Philosophers

Thomas Aquinas

(1225 - 7 March 1274), also known as Thomas Aquinas (/əˈkwaɪnəs/), was an Italian[3][4] Dominican friar and Catholic priest who was an immensely influential philosopher, theologian and jurist in the tradition of scholasticism, within which he is also known as the "Doctor Angelicus" and "Doctor Communis".[5] He is heralded as the most influential Western medieval legal scholar and theologist. The name "Aquinas" identifies his ancestral origins in the county of Aquino (in the present-day Lazio region), an area where his family held land until 1137. He was the foremost classical proponent of natural theology and the father of Thomism. His influence on Western thought is considerable, and much of modern philosophy developed or opposed his ideas, particularly in the areas of ethics, natural law, metaphysics, and political theory. Unlike many currents in the Church of the time,[6] Thomas embraced several ideas put forward by Aristotle — whom he called "the Philosopher" — and attempted to synthesize Aristotelian philosophy with the principles of Christianity.[7] The works for which he is best known are the Summa Theologica and the Summa contra Gentiles. His commentaries on Sacred Scripture and on Aristotle form an important part of his body of work. Furthermore, Thomas is distinguished for his eucharistic hymns, which form a part of the Church's liturgy.[8] The Catholic Church honors Thomas Aquinas as a saint and regards him as the model teacher for those studying for the priesthood, and indeed the highest expression of both natural reason and speculative theology. In modern times, under papal directives, the study of his works was long used as a core of the required program of study for those seeking ordination as priests or deacons, as well as for those in religious formation and for other students of the sacred disciplines (philosophy, Catholic theology, church history, liturgy, and canon law).[9] Also honored as a Doctor of the Church, Thomas is considered the Catholic Church's greatest theologian and philosopher. Pope Benedict XV declared: "This (Dominican) Order ... acquired new luster when the Church declared the teaching of Thomas to be her own and that Doctor, honored with the special praises of the Pontiffs, the master and patron of Catholic schools."[10]

John Stuart Mill

(20 May 1806 - 8 May 1873) was a British philosopher, political economist and civil servant. He was an influential contributor to social theory, political theory and political economy. He has been called "the most influential English-speaking philosopher of the nineteenth century".[3] Mill's conception of liberty justified the freedom of the individual in opposition to unlimited state control.[4] Mill expresses his view on freedom by illustrating how an individual's drive to better their station, and for self-improvement, is the sole source of true freedom. Only when an individual is able to attain such improvements, without impeding others in their own efforts to do the same, can true freedom prevail. Mill's linking of freedom and self-improvement has inspired many. By establishing that individual efforts to excel have worth, Mill was able to show how they should achieve self-improvement without harming others, or society at large. He was a proponent of utilitarianism, an ethical theory developed by Jeremy Bentham. He worked on the theory of the scientific method.[5] Mill was also a Member of Parliament and an important figure in liberal political philosophy.

Friedrich Nietszche

15 October 1844 - 25 August 1900) was a German philosopher, cultural critic, poet, composer, and Latin and Greek scholar. He wrote several critical texts on religion, morality, contemporary culture, philosophy, and science, displaying a fondness for metaphor[2] and irony. Nietzsche's key ideas include perspectivism, the will to power, master-slave morality, the death of God, the Übermensch and eternal recurrence. One of the key tenets of his philosophy is "life-affirmation", which embraces the realities of the world in which we live over the idea of a world beyond. It further champions the creative powers of the individual to strive beyond social, cultural, and moral contexts.[3] Nietzsche's attitude towards religion and morality was marked with atheism, psychologism and historism: he considered them to be human creations - effects of a historical development, mistaken as its first cause.[4] His radical questioning of the value and objectivity of truth has been the focus of extensive commentary, and his influence remains substantial, especially in schools of continental philosophy such as existentialism, postmodernism, and post-structuralism. His ideas of individual overcoming and transcendence beyond structure and context have had a profound impact on late-twentieth and early-twenty-first century thinkers, who have used these concepts as points of departure in the development of their philosophies.[5][6] Nietzsche began his career as a classical philologist—a scholar of Greek and Roman textual criticism—before turning to philosophy. In 1869, at age 24, he became the youngest-ever occupant of the Chair of Classical Philology at the University of Basel since the establishment of the university in 1460. He resigned in 1879 due to health problems that plagued him most of his life.[7] In 1889, at age 44, he suffered a collapse and a complete loss of his mental faculties. The breakdown was later ascribed to atypical general paresis due to tertiary syphilis, but this diagnosis has come into question.[8] Nietzsche lived his remaining years in the care of his mother (until her death in 1897) and then his sister Elisabeth Förster-Nietzsche. He died in 1900 of what was thought to be a stroke, however re-examination of Nietzsche's medical evaluation papers show that he almost certainly died of brain cancer.[9] As his caretaker, his sister assumed the roles of curator and editor of Nietzsche's manuscripts. Förster-Nietzsche, the widow of prominent German nationalist and antisemite Bernhard Förster, reworked Nietzsche's unpublished writings to fit her own ideology. Often she did so in ways contrary to her brother's stated opinions, which were strongly and explicitly opposed to antisemitism and nationalism. Through Förster-Nietzsche's editions, Nietzsche's name became associated with German militarism and Nazism, although later 20th-century scholars have counteracted this conception of his ideas.

