Age of Reason

17th century philosophy in the Western world is generally regarded as being the start of modern philosophy, and a departure from the medieval approach, especially Scholasticism.

(17th century philosophers)

Late 17th century philosophy is often called the Age of Reason or Age of Rationalism and is considered to succeed the Renaissance philosophy era and precede the Age of Enlightenment, but some consider it as the earliest part of the Enlightenment era in philosophy, extending that era to two centuries.

Meanwhile in Persia, early Islamic philosophy and Iranian philosophy witnessed their last major phase of development with the school of Transcendent Theosophy founded by Mulla Sadra.

Europe

In Western Philosophy, the period is usually taken to start in the seventeenth century with the work of René Descartes, who set much of the agenda as well as much of the methodology for those who came after him. The period is typified in Europe by the great system-builders — philosophers who present unified systems of epistemology, metaphysics, logic, and ethics, and often politics and the physical sciences too. Immanuel Kant classified his predecessors into two schools: the Rationalists and the Empiricists, and Early Modern Philosophy (as seventeenth- and eighteenth-century philosophy is known) is often characterised in terms of a supposed conflict between these schools. This division is a considerable oversimplification, and it is important to be aware that the philosophers involved did not think of themselves as belonging to these schools, but as being involved in a single philosophical enterprise.

Although misleading in many ways, this simplification has continued to be used to this day, especially when writing about the 17th and 18th centuries. The three main Rationalists are normally taken to have been Descartes, Baruch Spinoza, and Gottfried Leibniz. Building upon their English predecessors Francis Bacon and Thomas Hobbes, the three main Empiricists were John Locke, George Berkeley, and David Hume. The former were distinguished by the belief that, in principle (though not in practice), all knowledge can be gained by the power of our reason alone; the latter rejected this, believing that all knowledge has to come through the senses, from experience. Thus the Rationalists took mathematics as their model for knowledge, and the Empiricists took the physical sciences.

This emphasis on epistemology is at the root of Kant's distinction; looking at the various philosophers in terms of their metaphysical, moral, or linguistic theories, they divide up very differently. Even sticking to epistemology, though, the distinction is shaky: for example, most of the Rationalists accepted that in practice we had to rely on the sciences for knowledge of the external world, and many of them were involved in scientific research; the Empiricists, on the other hand, generally accepted that a priori knowledge was possible in the fields of mathematics and logic.

This period also saw the birth of some of the classics of political thought, especially Thomas Hobbes' Leviathan, and John Locke's Two Treatises of Government.

The seventeenth century in Europe saw the culmination of the slow process of detachment of philosophy from theology. Thus, while philosophers still talked about – and even offered arguments for the existence of – a deity, this was done in the service of philosophical argument and thought. (In the Enlightenment, the Age of Reason, 18th-century philosophy was to go still further, leaving theology and religion behind altogether.)

Persia

Meanwhile in Persia, early Islamic philosophy and Iranian philosophy witnessed their last major phase of development with the rise of Transcendent Theosophy (al-Hikmat al-Muta’liyah). This school of thought was founded by Mulla Sadra (1571–1640), who was himself a student of another famous Persian Islamic philosopher at the time, Mir Damad.

A concept that lies at the heart of Mulla Sadra's philosophy is the idea of "existence precedes essence", a key foundational concept of existentialism, which was not known in the West until the 19th century. This was also the opposite of the idea of "essence precedes existence" previously supported by Avicenna and his school of Avicennism as well as Shahab al-Din Suhrawardi and his school of Illuminationism. For Mulla Sadra, "existence precedes the essence and is thus principle since something has to exist first and then have an essence." This is primarily the argument that lies at the heart of Mulla Sadra's philosophy.

Another central concept of Mulla Sadra's philosophy is the theory of "substantial motion" (al-harakat al-jawhariyyah), which is "based on the premise that everything in the order of nature, including celestial spheres, undergoes substantial change and transformation as a result of the self-flow (fayd) and penetration of being (sarayan al-wujud) which gives every concrete individual entity its share of being. In contrast to Aristotle and Ibn Sina who had accepted change only in four categories, i.e., quantity (kamm), quality (kayf), position (wad’) and place (‘ayn), Sadra defines change as an all-pervasive reality running through the entire cosmos including the category of substance (jawhar)." Gottfried Leibniz later described a similar concept several decades later.

History of philosophy

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?

From left: Plato, Confucius, Avicenna

All cultures — be they prehistoric, medieval, 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 and Aristotle. The Medieval period runs until roughly the late 15th century 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

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 (all is apeiron).

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. 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.

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

Medieval philosophy was greatly concerned with Christianity, the nature of God and the application of Aristotle's logic and thought to every area of life. Attempts were made to reconcile these three things by means of scholasticism. One continuing interest in this time was to prove the existence of God, through logic alone, if possible. The point of this exercise was not so much to justify belief in God, since in the view of medieval Christianity this was self-evident, but to make classical philosophy, with its extra-biblical pagan origins, respectable in a Christian context.

Ionia, source of early Greek philosophy, in western Asia Minor

One early effort was the cosmological argument, conventionally attributed to Thomas Aquinas. The argument roughly is that everything that exists has a cause. But since 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 were 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

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 and American Enlightenment 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 and Thomas Paine and Thomas Jefferson who were philosophers of the American 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.

Also in the 19th century, the Danish philosopher Søren Kierkegaard took philosophy in a new direction by focusing less on abstract concepts and more on what it means to be an existing individual. His work provided impetus for many 20th century philosophical movements, including existentialism.

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 Ludwig Wittgenstein, Martin Heidegger, Bertrand Russell, Jean-Paul Sartre, and Edmund Husserl. Epistemology, the theory of knowledge, and its basis was a central concern, as seen from the work of Heidegger, Russell, Karl Popper, and Claude Lévi-Strauss. Phenomenologically oriented metaphysics undergirded existentialism (Sartre, Maurice Merleau-Ponty, Albert Camus) and finally poststructuralism (Gilles Deleuze, Jean-François Lyotard, Michel Foucault, Jacques Derrida). Pragmatist Richard Rorty has argued that these and other schools of 20th century philosophy, including his own, share an opposition to classical dualism that is both anti-essentialist and antimetaphysical. The psychoanalytic work of Sigmund Freud, Jacques Lacan, Julia Kristeva, and others has also been influential in contemporary continental philosophy.

A notable phenomenon of the latter half of the century was the rise of popular philosophers who promulgated systems for dealing with the world but were isolated from academic philosophy, such as Ayn Rand, who were radical critics of traditional philosophy and psychology and relied on unorthodox methods. 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.

The 21st century's philosophy is difficult to clarify due to the short span of time that has lapsed since the start of the new millennium. Only nearly one decade has passed since its beginning, however it is usually seen as being defined by the prominent 20th century philosophers who still survive today. These include the likes of Noam Chomsky, Saul Kripke and Jürgen Habermas, whose work as professors and educators in the field of philosophy have allowed them to reach prominence in the mainstream media. The 21st century continues to carry with it much of the philosophical debate seen in the former one, with continental and analytic traditions still reigning in major debate. A variety of new topics, however, have risen to the stage, resurrecting ethics into the modern philosophical discussion. For instance the implications of new media and information exchange, such as the Internet, have brought back interest in the philosophy of technology and science.

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. Hindu philosophy primarily begins with Upanishads, which can be dated around the middle of the first millennium BC. The oldest, such as the Brhadaranyaka and Chandogya Upanishads, have been dated to around the 8th 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