Humanism is a broad category of ethical, metaphysical, epistemological and political philosophies in which human interests, values and dignity predominate. It has an ultimate faith in humankind, believes that human beings possess the power or potentiality of solving their own problems, through reliance primarily upon reason and scientific method applied with courage and vision.

Rather than being a specific doctrine on its own, Humanism is more a general life stance or attitude that upholds human reason, ethics and justice, and is a component of a variety of more specific philosophical systems, and is incorporated into some religious schools of thought. It is an optimistic attitude to life whose ultimate goal is human flourishing (see the section on Eudaimonism), doing good and living well in the here and now, and leaving the world better for those who come after.

As an ethical doctrine, it affirms the dignity and worth of all people and their ability to determine right and wrong purely by appeal to universal human qualities, especially rationality. It searches for truth and morality through human means in support of human interests, and focuses on the human capacity for self-determination. It endorses universal morality (Moral Universalism) based on the commonality of the human condition.

As a metaphysical doctrine, Humanism believes in a naturalistic metaphysics or attitude toward the universe that considers all forms of the supernatural as myth, and regards Nature as the totality of being, and as a constantly changing system of matter and energy which exists independently of any mind or consciousness. It rejects the validity of transcendental justifications, such as a dependence on belief without reason, the supernatural, or texts of allegedly divine origin.

It considers faith an unacceptable basis for action, and holds that it is up to humans to find the truth, as opposed to seeking it through revelation, mysticism, tradition or anything else that is incompatible with the application of logic to the observable evidence. It is therefore generally compatible with Atheism and Agnosticism, but does not require these, and can be compatible with some religions. It is an ethical process, not a dogma about the existence or otherwise of gods. To some extent, it supplements or supplants the role of religions, and can be considered in some ways as "equivalent" to a religion.

As an epistemological doctrine, it supports scientific skepticism (i.e. it questions the veracity of claims lacking empirical evidence) and the scientific method (the collection of data through observation and experimentation, and the formulation and testing of hypotheses).

As a political philosophy, Humanism emphasizes individual freedom and responsibility, human values and compassion, and the need for tolerance and cooperation, and it rejects authoritarian beliefs. It affirms that we must take responsibility for our own lives and the communities and world in which we live.

The term "humanism" was coined in 1808, based on the 15th Century Italian term "umanista", which was originally used to designate a teacher or student of classic literature.

Humanist thought can be traced back to the time of Gautama Buddha (563 - 483 B.C.) in ancient India, and Confucius (551 - 479 B.C.) in ancient China, although the term "humanism" is more widely associated with Western Philosophy.

In ancient Greece, Thales, who is credited with creating the maxim "Know thyself" in the 6th Century B.C., is sometimes considered a proto-Humanist. Xenophanes of Colophon (570 - 480 B.C.), Anaxagoras, Pericles (c. 495 - 429 B.C.), Protagoras, Democritus and the historian Thucydides (c. 460 - 375 B.C.) were all instrumental in the move away from a spiritual morality based on the supernatural, and the development of freethought (the view that beliefs should be formed on the basis of science and logic, and not be influenced by emotion, authority, tradition or dogma).

Many medieval Muslim thinkers pursued humanistic, rational and scientific discourses in their search for knowledge, meaning and values, and were open to the humanistic ideas of Individualism, Skepticism and Liberalism. Certain aspects of Renaissance Humanism has its roots in the medieval Islamic world.

Renaissance Humanism was a movement in Europe, roughly covering the 15th and 16th Centuries. The revival of the study of Latin and Greek, and the resultant interpretations of Roman and Greek texts, affected the whole cultural, political, social and literary landscape of Europe. Humanists were opposed to the dominant Scholastic philosophy of the day (derived from St. Thomas Aquinas), and this opposition revived a classical debate which referred back to Plato and the Platonic dialogues. Renaissance Humanists promoted human worth and individual dignity, and believed in the practice of the liberal arts for all classes. Such Renaissance thinkers as the Italian poet Francesco Petrarch (1304 - 1374), the Dutch theologian Erasmus, the English philosopher Sir Thomas More, the French writer Francois Rabelais (c. 1494 - 1553), and the Italian scholar Giovanni Pico della Mirandola (1463 -1 494) can all be considered early Humanists.

In the 19th and 20th Centuries, various organizations were founded to promote humanist principles, including the Humanistic Religious Association (formed in 1853), the British Humanist Association (1896), the American Humanist Association (1941) and the International Humanist and Ethical Union (1952).

• Secular Humanism: The branch of Humanism that rejects theistic religious belief and adherence to belief in the existence of a supernatural world. Secular Humanists (who are often scientists and academics) generally believe that following humanist principles leads to secularism (which asserts the right to be free from religious rule and teachings), on the basis that supernatural beliefs cannot be supported using rational arguments, and therefore the supernatural aspects of religiously associated activity should be rejected. The term "humanism" in general usually refers to Secular Humanism as a default meaning.

• Religious Humanism: The branch of Humanism that considers itself religious, or embraces some form of Theism, Deism or supernaturalism, without necessarily being allied with organized religion. It is often associated with artists, scholars in the liberal arts and liberal Christians (especially Unitarian Universalists, Quakers, Anglicans and Lutherans). Religious Humanists feel that Secular Humanism is too coldly logical and ignores the full emotional experience that makes humans human.

• Renaissance Humanism (often known as Classical Humanism or simply Humanism): The initial flowering of humanist thought in the 15th and 16th Centuries, in opposition to the dominant Scholastic philosophy of the day. Renaissance Humanists promoted human worth and individual dignity, and believed in the practice of the liberal arts for all classes.

• Post-Humanism (or Posthumanism): A late 20th Century philosophy which attempts to bring Renaissance Humanism up to date in a modern technological world, and to counter the allegations of speciesism (discrimination in favour of one species, usually the human species, over others) and anthropocentrism (the belief that human beings and human society are, or should be, the central focus of existence) which have been levelled at Humanism.

• Educational Humanism: A current in education which began to dominate school systems in the 17th Century. It held that the studies that develop human intellect are those that make humans "most truly human". It was based on the concept of faculty psychology (which views the mind as a collection of separate modules or distinct intellectual faculties, such as the analytical, the mathematical, the linguistic, etc), which has been largely discredited in the 20th Century.

• Marxist Humanism: A branch of Marxism that primarily focuses on Marx's earlier writings, (especially the "Economic and Philosophical Manuscripts" of 1844 in which he develops his theory of alienation), as opposed to his later works, which are considered to be concerned more with his structural conception of capitalist society.

• Integral Humanism: The political philosophy developed by the Jana Sangh movement in India in the 1960s, in opposition to Western political philosophies which it sees as preoccupied with materialism and over-looks of the social well-being of the individual. It sees both Capitalism and Socialism as essentially flawed, and as stimulating greed, class antagonisms, exploitation and social anarchy.