Philosophy

The School of Athens fresco painted by Renaissance artist Raphael.

Philosophy is defined as the rational, abstract, and methodical consideration of reality. Philosophical inquiry, as a question of the fundamental decisions of human existence and experience, is a central part of the intellectual history of many civilizations. However, defining philosophy also proves very difficult. No brief definition or description can adequately capture, let alone express, the breadth and variety of philosophy. It has been described as the reasoned pursuit of fundamental truths, a quest for understanding, and a study of principles of conduct. Further, it can be defined as a critical study of the basic principles and concepts of a particular branch of knowledge or used to describe a system of principles for the guidance of practical matters.

A.C. Grayling, a professor of philosophy and a public intellectual, in his History of Philosophy, defines philosophy as:

The attempt to make sense of things, to achieve understanding and perspective, in relation to those many areas of life and thought where doubt, difficulty, obscurity, and ignorance prevail - which is to say: on the frontiers of all endeavors.

In English, the first known usage of the word—philosophie—was similar to the twelfth-century modern French usage and came in the thirteenth century. This came from the Latin philosophia, from the Greek philosophia, defined as "the love of knowledge, pursuit of wisdom, or systemic investigation of knowledge or wisdom." From the mid-fourteenth century, the definition of philosophy in English came to mean "the discipline of dealing in rational speculation or contemplation." By the Middle Ages, philosophy was understood to embrace all speculative sciences.

"Philosophy" is often also used to refer to a general or specific or individual worldview, ethic, or belief that can be considered utterly unrelated to any academic philosophical considerations. This meaning of the term is, to some, thought to be as important as the classical definition of philosophy, especially as this more personal definition of philosophy often unknowingly lives and operates based upon the personal set of values, beliefs, and ethics that form an individual's philosophy.

These often unexpressed and even unconscious philosophies can be incompatible and contradictory, as they may not be deeply interrogated. For example, if a person professes "only money counts in life," that individual is making a philosophical stance and is likely at odds with other convictions held by the same individual, such as a passion for art or love for their family.

However, philosophy remains more than a "way of life" or a worldview or something as narrow as choosing a body of thought an individual decides to believe in. Rather, it is best understood as a type of thinking or the activity of thought, specifically critical and comprehensive thought. This process can involve analytic and synthetic modes of thinking and analysis, which work to resolve confusion, assumptions, presuppositions, importance, testing positions, distortions, reasoning, worldviews, and conceptual frameworks. And this is done with the goal of increasing understanding, dispelling ignorance, developing imagination, and widening an individual's considerations.

In its broadest sense, philosophy is an activity undertaken by people who seek to understand fundamental truths about themselves, their world, and their relationship to that world and each other. As an academic discipline, philosophy is the same, with those studying it engaged in asking, answering, and arguing for answers to basic questions but with an attempt to make the study of philosophy more systemic. This attempt at systemic explanation in philosophy led to the development of the different branches of study in philosophy. The main, traditional branches of philosophy include metaphysics, epistemology, aesthetics, ethics (or aesthetics and ethics combined into axiology), and logic.

However, as philosophy has continued to evolve, there have emerged other branches of philosophy, including the philosophy of language, the philosophy of mind, the philosophy of science, political philosophy, the philosophy of religion, social philosophy, metaphilosophy, the philosophy of law, medical ethics, and business ethics. The questions of which branches are included in a taxonomy of philosophy depend on the individual asked, with many of the "philosophy of" and medical ethics and business ethics considered subfields of the larger branches. Meanwhile, others believe the work done in these fields to be impactful enough to consider these fields in their own right.

Metaphysics is the study of the nature of reality, of what exists in the world, what it is like, and how it is ordered. The field of metaphysics tends to deal with the following questions: Is there a God? Is there a thing such as truth? What is a person? What makes a person the same through time? What is the composition of matter?

Metaphysics tends to be a difficult field to define, though, as the nature of the field has changed over time. For instance, ancient and medieval philosophers might have said metaphysics was similar to chemistry or astrology and defined by its subject matter; for example, metaphysics was the study of "being as such" or "the first causes of things," but it is no longer possible to define metaphysics this way as the field has grown, with many more philosophical problems that are now considered to be metaphysical problems. Many of those topics that have been considered metaphysical in the post-medieval or early modern era include concepts such as the reality of the external world, theories of mind and body, existence as a problem, universals and particulars, causation, substance, identity, and persistence through time.

Epistemology is the study of knowledge and is primarily concerned with what people can know and how they can know it. The following are typical questions of epistemology: What is knowledge? How is knowledge known? Can people be said to know anything? Can people be justified in claiming to know things? The term epistemology comes from two Greek words: episteme and logos. Episteme can be translated as "knowledge" or "understanding" or "acquaintance." And logos can be translated as "account" or "argument" or "reason" and thus offer facets of interest in the field of epistemology. While the term epistemology is only a few centuries old, the questions around what can be known and how can anything be known are as old as philosophy.

Often epistemology sorts questions into two categories. The first is to determine the nature of knowledge, or what it means to say that someone knows, or fails to know, something. The second question, or task, is to determine the extent of human knowledge, or how much do or can people know.

The study of ethics, also called moral philosophy, is the discipline concerned with what is morally good and bad and morally right and wrong. The term has also been applied to any system or theory of moral values or principles. The term is derived from the Greek word ethos, which means "way of living" and tends to be the branch of philosophy concerned with how people should live, how they should live to live a good life, how people should conduct themselves individually and as a member of a society, and the rational justifications for moral judgments.

Concepts in the field of ethics have been derived from religions, philosophies, and cultures or societies and tend to infuse debates on various topics, such as abortion, human rights, and professional conduct. Philosophers often divide ethical theories into three areas: metaethics, normative ethics, and applied ethics.

• Metaethics deals with the nature of moral judgment and tends to look at the origins and meaning of ethical principles.
• Normative ethics is concerned with the content of moral judgments and the criteria for what is right and wrong.
• Applied ethics looks at controversial topics, such as war, animal rights, and capital punishment, and applies ethical theories to them.

Logic, the philosophy of logic, is the study from a philosophical perspective of the nature and types of logic, including problems in the field of logic and the relation of logic to mathematics and other disciplines. The study of logic relates to the human capacity to reason through problems, while logic can be considered the study of good versus bad reasoning or reasoning done correctly versus reasoning done incorrectly.

Aristotle defined logic as "new and necessary reasoning," as it allows people to learn what they do not know and because its conclusions are inescapable. Logic and logicians, in philosophy, tend to ask the following questions: What is correct reasoning? What distinguishes a good argument from a bad one? How can one detect a fallacy in reasoning? Logical systems should have consistency, soundness, and completeness. This means an argument's theorems cannot or should not contradict one another; it means the system's or argument's rules of proof will never allow a false inference from a true premise; and it means there are no true sentences in the system that cannot, at least in principle, be proved in the system.

Aesthetics, also spelled esthetics, is the philosophical study of beauty and taste and is closely related to the philosophy of art. This tends to involve the study of or critical reflection on art, culture, and nature and works to address the questions of the nature of art, beauty, taste, enjoyment, perception, and the creation and enjoyment of beauty. It is also sometimes defined as the study of sensory or sensori-emotional values, sometimes called judgments of sentiment and taste.

Aesthetics was introduced into the philosophical lexicon during the eighteenth century and has come to designate a kind of object, a kind of judgment, a kind of attitude, a kind of experience, and a kind of value. Often aesthetic theories have divided over particular questions: Are artworks aesthetic objects? How does one square the perceptual basis of aesthetic judgments to the reasons used to support them? How can one best capture the elusive contrast between an aesthetic attitude and a practical one? Can one define aesthetic experience according to its phenomenological or representational content? How does one best understand the relation between aesthetic value and aesthetic experience?

The philosophy of science works to explore the foundations, methods, history, implications, and purpose of scientific investigation. Many of the branches of the philosophy of science, some of which have grown into branches of philosophy itself, tend to correspond to specific branches of science. Often the philosophy of science will discuss the metaphysical, epistemological, and ethical issues related to the practice and goals of science. As such, the philosophy of science is concerned with the assumptions, foundations, methods, and implications of science and the use and merit of science, often with significant overlap amongst other philosophical branches.

The philosophy of science has been met with mixed responses from the scientific community, despite their common contributions to the field. Many of these mixed responses come from the feeling on the part of many scientists that the practical effect on their work is limited. The types of questions addressed by the philosophy of science are as follows: What are the laws of nature? Are there any in non-physical sciences such as biology or psychology? What kind of data can be used to distinguish between real causes and accidental regularities (causation versus correlation)? How much or what kinds of evidence are necessary before a hypothesis is accepted?

