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In philosophy, rationalism is the epistemological view that "regards
reason Reason is the capacity of consciously applying logic by drawing conclusions from new or existing information, with the aim of seeking the truth. It is closely associated with such characteristically human activities as philosophy, science, ...
as the chief source and test of knowledge" or "any view appealing to reason as a source of knowledge or justification".Lacey, A.R. (1996), ''A Dictionary of Philosophy'', 1st edition, Routledge and Kegan Paul, 1976. 2nd edition, 1986. 3rd edition, Routledge, London, 1996. p. 286 More formally, rationalism is defined as a
methodology In its most common sense, methodology is the study of research methods. However, the term can also refer to the methods themselves or to the philosophical discussion of associated background assumptions. A method is a structured procedure for br ...
or a
theory A theory is a rational type of abstract thinking about a phenomenon, or the results of such thinking. The process of contemplative and rational thinking is often associated with such processes as observational study or research. Theories may be ...
"in which the criterion of
truth Truth is the property of being in accord with fact or reality.Merriam-Webster's Online Dictionarytruth 2005 In everyday language, truth is typically ascribed to things that aim to represent reality or otherwise correspond to it, such as belie ...
is not sensory but intellectual and
deductive Deductive reasoning is the mental process of drawing deductive inferences. An inference is deductively valid if its conclusion follows logically from its premises, i.e. if it is impossible for the premises to be true and the conclusion to be fals ...
".Bourke, Vernon J., "Rationalism," p. 263 in Runes (1962). In an old John Locke (1690),
An Essay on Human Understanding ''An Essay Concerning Human Understanding'' is a work by John Locke concerning the foundation of human knowledge and understanding. It first appeared in 1689 (although dated 1690) with the printed title ''An Essay Concerning Humane Understand ...
controversy, rationalism was opposed to empiricism, where the rationalists believed that reality has an intrinsically logical structure. Because of this, the rationalists argued that certain truths exist and that the intellect can directly grasp these truths. That is to say, rationalists asserted that certain rational principles exist in
logic Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the science of deductively valid inferences or of logical truths. It is a formal science investigating how conclusions follow from premise ...
, mathematics,
ethics Ethics or moral philosophy is a branch of philosophy that "involves systematizing, defending, and recommending concepts of right and wrong behavior".''Internet Encyclopedia of Philosophy'' The field of ethics, along with aesthetics, concer ...
, and
metaphysics Metaphysics is the branch of philosophy that studies the fundamental nature of reality, the first principles of being, identity and change, space and time, causality, necessity, and possibility. It includes questions about the nature of conscio ...
that are so fundamentally true that denying them causes one to fall into contradiction. The rationalists had such a high confidence in reason that empirical proof and physical evidence were regarded as unnecessary to ascertain certain truthsin other words, "there are significant ways in which our concepts and knowledge are gained independently of sense experience".''Stanford Encyclopedia of Philosophy''
"Rationalism vs. Empiricism"
First published August 19, 2004; substantive revision March 31, 2013 cited on May 20, 2013.
Different degrees of emphasis on this method or theory lead to a range of rationalist standpoints, from the moderate position "that reason has precedence over other ways of acquiring knowledge" to the more extreme position that reason is "the unique path to knowledge".Audi, Robert, The Cambridge Dictionary of Philosophy, Cambridge University Press, Cambridge, UK, 1995. 2nd edition, 1999, p. 771. Given a pre-modern understanding of reason, rationalism is identical to philosophy, the Socratic life of inquiry, or the zetetic (
skeptical Skepticism, also spelled scepticism, is a questioning attitude or doubt toward knowledge claims that are seen as mere belief or dogma. For example, if a person is skeptical about claims made by their government about an ongoing war then the p ...
) clear interpretation of authority (open to the underlying or essential cause of things as they appear to our sense of certainty). In recent decades, Leo Strauss sought to revive "Classical Political Rationalism" as a discipline that understands the task of reasoning, not as foundational, but as maieutic.


