Thales (c. 624 – 546 BCE). Considered the first philosopher in the Greek tradition. First person to offer a purely natural explanation for the origin of the world, free from mythological ingredients. He believed that everything was made of water.
Anaximander (c. 610 – 546 BCE). Thales successor. Famous for the concept of apeiron ("the boundless"), something both infinite and indefinite. Hot and cold arose within the apeiron and began to struggle, producing the cosmos.
Anaximenes (c. 585 – 525 BCE). Anaximander’s successor. Believed that various types of matter arose out of air through condensation and rarefaction.
Heraclitus, materialist monist who claimed that the arche (origin, substance or principle) of the world was fire. Flux. We can not step into the same river twice
The Eleatic SchoolXenophanes of Colophon (c. 570 – 480 BCE). Criticized the anthropomorphism of the gods, saying that people made the gods in their own image. Advocated monotheism. Forerunner of the Eleatic school.
Parmenides of Elea (c. 515 – 450 BCE). Founder of the Eleatics. “What is” cannot have come into being and cannot pass away because it would have to have come out of nothing or to become nothing, whereas nothing by its very nature does not exist.
Zeno of Elea (c. 490 – 430 BCE). Known for his paradoxes. “First,” Aristotle says, “there is the argument about its being impossible to move because what moves must reach the half-way point earlier than the end” (Ph. 6.9, 239b11–13).
The PluralistsEmpedocles (492 – 432 BCE). Eclectic cosmogonist. Four material elements and two forces.
Anaxagoras of Clazomenae (c. 500 – 428 BCE). Described the world as a mixture of primary imperishable ingredients. Introduced the concept of Nous (Cosmic Mind) as an ordering force.
The AtomistsLeucippus of Miletus (First half of the 5th century BCE). Believed there are two fundamental principles of the physical world, empty space and filled space — the latter consisting of atoms.
PythagoreanismProtagoras of Abdera (c. 481 – 420 BCE). Sophist. Early advocate of relativism. Man is the measure of all things,
Gorgias (c. 483 – 375 BCE). Sophist. Early advocate of solipsism.
Socrates of Athens (c. 470 – 399 BCE). Best known for the Socratic method of question and answer, his claim that he was ignorant (or aware of his own absence of knowledge), and his claim that the unexamined life is not worth living.
Plato (c. 427 – 347 BCE) believed that the things people perceive with their senses are imperfect copies of eternal Forms. Knowledge is a process of remembering. In the myth of the cave (The Republic), Plato likened the ordinary person to a man sitting in a cave looking at a wall on which he sees nothing but the shadows of real things. Tripartite Soul - reason, desire, spirt (willpower or courage). Philosopher king - a philosophically aware class should govern socity.
Aristotle (c. 384 – 322 BCE)Rejected Plato's Theory of Forms. Form is always paired with matter. Form and Matter are inseparable, and cannot exist apart from each other.
Four causes - material, efficient, formal, final.
He thought that happiness could best be achieved by living a balanced life and avoiding excess by pursuing a golden mean.
StoicismPlotinus (c. 205 – 270). Neoplatonist. Developed a complex spiritual cosmology involving three foundational elements: the One, the Intelligence, and the Soul.
Porphyry (c. 232 – 304). Edited and published The Enneads, the only collection of the work of Plotinus.
Many Platonic notions were adopted by the Christian church which understood Plato's Forms as God's thoughts (a position also known as divine conceptualism).
Augustine of Hippo (c. 354 – 430). Neoplatonist. He believed that there is a spiritual, eternal realm of Truth, which he identified with God, beyond the world of the senses.
Boethius (c. 480–524)Among the great Islamic philosophers of the Medieval period were Avicenna (11th century, Persian) and Averröes (12th century, Spanish/Arabic).
ScholasticismAnselm of Canterbury (c. 1033/4 – 1109) Father of scholasticism. Ontological Argument for the existence of God.
Peter Abelard (c. 1079–1142). Scholastic philosopher. Dealt with problem of universals. Best known for his love affair with Héloïse.
Thomas Aquinas (c. 1221–1274). Aristotelian. Integrated Aristotle’s philosophy into Christian thought, just as early Church Fathers had integrated Plato’s thought. Held that reason is capable of operating within faith; while the philosopher relies solely on reason, the theologian accepts faith as his starting point and then proceeds to conclusion through the use of reason.
Duns Scotus (c. 1266–1308).
William of Ockham (c. 1288–1348). Ockham's razor.
HumanismPico della Mirandola (1463–1494). Renaissance humanist. Proposed to defend 900 theses on religion, philosophy, natural philosophy, and magic against all comers
Desiderius Erasmus (1466–1536). Humanist, advocate of free will. Intellectual father of the European Reformation
Sir Thomas More (1478–1535). Humanist. Utopia.
