it promote them. Rather,
it is the subject which provides the vocabulary
and logic with which such beliefs might be
analyzed and studied, for example to search
for inconsistencies both within themselves
and with other accepted systems such as Science.
== History and schools of metaphysics ==
=== 
Pre-history ===
Cognitive archeology such as analysis of cave
paintings and other pre-historic art and customs
suggests that a form of perennial philosophy
or Shamanism metaphysics may stretch back
to the birth of behavioral modernity, all
around the world. Similar beliefs are found
in present-day "stone age" cultures such as
Australian aboriginals. Perennial philosophy
postulates the existence of a spirit or concept
world alongside the day-to-day world, and
interactions between these worlds during dreaming
and ritual, or on special days or at special
places. It has been argued that perennial
philosophy formed the basis for Platonism,
with Plato articulating, rather than creating,
much older widespread beliefs.
=== Bronze age ===
Bronze Age cultures such as ancient Mesopotamia
and ancient Egypt (along with similarly structured
but chronologically later cultures such as
Mayans and Aztecs) developed belief systems
based on mythology, anthropomorphic gods,
mind-body dualism, and a spirit world, to
explain causes and cosmology. These cultures
appear to have been interested in astronomy
and may have associated or identified the
stars with some of these entities. In ancient
Egypt, the ontological distinction between
order (maat) and chaos (Isfet) seems to have
been important.
=== Pre-Socratic Greece ===
The first named Greek philosopher, according
to Aristotle, is Thales of Miletus, early
6th century BCE. He made use of purely physical
explanations to explain the phenomena of the
world rather than the mythological and divine
explanations of tradition. He is thought to
have posited water as the single underlying
principle (or Arche in later Aristotelian
terminology) of the material world. His fellow,
but younger Miletians, Anaximander and Anaximenes,
also posited monistic underlying principles,
namely apeiron (the indefinite or boundless)
and air respectively.
Another school was the Eleatics, in southern
Italy. The group was founded in the early
fifth century BCE by Parmenides, and included
Zeno of Elea and Melissus of Samos. Methodologically,
the Eleatics were broadly rationalist, and
took logical standards of clarity and necessity
to be the criteria of truth. Parmenides' chief
doctrine was that reality is a single unchanging
and universal Being. Zeno used reductio ad
absurdum, to demonstrate the illusory nature
of change and time in his paradoxes.
Heraclitus of Ephesus, in contrast, made change
central, teaching that "all things flow".
His philosophy, expressed in brief aphorisms,
is quite cryptic. For instance, he also taught
the unity of opposites.
Democritus and his teacher Leucippus, are
known for formulating an atomic theory for
the cosmos. They are considered forerunners
of the scientific method.
=== Classical China ===
Metaphysics in Chinese philosophy can be traced
back to the earliest Chinese philosophical
concepts from the Zhou Dynasty such as Tian
(Heaven) and Yin and Yang. The fourth century
BCE saw a turn towards cosmogony with the
rise of Taoism (in the Daodejing and Zhuangzi)
and sees the natural world as dynamic and
constantly changing processes which spontaneously
arise from a single immanent metaphysical
source or principle (Tao). Another philosophical
school which arose around this time was the
School of Naturalists which saw the ultimate
metaphysical principle as the Taiji, the "supreme
polarity" composed of the forces of Ying and
Yang which were always in a state of change
seeking balance. Another concern of Chinese
metaphysics, especially Taoism, is the relationship
and nature of Being and non-Being (you 有
and wu 無). The Taoists held that the ultimate,
the Tao, was also non-being or no-presence.
Other important concepts were those of spontaneous
generation or natural vitality (Ziran) and
"correlative resonance" (Ganying).
After the fall of the Han Dynasty (220 CE),
China saw the rise of the Neo-Taoist Xuanxue
school. This school was very influential in
developing the concepts of later Chinese metaphysics.
Buddhist philosophy entered China (c. 1st
century) and was influenced by the native
Chinese metaphysical concepts to develop new
theories. The native Tiantai and Huayen schools
of philosophy maintained and reinterpreted
the Indian theories of shunyata (emptiness,
kong 空) and Buddha-nature (Fo xing 佛性)
into the theory of interpenetration of phenomena.
Neo-Confucians like Zhang Zai under the influence
of other schools developed the concepts of
"principle" (li) and vital energy (qi).
=== Socrates and Plato ===
Socrates is known for his dialectic or questioning
approach to philosophy rather than a positive
metaphysical doctrine.