Background

Rationalismas an appeal to human reason as a way of obtaining knowledgehas a philosophical history dating from antiquity. The analytical nature of much of philosophical enquiry, the awareness of apparently a priori domains of knowledge such as mathematics, combined with the emphasis of obtaining knowledge through the use of rational faculties (commonly rejecting, for example, direct
revelation In religion and theology, revelation is the revealing or disclosing of some form of truth or knowledge through communication with a deity or other supernatural entity or entities. Background Inspiration – such as that bestowed by God on the ...
) have made rationalist themes very prevalent in the history of philosophy. Since the Enlightenment, rationalism is usually associated with the introduction of mathematical methods into philosophy as seen in the works of Descartes, Leibniz, and
Spinoza Baruch (de) Spinoza (born Bento de Espinosa; later as an author and a correspondent ''Benedictus de Spinoza'', anglicized to ''Benedict de Spinoza''; 24 November 1632 – 21 February 1677) was a Dutch philosopher of Portuguese-Jewish origin, ...
. This is commonly called continental rationalism, because it was predominant in the continental schools of Europe, whereas in Britain empiricism dominated. Even then, the distinction between rationalists and empiricists was drawn at a later period and would not have been recognized by the philosophers involved. Also, the distinction between the two philosophies is not as clear-cut as is sometimes suggested; for example, Descartes and Locke have similar views about the nature of human ideas. Proponents of some varieties of rationalism argue that, starting with foundational basic principles, like the axioms of
geometry Geometry (; ) is, with arithmetic, one of the oldest branches of mathematics. It is concerned with properties of space such as the distance, shape, size, and relative position of figures. A mathematician who works in the field of geometry is ...
, one could deductively derive the rest of all possible knowledge. Notable philosophers who held this view most clearly were Baruch Spinoza and
Gottfried Leibniz Gottfried Wilhelm (von) Leibniz . ( – 14 November 1716) was a German polymath active as a mathematician, philosopher, scientist and diplomat. He is one of the most prominent figures in both the history of philosophy and the history of mathem ...
, whose attempts to grapple with the epistemological and metaphysical problems raised by Descartes led to a development of the fundamental approach of rationalism. Both Spinoza and Leibniz asserted that, ''in principle'', all knowledge, including scientific knowledge, could be gained through the use of reason alone, though they both observed that this was not possible ''in practice'' for human beings except in specific areas such as mathematics. On the other hand, Leibniz admitted in his book ''
Monadology The ''Monadology'' (french: La Monadologie, 1714) is one of Gottfried Leibniz's best known works of his later philosophy. It is a short text which presents, in some 90 paragraphs, a metaphysics of simple substances, or '' monads''. Text Dur ...
'' that "we are all mere
Empirics In philosophy, empiricism is an epistemological theory that holds that knowledge or justification comes only or primarily from sensory experience. It is one of several views within epistemology, along with rationalism and skepticism. Empiri ...
in three fourths of our actions."


Political usage

In
politics Politics (from , ) is the set of activities that are associated with making decisions in groups, or other forms of power relations among individuals, such as the distribution of resources or status. The branch of social science that stud ...
, rationalism, since the Enlightenment, historically emphasized a "politics of reason" centered upon
rational choice Rational choice theory refers to a set of guidelines that help understand economic and social behaviour. The theory originated in the eighteenth century and can be traced back to political economist and philosopher, Adam Smith. The theory postula ...
,
deontology In moral philosophy, deontological ethics or deontology (from Greek: + ) is the normative ethical theory that the morality of an action should be based on whether that action itself is right or wrong under a series of rules and principles, r ...
,
utilitarianism In ethical philosophy, utilitarianism is a family of normative ethical theories that prescribe actions that maximize happiness and well-being for all affected individuals. Although different varieties of utilitarianism admit different chara ...
,
secularism Secularism is the principle of seeking to conduct human affairs based on secular, naturalistic considerations. Secularism is most commonly defined as the separation of religion from civil affairs and the state, and may be broadened to a sim ...
, and
irreligion Irreligion or nonreligion is the absence or rejection of religion, or indifference to it. Irreligion takes many forms, ranging from the casual and unaware to full-fledged philosophies such as atheism and agnosticism, secular humanism and ...
the latter aspect's
antitheism Antitheism, also spelled anti-theism, is the philosophical position that theism should be opposed. The term has had a range of applications. In secular contexts, it typically refers to direct opposition to the belief in any deity. Etymology T ...
was later softened by the adoption of pluralistic reasoning methods practicable regardless of religious or irreligious ideology. In this regard, the philosopher
John Cottingham John Cottingham (born 1943) is an English philosopher. The focus of his research has been early-modern philosophy (especially Descartes), the philosophy of religion and moral philosophy.Athanassoulis, Nafsika and Vice, Samantha eds. (2008) ''Th ...
noted how rationalism, a
methodology In its most common sense, methodology is the study of research methods. However, the term can also refer to the methods themselves or to the philosophical discussion of associated background assumptions. A method is a structured procedure for br ...
, became socially conflated with atheism, a
worldview A worldview or world-view or ''Weltanschauung'' is the fundamental cognitive orientation of an individual or society encompassing the whole of the individual's or society's knowledge, culture, and point of view. A worldview can include natural ...
:


Philosophical usage

Rationalism is often contrasted with empiricism. Taken very broadly, these views are not mutually exclusive, since a philosopher can be both rationalist and empiricist. Taken to extremes, the empiricist view holds that all ideas come to us ''a posteriori'', that is to say, through experience; either through the external senses or through such inner sensations as pain and gratification. The empiricist essentially believes that knowledge is based on or derived directly from experience. The rationalist believes we come to knowledge ''a priori''through the use of logic  and is thus independent of sensory experience. In other words, as
Galen Strawson Galen John Strawson (born 1952) is a British analytic philosopher and literary critic who works primarily on philosophy of mind, metaphysics (including free will, panpsychism, the mind-body problem, and the self), John Locke, David Hume, ...
once wrote, "you can see that it is true just lying on your couch. You don't have to get up off your couch and go outside and examine the way things are in the physical world. You don't have to do any science." Between both philosophies, the issue at hand is the fundamental source of human knowledge and the proper techniques for verifying what we think we know. Whereas both philosophies are under the umbrella of
epistemology Epistemology (; ), or the theory of knowledge, is the branch of philosophy concerned with knowledge. Epistemology is considered a major subfield of philosophy, along with other major subfields such as ethics, logic, and metaphysics. Epis ...
, their argument lies in the understanding of the warrant, which is under the wider epistemic umbrella of the
theory of justification Justification (also called epistemic justification) is the property of belief that qualifies it as knowledge rather than mere opinion. Epistemology is the study of reasons that someone holds a rationally admissible belief (although the term is a ...
. Part of
epistemology Epistemology (; ), or the theory of knowledge, is the branch of philosophy concerned with knowledge. Epistemology is considered a major subfield of philosophy, along with other major subfields such as ethics, logic, and metaphysics. Epis ...
, this theory attempts to understand the justification of propositions and
belief A belief is an attitude that something is the case, or that some proposition is true. In epistemology, philosophers use the term "belief" to refer to attitudes about the world which can be either true or false. To believe something is to take ...
s. Epistemologists are concerned with various epistemic features of belief, which include the ideas of justification, warrant, rationality, and
probability Probability is the branch of mathematics concerning numerical descriptions of how likely an event is to occur, or how likely it is that a proposition is true. The probability of an event is a number between 0 and 1, where, roughly speakin ...
. Of these four terms, the term that has been most widely used and discussed by the early 21st century is "warrant". Loosely speaking, justification is the reason that someone (probably) holds a belief. If ''A'' makes a claim and then ''B'' casts doubt on it, ''As next move would normally be to provide justification for the claim. The precise method one uses to provide justification is where the lines are drawn between rationalism and empiricism (among other philosophical views). Much of the debate in these fields are focused on
analyzing Analysis (plural, : analyses) is the process of breaking a complexity, complex topic or Substance theory, substance into smaller parts in order to gain a better understanding of it. The technique has been applied in the study of mathematics a ...
the nature of knowledge and how it relates to connected notions such as
truth Truth is the property of being in accord with fact or reality.Merriam-Webster's Online Dictionarytruth 2005 In everyday language, truth is typically ascribed to things that aim to represent reality or otherwise correspond to it, such as belie ...
,
belief A belief is an attitude that something is the case, or that some proposition is true. In epistemology, philosophers use the term "belief" to refer to attitudes about the world which can be either true or false. To believe something is to take ...
, and justification. At its core, rationalism consists of three basic claims. For people to consider themselves rationalists, they must adopt at least one of these three claims: the intuition/deduction thesis, the innate knowledge thesis, or the innate concept thesis. In addition, a rationalist can choose to adopt the claim of Indispensability of Reason and or the claim of Superiority of Reason, although one can be a rationalist without adopting either thesis. The indispensability of reason thesis: "The knowledge we gain in subject area, ''S'', by intuition and deduction, as well as the ideas and instances of knowledge in ''S'' that are innate to us, could not have been gained by us through sense experience." In short, this thesis claims that experience cannot provide what we gain from reason. The superiority of reason thesis: '"The knowledge we gain in subject area ''S'' by intuition and deduction or have innately is superior to any knowledge gained by sense experience". In other words, this thesis claims reason is superior to experience as a source for knowledge. Rationalists often adopt similar stances on other aspects of philosophy. Most rationalists reject skepticism for the areas of knowledge they claim are knowable ''a priori''. When you claim some truths are innately known to us, one must reject skepticism in relation to those truths. Especially for rationalists who adopt the Intuition/Deduction thesis, the idea of epistemic foundationalism tends to crop up. This is the view that we know some truths without basing our belief in them on any others and that we then use this foundational knowledge to know more truths.


The intuition/deduction thesis

Generally speaking, intuition is ''a priori'' knowledge or experiential belief characterized by its immediacy; a form of rational insight. We simply "see" something in such a way as to give us a warranted belief. Beyond that, the nature of intuition is hotly debated. In the same way, generally speaking, deduction is the process of reasoning from one or more general
premise A premise or premiss is a true or false statement that helps form the body of an argument, which logically leads to a true or false conclusion. A premise makes a declarative statement about its subject matter which enables a reader to either agre ...
s to reach a logically certain conclusion. Using valid arguments, we can deduce from intuited premises. For example, when we combine both concepts, we can intuit that the number three is prime and that it is greater than two. We then deduce from this knowledge that there is a prime number greater than two. Thus, it can be said that intuition and deduction combined to provide us with ''a priori'' knowledgewe gained this knowledge independently of sense experience. To argue in favor of this thesis,
Gottfried Wilhelm Leibniz Gottfried Wilhelm (von) Leibniz . ( – 14 November 1716) was a German polymath active as a mathematician, philosopher, scientist and diplomat. He is one of the most prominent figures in both the history of philosophy and the history of math ...
, a prominent German philosopher, says, Empiricists such as
David Hume David Hume (; born David Home; 7 May 1711 NS (26 April 1711 OS) – 25 August 1776) Cranston, Maurice, and Thomas Edmund Jessop. 2020 999br>David Hume" ''Encyclopædia Britannica''. Retrieved 18 May 2020. was a Scottish Enlightenment phil ...
have been willing to accept this thesis for describing the relationships among our own concepts. In this sense, empiricists argue that we are allowed to intuit and deduce truths from knowledge that has been obtained ''a posteriori''. By injecting different subjects into the Intuition/Deduction thesis, we are able to generate different arguments. Most rationalists agree mathematics is knowable by applying the intuition and deduction. Some go further to include ethical truths into the category of things knowable by intuition and deduction. Furthermore, some rationalists also claim
metaphysics Metaphysics is the branch of philosophy that studies the fundamental nature of reality, the first principles of being, identity and change, space and time, causality, necessity, and possibility. It includes questions about the nature of conscio ...
is knowable in this thesis. Naturally, the more subjects the rationalists claim to be knowable by the Intuition/Deduction thesis, the more certain they are of their warranted beliefs, and the more strictly they adhere to the infallibility of intuition, the more controversial their truths or claims and the more radical their rationalism. In addition to different subjects, rationalists sometimes vary the strength of their claims by adjusting their understanding of the warrant. Some rationalists understand warranted beliefs to be beyond even the slightest doubt; others are more conservative and understand the warrant to be belief beyond a reasonable doubt. Rationalists also have different understanding and claims involving the connection between intuition and truth. Some rationalists claim that intuition is infallible and that anything we intuit to be true is as such. More contemporary rationalists accept that intuition is not always a source of certain knowledgethus allowing for the possibility of a deceiver who might cause the rationalist to intuit a false proposition in the same way a third party could cause the rationalist to have perceptions of
nonexistent object An object of the mind is an object that exists in the imagination, but which, in the real world, can only be represented or modeled. Some such objects are abstractions, literary concepts, or fictional scenarios. Closely related are intentional ob ...
s.


