The 'history of
philosophy' is the study of philosophical ideas and concepts through time. Issues specifically related to history of philosophy might include (but are not limited to): How can changes in philosophy be accounted for historically? What drives the development of thought in its historical context? To what degree can philosophical texts from prior historical eras even be understood today?
All cultures — be they
prehistoric,
ancient,
mediæval, or
modern;
Eastern,
Western,
religious or
secular — have had their own unique schools of philosophy, arrived at through both inheritance and through independent discovery. Such theories have grown from different
premises and approaches, examples of which include (but are not limited to)
rationalism (theories arrived at through
logic),
empiricism (theories arrived at through observation), and even through
leaps of faith, hope and inheritance (such as the
supernaturalist philosophies and
religions).
History of philosophy seeks to catalogue and classify such development. The goal is to understand the development of philosophical ideas through time.
Western philosophy
Western philosophy has a long history, conventionally divided into four large eras - the Ancient, Medieval, Modern and Contemporary. The Ancient era runs through the fall of Rome and includes the Greek philosophers such as
Plato. The Medieval period runs until roughly the late
1400s and the
Renaissance. The "Modern" is a word with more varied use, which includes everything from
Post-Medieval through the specific period up to the
20th century. Contemporary philosophy encompasses the philosophical developments of the
20th century up to the present day.
Ancient philosophy
''See article
Ancient philosophy''
Western Philosophy is generally said to begin in the Greek cities of western Asia Minor (Ionia) with
Thales of Miletus, who was active around 585 B.C. and left us the opaque dictum, "all is water." His most noted students were
Anaximenes of Miletus ("all is air") and
Anaximander.
Other thinkers and schools appeared throughout Greece over the next couple of centuries. Among the most important were
Heraclitus ("all is fire", all is
chaotic and transitory),
Anaxagoras (reality is so ordered that it must be in all respects governed by mind), the
Pluralists and
Atomists (the world is composite of innumerable interacting parts), the
Eleatics Parmenides and
Zeno (all is One and change is impossible), the
Sophists (became known, perhaps unjustly, for claiming that truth was no more than opinion and for teaching people to argue fallaciously to prove whatever conclusions they wished). This whole movement gradually became more concentrated in
Athens, which had become the dominant city-state in
Greece.
There is considerable discussion about why Athenian culture encouraged philosophy, but a popular theory says that it occurred because Athens had a direct
democracy. It is known from Plato's writings that many sophists maintained schools of debate, were respected members of society, and were well paid by their students. Orators influenced Athenian history, possibly even causing its failure (See
Battle of Lade). Another theory explains the birth of philosophical debate in Athens with the presence of a slave labor workforce which performed the necessary functions that would otherwise have consumed the time of the free male citizenry. Freed from working in the fields or other manual economic activities, they were able to participate in the assemblies of Athens and spend long periods in discussions on popular philosophical questions. Students of Sophists needed to acquire the skills of oration in order to influence the Athenian Assembly and thereby increase respect and wealth. In response, the subjects and methods of debate became highly developed by the Sophists.
The key figure in transforming Greek philosophy into a unified and continuous project - the one still being pursued today - is
Socrates, who studied under several Sophists. It is said that following a visit to the
Oracle of Delphi he spent much of his life questioning anyone in Athens who would engage him, in order to disprove the oracular prophecy that there would be no man wiser than Socrates. Through these live dialogues, he examined common but critical concepts that lacked clear or concrete definitions, such as beauty and truth, and the virtues of piety, wisdom, temperance, courage, and justice. Socrates' awareness of his own ignorance allowed him to discover his errors as well as the errors of those who claimed knowledge based upon falsifiable or unclear precepts and beliefs. He wrote nothing, but inspired many disciples, including many sons of prominent Athenian citizens (including
Plato), which led to his
trial and execution in 399 B.C. on the charge that his philosophy and sophistry were undermining the youth,
piety, and moral fiber of the city. He was offered a chance to flee from his fate but chose to remain in Athens, abide by his principles, and drink the poison
hemlock.

Raphael's ''The School of Athens'' (1509) with Plato and Aristotle in the centre.
Socrates' most important student was Plato, who founded the
Academy of Athens and wrote a number of dialogues, which applied the
Socratic method of inquiry to examine philosophical problems. Some central ideas of Plato's dialogues are the
Theory of Forms, i.e., that the mind is imbued with an innate capacity to understand and contemplate concepts from a higher order preeminent world, concepts more real, permanent, and universal than or representative of the ''things of this world'', which are only changing and temporal; the idea of the immortal soul being superior to the body; the idea of evil as simple ignorance of truth; that true knowledge leads to true virtue; that art is subordinate to moral purpose; and that the society of the
city-state should be governed by a merit class of propertyless philosopher kings, with no permanent wives or paternity rights over their children, and be protected by an athletically gifted, honorable, duty bound military class. In the later dialogues Socrates figures less prominently, but Plato had previously woven his own thoughts into some of Socrates' words. Interestingly, in his most famous work, ''
The Republic'', Plato critiques democracy, condemns tyranny, and proposes a three tiered merit based structure of society, with workers, guardians and philosophers, in an equal relationship, where no innocents would ever be put to death again, citing the philosophers' relentless love of truth and knowledge of the forms or ideals, concern for general welfare and lack of propertied interest as causes for their being suited to govern.