His pupil, Plato is famous for his theory
of forms (which he places in the mouth of
Socrates in his dialogues). Platonic realism
(also considered a form of idealism) is considered
to be a solution to the problem of universals;
i.e., what particular objects have in common
is that they share a specific Form which is
universal to all others of their respective
kind.
The theory has a number of other aspects:
Epistemological: knowledge of the Forms is
more certain than mere sensory data.
Ethical: The Form of the Good sets an objective
standard for morality.
Time and Change: The world of the Forms is
eternal and unchanging. Time and change belong
only to the lower sensory world. "Time is
a moving image of Eternity".
Abstract objects and mathematics: Numbers,
geometrical figures, etc., exist mind-independently
in the World of Forms.Platonism developed
into Neoplatonism, a philosophy with a monotheistic
and mystical flavour that survived well into
the early Christian era.
=== Aristotle ===
Plato's pupil Aristotle wrote widely on almost
every subject, including metaphysics. His
solution to the problem of universals contrasts
with Plato's. Whereas Platonic Forms are existentially
apparent in the visible world, Aristotelian
essences dwell in particulars.
Potentiality and Actuality are principles
of a dichotomy which Aristotle used throughout
his philosophical works to analyze motion,
causality and other issues.
The Aristotelian theory of change and causality
stretches to four causes: the material, formal,
efficient and final. The efficient cause corresponds
to what is now known as a cause simplicity.
Final causes are explicitly teleological,
a concept now regarded as controversial in
science. The Matter/Form dichotomy was to
become highly influential in later philosophy
as the substance/essence distinction.
The opening arguments in Aristotle's Metaphysics,
Book I, revolve around the senses, knowledge,
experience, theory, and wisdom. The first
main focus in the Metaphysics is attempting
to determine how intellect "advances from
sensation through memory, experience, and
art, to theoretical knowledge". Aristotle
claims that eyesight provides us with the
capability to recognize and remember experiences,
while sound allows us to learn.
=== Classical India ===
More on Indian philosophy: Hindu philosophy
==== Sāṃkhya ====
Sāṃkhya is an ancient system of Indian
philosophy based on a dualism involving the
ultimate principles of consciousness and matter.
It is described as the rationalist school
of Indian philosophy. It is most related to
the Yoga school of Hinduism, and its method
was most influential on the development of
Early Buddhism.The Sāmkhya is an enumerationist
philosophy whose epistemology accepts three
of six pramanas (proofs) as the only reliable
means of gaining knowledge. These include
pratyakṣa (perception), anumāṇa (inference)
and śabda (āptavacana, word/testimony of
reliable sources).Samkhya is strongly dualist.
Sāmkhya philosophy regards the universe as
consisting of two realities; puruṣa (consciousness)
and prakṛti (matter). Jiva (a living being)
is that state in which puruṣa is bonded
to prakṛti in some form. This fusion, state
the Samkhya scholars, led to the emergence
of buddhi ("spiritual awareness") and ahaṅkāra
(ego consciousness). The universe is described
by this school as one created by purusa-prakṛti
entities infused with various permutations
and combinations of variously enumerated elements,
senses, feelings, activity and mind. During
the state of imbalance, one of more constituents
overwhelm the others, creating a form of bondage,
particularly of the mind. The end of this
imbalance, bondage is called liberation, or
moksha, by the Samkhya school.The existence
of God or supreme being is not directly asserted,
nor considered relevant by the Samkhya philosophers.
Sāṃkhya denies the final cause of Ishvara
(God). While the Samkhya school considers
the Vedas as a reliable source of knowledge,
it is an atheistic philosophy according to
Paul Deussen and other scholars. A key difference
between Samkhya and Yoga schools, state scholars,
is that Yoga school accepts a "personal, yet
essentially inactive, deity" or "personal
god".Samkhya is known for its theory of guṇas
(qualities, innate tendencies). Guṇa, it
states, are of three types: sattva being good,
compassionate, illuminating, positive, and
constructive; rajas is one of activity, chaotic,
passion, impulsive, potentially good or bad;
and tamas being the quality of darkness, ignorance,
destructive, lethargic, negative. Everything,
all life forms and human beings, state Samkhya
scholars, have these three guṇas, but in
different proportions. The interplay of these
guṇas defines the character of someone or
something, of nature and determines the progress
of life. The Samkhya theory of guṇas was
widely discussed, developed and refined by
various schools of Indian philosophies, including
Buddhism. Samkhya's philosophical treatises
also influenced the development of various
theories of Hindu ethics.