The innate knowledge thesis

The Innate Knowledge thesis is similar to the Intuition/Deduction thesis in the regard that both theses claim
knowledge Knowledge can be defined as Descriptive knowledge, awareness of facts or as Procedural knowledge, practical skills, and may also refer to Knowledge by acquaintance, familiarity with objects or situations. Knowledge of facts, also called pro ...
is gained ''a priori''. The two theses go their separate ways when describing how that knowledge is gained. As the name, and the rationale, suggests, the Innate Knowledge thesis claims knowledge is simply part of our rational nature. Experiences can trigger a process that allows this knowledge to come into our consciousness, but the experiences don't provide us with the knowledge itself. The knowledge has been with us since the beginning and the experience simply brought into focus, in the same way a photographer can bring the background of a picture into focus by changing the aperture of the lens. The background was always there, just not in focus. This thesis targets a problem with the nature of inquiry originally postulated by
Plato Plato ( ; grc-gre, Πλάτων ; 428/427 or 424/423 – 348/347 BC) was a Greek philosopher born in Athens during the Classical period in Ancient Greece. He founded the Platonist school of thought and the Academy, the first institution ...
in ''
Meno ''Meno'' (; grc-gre, Μένων, ''Ménōn'') is a Socratic dialogue by Plato. Meno begins the dialogue by asking Socrates whether virtue is taught, acquired by practice, or comes by nature. In order to determine whether virtue is teachabl ...
''. Here, Plato asks about inquiry; how do we gain knowledge of a theorem in geometry? We inquire into the matter. Yet, knowledge by inquiry seems impossible. In other words, "If we already have the knowledge, there is no place for inquiry. If we lack the knowledge, we don't know what we are seeking and cannot recognize it when we find it. Either way we cannot gain knowledge of the theorem by inquiry. Yet, we do know some theorems." The Innate Knowledge thesis offers a solution to this
paradox A paradox is a logically self-contradictory statement or a statement that runs contrary to one's expectation. It is a statement that, despite apparently valid reasoning from true premises, leads to a seemingly self-contradictory or a logically u ...
. By claiming that knowledge is already with us, either consciously or
unconsciously The unconscious mind (or the unconscious) consists of the processes in the mind which occur automatically and are not available to introspection and include thought processes, memories, interests, and motivations. Even though these processes exist ...
, a rationalist claims we don't really "learn" things in the traditional usage of the word, but rather that we simply bring to light what we already know.