Immanuel Kant

22 April 1724 - 12 February 1804) was a German philosopher, who is considered the central figure of modern philosophy.[2] Kant argued that fundamental concepts of the human mind structure human experience, that reason is the source of morality, that aesthetics arises from a faculty of disinterested judgment, that space and time are forms of our understanding, and that the world as it is "in-itself" is unknowable. Kant took himself to have effected a Copernican revolution in philosophy, akin to Copernicus' reversal of the age-old belief that the sun revolved around the earth. His beliefs continue to have a major influence on contemporary philosophy, especially the fields of metaphysics, epistemology, ethics, political theory, and aesthetics. Kant in his critical phase sought to 'reverse' the orientation of pre-critical philosophy by showing how the traditional problems of metaphysics can be overcome by supposing that the agreement between reality and the concepts we use to conceive it arises not because our mental concepts have come to passively mirror reality, but because reality must conform to the human mind's active concepts to be conceivable and at all possible for us to experience. Kant thus regarded the basic categories of the human mind as the transcendental "condition of possibility" for any experience.[3] Politically, Kant was one of the earliest exponents of the idea that perpetual peace could be secured through universal democracy and international cooperation. The exact nature of Kant's religious ideas continue to be the subject of especially heated philosophical dispute, with viewpoints ranging from the idea that Kant was an early and radical exponent of atheism who finally exploded the ontological proof for God's existence, to more critical treatments epitomized by Nietzsche who claimed that Kant had "theologian blood"[4] and that Kant was merely a sophisticated apologist for traditional Christian religious belief, writing that "Kant wanted to prove, in a way that would dumbfound the common man, that the common man was right: that was the secret joke of this soul."[5]

Baruch Spinoza

24 November 1632 - 21 February 1677, later Benedict de Spinoza) was a Dutch philosopher of Sephardi Portuguese origin.[2] The breadth and importance of Spinoza's work was not fully realized until many years after his death. By laying the groundwork for the 18th-century Enlightenment[4] and modern biblical criticism,[5] including modern conceptions of the self and the universe,[6] he came to be considered one of the great rationalists of 17th-century philosophy[7] His magnum opus, the posthumous Ethics, in which he opposed Descartes' mind-body dualism, has earned him recognition as one of Western philosophy's most important thinkers. In the Ethics, "Spinoza wrote the last indisputable Latin masterpiece, and one in which the refined conceptions of medieval philosophy are finally turned against themselves and destroyed entirely."[8] Hegel said, "You are either a Spinozist or not a philosopher at all."[9] His philosophical accomplishments and moral character prompted 20th-century philosopher Gilles Deleuze to name him "the 'prince' of philosophers".[10] Spinoza's given name varies between different languages: Hebrew: ברוך שפינוזה‎ Baruch Spinoza, Portuguese: Benedito or Bento de Espinosa and Latin: Benedictus de Spinoza; in all these languages, the given name means "Blessed". Spinoza was raised in the Portuguese Jewish community in Amsterdam. He developed highly controversial ideas regarding the authenticity of the Hebrew Bible and the nature of the Divine. The Jewish religious authorities issued a cherem (Hebrew: חרם, a kind of ban, shunning, ostracism, expulsion, or excommunication) against him, effectively excluding him from Jewish society at age 23. His books were also later put on the Catholic Church's Index of Forbidden Books. Spinoza lived an outwardly simple life as a lens grinder, turning down rewards and honours throughout his life, including prestigious teaching positions. Spinoza died at the age of 44 allegedly of a lung illness, perhaps tuberculosis or silicosis exacerbated by fine glass dust inhaled while grinding optical lenses. Spinoza is buried in the churchyard of the Christian Nieuwe Kerk in The Hague.[11]