==== Vedānta ====
Realization of the nature of Self-identity
is the principal object of the Vedanta system
of Indian metaphysics. In the Upanishads,
self-consciousness is not the first-person
indexical self-awareness or the self-awareness
which is self-reference without identification,
and also not the self-consciousness which
as a kind of desire is satisfied by another
self-consciousness. It is Self-realisation;
the realisation of the Self consisting of
consciousness that leads all else.The word
Self-consciousness in the Upanishads means
the knowledge about the existence and nature
of Brahman. It means the consciousness of
our own real being, the primary reality. Self-consciousness
means Self-knowledge, the knowledge of Prajna
i.e. of Prana which is Brahman. According
to the Upanishads the Atman or Paramatman
is phenomenally unknowable; it is the object
of realisation. The Atman is unknowable in
its essential nature; it is unknowable in
its essential nature because it is the eternal
subject who knows about everything including
itself. The Atman is the knower and also the
known.Metaphysicians regard the Self either
to be distinct from the Absolute or entirely
identical with the Absolute. They have given
form to three schools of thought – a) the
Dualistic school, b) the Quasi-dualistic school
and c) the Monistic school, as the result
of their varying mystical experiences. Prakrti
and Atman, when treated as two separate and
distinct aspects form the basis of the Dualism
of the Shvetashvatara Upanishad. Quasi-dualism
is reflected in the Vaishnavite-monotheism
of Ramanuja and the absolute Monism, in the
teachings of Adi Shankara.Self-consciousness
is the Fourth state of consciousness or Turiya,
the first three being Vaisvanara, Taijasa
and Prajna. These are the four states of individual
consciousness.
There are three distinct stages leading to
Self-realisation. The First stage is in mystically
apprehending the glory of the Self within
us as though we were distinct from it. The
Second stage is in identifying the "I-within"
with the Self, that we are in essential nature
entirely identical with the pure Self. The
Third stage is in realising that the Atman
is Brahman, that there is no difference between
the Self and the Absolute. The Fourth stage
is in realising "I am the Absolute" – Aham
Brahman Asmi. The Fifth stage is in realising
that Brahman is the "All" that exists, as
also that which does not exist.
=== Buddhist metaphysics ===
In Buddhist philosophy there are various metaphysical
traditions that have proposed different questions
about the nature of reality based on the teachings
of the Buddha in the early Buddhist texts.
The Buddha of the early texts does not focus
on metaphysical questions but on ethical and
spiritual training and in some cases, he dismisses
certain metaphysical questions as unhelpful
and indeterminate Avyakta, which he recommends
should be set aside. The development of systematic
metaphysics arose after the Buddha's death
with the rise of the Abhidharma traditions.
The Buddhist Abhidharma schools developed
their analysis of reality based on the concept
of dharmas which are the ultimate physical
and mental events that make up experience
and their relations to each other. Noa Ronkin
has called their approach "phenomenological".Later
philosophical traditions include the Madhyamika
school of Nagarjuna, which further developed
the theory of the emptiness (shunyata) of
all phenomena or dharmas which rejects any
kind of substance. This has been interpreted
as a form of anti-foundationalism and anti-realism
which sees reality has having no ultimate
essence or ground. The Yogacara school meanwhile
promoted a theory called "awareness only"
(vijnapti-matra) which has been interpreted
as a form of Idealism or Phenomenology and
denies the split between awareness itself
and the objects of awareness.
=== Islamic metaphysics ===
Islamic metaphysics was highly active during
Europe's 'Dark Ages', beginning with the arrival
and translation of Aristotle into Arabic.
=== Scholasticism and the Middle Ages ===
More on medieval philosophy and metaphysics:
Medieval Philosophy
Between about 1100 and 1500, philosophy as
a discipline took place as part of the Catholic
church's teaching system, known as scholasticism.
Scholastic philosophy took place within an
established
framework blending Christian theology with
Aristotelian teachings. Although fundamental
orthodoxies were not commonly challenged,
there were nonetheless deep metaphysical disagreements,
particularly over the problem of universals,
which engaged Duns Scotus and Pierre Abelard.
William of Ockham is remembered for his principle
of ontological parsimony.
=== Rationalism and Continental Rationalism
===
In the early modern period (17th and 18th
centuries), the system-building scope of philosophy
is often linked to the rationalist method
of philosophy, that is the technique of deducing
the nature of the world by pure reason. The
scholastic concepts of substance and accident
were employed.
Leibniz proposed in his Monadology a plurality
of non-interacting substances.
Descartes is famous for his Dualism of material
and mental substances.
Spinoza believed reality was a single substance
of God-or-nature.