The philosophy of language, or the philosophy of linguistics, involves the philosophical investigation of the nature of language; the relations between language, language users, and the world; and the concepts with which language is described and analyzed, both in everyday speech and in scientific linguistic studies. The investigations are conceptual rather than empirical, which distinguishes the philosophy of language from linguistics, but they remain interrelated.

Some mark a distinction between the philosophy of language from the philosophy of linguistics, as the philosophy of language is traditionally concerned with matters of meaning and reference, while the philosophy of linguistics tends to be the philosophy of science applied to linguistics.

The history of the philosophy of language is in the analytical tradition, which began with advances in logic and within the traditional accounts of the mind and its contents at the end of the nineteenth century. This led to a revolution of sorts, often referred to as the "Linguistic Turn" in philosophy, but the early programs ran into serious difficulties by the mid-twentieth century, which led to further changes in the direction of the branch of philosophy.

The philosophy of religion, as the name implies, is the philosophical investigation into the meaning and nature of religion. This can include the analyses of religious concepts, beliefs, terms, arguments, and practices of religious adherents. The scope of a lot of the work in the philosophy of religion has been limited to various theistic religions, although more recent work has involved a broader and more global approach that takes into consideration theistic and non-theistic religious traditions. Philosophy of religion also includes the investigation and assessment of worldviews that are considered alternatives to religious worldviews, such as secular naturalism.

Many of the traditional philosophers who are included in the tradition of the philosophy of religion include questions around religion in their larger philosophical investigations, borrowing many investigations from metaphysics, epistemology, ethics, the philosophy of education, law, and politics in order to examine religion. These early investigations led to the development of the philosophy of religion, which has since specialized into its own field with specialized courses, journals, and disciplines in academic training.

The philosophy of law, also called jurisprudence, is the branch of philosophy investigating the nature of law and its relation to human values, attitudes, practices, and political communities. The philosophy of law proceeds with articulations and defenses of propositions about the law in the general and abstract, but not true of a particular legal system at a specific time and instead could be said to be true of all legal systems in the present and the law at all times. This deals with the problems of authority, law and order, obligation, and self-interest in regard to the law, especially as most laws are considered artificial and arrived at through the consent of the majority.

Topics in the philosophy of law tend to be closely related to topics in political philosophy and applied ethics. There are roughly three major categories into which the topics of legal philosophy fall: analytic jurisprudence, normative jurisprudence, and critical theories of law. Analytic jurisprudence involves an analysis of the essence of law to understand what differentiates it from other normative systems, such as ethics. Normative jurisprudence involves the examination of normative, evaluative, and prescriptive issues about the law. And critical theories of law challenge more traditional forms of legal philosophy.

Political philosophy is the branch of philosophy concerned with the concepts and arguments involved in political opinion. Even the term "political" is a problematic term in political philosophy, based on what can or cannot be considered political, but it is broadly used to characterize as political all practices and institutions concerned with the government. Political philosophers seek to establish basic principles that will, for instance, justify a form of state, show that individuals have certain inalienable rights, or establish how a society's material resources should be shared among its members.

Despite the shared topics and links in issues and methods, political philosophy can be distinguished from political science. Often political science is characterized with dealing with existing states of affairs, whereas political philosophy questions a better political life, such as what the ruling set of values and institutions should be.The following are common questions in political philosophy: What is a government? Why are governments needed? What makes a government legitimate? What rights and freedoms should a government protect? What duties do citizens owe to a legitimate government, if any? When may a government be legitimately overthrown, if ever?

Social philosophy is a branch of philosophy that examines questions about the foundations of social institutions, social behavior, and interpretations of society in terms of ethical values. Social philosophers tend to emphasize understanding the social contexts for political, legal, moral, and cultural questions, and the development of novel theoretical frameworks such as social ontology, care ethics, cosmopolitan theories of democracy, natural law, human rights, gender equity, and justice.

Social philosophy works to contribute to social change, with examinations into gender studies, black studies, and disability studies, while being continuous with traditional areas of philosophy such as metaphysics or epistemology.

Metaphilosophy is the study of the nature of philosophy. As a branch, it tends to ask these questions: What is philosophy? What is philosophy for? How should philosophy be done? More modern metaphilosophy has been roughly divided according to different philosophical traditions, including analytic philosophy, pragmatist philosophy, and continental philosophy. Often metaphilosophy is considered the "philosophy of philosophy," and despite being recursive, it is seen as an integral part of the philosophical enterprise and is a part of all branches of philosophy. Central questions of metaphilosophy can include questions about the nature of the philosophical inquiry.

The topic of when and where philosophy began to develop has been debated and continues to be debated, with many suggesting the simplest answer is that it would have begun the first time someone asked why they were born, what their purpose was, or how they were supposed to understand their lives. While philosophy has grown into formalized secular or religious systems of thought or a communal understanding, in each case, the purpose of the system likely began as an attempt to answer such questions.

However, systematic philosophical thought is believed to have first developed in Mesopotamia and Egypt. In Egypt, around 4000 BCE, the first depictions of gods and the afterlife and a certain religious worldview were carved into tomb walls. While in Mesopotamia, around 2150 BCE, The Epic of Gilgamesh, a partly written philosophical account in narrative form was written. In India, 1500 to 500 BCE was the development of the Vedic period. Around 1500 BCE was the development of Zoroastrianism in Persia. In China, around 1046 to 256 BCE, was the Zhou Dynasty. And in Greece, from 585 to 322 BCE came the time of Thales of Miletus to the death of Aristotle of Stagira.

The writing of the history of philosophy and the organization of the history in its presentation or where the lines are drawn have been controlled by a variety of cultural habits. Often the history is divided into ancient, medieval, Renaissance, modern, and contemporary. This distinction is as old as the seventeenth century. In the field, the treatment has generally been ordered into common types, either as a history of ideas or a history of intellectual products of human beings. This makes any ordering of the history of philosophy difficult.

It is difficult and potentially impossible to find two philosophers who define philosophy in the same way. The meaning of the word or the concept has meant different things throughout the history of the West. It can be a challenge to determine if there is a common element that can be found in all of the diversity and whether any core meaning could serve as a universal or all-inclusive definition. Part of this difficulty comes in finding any consensus among philosophers about the definition of their discipline, which is influenced by the difference in their opinions, histories, interests, concerns, and areas of expertise they have brought to these disciplines. Therefore, the history of Western philosophy reveals in detail the concentrated activity of a multitude of serious and able thinkers reflecting upon, reasoning about, and considering deeply the nature of experience.

Etching of Thales of Miletus.

Philosophical traditions are often split over geographic and historical continuations of types of thought or engagement with specific thinkers, which creates a threat throughout history. However, as with many delineations, the truth is much messier than the clean lines drawn in histories of philosophy. For example, the tradition of Western philosophy is considered to begin in Ancient Greece, with Thales of Miletus, despite the tradition of that thought being maintained by Middle Eastern and North African thinkers during what has been called the European Dark Ages, until they are rediscovered in the Renaissance and return to the forefront of medieval European thought.

However, traditional philosophical histories hold that the beginning of western philosophy is in these pre-Socratic philosophers and the major issues including the establishment of the underlying substance of the world. For instance, Thales of Miletus thought the universe was composed of different forms of water; Anaximenes thought matter was made of air, while Heraclitus thought it was made of fire; and Anaximander thought it was an unexplainable substance often translated as "the infinite" or "the boundless."

Renaissance painting of Heraclitus.

Another major issue for the pre-socratic philosophers was the problem of change, or how objects appear to change from one form to another. At the extremes were Heraclitus, who believed everything was under an ongoing process of perpetual change, and Parmenides, who argued that there was no such thing as change at all and that everything that exists is permanent and indestructible. While these may seem simplistic in light of modern scientific knowledge, these often presented the first attempts at analytical thinking to understand the world and early scientific inquiry. As well, there were some surprising insights, such as Democritus, who developed the idea of atomism, or the theory that all of reality is composed of tiny, indivisible, indestructible building blocks called atoms.