Michel de Montaigne (1533–1592). Humanist, skeptic. The Essays.
Important Theologians and Religious PhilosophersJohn Calvin (1509–1564).
Blaise Pascal (1623–1662). Physicist, scientist. Noted for Pascal's wager.
Early Political PhilosophyNiccolo Machiavelli. The rise of secular power during the Renaissance stimulated the growth of political philosophy. Explored techniques for the seizure and retention of power.
Thomas Hobbes (1588–1679). Leviathan. In the “state of nature” that preceded civilization, “every man’s hand [was] raised against every other” and human life was accordingly “solitary, poor, nasty, brutish, and short.” A social contract was thus agreed upon to convey all private rights to a single sovereign in return for general protection and the institution of a reign of law.
The Scientific RevolutionThe adoption of the scientific method, popularized by Francis Bacon, was an important aspect of the Scientific Revolution. The scientific method requires abandoning preconceived assumptions and promotes the use of systematic experimentation, empirical observation and inductive reasoning (in contrast to the earlier, Aristotelian approach of deduction). (The premises of an inductive argument are viewed as supplying some evidence for the truth of a conclusion. The conclusion of an inductive argument is only probable, based upon the evidence given. The conclusion of a deductive argument is certain.)
Materialism, idealism, rationalism, and empiricismMaterialism is a form of philosophical monism that holds that matter is the fundamental substance in nature, and that all things, including mental states and consciousness, are results of material interactions.
Idealism asserts that reality is fundamentally mental, mentally constructed, or otherwise immaterial. In contrast to materialism, idealism asserts that consciousness creates and determines material existence.
Rationalism is the belief that all knowledge arises from intellectual and deductive reason, rather than from the senses. Empiricism is the belief that the origin of all knowledge is sense experience.
Empiricism and rationalism are concerns of epistemology (does knowledge come from the senses or innately through reason?), while idealism and materialism belong to metaphysics (is the world made of matter or ideas?).
RationalismBaruch Spinoza (1632–1677). Rationalism.
Nicolas Malebranche (1638–1715). Cartesian.
Gottfried Leibniz (1646–1716). Co-inventor of calculus.
Descartes sought to ground natural science not in sensation and probability (as did Bacon) but in premises that could be known with absolute certainty:
From the indubitability of the self, Descartes inferred the existence of a perfect God; and, from the fact that a perfect being is incapable of falsification or deception, he concluded that the ideas about the physical world that God has implanted in human beings must be true.
Descartes saw the human body as a kind of machine that follows the mechanical laws of physics, while the mind (or consciousness) was a separate entity, not subject to the laws of physics. This dualism (Cartesian dualism) is sometimes referred to as the mind–body problem in philosophy.
Spinoza rejected Descartes' dualism in favor of a kind of monism where mind and body were just two different aspects of a single underlying substance which might be called Nature (and which he also equated with a God of infinitely many attributes, effectively a kind of Pantheism).
(The term "monism" was introduced in the 18th century by Christian von Wolff to describe philosophical thought that attempted to eliminate the dichotomy of body and mind and explain all phenomena as manifestations of a single substance. Thereafter the term was more broadly used for any theory postulating a unifying principle.)
Leibniz’s pluralism contrasted with Descartes’s dualism and Spinoza’s monism. According to Leibniz, the real world is composed of eternal, non-material and mutually-independent elements he called monads, and the material world that we see and touch is actually just phenomena (appearances or by-products of the underlying real world).
EmpiricismJohn Locke (1632–1704). Major Empiricist. Political philosopher.
George Berkeley (1685–1753). Idealist, empiricist.
David Hume (1711–1776). Empiricist, skeptic.
In the natural sciences, empiricism is associated with the scientific method and states that "knowledge is based on experience" and that "knowledge is tentative and probabilistic, subject to continued revision and falsification" (Shelley, M., Encyclopedia of educational leadership and administration, 2006). Sir Francis Bacon was the leading figure of Renaissance empiricism.
Philosophical empiricists hold no knowledge to be properly inferred or deduced unless it is derived from one's sense-based experience. John Locke, George Berkeley, and David Hume were the primary exponents of empiricism during the 18th century Enlightenment. They are the leading figures of the philosophical movement known as British empiricism.
In "An Essay Concerning Human Understanding," John Locke proposed that the only knowledge humans can have is a posteriori, i.e., based upon experience. Locke, like Avicenna before him, believed that the mind was a tabula rasa (or blank slate). Locke believed:
Locke also made a distinction between “primary qualities” (such as solidity, figure, extension, motion, and rest), which are real properties of physical objects, and “secondary qualities” (such as color, taste, and smell), which are effects of the mind.