The innate concept thesis

Similar to the Innate Knowledge thesis, the Innate Concept thesis suggests that some concepts are simply part of our rational nature. These concepts are ''a priori'' in nature and sense experience is irrelevant to determining the nature of these concepts (though, sense experience can help bring the concepts to our
conscious mind Consciousness, at its simplest, is sentience and awareness of internal and external existence. However, the lack of definitions has led to millennia of analyses, explanations and debates by philosophers, theologians, linguisticians, and scient ...
). In his book, ''
Meditations on First Philosophy ''Meditations on First Philosophy, in which the existence of God and the immortality of the soul are demonstrated'' ( la, Meditationes de Prima Philosophia, in qua Dei existentia et animæ immortalitas demonstratur) is a philosophical treatise ...
'',
René Descartes René Descartes ( or ; ; Latinized: Renatus Cartesius; 31 March 1596 – 11 February 1650) was a French philosopher, scientist, and mathematician, widely considered a seminal figure in the emergence of modern philosophy and science. Ma ...
postulates three classifications for our
idea In common usage and in philosophy, ideas are the results of thought. Also in philosophy, ideas can also be mental representational images of some object. Many philosophers have considered ideas to be a fundamental ontological category of bei ...
s when he says, "Among my ideas, some appear to be innate, some to be adventitious, and others to have been invented by me. My understanding of what a thing is, what truth is, and what thought is, seems to derive simply from my own nature. But my hearing a noise, as I do now, or seeing the sun, or feeling the fire, comes from things which are located outside me, or so I have hitherto judged. Lastly,
sirens Siren or sirens may refer to: Common meanings * Siren (alarm), a loud acoustic alarm used to alert people to emergencies * Siren (mythology), an enchanting but dangerous monster in Greek mythology Places * Siren (town), Wisconsin * Siren, Wisco ...
,
hippogriff The hippogriff, or sometimes spelled hippogryph ( el, Ἱππόγρυπας), is a legendary creature with the front half of an eagle and the hind half of a horse. It was invented by Ludovico Ariosto in his ''Orlando Furioso'', at the beginning o ...
s and the like are my own invention." Adventitious ideas are those concepts that we gain through sense experiences, ideas such as the sensation of heat, because they originate from outside sources; transmitting their own likeness rather than something else and something you simply cannot will away. Ideas invented by us, such as those found in
mythology Myth is a folklore genre consisting of narratives that play a fundamental role in a society, such as foundational tales or origin myths. Since "myth" is widely used to imply that a story is not objectively true, the identification of a narra ...
,
legend A legend is a genre of folklore that consists of a narrative featuring human actions, believed or perceived, both by teller and listeners, to have taken place in human history. Narratives in this genre may demonstrate human values, and possess ...
s, and fairy tales are created by us from other ideas we possess. Lastly, innate ideas, such as our ideas of
perfection Perfection is a state, variously, of completeness, flawlessness, or supreme excellence. The term is used to designate a range of diverse, if often kindred, concepts. These have historically been addressed in a number of discrete disciplines, ...
, are those ideas we have as a result of mental processes that are beyond what experience can directly or indirectly provide.
Gottfried Wilhelm Leibniz Gottfried Wilhelm (von) Leibniz . ( – 14 November 1716) was a German polymath active as a mathematician, philosopher, scientist and diplomat. He is one of the most prominent figures in both the history of philosophy and the history of math ...
defends the idea of innate concepts by suggesting the mind plays a role in determining the nature of concepts, to explain this, he likens the mind to a block of marble in the ''
New Essays on Human Understanding ''New Essays on Human Understanding'' (french: Nouveaux essais sur l'entendement humain) is a chapter-by-chapter rebuttal by Gottfried Leibniz of John Locke's major work '' An Essay Concerning Human Understanding''. It is one of only two full-leng ...
'', Some philosophers, such as John Locke (who is considered one of the most influential thinkers of the Enlightenment and an empiricist) argue that the Innate Knowledge thesis and the Innate Concept thesis are the same. Other philosophers, such as Peter Carruthers, argue that the two theses are distinct from one another. As with the other theses covered under the umbrella of rationalism, the more types and greater number of concepts a philosopher claims to be innate, the more controversial and radical their position; "the more a concept seems removed from experience and the mental operations we can perform on experience the more plausibly it may be claimed to be innate. Since we do not experience perfect triangles but do experience pains, our concept of the former is a more promising candidate for being innate than our concept of the latter.


History


Rationalist philosophy in Western antiquity

Although rationalism in its modern form post-dates antiquity, philosophers from this time laid down the foundations of rationalism. In particular, the understanding that we may be aware of knowledge available only through the use of rational thought.


Pythagoras (570–495 BCE)

Pythagoras was one of the first Western philosophers to stress rationalist insight. He is often revered as a great
mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, structure, space, models, and change. History On ...
, mystic and
scientist A scientist is a person who conducts scientific research to advance knowledge in an area of the natural sciences. In classical antiquity, there was no real ancient analog of a modern scientist. Instead, philosophers engaged in the philosoph ...
, but he is best known for the Pythagorean theorem, which bears his name, and for discovering the mathematical relationship between the length of strings on lute and the pitches of the notes. Pythagoras "believed these harmonies reflected the ultimate nature of reality. He summed up the implied metaphysical rationalism in the words "All is number". It is probable that he had caught the rationalist's vision, later seen by Galileo (1564–1642), of a world governed throughout by mathematically formulable laws". It has been said that he was the first man to call himself a philosopher, or lover of wisdom.


Plato (427–347 BCE)

Plato held rational insight to a very high standard, as is seen in his works such as
Meno ''Meno'' (; grc-gre, Μένων, ''Ménōn'') is a Socratic dialogue by Plato. Meno begins the dialogue by asking Socrates whether virtue is taught, acquired by practice, or comes by nature. In order to determine whether virtue is teachabl ...
and The Republic. He taught on the
Theory of Forms The theory of Forms or theory of Ideas is a philosophical theory, fuzzy concept, or world-view, attributed to Plato, that the physical world is not as real or true as timeless, absolute, unchangeable ideas. According to this theory, ideas in th ...
(or the Theory of Ideas) which asserts that the highest and most fundamental kind of reality is not the material world of change known to us through sensation, but rather the abstract, non-material (but substantial) world of forms (or ideas). For Plato, these forms were accessible only to reason and not to sense. In fact, it is said that Plato admired reason, especially in
geometry Geometry (; ) is, with arithmetic, one of the oldest branches of mathematics. It is concerned with properties of space such as the distance, shape, size, and relative position of figures. A mathematician who works in the field of geometry is ...
, so highly that he had the phrase "Let no one ignorant of geometry enter" inscribed over the door to his academy.


Aristotle (384–322 BCE)

Aristotle Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher and polymath during the Classical period in Ancient Greece. Taught by Plato, he was the founder of the Peripatetic school of ph ...
's main contribution to rationalist thinking was the use of syllogistic logic and its use in argument. Aristotle defines syllogism as "a discourse in which certain (specific) things having been supposed, something different from the things supposed results of necessity because these things are so." Despite this very general definition, Aristotle limits himself to categorical syllogisms which consist of three categorical propositions in his work '' Prior Analytics''. These included categorical modal syllogisms.