Over ninety pre-Socratic philosophers are known to have contributed something to contemporary thinking, and there may have been more that did not survive history. However, many pare down the number to a more manageable fifteen thinkers whose contributions directly or indirectly influenced Greek culture and the later works of Plato and Aristotle. These consist of the following:

• Thales of Miletus—c. 585 BCE
• Anaximander—c. 610-546 BCE
• Anaximenes—c. 546 BCE
• Pythagoras—c. 571-497 BCE
• Xenophanes of Colophon—c. 579-478 BCE
• Heraclitus of Ephesus—c. 500 BCE
• Parmenides—c. 485 BCE
• Zeno of Elea—c. 465 BCE
• Empedocles—c. 484-424 BCE
• Anaxagoras—c. 500-428 BCE
• Democritus—c. 460-370 BCE
• Leucippus—c. 5th century BCE
• Protagoras—c. 485-415 BCE
• Gorgias—c. 427 BCE
• Critias—c. 460-403 BCE

Jacques Louis David's painting of the Death of Socrates.

Philosophy is considered to have gained popularity and understanding with Socrates and Plato in the fifth and fourth centuries BCE. Unlike those who preceded him, Socrates was concerned with how people should behave. He has been considered the first major philosopher of ethics and worked on a system of critical reasoning to work out how people should live properly and how to tell the difference between right and wrong. This system, referred to as the Socratic Method, was designed to break problems into a series of questions, the answering of which would distill a solution.

Bust of Plato.

Socrates did not write anything down, but his views were passed down through the writings of his student, Plato, who is known as one of the most influential philosophers of all time. Plato blended ethics, metaphysics, political philosophy, and epistemology into an interconnected and systematic philosophy. He also provided the first opposition to the materialist beliefs of the pre-Socratic philosophers. Plato also developed doctrines such as Platonic realism, essentialism, and idealism, and his theory of forms and universals.

Bust of Aristotle.

The third of the major trio of this period was Aristotle, Plato's student. He created a more comprehensive system of philosophy, encompassing ethics, aesthetics, politics, metaphysics, logic, and science, and his work influenced almost all later philosophical thinking, especially in the medieval period. Unlike Plato, Aristotle held that form and matter were inseparable and could not exist apart. Further, Aristotle realized ethics is a complex concept, and an individual cannot always control their moral environment. He thought happiness could best be achieved by pursuing a "golden mean"—living a balanced life between extremes of deficiency and excess.

In the philosophical atmosphere of the succeeding Hellenistic and Roman civilizations, many other schools and philosophical movements held sway. Many of these were developed in the school and academy developed by Plato and Aristotle respectively and were paraded through the Athenian Agora. While in Rome, much like Roman mythology and theatre, a lot of the philosophy that was adopted and practiced was based on Greek thought they were introduced to in the Roman conquest of Greece. These schools included the following:

Medieval philosophy is marked by the fall of the Western Roman Empire and later the Holy Roman Empire, after which, during the fourth or fifth centuries CE, Europe entered a so-called Dark Ages. During this period, little to no new thoughts and philosophies were developed, and the few that were did not survive. By the eleventh century, there was a renewed flowering of thought through Christian Europe and in the Muslim and Jewish Middle East. Most of the philosophers of this time were concerned with proving the existence of God and reconciling Christianity or Islam with the classical philosophy of Greece. During this period was also the establishment of the first universities, which was an important factor in the subsequent development of philosophy.

Image of Avicenna.

Among the Islamic philosophers of the medieval period, Avicenna and Averroes were prominent thinkers. Avicenna worked to reconcile the rational philosophy of Aristotle and Neo-Platonism with Islamic theology and developed an individual system of logic known as Avicennian logic. He also introduced the concept of tabula rasa—that humans are born with no innate or built-in mental content and are a "blank slate." This concept would influence later empiricists. Averroes's translations and commentaries on Aristotle had an impact on the Scholastic movements in Europe, and part of those claims was that Avicenna's interpretations were a distortion of genuine Artistotelianism. The Jewish philosopher Maimonides, during this same period, attempted to reconcile Aristotle with Hebrew scriptures.

Medieval Christian philosophers were part of a movement called Scholasticism, which tried to combine logic, metaphysics, epistemology, and semantics into a single discipline and reconcile the philosophy of the ancient classical philosophers with Christian theology. The Scholastic method requires to thoroughly and critically read the works of renowned scholars, note disagreements and points of contention, and resolve them through formal logic and an analysis of language. However, the school has been criticized for spending too much time discussing infinitesimal and pedantic details. Prominent members of the school include Thomas Aquinas, St. Anselm, Peter Abelard, Jean Buridan, John Duns Scotus, and William of Ockham.

Image of Anselm of Canterbury, or St. Anselm.

St. Anselm is best known as the originator of the Ontological Argument and has been considered the originator of the Scholastics. While Thomas Aquinas, known for his five rational proofs for the existence of God, is generally considered the greatest of the Scholastics by influence if nothing else. The influence of Thomas Aquinas extended to the theology of the Catholic Church. The other thinkers of the movement had contributions to slight variations of the same general belief. For example, Peter Abelard introduced the doctrine of limbo for unbaptized babies. John Duns Scotus rejected the distinction between essence and existence that Aquinas insisted on. William of Ockham introduced an important methodological principle known as Ockham's Razor, which says one should not multiply arguments beyond the necessary.

During this period, Roger Bacon was an exception to the major strain of thought, often criticizing the prevailing Scholastic system because it was based on tradition and scriptural authority. He is sometimes credited as the earliest European advocate of the modern scientific method and empiricism—the theory that the origin of all knowledge is sense experience.

During the fifteenth and sixteenth centuries, the revival of classical civilization and learning, known as the Renaissance, brought the medieval period to a close. This period was marked by a movement away from religion and medieval Scholasticism and toward humanism and a new sense of critical inquiry. The following are some of the major figures in the Renaissance period:

• Desiderius Erasmus—who challenged many of the traditions of the Catholic Church and popular superstitions
• Niccolo Machiavelli—whose cynical, and sometimes described as devious, political philosophy became notorious and associated with his name
• Thomas More—who was a Christian humanist whose book Utopia influenced generations of philosophers and planners and the early development of Socialist ideas
• Francis Bacon—who developed an empiricist belief that truth requires evidence from the real world; his application of inductive reasoning was influential in the development of modern scientific methodology

The Age of Reason of the seventeenth century and the Age of Enlightenment in the eighteenth century, along with advances in science, the growth of religious tolerance, and the rise of liberalism that went with them, have often been used to mark the beginnings of modern philosophy. The period has been described as an ongoing battle between opposing doctrines: rationalism, which is the belief that all knowledge arises from intellectual and deductive reason rather than the sense, and empiricism, which is the belief that the origin of all knowledge is based on sense experience. There were also various non-aligned philosophers of this period:

Painting of Rene Descartes, born 1596 and died 1650.

The first figure who, arguably, began the revolution in philosophical thought in Europe that was rationalism was the French philosopher and mathematician Rene Descartes. As one of the first figures in the loose movement known as rationalism, much of subsequent Western philosophy can be seen as a response to his ideas. His method, known as methodological skepticism, aimed to dispel skepticism by removing any ideas that have even a suspicion of doubt, such as unreliable sense, to arrive at the single indubitable principle that because he possessed consciousness, he was able to think. He argued, unsatisfactorily for some, that a person's perception of the world must be created by God. Further, he saw the human body as a machine following the mechanical laws of physics, and the mind, or consciousness, was a separate entity not subject to the laws of physics and only able to influence the body and deal with the outside world through a mysterious two-way interaction. This idea would come to be known as dualism and would set the agenda for the mind-body problem for centuries. Despite his innovation and his intellectual boldness, Descartes, as a product of his time, never rejected the traditional idea of God.

Painting of Baruch Spinoza, born 1632 and died 1677.

The second major figure of rationalism was Baruch Spinoza. His concept of the world was quite different from Descartes's, and he built an original self-contained metaphysical system that rejected Descartes's dualism in favor of a monism in which the mind and body were considered to be two different aspects of a single underlying substance that could be called nature. Spinoza was a determinist, who believed everything occurs through the operation of necessity, leaving no room for free will and spontaneity. He also took a moral relativist position, in which he believed nothing can in itself be good or bad, except to the extent that it is subjectively perceived to be so by an individual.

Painting of Gottfried Wilhelm Leibniz, born 1646 an died 1716.

Another great figure from the period and of the rationalist movement was the German Gottfried Leibniz. He worked to overcome what he saw as drawbacks and inconsistencies in the theories of Descartes and Spinoza by devising an eccentric metaphysical theory of monads operating according to a pre-established divine harmony. According to Leibniz's theory, the world is composed of eternal, non-material, and mutually-independent elements that these monads and the material world people interact with and is a phenomenon and nothing more. The apparent harmony of the arrangement among the monads, according to Leibniz, is because of the will of God, who arranges everything in the world in a deterministic manner. Leibniz saw this as overcoming the problematic interaction between mind and body in Descartes's system. Leibniz has also been considered one of the more important logicians between Aristotle and the formal mid-nineteenth century development of modern logic.