George Berkeley argued that things only exist either as a result of their being perceived, or by virtue of the fact that they are an entity doing the perceiving. An object only really exists if someone is there to see or sense it ("to be is to be perceived"), although, he added, the infinite mind of God perceives everything all the time, and so in this respect the objects continue to exist.
Hume argued that, although we may form beliefs and make inductive inferences about things outside our experience (by means of instinct, imagination and custom), they cannot be conclusively established by reason and we should not make any claims to certain knowledge about them (a hard-line attitude verging on complete Skepticism). For example, he argued that our belief in the power of cause and effect is not justified by either observation or by logical deduction. We only ever see one thing following another: we never observe any power that makes one thing necessitate an effect.
The EnlightenmentJean–Jacques Rousseau (1712–1778). Social contract political philosopher.
Voltaire (1694–1778). Advocate for freedoms of religion and expression.
Although the terms Middle Ages and Renaissance were not invented until well after the historical periods they designate, scholars of the 18th century called their age “the Enlightenment” with self-conscious enthusiasm and pride.
The 18th century was the age of the democratic revolutions, and the Enlightenment theories of Locke and Jean-Jacques Rousseau championed the freedom and equality of citizens. The germ of modern liberalism is found in these two theorists: faith in representative democracy, in civil liberties, and in the basic dignity of human beings.
The Enlightenment emerged from Renaissance humanism. It viewed reason and the evidence of the senses as the primary sources of knowledge and drew inspiration from the Scientific Revolution. Enlightenment thinkers also advanced ideals such as liberty, progress, toleration, fraternity, constitutional government and separation of church and state. They believed that the tremendous intellectual and scientific progress of the age would dramatically improve human society.
Immanuel Kant (1724–1804)Kant claims that we know more than Berkeley's ideas in our minds, in that we also directly know of at least the possibility of "noumena" ("things-in-themselves"), even if they cannot be directly and immediately known.
The human self constructs knowledge out of sense impressions and from universal concepts called categories that it imposes upon them. Ideas, the raw matter of knowledge, must somehow be due to realities existing independently of human minds; but he held that such things-in-themselves must remain forever unknown. Human knowledge cannot reach to them because knowledge can only arise in the course of synthesizing the ideas of sense.
We grasp reality and make sense of the world through several categories of thought: quantity (unity, plurality, totality); quality (reality, negation, limitation); relation (substance, cause, community) and modality (possibility, existence, necessity). These categories are not so much read out of experience as read into it and, hence, are a priori, or pure, as opposed to empirical.
Knowledge must rest on judgments that are 1) a priori (from reason alone, as in Rationalism) and yet also 2) synthetic (a posteriori knowledge from experience alone, as in Empiricism), so that the predicate term contains something more than is analytically contained in the subject.
Thus, for example, the proposition that all bodies are extended is not synthetic but analytic because the notion of extension is contained in the very notion of body, whereas the proposition that all bodies are heavy is synthetic because weight supposes, in addition to the notion of body, that of bodies in relation to one another.
Kant's contributions to ethics include his concept of the categorical imperative, a moral law that is absolute for all agents and does not depend on any ulterior motive. “Thou shalt not steal,” for example, is categorical as distinct from hypothetical imperatives, such as "Do not steal if you want to be popular." Kant offered several formulations of the categorical imperative, including "So act as to treat humanity, whether in your own person or in another, always as an end, and never as only a means."
German IdealismG. W. F. Hegel (1770–1831). German idealist.
F. W. J. von Schelling (1775–1854). German idealist.
Earlier "idealists" maintained that reality is ultimately intellectual rather than material (Plato) or that the existence of objects is mind-dependent (Berkeley).
Kant’s transcendental idealism claimed that the objects of human cognition are appearances and not things-in-themselves. Fichte, Schelling, and Hegel radicalized this view, transforming Kant’s transcendental idealism into absolute idealism, which holds that things-in-themselves are a contradiction in terms, because a thing must be an object of our consciousness if it is to be an object at all.
Johann Fichte believed that there can be no thing-in-itself, because a thing is only a thing when it is something for us. Even the thing in itself is, in fact, a product of our own conscious thought.
Friedrich Schelling maintained that the "I" needs the Not-I, because there is no subject without object, and vice versa. The existence of the I precedes all thinking (I must exist in order to think) and thinking determines all being (A thing is nothing other than an object of thought).
Hegel advocated a kind of historically-minded absolute idealism, in which the universe would realize its spiritual potential through the development of human society, and in which mind and nature can be seen as two abstractions of one indivisible whole Spirit.
The fundamental notion of Hegel's dialectic is that things or ideas have internal contradictions. These contradictions lead to the dissolution of the thing or idea in the simple form to a higher-level, more complex thing or idea, which has its own internal contradictions.
This process would continue effectively ad infinitum, until reaching the ultimate synthesis, which is what Hegel called the Absolute Idea.