Plato's most outstanding student was
Aristotle, perhaps the first truly systematic philosopher.
Aristotelian logic was the first type of
logic to attempt to categorize every valid
syllogism. A syllogism is a form of argument that is guaranteed to be accepted, because it is known (by all educated persons) to be
valid. A crucial assumption in
Aristotelian logic is that it has to be about real objects. Two of Aristotle's syllogisms are invalid to modern eyes. For example, "All A are B. All A are C. Therefore, some B are C." This syllogism fails if set A is empty, but there are real members of set B. In Aristotle's syllogistic logic you could say this, because his logic should only be used for things that really exist ("no empty classes")
The application of
Aristotelian logic is preceded by having the student memorize a rather large set of syllogisms. The memorization proceeded from diagrams, or learning a key sentence, with the first letter of each word reminding the student of the names of the syllogisms.
Each syllogism had a name, for example: "Modus Ponens" had the form of "If A is true, then B is true. A is true, therefore B is true."
Most university students of logic memorized Aristotle's 19 syllogisms of two subjects, permitting them to validly connect a subject and object. A few geniuses developed systems with three subjects, or described a way of elaborating the rules of three subjects.
Medieval philosophy
''See article
Medieval philosophy''
Medieval philosophy was greatly concerned with the nature of God, and the application of
Aristotle's
logic and thought to every area of life.
If God exists at all, surely He is the most important feature of the universe, and therefore worthy of study. One continuing interest in this time was to prove the existence of God, through logic alone, if possible.
One early effort was the
cosmological argument, conventionally attributed to
Thomas Aquinas. The argument roughly is that everything that exists has a cause. But there could not be an infinite chain of causes back into the past, there must have been an uncaused "first cause." This is God. Aquinas also adapted this argument to prove the goodness of God. Everything has some goodness, and the cause of each thing is better than the thing caused. Therefore, the first cause is the best possible thing. Similar arguments are used to prove God's power and uniqueness.
Another important argument for proof of the existence of God was the
ontological argument, advanced by
St. Anselm. Basically, it says that God has all possible good features. Existence is good, and therefore God has it, and therefore exists. This argument has been used in different forms by philosophers from Descartes forward.
As well as Aquinas, other important names from the medieval period include
Duns Scotus and
Pierre Abélard.
The definition of the word "philosophy" in English has changed over the centuries -- in medieval times, any research outside the fields of
theology or
medicine was called "philosophy", hence the
Philosophical Transactions of the Royal Society is a scientific journal dating from
1665, the
Doctor of Philosophy (Ph.D.) degree covers a wide range of subjects, and the
Cambridge Philosophical Society is actually concerned with what we would now call
science and not modern philosophy.
Modern philosophy
''See article
19th-century philosophy''
As with many periodizations, there are multiple current usages for the term "Modern Philosophy" that exist in practice. One usage is to date modern philosophy from the "
Age of Reason", where systematic philosophy became common, excluding
Erasmus and
Machiavelli as "modern philosophers". Another is to date it, the way the entire larger modern period is dated, from the
Renaissance. In some usages, "Modern Philosophy" ended in 1800, with the rise of Hegelianism and Idealism. There is also the
lumpers/splitters problem, namely that some works split philosophy into more periods than others: one author might feel a strong need to differentiate between "The Age of Reason" or "Early Modern Philosophers" and "The Enlightenment", another author might write from the perspective that 1600-1800 is essentially one continuous evolution, and therefore a single period. Wikipedia's philosophy section therefore hews more closely to centuries as a means of avoiding long discussions over periods, but it is important to note the variety of practice that occurs.
A broad overview would then have
Erasmus,
Francis Bacon,
Niccolò Machiavelli, and
Galileo Galilei represent the rise of empiricism and humanism in place of scholastic tradition.
17th-century philosophy is dominated by the need to organize philosophy on rational, skeptical, logical and axiomatic grounds, such as the work of
René Descartes,
Blaise Pascal, and
Thomas Hobbes. This type of philosophy attempts to integrate religious belief into philosophical frameworks, and, often to combat atheism or other unbeliefs, by adopting the idea of material reality, and the
dualism between spirit and material. The extension, and reaction, against this would be the monism of
George Berkeley (
idealism) and
Benedict de Spinoza (
dual aspect theory). It was during this time period that the empiricism was developed as an alternative to skepticism by
John Locke,
George Berkeley and others. It should be mentioned that
John Locke,
Thomas Hobbes and
Edmund Burke developed their well known political philosophies during this time, as well.