Another important figure of the seventeenth century and the rationalist movement was the Frenchman Nicolas Malebranche. A follower of Descartes, he believed humans attained knowledge through ideas and immaterial representations of the mind. However, Malebranche argued that all ideas only exist in God, and God was the only active power. Thus he believed that any "interaction" between body and mind is caused by God.

Painting of John Locke, born 1632 and died 1704.

In opposition to the rationalism movement, which was mainly developed on the European continent, came the empiricism movement, which was developed largely in the British isles. One of the first figures of the movement was John Locke, who argued that all ideas, whether simple or complex, are derived from experience, such that knowledge of which a person is capable is limited in its scope and certainty. Locke's view was that the inner nature (or primary qualities, as he called them) of a thing can never be known, and therefore a person can never be said to know them truly. Similar to Avicenna before him, Locke believed in the tabula rasa view of the mind but went further to suggest that humans were also born with absolute rights that are inherent in the nature of ethics. Along with later thinkers Hobbes and Rousseau, John Locke was an originator of contractarianism, or Social Contract Theory, which was used to form the underpinning of democracy, liberalism, and lIbertarianism, and his views have been credited for influencing the French and American revolutions.

Bishop George Berkeley, born in 1685 and died in 1753.

Another prominent figure in empiricism was Bishop George Berkeley, although his empiricism was of a more radical kind, mixed with idealism. His dense but cogent argument developed a rather counterintuitive system known as immaterialism, sometimes called subjective idealism, which held that underlying reality consists exclusively of minds and their ideas. He argued further that individuals can only know ideas or perceptions, but not objects themselves, through experience. Thus, in Berkeley's theory, an object only exists if someone is there to sense or see it, except in the case of God, whose mind perceives everything all the time, and in this respect only can objects be said to continue to exist.

Painting of David Hume, born in 1711 and died in 1776.

The third, and arguably most important of the British empiricists of this period was David Hume. Hume believed that human experience is as close as people are going to get to the truth and that experience and observation must form the foundations of any logical argument. He also argued that despite beliefs formed and inductive inferences made about things outside of a person's experience, they cannot be conclusively established by reason. Therefore, an individual should not make claims about their knowledge about them. Although he never declared himself an atheist, Hume found the idea of God effectively nonsensical because, by his way of arguing, there was no way of arriving at the idea of God through sensory data. He attacked many of the basic assumptions of religion and gave many of the classic criticisms of some of the arguments for the existence of God. In his political philosophy, David Hume stressed the importance of moderation, and his work contains elements of both conservatism and liberalism.

Portrait of Immanuel Kant, born in 1724 and died in 1804.

Toward the end of the Age of Enlightenment came another thinker, Immanuel Kant, who was similar to Rene Descartes 150 years earlier, who caused an important paradigm shift in philosophical thought that in many ways marked the shift to what is known as modern philosophy. Immanuel Kant sought to improve philosophy and move it beyond the debate between rationalism and empiricism and attempted to do so through a combination of these apparently contradictory doctrines into a single, overarching system. This caused the development of a whole movement, known as Kantianism, which would develop in the wake of his work. Many subsequent philosophies can be seen as responses, in one way or another, to the ideas developed by Kant.

Kant would go on to show that empiricism and rationalism could be combined and that statements were possible that were both synthetic, or were a posteriori knowledge from experience alone as found in empiricism, and also a priori, or from reason alone as found in rationalism. Thus, without the senses, a person could be aware of any object, but without reason and understanding, a person could not form a conception of the object. Further, Kant said, a sense can only tell a person about the appearance or phenomenon of the thing, rather than that "thing-in-itself" or noumenon, which Kant believed was essentially unknowable. However, he suggested people have certain innate predispositions as to what exists, which was also called transcendental idealism.

Meanwhile, Kant also contributed to ethics by developing his theory of the categorical imperative. This imperative suggested that people should only act in such a way that those actions could become a universal law, applicable to everyone in a similar situation, known as moral universalism, and that people should treat other individuals as ends in themselves, not as mere means—also known as moral absolutism. Kant suggested these actions should even be taken if it means sacrificing a person for the greater good. Further, Kant believed that any attempts to prove God's existence were a waste of time because the concepts only work properly in the empirical world, which Kant held God was above. But he also argued it was not irrational to believe in something that clearly cannot be proven either way.

Image of Johann Gottlieb Fichte, born in 1762 and died in 1814.

One of the first major schools of thought to rise in the modern period of philosophy, born out of Kantian philosophy, was German idealism, and each philosopher from this school developed their own interpretation of Kant's ideas. Johann Fichte, one of these thinkers, rejected Kant's separation of "things in themselves" and "things as they appear," which he saw as an invitation to skepticism, but he did accept that consciousness of the self depends on the existence of something that is not a part of the self. Fichte's philosophy, especially his political philosophy, has also been considered to have contributed to the later rise of German nationalism.

Friedrich Schelling, another German idealist, developed a unique form of idealism called aesthetic idealism, in which Schelling argued that only art was able to harmonize and sublimate the contradictions between opposites, such as subjectivity and objectivity or freedom and necessity. He also tried to establish a connection or synthesis between conceptions of nature and spirit.

Arthur Schopenhauer, photographed in 1859, a year before his death.

Following Schelling came Arthur Schopenhauer, who was also considered a German idealist and a part of the romanticism movement, although his philosophy was very much his own. Schopenhauer was a pessimist who believed the "will-to-life" or drive to survive and reproduce was the underlying driving force of the world, and that the pursuit of happiness, love, and intellectual satisfaction were secondary and essentially futile. Further, Schopenhauer saw art and ascetic forms of awareness as the only ways to overcome the fundamentally frustration-filled and painful human condition.

Portrait of Georg Wilhelm Friedrich Hegel, born in 1770 and died in 1831.

Perhaps the greatest, or at least most influential, of the German idealists was Georg Hegel. His works have a reputation for abstractness and difficulty, and he is often considered the summit of early nineteenth century German thought with a profound influence on later thought. He extended Aristotle's process of dialectic by resolving a thesis and its opposing antithesis into a synthesis, to apply to the real world in an ongoing process of conflict resolution towards what he called the Absolute Idea. However, he stressed that what is really the changing process is the underlying "Geist" for mind, spirit, or soul. And Hegel saw each person's individual consciousness as part of an Absolute Mind, sometimes also referred to as an Absolute idealism.

Hegel's dialectical method and his analysis of history became a strong influence on the later thought and theories of Karl Marx. The Marxist theory, including the concepts of historical materialism, class struggle, the labor theory of value, and the concept of the bourgeoisie, developed with friend Friedrich Engels, was influenced by Hegel and formed as a reaction against the rampant capitalism of the nineteenth century Europe. These theories would provide the intellectual base for later radical and revolutionary socialism and communism.

Another major thinker of the nineteenth century, and another product of the differences in thought between continental Europe and the England of his birth, was John Stuart Mill. He was part of the utilitarian movement, which came out of the British empiricist tradition of the previous centuries. Utilitarianism was founded by radical social reformer Jeremy Bentham but would be popularized by his protege, John Stuart Mill. The doctrine of utilitarianism is a type of consequentialism, or an approach to ethics that stresses an action's outcome or consequence to determine whether an action was good or bad. Utilitarianism holds that the right action is that which causes the greatest happiness for the greatest number, but Mill refined the theory to stress the quality, not just the quantity of happiness, and intellectual and moral pleasures over more physical forms. He counseled that coercion in society is only justifiable to defend oneself or to defend others from harm.

Another thinker of the nineteenth century who did not belong to the German idealists was August Comte, a French sociologist and philosopher who founded the influential positivism movement around the belief that the only authentic knowledge was scientific knowledge, which is based on actual sense experience and a strict application of the scientific method. Comte saw this as a final phase in the evolution of humanity and created a non-theistic, pseudo-mystical "positive religion" around the idea.

Søren Kierkegaard was a Danish philosopher who pursued his own, relatively unique trail of thought. He was a kind of fideist and has been considered an extremely religious man, regardless of attacks on the Danish state church. But his analysis of the way human freedom tends to lead to "angst" or dread, the call of the infinite, and eventually to despair and was influential on later existentialists, such as Heidegger and Sartre.