David Hume

26 April 1711 OS) - 25 August 1776) was a Scottish philosopher, historian, economist, and essayist, who is best known today for his highly influential system of radical philosophical empiricism, skepticism, and naturalism. Hume's empiricist approach to philosophy places him with John Locke, George Berkeley, Francis Bacon, and Thomas Hobbes as a British Empiricist.[2] Beginning with his A Treatise of Human Nature (1739), Hume strove to create a total naturalistic science of man that examined the psychological basis of human nature. Against rationalists, Hume held that passion rather than reason governs human behaviour. He argued against the existence of innate ideas, postulating that humans can have knowledge only of the objects of experience, and the relations of ideas, calling the rest "nothing but sophistry and illusion",[3] a dichotomy later given the name Hume's fork. He also argued that inductive reasoning, and therefore causality, cannot, ultimately, be justified rationally: our belief in causality and induction instead results from custom, habit, and experience of "Constant conjunction" rather than logic.[4] He denied that humans have an actual conception of the self, positing that we experience only a bundle of sensations, and that the self is nothing more than this bundle of causally-connected perceptions. Hume's compatibilist theory of free will takes causal determinism as fully compatible with human freedom, and has proved extremely influential on subsequent moral philosophy.[5] Hume was also a sentimentalist who held that ethics are based on emotion or sentiment rather than abstract moral principle, famously proclaiming that "Reason Is and Ought Only to Be the Slave of the Passions". Contemporary scholars view Hume's moral theory as a unique attempt to synthesize the modern sentimentalist moral tradition to which Hume belonged, with the virtue ethics tradition of ancient philosophy, with which Hume concurred in regarding traits of character, rather than acts or their consequences, as ultimately the proper objects of moral evaluation.[6] Hume's moral theory maintained an early commitment to naturalistic explanations of moral phenomena, and is usually taken to have first clearly expounded the is-ought problem, or the idea that a statement of fact alone can never give rise to a normative conclusion of what ought to be done.[6]

Ludwig Wittgenstein

26 April 1889 - 29 April 1951) was an Austrian-British philosopher who worked primarily in logic, the philosophy of mathematics, the philosophy of mind, and the philosophy of language.[5] From 1929 to 1947, Wittgenstein taught at the University of Cambridge.[6] During his lifetime he published just one slim book, the 75-page Tractatus Logico-Philosophicus (1921), one article, one book review and a children's dictionary.[7] His voluminous manuscripts were edited and published posthumously. Philosophical Investigations appeared as a book in 1953, and by the end of the century it was considered an important modern classic.[8] His teacher Bertrand Russell described Wittgenstein as "the most perfect example I have ever known of genius as traditionally conceived; passionate, profound, intense, and dominating".[9] Born in Vienna into one of Europe's richest families, he inherited a large fortune from his father in 1913. He gave some considerable sums to poor artists. In a period of severe personal depression after the first World War, he then gave away his entire fortune to his brothers and sisters.[10][11] Three of his brothers committed suicide, with Wittgenstein contemplating it too.[12] He left academia several times—serving as an officer on the front line during World War I, where he was decorated a number of times for his courage; teaching in schools in remote Austrian villages where he encountered controversy for hitting children when they made mistakes in mathematics; and working as a hospital porter during World War II in London where he told patients not to take the drugs they were prescribed while largely managing to keep secret the fact that he was one of the world's most famous philosophers.[13] He described philosophy, however, as "the only work that gives me real satisfaction."[14] His philosophy is often divided into an early period, exemplified by the Tractatus, and a later period, articulated in the Philosophical Investigations. The early Wittgenstein was concerned with the logical relationship between propositions and the world and believed that by providing an account of the logic underlying this relationship, he had solved all philosophical problems. The later Wittgenstein rejected many of the assumptions of the Tractatus, arguing that the meaning of words is best understood as their use within a given language-game.[15] Wittgenstein's influence has been felt in nearly every field of the humanities and social sciences, yet there are diverging interpretations of his thought. In the words of his friend and colleague Georg Henrik von Wright: He was of the opinion... that his ideas were generally misunderstood and distorted even by those who professed to be his disciples. He doubted he would be better understood in the future. He once said he felt as though he was writing for people who would think in a different way, breathe a different air of life, from that of present-day men.[16]