The
18th-century philosophy article deals with the period often called the early part of "The Enlightenment" in the shorter form of the word, and centers on the rise of systematic empiricism, following after
Sir Isaac Newton's natural philosophy. Thus
Diderot,
Voltaire,
Rousseau,
Montesquieu,
Kant and the political philosophies embodied by and influencing the
American Revolution are part of
The Enlightenment. Other prominent philosophers of this time period were
David Hume and
Adam Smith, who, along with
Francis Hutcheson, were also the primary philosophers of the
Scottish Enlightenment.
The
19th century took the radical notions of self-organization and intrinsic order from Goethe and Kantian metaphysics, and proceeded to produce a long elaboration on the tension between systematization and organic development. Foremost was the work of
Hegel, whose ''Logic'' and ''Phenomenology of Spirit'' produced a "dialectical" framework for ordering of knowledge. The 19th century would also include
Schopenhauer's negation of the will. As with the 18th century, it would be developments in science that would arise from, and then challenge, philosophy: most importantly the work of Charles Darwin, which was based on the idea of organic self-regulation found in philosophers such as
Adam Smith, but fundamentally challenged established conceptions.
Contemporary philosophy
The
20th century deals with the upheavals produced by a series of conflicts within philosophical discourse over the basis of knowledge, with classical certainties overthrown, and new social, economic, scientific and logical problems. 20th century philosophy was set for a series of attempts to reform and preserve, and to alter or abolish, older knowledge systems. Seminal figures include
Sigmund Freud,
Friedrich Nietszche,
Ernst Mach,
John Dewey.
Epistemology (theory of knowledge) and its basis was a central concern, as seen from the work of
Heidegger,
Karl Popper,
Claude Lévi-Strauss and
Bertrand Russell. Phenomenologically oriented metaphysics undergirded
existentialism (
Jean-Paul Sartre,
Søren Kierkegaard,
Albert Camus) and finally
poststructuralism (
Gilles Deleuze,
Jean-François Lyotard,
Michel Foucault,
Jacques Derrida). Also notable was the rise of "pop" philosophers who promulgated systems for dealing with the world but were isolated philosophically, including
Ayn Rand. Conversely, some philosophers have attempted to define and rehabilitate older traditions of philosophy. Most notably,
Hans-Georg Gadamer and
Alasdair MacIntyre have both, albeit in different ways, revived the tradition of
Aristotelianism.
Eastern philosophy
In
the West, the term
Eastern philosophy refers very broadly to the various
philosophies of "the East," namely
Asia, including
China,
India,
Japan,
Persia and the general area. One must take into account that this term ignores that these countries do not belong to a single culture.
Ancient eastern philosophy developed mainly in
India and
China. The Indian or Hindu schools of philosophy can be considered the oldest schools of philosophy - they predate Greek philosophy by almost 500 years. Hindu philosophy primarily begins with
Upanishads, which can be dated close to 800 BC. The oldest, such as the Brhadaranyaka and Chandogya Upanishads, have been dated to around the eighth century BCE. The philosophical edifice of Indian religions viz.,
Hinduism,
Jainism,
Buddhism is built on the foundation laid by the Upanishads. Hindu philosophy is followed by the Buddhist and Jain philosophies.
Confucianism can be considered as the oldest school of philosophy in China. Confucianism developed in China around the same time as Buddhism and Jainism developed in India. Another school of philosophy,
Taoism, developed in China around 200 BC.
Indian philosophy
''See article
Indian philosophy
''See also
Hindu philosophy and
Jainism''
Persian philosophy
''See article
Philosophy in Iran''
''See also
Zoroastrianism''
Chinese philosophy
''See article
Chinese philosophy''
Buddhist philosophy
''See article
Buddhist philosophy''
Abrahamic philosophy
Abrahamic philosophy, in its loosest sense, comprises the series of philosophical schools that emerged from the study and commentary of the common ancient
Semitic tradition which can be traced by their adherents to
Abraham ("Father/Leader of many" Hebrew אַבְרָהָם ("Avraham") Arabic ابراهيم ("Ibrahim"), a patriarch whose life is narrated in the
Hebrew Bible/
Old Testament, and as a prophet in the
Qur'an and also called a prophet in
Genesis 20:7.
The standard text common to all of these subsequent traditions are what is known as the
Hebrew Bible, roughly the first five books of the
Old Testament, starting with the
book of Genesis through to
Deuteronomy. However, each of them added substantially different texts to their emerging canons, and hence their respective philosophical developments varied widely.
Jewish philosophy
''See article
Jewish philosophy''
Christian philosophy
''See article
Christian philosophy''
Islamic philosophy
''See articles
Islamic philosophy,
Early Islamic philosophy, and
Modern Islamic philosophy''
Judeo-Islamic philosophy
''See article
Judeo-Islamic philosophies (800 - 1400)''
African philosophy
Main articles: African philosophy
See also
★
History of Ideas
★
Intellectual History
★
Continuity thesis
External links
★
The history of religious and philosophical ideas, in ''Dictionary of the History of Ideas''
★
Evil in Modern Thought: An Alternative History of Philosophy. A documentary film about the problem of evil.