Picture of Friedrich Nietzsche born in 1844 and died in 1900.

Another singular thinker of this period was the German Friedrich Nietzsche. Described as atypical, original, and controversial, Nietzsche was another important forerunner of existentialism. His thinking challenged the foundations of Christianity and traditional morality, which led to charges of atheism, moral skepticism, relativism, and nihilism levied at his thought. Further, he developed original notions as the "will to power" as a motivating principle for humanity, of the "ubermensch" or superman as the goal of the individual, and of "eternal return" as a means of evaluating one's life, all of which have all generated much debate and argument among scholars.

Picture of Ralph Waldo Emerson, born in 1803 and died in 1882.

During the nineteenth century, the relatively new country of America developed its own philosophical traditions. Ralph Waldo Emerson established the transcendentalism movement in the middle of the century, which was rooted in the transcendental philosophy of Kant, German idealism, and romanticism. It was part of Emerson's desire to ground religion in the inner spiritual or mental essence of humanity rather than as a sensuous experience. Emerson's student, Henry David Thoreau, further developed these ideas, stressing intuition, self-examination, individualism, and exploration of the beauty of nature. Thoreau's advocacy of civil disobedience influenced the generations of social reformers.

The other main American movement of the late nineteenth century was pragmatism, which was initiated by C. S. Peirce and developed and popularized by William James and John Dewey. The theory of pragmatism was based on Peirce's pragmatic maxim that the meaning of any concept is the same as its operational or practical consequences or that something is only true insofar as it works in practice. Peirce also introduced the idea of fallibilism—the theory that all truths and facts are necessarily provisional, and they can never be certain but only probable.

Picture of William James, born in 1842 and died in 1904.

William James, in addition to his psychological work, extended pragmatism, both as a method for analyzing philosophic problems and as a theory for truth. He further developed his own version of fideism, that beliefs are arrived at by an individual process that lies beyond reason and evidence, and voluntarism, that the will is superior to the intellect and emotion, among others. John Dewey's interpretation of pragmatism is better known as instrumentalism—the methodological view that concepts and theories are useful instruments, best measured by how effective the concept or theory is in explaining and predicting phenomena and not by whether they are true or false, which he claimed was impossible. Dewey made further contributions to the philosophy of education and to modern progressive education.

Although they tended to mix through the cauldron of the fertile valley and ancient Greece, Eastern philosophy and Western philosophy tend to be held separate throughout history as the philosophical traditions of both regions tend to have different histories and focuses that do not necessarily mix in any meaningful way until the nineteenth century. Eastern philosophy is expansive and goes as far back as 5,000 years. These are intricate and popular philosophies, with many adherents to the religious philosophies thousands of years old.

Another defining characteristic of Eastern philosophy, especially compared with ancient Greek philosophers and the traditions born out of Greek philosophy that was increasingly secular, is that Eastern philosophies are intimately tied to their respective religious traditions of Hinduism, Buddhism, Confucianism, and Daoism. Distinguishing Eastern philosophy from the respective religion comes down to emphasis, with the philosophy dealing with some secular questions, such as an individual's relation to the cosmos or understanding how some ultimate reality or God relates to the world.

Hinduism is considered one of the oldest texts in the Eastern philosophical tradition, with concepts directly or indirectly influencing other Eastern philosophical traditions. While many religious traditions are founded by renowned people, Hinduism has no founding figure and covers a diversity of views of the people of India going as far back as 3,500 BCE.

Most generally, "Hinduism" means the religion of the Indus River region. Early Hindu religion was polytheistic, similar to religions in other parts of the world during the period. The sacred text of the religion is called the Vedas, translated as "bodies of knowledge," and is estimated to have been written around 1,500-800 BCE in the Sanskrit language. The text describes features of gods, rituals to appease them, and hymns to chant to them. Philosophical discussions within Hinduism emerged between 800 BCE to 200 CE, which emphasized the pantheistic notion of the divine reality that permeates the cosmos, called the Atman-Brahman, meaning the Self-God.

The Self-God concept is that an individual, any individual, is or could be the God of the cosmos. This could sound strange, but classical Hindu philosophers provide the explanation that the Atman is the true self at the core of an individual's identity, and it is only this part that is identical to God. Further, there is the analogy of the onion, in which the layers of an individual's identity are described; each outer layer involves common-sense views the individual experiences empirically, including the physical body, sensations, thoughts, and feelings. The Self-God is the inner core of the onion, hiding behind the layers, and because it is obscured, the individual may fail to comprehend the existence of the inner core and their divine status.

This doctrine was discussed in two Hindu works: The Upanishads and The Bhagavad Gita. The Upanishads are a series of 180-200 anonymously written texts, and Hindu tradition gives special emphasis to thirteen of the texts composed between 800 to 100 BCE. In these texts, the Self-God concept is explored and explained to exist beneath the physical structure of things, including plants, animals, humans, and everything else, and that this unites all of these things. The merge of these realities is an undifferentiated reality. In a story in one of the texts, a father describes this concept to his son, saying "you are that" to convey to his son that he is the Self-God. The phrase "you are that" has been further used to encapsulate the message of all of The Upanishads.

Image inspired by the Bhagavad Gita.

In the Bhagavad Gita, Sanskrit for "Song of God," a one-hundred-page section of an epic poem called the Mahabharata explores the concept of the Self-God. The epic Mahabharata is around 5,000 pages, is one of the world's longest epic poems, and was composed over an 800-year period. The poem chronicles a feud between branches of the royal family. The story of the Bhagavad Gita focuses on prince Arjuna, a leader on one side of the feud, who feels despair about the coming battle. He expresses his grief to his charioteer Krishna, who is the manifestation of the Hindu god Vishu in human form. Krishna comforts Arjuna with a philosophy lesson about discovering God, in which the point of the Self-God comes forward and Krishan comforts Arjuna by saying that through the virtue of the Self-God, all individuals are eternal and what happens to the body is insignificant; therefore, Arjuna should not worry about the coming conflict as it cannot touch his inner self.

Hindu religion, and by extension philosophy, has long had a tradition of belief in reincarnation. This view holds the end of a person's present life is followed by a new life in a different physical body. The components of rebirth are twofold. The first is the process of rebirth, in which, at death, the true self is reborn into another body, and when that second body dies, the true self is reborn into another, and so on. The second component of rebirth is the moral consequences of a person's life that can be carried into the next, also known as Karma. Karma dictates the reincarnation of a person's true self will be swayed by the behavior of the person in their past life and their good or bad actions in those previous lives. This dictates the person's place in rebirth, including rebirth in a non-human life.

While rebirth is thought of as a good thing, instead, it is intended as something to be dreaded, for it places the true self in an endless cycle of struggles. Hindu writings stress approaches to release, two of which are especially dominant. The first approach is a matter of accumulating an abundance of good karma over an individual's various lives. This approach emphasizes that life is a moral journey with perfection as the ultimate goal. The second approach involves discovering the Self-God through reflection and meditation. This approach emphasizes a more direct approach to release through knowing and experiencing the Self-God. However, both approaches are interconnected, with the ability to experience the Self-God often coming from living a moral life.

To assist the individual to discover the Self-God within, Hindu tradition offers a series of yoga techniques. The term yoga means "to yoke" or "to harness," but it has a more general meaning related to disciplines, and the Bhagavad Gita is something like a handbook of various yoga methods.

Image intended to capture the enlightenment offered by Yoga.

One such method is the yoga of selfless action. This involves behaving with indifference to the fruits of the individual's actions. This allows the individual to engage in pure action, and a person distances themselves from the outer layers of their identity and their perception of the world. This is intended to help train a person to disassociate themselves from everything they do, removing the distractions from the outer layers of the self and helping the person experience their true inner self. Doing so brings the person closer to the ending cycle of reincarnation.

Another portion of the Bhagavad Gita provides instruction on meditation, called the Yoga of Meditation, and is similar to what is commonly understood in contemporary discussions of yoga. This instruction works to help the individual subdue their thoughts and sense and lose self-consciousness in order to experience the Self-God within. Through the practice, the individual works to subdue their passions and restrain their thoughts, which both highlights the challenges of yoga and explores how yoga can be referred to as a discipline. According to this doctrine, even if a person fails at the yoga of meditation, through good deeds they can be reincarnated as a yogi and succeed at the meditation.

In philosophy, monism is the view that the universe is composed of a single type of thing. Hinduism tends to be monistic with its conception of God enveloping everything. The issue of monism was debated, beginning around the eighth century CE, within Hinduism's Vedanta tradition, which drew its inspiration from the Upanishads. The debate started with the views of a scholar named Sankara (788-820 CE).