Jean-Jacques Rousseau

28 June 1712 - 2 July 1778) was a philosopher, writer, and composer of the 18th century. His political philosophy influenced the Enlightenment in France and across Europe, as well as aspects of the French Revolution and the overall development of modern political and educational thought. Rousseau's novel Emile, or On Education is a treatise on the education of the whole person for citizenship. His sentimental novel Julie, or the New Heloise was of importance to the development of pre-romanticism[2] and romanticism in fiction.[3] Rousseau's autobiographical writings — his Confessions, which initiated the modern autobiography, and his Reveries of a Solitary Walker — exemplified the late 18th-century movement known as the Age of Sensibility, and featured an increased focus on subjectivity and introspection that later characterized modern writing. His Discourse on Inequality and The Social Contract are cornerstones in modern political and social thought. Rousseau was a successful composer of music, who wrote seven operas as well as music in other forms, and made contributions to music as a theorist. As a composer, his music was a blend of the late Baroque style and the emergent Classical fashion, and he belongs to the same generation of transitional composers as Christoph Willibald Gluck and C. P. E. Bach. One of his more well-known works is the one-act opera Le devin du village, containing the duet "Non, Colette n'est point trompeuse" which was later rearranged as a standalone song by Beethoven.[4] During the period of the French Revolution, Rousseau was the most popular of the philosophes among members of the Jacobin Club. Rousseau was interred as a national hero in the Panthéon in Paris, in 1794, 16 years after his death.

John Locke

29 August 1632 - 28 October 1704) was an English philosopher and physician regarded as one of the most influential of Enlightenment thinkers and known as the "Father of Classical Liberalism".[1][2][3] Considered one of the first of the British empiricists, following the tradition of Sir Francis Bacon, he is equally important to social contract theory. His work greatly affected the development of epistemology and political philosophy. His writings influenced Voltaire and Rousseau, many Scottish Enlightenment thinkers, as well as the American revolutionaries. His contributions to classical republicanism and liberal theory are reflected in the United States Declaration of Independence.[4] Locke's theory of mind is often cited as the origin of modern conceptions of identity and the self, figuring prominently in the work of later philosophers such as Hume, Rousseau, and Kant. Locke was the first to define the self through a continuity of consciousness. He postulated that, at birth, the mind was a blank slate or tabula rasa. Contrary to Cartesian philosophy based on pre-existing concepts, he maintained that we are born without innate ideas, and that knowledge is instead determined only by experience derived from sense perception.[5]

Socrates

470/469 - 399 BC)[1] was a classical Greek (Athenian) philosopher credited as one of the founders of Western philosophy. He is an enigmatic figure known chiefly through the accounts of classical writers, especially the writings of his students Plato and Xenophon and the plays of his contemporary Aristophanes. Plato's dialogues are among the most comprehensive accounts of Socrates to survive from antiquity, though it is unclear the degree to which Socrates himself is "hidden behind his 'best disciple', Plato".[3] Through his portrayal in Plato's dialogues, Socrates has become renowned for his contribution to the field of ethics, and it is this Platonic Socrates who lends his name to the concepts of Socratic irony and the Socratic method, or elenchus. The latter remains a commonly used tool in a wide range of discussions, and is a type of pedagogy in which a series of questions is asked not only to draw individual answers, but also to encourage fundamental insight into the issue at hand. Plato's Socrates also made important and lasting contributions to the field of epistemology, and the influence of his ideas and approach remains a strong foundation for much western philosophy that followed.