=== 
British empiricism ===
British empiricism marked something of a reaction
to rationalist and system-building metaphysics,
or speculative metaphysics as it was pejoratively
termed. The skeptic David Hume famously declared
that most metaphysics should be consigned
to the flames (see below). Hume was notorious
among his contemporaries as one of the first
philosophers to openly doubt religion, but
is better known now for his critique of causality.
John Stuart Mill, Thomas Reid and John Locke
were less skeptical, embracing a more cautious
style of metaphysics based on realism, common
sense and science. Other philosophers, notably
George Berkeley were led from empiricism to
idealistic metaphysics.
=== Wolff ===
Christian Wolff had theoretical philosophy
divided into an ontology or philosophia prima
as a general metaphysics, which arises as
a preliminary to the distinction of the three
"special metaphysics" on the soul, world and
God: rational psychology, rational cosmology
and rational theology. The three disciplines
are called empirical and rational because
they are independent of revelation. This scheme,
which is the counterpart of religious tripartition
in creature, creation, and Creator, is best
known to philosophical students by Kant's
treatment of it in the Critique of Pure Reason.
In the "Preface" of the 2nd edition of Kant's
book, Wolff is defined "the greatest of all
dogmatic philosophers."
=== 
Kant ===
Immanuel Kant attempted a grand synthesis
and revision of the trends already mentioned:
scholastic philosophy, systematic metaphysics,
and skeptical empiricism, not to forget the
burgeoning science of his day. As did the
systems builders, he had an overarching framework
in which all questions were to be addressed.
Like Hume, who famously woke him from his
'dogmatic slumbers', he was suspicious of
metaphysical speculation, and also places
much emphasis on the limitations of the human
mind.
Kant described his shift in metaphysics away
from making claims about an objective noumenal
world, towards exploring the subjective phenomenal
world, as a Copernican Revolution, by analogy
to (though opposite in direction to) Copernicus'
shift from man (the subject) to the sun (an
object) at the center of the universe.
Kant saw rationalist philosophers as aiming
for a kind of metaphysical knowledge he defined
as the synthetic apriori—that is knowledge
that does not come from the senses (it is
a priori) but is nonetheless about reality
(synthetic). Inasmuch as it is about reality,
it differs from abstract mathematical propositions
(which he terms analytical apriori), and being
apriori it is distinct from empirical, scientific
knowledge (which he terms synthetic aposteriori).
The only synthetic apriori knowledge we can
have is of how our minds organise the data
of the senses; that organising framework is
space and time, which for Kant have no mind-independent
existence, but nonetheless operate uniformly
in all humans. Apriori knowledge of space
and time is all that remains of metaphysics
as traditionally conceived. There is a reality
beyond sensory data or phenomena, which he
calls the realm of noumena; however, we cannot
know it as it is in itself, but only as it
appears to us. He allows himself to speculate
that the origins of phenomenal God, morality,
and free will might exist in the noumenal
realm, but these possibilities have to be
set against its basic unknowability for humans.
Although he saw himself as having disposed
of metaphysics, in a sense, he has generally
been regarded in retrospect as having a metaphysics
of his own, and as beginning the modern analytical
conception of the subject.
=== Kantians ===
Nineteenth century philosophy was overwhelmingly
influenced by Kant and his successors. Schopenhauer,
Schelling, Fichte and Hegel all purveyed their
own panoramic versions of German Idealism,
Kant's own caution about metaphysical speculation,
and refutation of idealism, having fallen
by the wayside. The idealistic impulse continued
into the early twentieth century with British
idealists such as F.H. Bradley and J.M.E.
McTaggart. Followers of Karl Marx took Hegel's
dialectic view of history and re-fashioned
it as materialism.
=== Early analytical philosophy and positivism
===
During the period when idealism was dominant
in philosophy, science had been making great
advances. The arrival of a new generation
of scientifically minded philosophers led
to a sharp decline in the popularity of idealism
during the 1920s.
Analytical philosophy was spearheaded by Bertrand
Russell and G.E. Moore. Russell and William
James tried to compromise between idealism
and materialism with the theory of neutral
monism.
The early to mid twentieth century philosophy
saw a trend to reject metaphysical questions
as meaningless. The driving force behind this
tendency was the philosophy of logical positivism
as espoused by the Vienna Circle, which argued
that the meaning of a statement was its prediction
of observable results of an experiment, and
thus that there is no need to postulate the
existence of any objects other than these
perceptual observations.
At around the same time, the American pragmatists
were steering a middle course between materialism
and idealism.