Image of Sankara teaching pupils.

The first, which can be called weak monism, is a view that the universe consists of one basic thing, which is divided into subunits. An example of this is an orange, which presents a unified whole but clearly has individual parts. The second type of monism, which is called strong monism, is the view that the universe consists of one undifferentiated thing that has no subunits. A cannonball is an example of this second type, in which there are no obvious internal differentiating parts. Sankara, in reflection on themes of monism in Upanishads, works to decide between interpreting them as weak monism or strong monism. In this reflection, he took the Upanishad's notion of unity and decided in favor of strong monism.

The implications with strong monism include that reality as a whole is a single, unchanging God, and this can be taken to mean there is something unreal about the common-sense perception of the world. Sankara agreed that common-sense perceptions were unreal and that the truth is that beneath these common-sense perceptions, which was the underlying unity of God beneath the unreal appearance of things. This means all elements of the world of appearance, for Sankara, are unreal. Although that asks the question of why a person should perceive the world in an illusory way, to which Sankara says the deception is caused by a force called Maya (illusion), similar to a magician creating illusions to shield people from knowledge of God, which the person is expected to overcome.

Image of Hindu theologian and philosopher Ramanuja.

A rival Vedanta scholar, Ramanuja (1017-1137 CE), rejected strong monism in favor of weak monism. This was based on Ramanuja's notion that if Sankara's strong monism is correct, and the only thing that exists in the universe is a single, unchanging, undifferentiated God, and everything else that exists is a matter of deception, and the true inner self is God, then by worshipping God a person is worshipping themselves, which Ramanuja found silly. As well, Ramanuja found that any acts of worship a person performs then undermine the notion of religious worship, as it becomes self-worship, and he concluded from this that Sankara's strong monism should be rejected in favor of weak monism.

According to Ramanuja's weak monism, although the world is unified in a single God, the God has differentiated parts, so people are in a sense united with God but in another sense distinct from God. This approach rescues the world of appearances, which Ramanuja suggests are real and all a part of God. As well, when a person distinguishes between their own personal identity and others around them, the person is again perceiving distinctions in God.

Image of Gautama Siddhartha.

Buddhism was traditionally founded by a former Hindu monk in India named Gautama Siddhartha (563-483 BCE), who was known as Buddha, or "enlightened one." Buddha came from a wealthy family, and his mother is said to have dreamed a white elephant entered her womb the night before he was born, which was interpreted by Hindu priests as a dual destiny: he would either be a universal monarch or a universal teacher. His family sheltered him from the ugly experiences of life until, at twenty-nine, he was said to have three occasions to glimpse the world, in which he witnessed suffering. First, he saw an old man, then a sick man, and then a dead body. He left his family estate to pursue a life of religious devotion and wandered for six years, learning from holy people to find a solution to the human predicament. He then joined a band of ascetic monks who taught Buddha the practice of self-renunciation, and his efforts left him almost dead of starvation until he ate to regain health and the ascetic monks left him disappointed.

Disheartened by his failures, Buddha sat under a fig tree, vowing not to rise until he achieved supreme awakening. He stayed up all night, and at the first glimpse of the morning star, he was said to have become enlightened. This drew crowds to him until he eventually died by accidentally eating poisoned mushrooms. Through his enlightenment, Buddha became dissatisfied with traditional Hindu teachings, but his underlying philosophy drew from Hinduism. Buddha never wrote anything, and the oldest accounts of his teachings are in a collection called the Pali Canon, compiled during the first five centuries after Buddha's death.

One of the most famous parts of the Pali Canon is a section known as "The First Discourse," which according to tradition, Buddha delivered to his ascetic friends after his enlightenment. The content of the discourse presents the Four Noble Truths concerning the quest for enlightenment. The first truth is that life is suffering. Buddha noted that birth comes with pain, decay is painful, disease is painful, death is painful, union with the unpleasant is painful, separation from the pleasant is painful, and unsatisfied cravings are painful.

The second noble truth is that the cause of suffering is desire. In this, Buddha says desire is the origin of suffering, and it is thirst or craving for a future life or for success in this life that causes suffering, rather than the thirst or craving that causes the renewal of existence. The third noble truth is that the end of suffering is achieved by extinguishing a person's desire, known as the state of Nirvana, or "to extinguish." Buddha suggests that the elimination of suffering is the destruction of the thirst or craving or being free from and no longer harboring the thirst for success, which leads to Nirvana, the destruction of suffering.

The fourth and final noble truth tells of the path to extinguish desires, including the adoption of a series of moral attitudes, beliefs, and actions, which Buddha calls the eightfold path. The following are the eight recommendations:

1. We should adopt right views that are free from superstition or delusion.
2. We should have right aims that are high and worthy of the intelligent and earnest person.
3. We should practice right speech, which is kindly, open, and truthful.
4. We should perform right conduct that is peaceful, honest, and pure.
5. We should adopt a right livelihood that brings no harm or danger to living things.
6. We should put forth the right effort in self-training and self-control.
7. We should have right mindfulness insofar as we are fully aware of the present moment and not preoccupied with hopes or worries.
8. We should engage in right concentration, which involves proper meditation that leads to the Nirvana experience.

Buddha explains that the eight recommendations involve adopting a middle way, which is described as a calm detachment achieved by avoiding the extremes of asceticism and self-indulgence.

Around 100 CE, Buddhism split into two main denominations: Theravada and Mahayana. Theravadists held fast to the teachings of the Pali Canon, while Mahayanists went on to argue that Buddha's more advanced teachings were transmitted orally and recorded in later, Mahayana texts. A theme within Mahayana texts is the notion of emptiness, a view that all reality is devoid of discernable content or description. This is not intended as a nihilistic denial of reality; rather it is a denial that reality has describable distinctions. In this case, the metaphor of emptiness presumes a container, which they call "reality," and which is empty in the sense that reality is not as it initially appears. Or that when a person looks inside the container, they find it has no distinguishable parts or qualities to define its true nature—making it empty for all purposes.

Grasping the notion of emptiness has proven a challenge, and in China, around the fifth-century CE, Zen Buddhism was founded. This school of Buddhism is famous for paradoxical meditative puzzles, and it resists any verbal formula or creeds. Rather, the focus of Zen is on experience. Rational discourse and doctrine do not play a part in the attainment of enlightenment. In Zen, enlightenment as an experience can be passed from a teacher to a student in training. The Zen approach is based on one of Buddha's discourses known as the Flower Sermon, in which he held up a golden lotus flower.

A few centuries later, Zen Buddhism made its way to Japan, where one of the main schools developed, known as the koan system. Koans are absurd riddles that defy any logical response. The koan system involves the Zen master having a student answer a series of up to fifty riddles over the course of many years. Around the eleventh century, famous koans were assembled in written collections. A student struggling with these riddles was expected to have their mind loosened from traditional reasoning, see that reality is not discoverable, and experience the emptiness of all things.

Around 500 BCE, China was going through what was known as the Warring States period, a time of social upheaval when national emperors lost control over the various territories of China while local rulers increased their strength. These various states waged war against each other until only the strongest states survived. In response to the chaos that resulted from this period came the Period of 100 Philosophers. It was in this context that Confucius emerged.

Confucius lived from 551 to 479 BCE and was born in what is now China's Shandong province. His family name was Kung, and he was known as Kung Fu-Tzu, which means "master Kung" and was Latinized into "Confucius." During the period of conflict, Confucius developed his teachings, such as his solution to the problem of anarchy, which was to return to old Chinese customs and cultural traditions. He wrote nothing of his own views, but his discussions were recorded by his students after his death in a work called the Analects. These texts offer a picture of his central teachings, including thoughts that were foremost on ethics, where he focused on four specific themes: ritual conduct, humaneness and the superior person, child obedience, and good government.

One of the foremost teachings of Confucius was the notion of ritual conduct, which is the effortless adherence to social norms and the performance of custom. This is not to be confused with ceremonial formality but is used to include customs such as holiday celebrations and simple greetings. For Confucius, rituals and traditions were the invisible glue that bound society together, and every activity had a proper way of behaving, which, when not followed, caused a person to behave like a bumbling fool.

The Confucian notion of humaneness is the attitude of goodness, benevolence, and altruism toward others. To acquire humaneness, the individual should develop the virtues of dignity and patience, which help a person be at peace regardless of the difficulties in a person's life. Central to this concept is the principle of reciprocity, which is often worded as "do not do to others what you would not have them do to you." This is a principle familiar to the Golden Rule, except the Confucian principle involves negative duties to avoid harm.