Thomas Hobbes

5 April 1588 - 4 December 1679), in some older texts Thomas Hobbs of Malmsbury,[a] was an English philosopher, best known today for his work on political philosophy. His 1651 book Leviathan established social contract theory, the foundation of most later Western political philosophy.[1] Though on rational grounds a champion of absolutism for the sovereign, Hobbes also developed some of the fundamentals of European liberal thought: the right of the individual; the natural equality of all men; the artificial character of the political order (which led to the later distinction between civil society and the state); the view that all legitimate political power must be "representative" and based on the consent of the people; and a liberal interpretation of law which leaves people free to do whatever the law does not explicitly forbid.[2] He was one of the founders of modern political philosophy and political science.[3][4] His understanding of humans as being matter and motion, obeying the same physical laws as other matter and motion, remains influential; and his account of human nature as self-interested cooperation, and of political communities as being based upon a "social contract" remains one of the major topics of political philosophy. In addition to political philosophy, Hobbes also contributed to a diverse array of other fields, including history, geometry, the physics of gases, theology, ethics, and general philosophy.

Karl Marx

5 May 1818 - 14 March 1883) was a philosopher, economist, sociologist, journalist, and revolutionary socialist. Born in Prussia, he later became stateless and spent much of his life in London in the United Kingdom. Marx's work in economics laid the basis for much of the current understanding of labour and its relation to capital, and subsequent economic thought.[5][6][7][8] He published numerous books during his lifetime, the most notable being The Communist Manifesto (1848) and Das Kapital (1867-1894). Born into a wealthy middle-class family in Trier in the Prussian Rhineland, Marx studied at the universities of Bonn and Berlin where he became interested in the philosophical ideas of the Young Hegelians. After his studies he wrote for the Rheinische Zeitung, a radical newspaper in Cologne, and began to work out the theory of the materialist conception of history. He moved to Paris in 1843, where he began writing for other radical newspapers and met Friedrich Engels, who would become his lifelong friend and collaborator. In 1849 he was exiled and moved to London together with his wife and children, where he continued writing and formulating his theories about social and economic activity. He also campaigned for socialism and became a significant figure in the International Workingmen's Association. Marx's theories about society, economics and politics—the collective understanding of which is known as Marxism—hold that human societies progress through class struggle: a conflict between an ownership class that controls production and a dispossessed labouring class that provides the labour for production. States, Marx believed, were run on behalf of the ruling class and in their interest while representing it as the common interest of all;[9] and he predicted that, like previous socioeconomic systems, capitalism produced internal tensions which would lead to its self-destruction and replacement by a new system: socialism. He argued that class antagonisms under capitalism between the bourgeoisie and proletariat would eventuate in the working class' conquest of political power and eventually establish a classless society, communism, a society governed by a free association of producers.[10][11] Marx actively fought for its implementation, arguing that the working class should carry out organised revolutionary action to topple capitalism and bring about socio-economic change.[12]

Gottlob Frege

8 November 1848 - 26 July 1925) was a German philosopher, logician, and mathematician. He is considered to be one of the founders of modern logic and made major contributions to the foundations of mathematics. He is generally considered to be the father of analytic philosophy, for his writings on the philosophy of language and mathematics. While he was mainly ignored by the intellectual world when he published his writings, Giuseppe Peano (1858-1932) and Bertrand Russell (1872-1970) introduced his work to later generations of logicians and philosophers. The Frege programming language is named after him.