Middle Ages

Although the three great Greek philosophers disagreed with one another on specific points, they all agreed that rational thought could bring to light knowledge that was self-evidentinformation that humans otherwise could not know without the use of reason. After Aristotle's death, Western rationalistic thought was generally characterized by its application to theology, such as in the works of
Augustine Augustine of Hippo ( , ; la, Aurelius Augustinus Hipponensis; 13 November 354 – 28 August 430), also known as Saint Augustine, was a theologian and philosopher of Berber origin and the bishop of Hippo Regius in Numidia, Roman North A ...
, the Islamic philosopher Avicenna (Ibn Sina), Averroes (Ibn Rushd), and Jewish philosopher and theologian
Maimonides Musa ibn Maimon (1138–1204), commonly known as Maimonides (); la, Moses Maimonides and also referred to by the acronym Rambam ( he, רמב״ם), was a Sephardic Jewish philosopher who became one of the most prolific and influential Tora ...
. One notable event in the Western timeline was the philosophy of
Thomas Aquinas Thomas Aquinas, OP (; it, Tommaso d'Aquino, lit=Thomas of Aquino; 1225 – 7 March 1274) was an Italian Dominican friar and priest who was an influential philosopher, theologian and jurist in the tradition of scholasticism; he is known wit ...
who attempted to merge Greek rationalism and Christian revelation in the thirteenth-century. Generally, the
Roman Catholic Church The Catholic Church, also known as the Roman Catholic Church, is the largest Christian church, with 1.3 billion baptized Catholics worldwide . It is among the world's oldest and largest international institutions, and has played a ...
viewed Rationalists as a threat, labeling them as those who "while admitting revelation, reject from the word of God whatever, in their private judgment, is inconsistent with human reason."


Classical rationalism


René Descartes (1596–1650)

Descartes was the first of the modern rationalists and has been dubbed the 'Father of Modern Philosophy.' Much subsequent
Western philosophy Western philosophy encompasses the philosophical thought and work of the Western world. Historically, the term refers to the philosophical thinking of Western culture, beginning with the ancient Greek philosophy of the pre-Socratics. The word ' ...
is a response to his writings, which are studied closely to this day. Descartes thought that only knowledge of eternal truthsincluding the truths of mathematics, and the epistemological and metaphysical foundations of the sciences could be attained by reason alone; other knowledge, the knowledge of physics, required experience of the world, aided by the
scientific method The scientific method is an empirical method for acquiring knowledge that has characterized the development of science since at least the 17th century (with notable practitioners in previous centuries; see the article history of scientific ...
. He also argued that although
dream A dream is a succession of images, ideas, emotions, and sensations that usually occur involuntarily in the mind during certain stages of sleep. Humans spend about two hours dreaming per night, and each dream lasts around 5 to 20 minutes, althou ...
s appear as real as sense experience, these dreams cannot provide persons with knowledge. Also, since conscious sense experience can be the cause of illusions, then sense experience itself can be doubtable. As a result, Descartes deduced that a rational pursuit of truth should doubt every belief about sensory reality. He elaborated these beliefs in such works as ''
Discourse on the Method ''Discourse on the Method of Rightly Conducting One's Reason and of Seeking Truth in the Sciences'' (french: Discours de la Méthode Pour bien conduire sa raison, et chercher la vérité dans les sciences) is a philosophical and autobiographical ...
'', ''
Meditations on First Philosophy ''Meditations on First Philosophy, in which the existence of God and the immortality of the soul are demonstrated'' ( la, Meditationes de Prima Philosophia, in qua Dei existentia et animæ immortalitas demonstratur) is a philosophical treatise ...
'', and '' Principles of Philosophy''. Descartes developed a method to attain truths according to which nothing that cannot be recognised by the intellect (or
reason Reason is the capacity of consciously applying logic by drawing conclusions from new or existing information, with the aim of seeking the truth. It is closely associated with such characteristically human activities as philosophy, science, ...
) can be classified as knowledge. These truths are gained "without any sensory experience," according to Descartes. Truths that are attained by reason are broken down into elements that intuition can grasp, which, through a purely deductive process, will result in clear truths about reality. Descartes therefore argued, as a result of his method, that reason alone determined knowledge, and that this could be done independently of the senses. For instance, his famous dictum, ''
cogito ergo sum The Latin , usually translated into English as "I think, therefore I am", is the "first principle" of René Descartes's philosophy. He originally published it in French as , in his 1637 ''Discourse on the Method'', so as to reach a wider audien ...
'' or "I think, therefore I am", is a conclusion reached '' a priori'' i.e., prior to any kind of experience on the matter. The simple meaning is that doubting one's existence, in and of itself, proves that an "I" exists to do the thinking. In other words, doubting one's own doubting is absurd. This was, for Descartes, an irrefutable principle upon which to ground all forms of other knowledge. Descartes posited a metaphysical dualism, distinguishing between the substances of the human body ("''res extensa''") and the mind or soul ("''res cogitans''"). This crucial distinction would be left unresolved and lead to what is known as the mind-body problem, since the two substances in the Cartesian system are independent of each other and irreducible.