Because of its emphasis on avoidance, the principle of reciprocity is sometimes criticized for being too passive. It is one thing to say a person should avoid harming another, but another to say an individual should seek another's improvement. However, others note that the wording of the principle of reciprocity is flexible enough to include positive as well as negative duties.

For Confucius, the superior person is the ideal person who personifies the virtue of humaneness. The term originally referred to children who inherited their family estates, but, like the term "gentleman" in English, the notion of the superior person acquired broader ethical meaning. Confucius saw the superior person as the ideal to which a person should strive, with his definition of a superior person being a person consistently exhibiting a range of virtuous qualities, including humility, respectfulness, kindness, justice, impartiality, honesty, consistency, caution, and studiousness.

In his thinking, the superior man is not seen to be driven by a need for fame, but by a desire to be thought well of past death. Despite the seeming list of values the superior person holds, Confucius stressed that the superior person was not a rule or by-the-book follower with rigidly fixed beliefs but is flexible and has attitudes and a psychological state of tranquility to which the superior person must rise.

Confucius held that there were five relationships that underlie the order of society:

1. Father and son
2. Elder brother and younger brother
3. Husband and wife
4. Elder friend and junior friend
5. Ruler and subject

There are some writings that refer to a shorter list of relationships; regardless, any of these Confucian relationships involves a superior and subordinate, and there are duties required of both parties. In each of the five relationships, the subordinate is duty-bound to show obedience, and the superior person to show kindness. Of the five, the two relationships Confucius discusses most commonly are the father-son and ruler-subject.

The relationships between father and son, often referred to as child obedience or filial piety, set a standard for others. Respect for all superiors is an extension of respect for one's parents, and all children should treat elders with the respect of surrogate parents. By respecting elders and parents, people are considered less likely to undermine the social order, in or outside the home. And Confucius stresses it is not enough to simply abide by this principle, but they must have the proper inner attitude when fulfilling this duty; otherwise, it is not correct. Further, this principle does not mean a child blindly obeys their elder; instead, if the command from the parent is wrong, the child should resist and remind the parent of their moral duty and prevent them from committing some wrong.

Confucius saw himself as a political reformer and held that the subject-ruler relationship set the stage for good governing. Namely, Confucius held that good governing consists of the ruler setting the moral example for the whole country. Confucius felt that the moral goodness of the ruler would trickle down through the various layers of social hierarchy, and the whole country can prosper when the ruler is benevolent. Further, in his writings, Confucius felt the ruler should discover their subjects' natural capacities and encourage them to work in those areas.

One of the most influential Confucian philosophers, or philosophers of the Confucian tradition, was Mengzi (390-305 BCE), Latinized as Mencius. A few generations removed from Confucius, Mengzi traveled around China to promote political reform. Mengzi believed that governments should be run through exemplary conduct with goodness as the goal. The most well-known aspect of Mengzi's thought is the view of the inherent goodness of people, which he expressed as a person's heart and mind moving inherently toward moral goodness and evil resulting from bad social influences that reduce a person's moral strength.

Like Confucianism, Daoism emerged during the Warring States period of China. Daoism's recommendation for ending social chaos was to return to the primitive tradition of China before the appearance of kings and feudal systems. Traditionally, the founding of Daoism is credited to a figure named Lao-Tzu or "Master Lao," but almost nothing is known about him, and some scholars argue that the figure of Lao-Tzu was developed by Daoists as a figure to rival Confucius. Tradition also credits Lao-Tzu with writing Daoism's most important test, Dao de Jing (Tao te Ching) which is translated as The Book of the Way and Its Power.

The notion of the Dao is the central concept of Daoism, and the term means the "way" or the "path," but more specifically is intended to refer to the fundamental ordering principle behind nature, society, and individual people. It is the ultimate reality of the cosmos. However, an initial obstacle to understanding the concept of the Dao is that it has an unspeakable mystical quality and cannot be defined. For example, the Dao is often referred to as the eternal and unchanging Dao that cannot be named; a Dao that can be named is not the Dao.

A central theme of Daoism is that of return. As per this, all things eventually decay and return to their ultimate source within the Dao. There are natural cycles in the cosmos: everything has been and will again be recycled. Therefore, according to the Dao, people should submit to the natural process of transformation, and to do otherwise amounts to disobedience.

Another central tenet, and sometimes considered the most practical part of Daoism, is the tenet of non-action, or effortless action. This tenet suggests that everything a person does should flow with simple spontaneity and without contrivance. Artificial action runs counter to the natural course of things and can involve aggression and competition. Passivity, rather than aggression, is the attitude that the Dao suggests people should adopt. In the natural world, weakness is linked with life, and strength with death.

Paralleling the notion of non-action is that of non-mind, which suggests that a person needs to eliminate knowledge and act spontaneously through natural intuition. Accumulated knowledge hinders creativity and can make one inflexible or subject to a false sense of security. Since the Dao runs through each person, everything the person needs to know about life is already within them. And that nature will direct the individual when the needs arise, and Daoism rejects traditional methods of education, such as learning from a master or traveling around to gain knowledge through experience. Most important, Daoism teaches that the true nature of the Dao and understanding of the Dao can only come from the practice of non-mind.

The Dao de Jing, in its political treatment, insists that rulers follow the Dao to result in states that are well ordered and in natural harmony. To rule in accord with the Dao, leaders must abandon notions of governance, such as authoritatively imposing their wills on the people, and instead a more Dao-centered way of ruling involves not ruling at all but allowing society to function normally.

Following this is the idea that nature needs no help from rulers, and when the general public follows the Dao, each person finds peaceful and simple ways to flourish; but even a well-intentioned ruler disrupts the natural flow of social order by imposing rules. The mere existence of rules will generate rule-breakers, and Daoism thus recommends political anarchy in the true sense—namely, a peaceful state of no rule in which a member of the society can find their place. Following this, the best style of ruling is through the practice of non-action.

Another important book in Daoism is the Lieh-Tzu, meaning "Master Lieh." Tradition attributes this work to a scholar named Lieh Yukou from the period of 100 philosophers, although some scholars date the composition of the book to around 300 CE. Sometimes called the Classic of Complete Emptiness, the book recommends pursuing the path of emptiness as a means of becoming united with the Dao. The work tends to have a skeptical and dismal undertone, emphasizing the certainty of annihilation, resigning oneself to fate, and abandoning efforts in life.

One part of the book criticizes the emphasis people place on pleasing others and acquiring notoriety that lasts beyond the grave. This is based on an examination of the shortness of an individual life and the suggestion that this brevity should not be wasted forgoing pleasures to attain fame or empty praise. The suggested solution is to enjoy life's pleasure when the opportunity arises and avoid conforming for the sake of praise from others. It goes on to say it is irrelevant whether a person leaves an honorable or dishonorable legacy after their death since, once dead, the person will not be conscious of their legacy.

Although the study of the history of European philosophy has a long, recorded history, the study of the history of African philosophy, particularly of sub-Saharan Africa, is considered to be a young discipline that has come to maturation during the twentieth century. This has been in part because the ability for Africans to philosophize has been entirely denied, and Africa has been denied as a part of world philosophy. The characterization of Africa's pre-colonial cultures and societies as "a-historical" or "primitive" has been an obstacle to unprejudiced research in the history of philosophy of the region. Further, many prominent European philosophers regarded Africans as incapable of intellectual reflection and, therefore, incapable of philosophizing. This history of prejudice and disregard for the possibility of philosophy on the African continent has further denied the potential for a tradition of philosophy. During the twentieth century, African philosophy and its history began to be recorded, and debates began around what the history of African philosophy has been and what is meant by the term "African philosophy."

There is a position that is held by many philosophers, historians, and Egyptologists, that humanity originated in Africa, so did philosophical thinking, and this type of thinking emerged in ancient Egypt. This view is held by thinkers including Cheikh Anta Diop, Mubabingo Bilolo, Martin Bernal, Molefi Kete Asante, Theophile Obenga, and Maulana Karenga. The hypothesis is that the origins of philosophy in Africa can be traced back to ancient Egypt, which challenges the paradigm that philosophy originated in Greece, where the transition from mythological to rational thinking was supposed to take place for the first time in history.