Plato

Along with his teacher, Socrates, and his most famous student, Aristotle, Plato laid the very foundations of Western philosophy and science.[5] Alfred North Whitehead once noted: "the safest general characterization of the European philosophical tradition is that it consists of a series of footnotes to Plato."[6] In addition to being a foundational figure for Western science, philosophy, and mathematics, Plato has also often been cited as one of the founders of Western religion and spirituality,[7] particularly Christianity, which Friedrich Nietzsche, amongst other scholars, called "Platonism for the people."[8] Plato's influence on Christian thought is often thought to be mediated by his major influence on Saint Augustine of Hippo, one of the most important philosophers and theologians in the history of Christianity. Plato was the innovator of the dialogue and dialectic forms in philosophy, which originate with him. Plato appears to have been the founder of Western political philosophy, with his Republic, and Laws among other dialogues, providing some of the earliest extant treatments of political questions from a philosophical perspective. Plato's own most decisive philosophical influences are usually thought to have been Socrates, Parmenides, Heraclitus, and Pythagoras, although few of his predecessors' works remain extant and much of what we know about these figures today derives from Plato himself.[9] The Stanford Encyclopedia of Philosophy describes Plato as "...one of the most dazzling writers in the Western literary tradition and one of the most penetrating, wide-ranging, and influential authors in the history of philosophy. ... He was not the first thinker or writer to whom the word "philosopher" should be applied. But he was so self-conscious about how philosophy should be conceived, and what its scope and ambitions properly are, and he so transformed the intellectual currents with which he grappled, that the subject of philosophy, as it is often conceived—a rigorous and systematic examination of ethical, political, metaphysical, and epistemological issues, armed with a distinctive method—can be called his invention. Few other authors in the history of Western philosophy approximate him in depth and range: perhaps only Aristotle (who studied with him), Aquinas, and Kant would be generally agreed to be of the same rank."[10]

Aristotle

At eighteen, he joined Plato's Academy in Athens and remained there until the age of thirty-seven (c. 347 BC). His writings cover many subjects - including physics, biology, zoology, metaphysics, logic, ethics, aesthetics, poetry, theater, music, rhetoric, linguistics, politics and government - and constitute the first comprehensive system of Western philosophy. Shortly after Plato died, Aristotle left Athens and, at the request of Philip of Macedon, tutored Alexander the Great starting from 343 BC.[4] According to the Encyclopædia Britannica, "Aristotle was the first genuine scientist in history ... [and] every scientist is in his debt."[5] Teaching Alexander the Great gave Aristotle many opportunities and an abundance of supplies. He established a library in the Lyceum which aided in the production of many of his hundreds of books. The fact that Aristotle was a pupil of Plato contributed to his former views of Platonism, but, following Plato's death, Aristotle immersed himself in empirical studies and shifted from Platonism to empiricism.[6] He believed all peoples' concepts and all of their knowledge was ultimately based on perception. Aristotle's views on natural sciences represent the groundwork underlying many of his works. Aristotle's views on physical science profoundly shaped medieval scholarship. Their influence extended into the Renaissance and were not replaced systematically until the Enlightenment and theories such as classical mechanics. His works contain the earliest known formal study of logic, which was incorporated in the late 19th century into modern formal logic.

Hegel

Georg Wilhelm Friedrich Hegel (/ˈheɪɡəl/;[2] German: [ˈɡeɔɐ̯k ˈvɪlhɛlm ˈfʁiːdʁɪç ˈheːɡəl]; August 27, 1770 - November 14, 1831) was a German philosopher of the late Enlightenment. He achieved wide renown in his day and, while primarily influential within the Continental tradition of philosophy, has become increasingly influential in the Analytic tradition as well.[3] Although he remains a divisive figure, his canonical stature within Western philosophy is universally recognized.[4] Hegel's principal achievement is his development of a distinctive articulation of idealism sometimes termed "absolute idealism,"[5] in which the dualisms of, for instance, mind and nature and subject and object are overcome. His philosophy of spirit conceptually integrates psychology, the state, history, art, religion, and philosophy. His account of the master-slave dialectic has been highly influential, especially in 20th-century France.[6] Of special importance is his concept of spirit (Geist: sometimes also translated as "mind") as the historical manifestation of the logical concept and the "sublation" (Aufhebung: integration without elimination or reduction) of seemingly contradictory or opposing factors; examples include the apparent opposition between nature and freedom and between immanence and transcendence. Hegel has been seen in the 21st century as the originator of the thesis, antithesis, synthesis triad; however this originated with Johann Fichte.[7] Hegel has influenced many thinkers and writers whose own positions vary widely.[8] Karl Barth described Hegel as a "Protestant Aquinas,"[9] while Maurice Merleau-Ponty wrote that "All the great philosophical ideas of the past century—the philosophies of Marx and Nietzsche, phenomenology, German existentialism, and psychoanalysis—had their beginnings in Hegel."[10]