Hegel saw history as a progression, always moving forward, never static, in which each successive movement emerges as a solution to the contradictions inherent in the preceding movement.
UtilitarianismJames Mill (1773–1836). Utilitarian.
John Stuart Mill social theory was an attempt to combat the evils of the Industrial Revolution. His ethics, expressed in Utilitarianism (1861), built on the formulations of Jeremy Bentham. Mill believed the purpose of society was to produce the greatest quantity of happiness for its members.
MarxismKarl Marx (1818–1883). Socialist, formulated historical materialism.
Friedrich Engels (1820–1895). Egalitarian, dialectical materialist.
A radical counterbalance to Mill’s liberal ideas was provided by Karl Marx. Marx believed that society is a moving balance (dialectic) of antithetical forces that produce social change.
ExitentialismSøren Kierkegaard (1813–1855). Existentialist.
Friedrich Nietzsche (1844–1900). Naturalistic philosopher, influence on Existentialism.
Jean-Paul Sartre (1905–1980). Humanism, existentialism.
Karl Jaspers (1883–1969). Existentialist.
Meanwhile, he philosophy of Kierkegaard, Schopenhauer, and Nietzsche placed an emphasis on the irrational. They viewed the mind as dark, obscure, hidden, and deep.
Existentialism is a reaction against traditional philosophies, such as Rationalism, Empiricism and Positivism, that seek to discover an ultimate order and universal meaning. It is the view that humans define their own meaning in life, and try to make rational decisions despite existing in an irrational universe. The only way to rise above the essentially absurd conditions of life is by exercising our personal freedom and choice.
Existence is prior to essence (essence is the meaning that may be ascribed to life). As Sartre put it: "At first [Man] is nothing. Only afterward will he be something, and he himself will have made what he will be."
PragmaticsmWilliam James (1842–1910). Pragmatism, Radical empiricism.
John Dewey (1859–1952). Pragmatism.
In America, there was a strong reaction against idealism fostered the pragmatic movement, led by Charles Sanders Peirce and William James. Peirce held that the function of all inquiry is to eradicate doubt and that the meaning of a concept consists of its practical consequences.
Sigmund Freud (1856–1939). Neurologist, founded psychoanalysis, posited structural model of mind.
PhenomenologyMartin Heidegger (1889–1976). Phenomenologist.
Phenomenology has its roots in idealism. It is based on the premise that reality consists of objects and events ("phenomena") as they are perceived or understood in the human consciousness, and not of anything independent of human consciousness. It studies experience from a subjective or first-person point of view.
PositivismBertrand Russell (1872–1970). Analytic philosopher, nontheist, influential.
Alfred North Whitehead
G. E. Moore (1873–1958). Common sense theorist, ethical non–naturalist.
Ludwig Wittgenstein (1889–1951). Analytic philosopher, philosophy of language, philosophy of mind, influential.
Analytic Philosophy is used as a catch-all phrase to include (mainly Anglophone) branches of contemporary philosophy, such as Logical Positivism and Ordinary Language Philosophy. It is often understood in contrast to other philosophical traditions, most notably continental philosophies such as existentialism, phenomenology, and Hegelianism.
Analytic Philosophy as a specific movement was led by Bertrand Russell, Alfred North Whitehead, G. E. Moore and Ludwig Wittgenstein. They turned away from then-dominant forms of Hegelianism, (particularly objecting to its Idealism and its almost deliberate obscurity). For many Analytic Philosophers, language is the principal (perhaps the only) tool, and philosophy consists in clarifying how language can be used.
Logical Positivism / Logical Empiricism / Vienna CircleLudwig Wittgenstein (1889–1951). Analytic philosopher, philosophy of language, philosophy of mind, influential.
Moritz Schlick (1882–1936). Founder of Vienna Circle, logical positivism.
The most important early figures in Logical Positivism were the Bohemian-Austrian Positivist philosopher Ernst Mach (1838 - 1916) and the Austrian Ludwig Wittgenstein (especially his "Tractatus" of 1921, a text of great importance for Logical Positivists).
A statement is meaningful only if it is either purely formal (essentially, mathematics and logic) or capable of empirical verification.
This effectively resulted in an almost complete rejection of Metaphysics (and to a large extent Ethics) on the grounds that it is unverifiable.
The Vienna Circle met under the (nominal) leadership of Moritz Schlick from 1924 to 1936
Western MarxismProminent figures in the evolution of Western Marxism included the central Europeans György Lukács, Karl Korsch, and Lucien Goldmann; Antonio Gramsci of Italy; the German theorists who constituted the Frankfurt School, especially Max Horkheimer, Theodor Adorno, Herbert Marcuse, and Jürgen Habermas; and Henri Lefebvre, Jean-Paul Sartre, and Maurice Merleau-Ponty of France.
Cultural Theory, Structuralism, Postmodernism