Baruch Spinoza (1632–1677)

The philosophy of Baruch Spinoza is a systematic, logical, rational philosophy developed in seventeenth-century
Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located entirel ...
. Spinoza's philosophy is a system of ideas constructed upon basic building blocks with an internal consistency with which he tried to answer life's major questions and in which he proposed that "God exists only philosophically." He was heavily influenced by Descartes,
Euclid Euclid (; grc-gre, Εὐκλείδης; BC) was an ancient Greek mathematician active as a geometer and logician. Considered the "father of geometry", he is chiefly known for the '' Elements'' treatise, which established the foundations of ...
and
Thomas Hobbes Thomas Hobbes ( ; 5/15 April 1588 – 4/14 December 1679) was an English philosopher, considered to be one of the founders of modern political philosophy. Hobbes is best known for his 1651 book ''Leviathan'', in which he expounds an influ ...
, as well as theologians in the Jewish philosophical tradition such as
Maimonides Musa ibn Maimon (1138–1204), commonly known as Maimonides (); la, Moses Maimonides and also referred to by the acronym Rambam ( he, רמב״ם), was a Sephardic Jewish philosopher who became one of the most prolific and influential Tora ...
. But his work was in many respects a departure from the Judeo-Christian tradition. Many of Spinoza's ideas continue to vex thinkers today and many of his principles, particularly regarding the
emotions Emotions are mental states brought on by neurophysiological changes, variously associated with thoughts, feelings, behavioral responses, and a degree of pleasure or displeasure. There is currently no scientific consensus on a definition. ...
, have implications for modern approaches to
psychology Psychology is the scientific study of mind and behavior. Psychology includes the study of conscious and unconscious phenomena, including feelings and thoughts. It is an academic discipline of immense scope, crossing the boundaries between ...
. To this day, many important thinkers have found Spinoza's "geometrical method" difficult to comprehend:
Goethe Johann Wolfgang von Goethe (28 August 1749 – 22 March 1832) was a German poet, playwright, novelist, scientist, statesman, theatre director, and critic. His works include plays, poetry, literature, and aesthetic criticism, as well as tr ...
admitted that he found this concept confusing. His ''
magnum opus A masterpiece, ''magnum opus'' (), or ''chef-d’œuvre'' (; ; ) in modern use is a creation that has been given much critical praise, especially one that is considered the greatest work of a person's career or a work of outstanding creativity, ...
'', ''
Ethics Ethics or moral philosophy is a branch of philosophy that "involves systematizing, defending, and recommending concepts of right and wrong behavior".''Internet Encyclopedia of Philosophy'' The field of ethics, along with aesthetics, concer ...
'', contains unresolved obscurities and has a forbidding mathematical structure modeled on Euclid's geometry. Spinoza's philosophy attracted believers such as
Albert Einstein Albert Einstein ( ; ; 14 March 1879 – 18 April 1955) was a German-born theoretical physicist, widely acknowledged to be one of the greatest and most influential physicists of all time. Einstein is best known for developing the theory ...
and much intellectual attention.


Gottfried Leibniz (1646–1716)

Leibniz was the last major figure of seventeenth-century rationalism who contributed heavily to other fields such as
metaphysics Metaphysics is the branch of philosophy that studies the fundamental nature of reality, the first principles of being, identity and change, space and time, causality, necessity, and possibility. It includes questions about the nature of conscio ...
,
epistemology Epistemology (; ), or the theory of knowledge, is the branch of philosophy concerned with knowledge. Epistemology is considered a major subfield of philosophy, along with other major subfields such as ethics, logic, and metaphysics. Epis ...
,
logic Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the science of deductively valid inferences or of logical truths. It is a formal science investigating how conclusions follow from premise ...
, mathematics,
physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...
,
jurisprudence Jurisprudence, or legal theory, is the theoretical study of the propriety of law. Scholars of jurisprudence seek to explain the nature of law in its most general form and they also seek to achieve a deeper understanding of legal reasoning a ...
, and the
philosophy of religion Philosophy of religion is "the philosophical examination of the central themes and concepts involved in religious traditions". Philosophical discussions on such topics date from ancient times, and appear in the earliest known texts concerning ph ...
; he is also considered to be one of the last "universal geniuses".Stanford Encyclopedia of Philosophy
Gottfried Wilhelm Leibniz
He did not develop his system, however, independently of these advances. Leibniz rejected Cartesian dualism and denied the existence of a material world. In Leibniz's view there are infinitely many simple substances, which he called " monads" (which he derived directly from Proclus). Leibniz developed his theory of monads in response to both Descartes and
Spinoza Baruch (de) Spinoza (born Bento de Espinosa; later as an author and a correspondent ''Benedictus de Spinoza'', anglicized to ''Benedict de Spinoza''; 24 November 1632 – 21 February 1677) was a Dutch philosopher of Portuguese-Jewish origin, ...
, because the rejection of their visions forced him to arrive at his own solution. Monads are the fundamental unit of reality, according to Leibniz, constituting both inanimate and animate objects. These units of reality represent the universe, though they are not subject to the laws of causality or space (which he called " well-founded phenomena"). Leibniz, therefore, introduced his principle of pre-established harmony to account for apparent causality in the world.