Leibniz

July 1, 1646 - November 14, 1716) was a German polymath and philosopher, and to this day he occupies a prominent place in the history of mathematics and the history of philosophy. Most scholars believe Leibniz developed calculus independently of Isaac Newton, and Leibniz's notation has been widely used ever since it was published. It was only in the 20th century that his Law of Continuity and Transcendental Law of Homogeneity found mathematical implementation (by means of non-standard analysis). He became one of the most prolific inventors in the field of mechanical calculators. While working on adding automatic multiplication and division to Pascal's calculator, he was the first to describe a pinwheel calculator in 1685[8] and invented the Leibniz wheel, used in the arithmometer, the first mass-produced mechanical calculator. He also refined the binary number system, which is the foundation of virtually all digital computers. In philosophy, Leibniz is most noted for his optimism, i.e., his conclusion that our Universe is, in a restricted sense, the best possible one that God could have created, an idea that was often lampooned by others such as Voltaire. Leibniz, along with René Descartes and Baruch Spinoza, was one of the three great 17th century advocates of rationalism. The work of Leibniz anticipated modern logic and analytic philosophy, but his philosophy also looks back to the scholastic tradition, in which conclusions are produced by applying reason of first principles or prior definitions rather than to empirical evidence. Leibniz made major contributions to physics and technology, and anticipated notions that surfaced much later in philosophy, probability theory, biology, medicine, geology, psychology, linguistics, and computer science. He wrote works on philosophy, politics, law, ethics, theology, history, and philology. Leibniz's contributions to this vast array of subjects were scattered in various learned journals, in tens of thousands of letters, and in unpublished manuscripts. He wrote in several languages, but primarily in Latin, French, and German.[9] There is no complete gathering of the writings of Leibniz.[10]

Kierkegaard

May 1813 - 11 November 1855) was a Danish philosopher, theologian, poet, social critic and religious author who is widely considered to be the first existentialist philosopher.[1][2] He wrote critical texts on organized religion, Christendom, morality, ethics, psychology, and the philosophy of religion, displaying a fondness for metaphor, irony and parables. Much of his philosophical work deals with the issues of how one lives as a "single individual", giving priority to concrete human reality over abstract thinking and highlighting the importance of personal choice and commitment.[3] He was against literary critics who defined idealist intellectuals and philosophers of his time. Swedenborg,[4] Hegel,[5] Goethe,[6] Fichte, Schelling, Schlegel and Hans Christian Andersen were all "understood" far too quickly by "scholars".[7] Kierkegaard's theological work focuses on Christian ethics, the institution of the Church, the differences between purely objective proofs of Christianity, the infinite qualitative distinction between man and God, and the individual's subjective relationship to the God-Man Jesus the Christ,[8] which came through faith.[9][10] Much of his work deals with the art of Christian love. He was extremely critical of the practice of Christianity as a state religion, primarily that of the Church of Denmark. His psychological work explored the emotions and feelings of individuals when faced with life choices.[11] Kierkegaard's early work was written under various pseudonyms that he used to present distinctive viewpoints and to interact with each other in complex dialogue.[12] He explored particularly complex problems from different viewpoints, each under a different pseudonym. He wrote many Upbuilding Discourses under his own name and dedicated them to the "single individual" who might want to discover the meaning of his works. Notably, he wrote: "Science[13] and scholarship want to teach that becoming objective is the way. Christianity teaches that the way is to become subjective, to become a subject."[14] While scientists can learn about the world by observation, Kierkegaard emphatically denied that observation could reveal the inner workings of the spiritual world.[15] Some of Kierkegaard's key ideas include the concept of "Truth as Subjectivity", the knight of faith, the recollection and repetition dichotomy, angst, the infinite qualitative distinction, faith as a passion, and the three stages on life's way. Kierkegaard's writings were written in Danish and were initially limited to Scandinavia, but by the turn of the 20th century, his writings were translated into major European languages, such as French and German. By the mid-20th century, his thought exerted a substantial influence on philosophy,[16] theology,[17] and Western culture.[18]