However, the hypothesis of the scholars has no genetic or long-range linguistic and historical analysis and often does not rely on comparative analysis and instead interprets a selection of ancient Egyptian manuscripts and concepts under a philosophical perspective. In doing so, the hypothesis uses the discourse of ancient Greece, mainly the philosophy of Socrates and Plato, as an underlying model to prove the philosophical relevance of Egyptian texts done through parallels drawn between concepts and argumentative techniques.

This hypothesis has been criticized, such as in the work of George James (an African-American teacher of Greek), that even if Greek philosophy had roots in Egypt, as it almost certainly did, it did not imply that Egyptians were dark, as the term "Africans" created a demarcation in George James's work to preclude the lighter complexioned peoples of North Africa, and referred specifically to the darker complexioned people of sub-Saharan Africa.

Beyond the assertion of an ancient tradition of African philosophy, traditional notions of African philosophy see the emergence of systematic African philosophy around the 1920s. In this period, a host of Africans studied in the West where they experienced terrible racism and discrimination, which they carried with them when they returned to their native lands to suffer the same maltreatment from colonial officials. This led to frustration, to put it mildly, which is said to have put them on the path to establishing systematic African philosophy.

In the history of philosophy, there are specific subsets of wonder that are thought to inspire systematic philosophical thinking. One is called thaumazein, interpreted as "awe," and the other is called miraculum, interpreted as "curiosity." In the emergence of systematic African philosophy, the frustration experienced by the future philosophers generated another subset of wonder called onuma, which is interpreted as "frustration."

The reaction to the caricatures of Africans as intellectually docile, culturally naive, and rationally inept led to the systematic beginning of philosophy in the early twentieth century to be focused on the identity of African people, their place in history, and their contributions to civilization, and to work to dethrone the colonially-built episteme. This history was born out of the thinking and criticisms of Aime Cisaire, Leopold Senghor, Kwame Nkrumah, Julius Nyerere, William Abraham, John Mbiti, and expatriates such as Placid Tempels, Janheinz Jah, and George James.

Systematic study of philosophy in Africa has a short documented history, with epochs in the short, dense period with considerable overlap. This occurred in part because after colonialism, people realized Africa had been sucked into the global matrix unprepared, as they had been quickly abandoned by the colonial Western, especially European, identity. This created a sudden, urgent need to search for a post-colonial African identity and to discover or rediscover that identity to initiate a non-colonial or original history for Africa.

In the twentieth century, the sum of what African philosophers have achieved has been presented in two broad categories: the pre-systematic era and the systematic era. The former refers to Africa's philosophical culture and thoughts of anonymous African thinkers and may include the problems of Egyptian legacy. The latter refers to the periods marking the return of Africa's first eleven, western-tutored philosophers from the 1920s. This latter category has been further delineated into four periods:

• Early period 1920s-1960s
• Middle period 1960s-1980s
• Later period 1980s-1990s
• New era 1990s on

This is not considered a commitment to saying that previous to the 1920s, people in Africa never philosophized. They did. But due to a lack of documentation, scholars cannot in good faith attest to their systematicity or sources, and hence the periodization shows how African philosophy as a system first emerged in the late 1920s.

Four main movements have been identified in the history of African philosophy: excavationism, Afro-constructionism/Afro-deconstructionism, critical reconstructionism/Afro-eclecticism, and conversationalism.

Contemporary philosophy, beginning in the early twentieth century, has largely been dominated by the rivalry between two general philosophic traditions: analytical philosophy, a largely anglophone mindset that philosophy should apply logical techniques and be consistent with modern science; and continental philosophy, which tends to serve as a catch-all label for everything else, especially on mainland Europe, and in general rejects scientism in favor of historicism.

A precursor to the analytical philosophy tradition was logicism, which developed during the late nineteenth century and was advanced by Gottlob Frege. Logicism sought to show that mathematics was reducible to logic, and Frege's work revolutionized modern mathematical logic. It was furthered in the early twentieth century by the British logicians Bertrand Russell and Alfred North Whitehead, who continued to champion these ideas in the groundbreaking work Principia Mathematica. This work, in turn, fell to Kurt Godel's Incompleteness Theorems of 1931, which mathematically proved the inherent limitations of all but the most trivial formal systems.

Russell and Whitehead went on to develop other philosophies, with Russell's work mostly in the area of the philosophy of language, while Whitehead developed a metaphysical approach known as process philosophy, positing ever-changing subjective forms to complement Plato's eternal forms. However, their logicism, combined with Comte's positivism, influenced the development of logical positivism. The logical positivists tried to systematically reduce all human knowledge to logical and scientific foundations, claiming that a statement can only be meaningful if it is either purely formal or capable of empirical verification.

Ludwig Wittgenstein.

The Tractatus of Ludwig Wittgenstein, published in 1921, was another large text in logical positivism. Wittgenstein has been considered one of the most important philosophers of the twentieth century. A central part of the philosophy of the Tractatus was the picture of meaning, which asserted that thoughts are expressed in language, and the structure of language is determined by the structure of reality. Wittgenstein later abandoned the philosophy of the Tractatus in favor of a new direction, in which he saw the meaning of the word as just its use in language and looked at language as a kind of game in which the different parts function and have meaning. This led to the development of ordinary language philosophy, which shifted the emphasis from the ideal or formal language of logical positivism to everyday language and its actual use. Some have seen ordinary language philosophy as a break with or reaction against analytical philosophy, while others have seen it as an extension of it.

G. E. Moore.

Another important philosopher in analytical philosophy of the early twentieth century was G. E. Moore, a contemporary of Russell. His 1903 Principia Ethica became a standard text of modern ethics and meta-ethics and inspired the larger movement from ethical naturalism toward ethical non-naturalism. He would point to the term "good," which could be considered indefinable because it lacks natural properties in the way "blue" or "smooth" have easily defined qualities. Moore also defended what he called "common sense" realism on the grounds that common sense claims about the knowledge of the world are as plausible as other metaphysical premises.

Edmund Husserl

On the side of continental philosophy, one of the important early figures was the German Edmund Husserl, who founded the movement of phenomenology. He developed the idea, parts of which date back to Descartes and Plato, that what is considered to be reality in actuality consists of objects and events as they are perceived or understood by consciousness. And it discredits that anything can exist independent of human consciousness. Thus, sensory data can be ignored, and people can deal only with the "intentional content" or the mind's built-in mental description of external reality through which a person is able to perceive aspects of the real world outside.

Martin Heidegger.

Another German, Martin Heidegger, was largely responsible for the decline of phenomenology with his Being and Time, published in 1927, in which he gave concrete examples of how Husserl's view broke down in certain circumstances and how the existence of objects only has real significance and meaning within a social context. He further argued that existence was inextricably linked with time and that being is an ongoing process of becoming. This led Heidegger to speculate that a person can only avoid what he called an "inauthentic" life by accepting how things are in the real world and responding to situations in an individualistic way. This led him to be considered the founder of existentialism. Heidegger also thought the end of philosophy had been reached and that every possible permutation of philosophical thought had been tried and discarded.

Out of Heidegger's philosophy came the existentialist movement, one of the more popular philosophical movements of the twentieth century. A main figurehead of the movement was Jean-Paul Sartre, along with his contemporaries Albert Camus, Simone de Beauvoir, and Maurice Merleau-Ponty. Sartre was a confirmed atheist, committed Marxist, and communist for much of his life. He worked to adapt and extend the work of Kierkegaard, Nietzsche, Husserl, and Heidegger to eventually conclude that "existence is prior to essence"—that people are thrust into an unfeeling, godless universe against their will. He believed that a person is then responsible for establishing meaning in their life by what they do and how they act. Sartre believed there are always choices and that, while this freedom is empowering, it also brings moral responsibility and existential dread, also called against. This means, according to Sartre, genuine human dignity can only be achieved by active acceptance of angst and despair.

Michel Foucault, a French philosopher, was further associated with all of these movements, though he rejected any such label. Much of his work was language-based, and he inspected how certain underlying conditions of truth have constituted what was acceptable at different times in history and how the body and sexuality are cultural constructs instead of natural phenomena. Although he was criticized for lax standards of scholarships, Foucault's ideas have been frequently cited across disciplines.

In continental philosophy, there was also the development of deconstructionism, a theory of literary criticism that questions traditional assumptions about certainty, identity, and truth and looks at the underlying assumptions, other spoken or unspoken, as well as the ideas and frameworks that form the basis for thought. The method was developed by Jacques Derrida, who has also been credited as a significant figure in post-structuralism. His work has been criticized for being highly cerebral and self-consciously difficult and has been accused of pseudo-philosophy and sophistry.