System-building metaphysics, with a fresh
inspiration from science, was revived by A.N.
Whitehead and Charles Hartshorne.
=== Continental philosophy ===
The forces that shaped analytical philosophy—the
break with idealism, and the influence of
science—were much less significant outside
the English speaking world, although there
was a shared turn toward language. Continental
philosophy continued in a trajectory from
post Kantianism.
The phenomenology of Husserl and others was
intended as a collaborative project for the
investigation of the features and structure
of consciousness common to all humans, in
line with Kant's basing his synthetic apriori
on the uniform operation of consciousness.
It was officially neutral with regards to
ontology, but was nonetheless to spawn a number
of metaphysical systems. Brentano's concept
of intentionality would become widely influential,
including on analytical philosophy.
Heidegger, author of Being and Time, saw himself
as re-focusing on Being-qua-being, introducing
the novel concept of Dasein in the process.
Classing himself an existentialist, Sartre
wrote an extensive study of Being and Nothingness.
The speculative realism movement marks a return
to full blooded realism.
=== Process metaphysics ===
There are two fundamental aspects of everyday
experience: change and persistence. Until
recently, the Western philosophical tradition
has arguably championed substance and persistence,
with some notable exceptions, however. According
to process thinkers, novelty, flux and accident
do matter, and sometimes they constitute the
ultimate reality.
In a broad sense, process metaphysics is as
old as Western philosophy, with figures such
as Heraclitus, Plotinus, Duns Scotus, Leibniz,
David Hume, Georg Wilhelm Friedrich Hegel,
Friedrich Wilhelm Joseph von Schelling, Gustav
Theodor Fechner, Friedrich Adolf Trendelenburg,
Charles Renouvier, Karl Marx, Ernst Mach,
Friedrich Wilhelm Nietzsche, Émile Boutroux,
Henri Bergson, Samuel Alexander and Nicolas
Berdyaev. It seemingly remains an open question
whether major "Continental" figures such as
the late Martin Heidegger, Maurice Merleau-Ponty,
Gilles Deleuze, Michel Foucault, or Jacques
Derrida should be included.In a strict sense,
process metaphysics may be limited to the
works of a few founding fathers: G.W.F. Hegel,
Charles Sanders Peirce, William James, Henri
Bergson, A.N. Whitehead, and John Dewey. From
a European perspective, there was a very significant
and early Whiteheadian influence on the works
of outstanding scholars such as Émile Meyerson
(1859–1933), Louis Couturat (1868–1914),
Jean Wahl (1888–1974), Robin George Collingwood
(1889–1943), Philippe Devaux (1902–1979),
Hans Jonas (1903–1993), Dorothy M. Emmett
(1904–2000), Maurice Merleau Ponty (1908–1961),
Enzo Paci (1911–1976), Charlie Dunbar Broad
(1887–1971), Wolfe Mays (1912–2005), Ilya
Prigogine (1917–2003), Jules Vuillemin (1920–2001),
Jean Ladrière (1921–2007), Gilles Deleuze
(1925–1995), Wolfhart Pannenberg (1928–2014),
and Reiner Wiehl (1929–2010).
=== Contemporary analytical philosophy ===
While early analytic philosophy tended to
reject metaphysical theorizing, under the
influence of logical positivism, it was revived
in the second half of the twentieth century.
Philosophers such as David K. Lewis and David
Armstrong developed elaborate theories on
a range of topics such as universals, causation,
possibility and necessity and abstract objects.
However, the focus of analytical philosophy
generally is away from the construction of
all-encompassing systems and toward close
analysis of individual ideas.
Among the developments that led to the revival
of metaphysical theorizing were Quine's attack
on the analytic–synthetic distinction, which
was generally taken to undermine Carnap's
distinction between existence questions internal
to a framework and those external to it.The
philosophy of fiction, the problem of empty
names, and the debate over existence's status
as a property have all come of relative obscurity
into the limelight, while perennial issues
such as free will, possible worlds, and the
philosophy of time have had new life breathed
into them.The analytic view is of metaphysics
as studying phenomenal human concepts rather
than making claims about the noumenal world,
so its style often blurs into philosophy of
language and introspective psychology. Compared
to system-building, it can seem very dry,
stylistically similar to computer programming,
mathematics or even accountancy (as a common
stated goal is to "account for" entities in
the world).
== See also ==
Feminist metaphysics
Metaphilosophy
Metaethics
Metaphysical fiction novels
Metaphysics of presence
Personal identity
Philosophical logic
Philosophical realism
Philosophical theology
Philosophy of physics