Augustine of Hippo

November 354 - 28 August 430), also known as Saint Augustine or Saint Austin,[4] and also sometimes as Blessed Augustine in the Eastern Orthodox Church,[5] was an early Christian theologian and philosopher[6] whose writings influenced the development of Western Christianity and Western philosophy. He was the bishop of Hippo Regius (modern-day Annaba, Algeria), located in Numidia (Roman province of Africa). He is viewed as one of the most important Church Fathers in Western Christianity for his writings in the Patristic Era. Among his most important works are The City of God and Confessions. According to his contemporary, Jerome, Augustine "established anew the ancient Faith."[7] In his early years, he was heavily influenced by Manichaeism and afterward by the Neo-Platonism of Plotinus. After his baptism and conversion to Christianity in 387, Augustine developed his own approach to philosophy and theology, accommodating a variety of methods and perspectives.[8] Believing that the grace of Christ was indispensable to human freedom, he helped formulate the doctrine of original sin and made seminal contributions to the development of just war theory. When the Western Roman Empire began to disintegrate, Augustine developed the concept of the pre-Schism Catholic Church as a spiritual City of God, distinct from the material Earthly City.[9] His thoughts profoundly influenced the medieval worldview. The segment of the Church that adhered to the concept of the Trinity as defined by the Council of Nicaea and the Council of Constantinople[10] closely identified with Augustine's City of God. In the Catholic Church and the Anglican Communion, he is a saint, a preeminent Doctor of the Church, and the patron of the Augustinians. His memorial is celebrated on 28 August, the day of his death. He is the patron saint of brewers, printers, theologians, the alleviation of sore eyes, and a number of cities and dioceses.[11] Many Protestants, especially Calvinists, consider him to be one of the theological fathers of the Protestant Reformation due to his teachings on salvation and divine grace.

Descartes

Renatus Cartesius; adjectival form: "Cartesian";[6] 31 March 1596 - 11 February 1650) was a French philosopher, mathematician, and scientist who spent about 20 years of his life in the Dutch Republic. He has been dubbed the father of modern philosophy, and much subsequent Western philosophy is a response to his writings,[7][8] which are studied closely to this day. In particular, his Meditations on First Philosophy continues to be a standard text at most university philosophy departments. Descartes's influence in mathematics is equally apparent; the Cartesian coordinate system — allowing reference to a point in space as a set of numbers, and allowing algebraic equations to be expressed as geometric shapes in a two- or three-dimensional coordinate system (and conversely, shapes to be described as equations) — was named after him. He is credited as the father of analytical geometry, the bridge between algebra and geometry, used in the discovery of infinitesimal calculus and analysis. Descartes was also one of the key figures in the scientific revolution. Descartes refused to accept the authority of previous philosophers, and refused to trust his own senses. He frequently set his views apart from those of his predecessors. In the opening section of the Passions of the Soul, a treatise on the early modern version of what are now commonly called emotions, Descartes goes so far as to assert that he will write on this topic "as if no one had written on these matters before". Many elements of his philosophy have precedents in late Aristotelianism, the revived Stoicism of the 16th century, or in earlier philosophers like Augustine. In his natural philosophy, he differs from the schools on two major points: First, he rejects the splitting of corporeal substance into matter and form; second, he rejects any appeal to final ends—divine or natural—in explaining natural phenomena.[9] In his theology, he insists on the absolute freedom of God's act of creation. Descartes laid the foundation for 17th-century continental rationalism, later advocated by Baruch Spinoza and Gottfried Leibniz, and opposed by the empiricist school of thought consisting of Hobbes, Locke, Berkeley, and Hume. Leibniz, Spinoza[citation needed] and Descartes were all well versed in mathematics as well as philosophy, and Descartes and Leibniz contributed greatly to science as well. His best known philosophical statement is "Cogito ergo sum" (French: Je pense, donc je suis; I think, therefore I am), found in part IV of Discourse on the Method (1637 - written in French but with inclusion of "Cogito ergo sum") and §7 of part I of Principles of Philosophy (1644 - written in Latin).