Immanuel Kant (1724–1804)

Kant is one of the central figures of modern philosophy, and set the terms by which all subsequent thinkers have had to grapple. He argued that human perception structures natural laws, and that reason is the source of morality. His thought continues to hold a major influence in contemporary thought, especially in fields such as metaphysics, epistemology, ethics, political philosophy, and aesthetics. Kant named his brand of epistemology " Transcendental Idealism", and he first laid out these views in his famous work '' The Critique of Pure Reason''. In it he argued that there were fundamental problems with both rationalist and empiricist dogma. To the rationalists he argued, broadly, that pure reason is flawed when it goes beyond its limits and claims to know those things that are necessarily beyond the realm of every possible experience: the
existence of God The existence of God (or more generally, the existence of deities) is a subject of debate in theology, philosophy of religion and popular culture. A wide variety of arguments for and against the existence of God or deities can be categorize ...
, free will, and the immortality of the human soul. Kant referred to these objects as "The Thing in Itself" and goes on to argue that their status as objects beyond all possible experience by definition means we cannot know them. To the empiricist, he argued that while it is correct that experience is fundamentally necessary for human knowledge, reason is necessary for processing that experience into coherent thought. He therefore concludes that both reason and experience are necessary for human knowledge. In the same way, Kant also argued that it was wrong to regard thought as mere analysis. "In Kant's views, a priori concepts do exist, but if they are to lead to the amplification of knowledge, they must be brought into relation with empirical data".


Contemporary rationalism

Rationalism has become a rarer label of philosophers today; rather many different kinds of specialised rationalisms are identified. For example, Robert Brandom has appropriated the terms "rationalist expressivism" and "rationalist pragmatism" as labels for aspects of his programme in ''Articulating Reasons'', and identified "linguistic rationalism", the claim that the contents of propositions "are essentially what can serve as both premises and conclusions of inferences", as a key thesis of Wilfred Sellars.''Articulating reasons'', 2000. Harvard University Press.


Criticism

Rationalism was criticized by American psychologist William James for being out of touch with reality. James also criticized rationalism for representing the universe as a closed system, which contrasts with his view that the universe is an open system.


See also


Notes


Citations


References


Primary sources

* René Descartes, Descartes, René (1637), ''
Discourse on the Method ''Discourse on the Method of Rightly Conducting One's Reason and of Seeking Truth in the Sciences'' (french: Discours de la Méthode Pour bien conduire sa raison, et chercher la vérité dans les sciences) is a philosophical and autobiographical ...
''. * Baruch Spinoza, Spinoza, Baruch (1677), ''Ethics (Spinoza), Ethics''. * Gottfried Leibniz, Leibniz, Gottfried (1714), ''
Monadology The ''Monadology'' (french: La Monadologie, 1714) is one of Gottfried Leibniz's best known works of his later philosophy. It is a short text which presents, in some 90 paragraphs, a metaphysics of simple substances, or '' monads''. Text Dur ...
''. * Immanuel Kant, Kant, Immanuel (1781/1787), ''Critique of Pure Reason''.


Secondary sources

* Robert Audi, Audi, Robert (ed., 1999), ''The Cambridge Dictionary of Philosophy'', Cambridge University Press, Cambridge, 1995. 2nd edition, 1999. * * Simon Blackburn, Blackburn, Simon (1996), ''The Oxford Dictionary of Philosophy'', Oxford University Press, Oxford, 1994. Paperback edition with new Chronology, 1996. * Vernon J. Bourke, Bourke, Vernon J. (1962), "Rationalism," p. 263 in Runes (1962). * Douglas, Alexander X.: ''Spinoza and Dutch Cartesianism: Philosophy and Theology''. (Oxford: Oxford University Press, 2015) * * Förster, Eckart; Melamed, Yitzhak Y. (eds.): ''Spinoza and German Idealism''. (Cambridge: Cambridge University Press, 2012) * Fraenkel, Carlos; Perinetti, Dario; Smith, Justin E. H. (eds.): ''The Rationalists: Between Tradition and Innovation''. (Dordrecht: Springer, 2011) * Hampshire, Stuart: ''Spinoza and Spinozism''. (Oxford: Clarendon Press; New York: Oxford University Press, 2005) * Huenemann, Charles; Gennaro, Rocco J. (eds.): ''New Essays on the Rationalists''. (New York: Oxford University Press, 1999) * Lacey, A.R. (1996), ''A Dictionary of Philosophy'', 1st edition, Routledge and Kegan Paul, 1976. 2nd edition, 1986. 3rd edition, Routledge, London, 1996. * Loeb, Louis E.: ''From Descartes to Hume: Continental Metaphysics and the Development of Modern Philosophy''. (Ithaca, New York: Cornell University Press, 1981) * Nyden-Bullock, Tammy: ''Spinoza's Radical Cartesian Mind''. (Continuum, 2007) * Pereboom, Derk (ed.): ''The Rationalists: Critical Essays on Descartes, Spinoza, and Leibniz''. (Lanham, MD: Rowman & Littlefield, 1999) * Phemister, Pauline: ''The Rationalists: Descartes, Spinoza and Leibniz''. (Malden, MA: Polity Press, 2006) * Dagobert D. Runes, Runes, Dagobert D. (ed., 1962), ''Dictionary of Philosophy'', Littlefield, Adams, and Company, Totowa, NJ. * Strazzoni, Andrea: ''Dutch Cartesianism and the Birth of Philosophy of Science: A Reappraisal of the Function of Philosophy from Regius to 's Gravesande, 1640–1750''. (Berlin: De Gruyter, 2018) * Verbeek, Theo: ''Descartes and the Dutch: Early Reactions to Cartesian Philosophy, 1637–1650''. (Carbondale: Southern Illinois University Press, 1992)


External links

* * * * * * John F. Hurst (1867),
History of Rationalism Embracing a Survey of the Present State of Protestant Theology
' {{Authority control Rationalism, Concepts in epistemology History of philosophy Internalism and externalism Justification (epistemology) Philosophical movements Philosophy of mind Reasoning Thought