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|First Name=ReneRené

|SummaryBrief=Rene Descartes (1596CE-1650CE) was a French mathematician and natural philosopher. In A History ; who is today considered one of Western Philosophy Bertrand Russell calls the most influential figures in modern philosophy|Summary=Descartes rejected the “founder of modern philosophy” Aristotelian-medieval mosaic accepted for his rejection most of the scholastic previous two thousand years, and laid the foundations of his predecessors<ref name="test">a new mechanistic mosaic.[[CiteRef::Russell (1945)|p. Descartes’ Discourse on 524]][[CiteRef::Newman (2014)]][[CiteRef::Garber (1993)]] Aristotelians had maintained that intuition schooled by experience was the Method (full title route to knowledge. Descartes, in his ''Discourse on the Method of Rightly Conducting One’s Reason and of Seeking Truth in the Sciences'' (''Discourse on Method''), first published in 1637, laid down the foundation for a break with the Aristotelian methodology that had pervaded through the better part of the previous two-thousand years . [[CiteRef::Descartes posited (2007)]] put forward a normative rationalist scientific methodology whereby in which a proposition is acceptable only if it can be clearly and distinctly perceived by the intellect beyond all reasonable doubt or follows deductively from such propositions. Descartes advanced [[CiteRef::Newman (2014)]] This allowed him to advance a mathematical, apriorist a priorist approach to scientific knowledge and inquiry.|Historical Context=Descartes’ work developed as a response to [[CiteRef::Garber (1992)]][[CiteRef::Clarke (1992)]] Rejecting the Aristotelian-Scholastic tradition that had come to form the centerpiece world of the contemporary mosaic forms, substances, and teleology, he posited a mechanical world in the early seventeenthwhich matter possessed only spatial extension and interacted only by contact. In mathematics he developed techniques that made possible analytic geometry. In natural philosophy, he was co-century. Descartes had been well educated in this tradition over framer of the course sine law of his education at La Fleche where he studied light refraction, developed a traditional Scholastic curriculum theory of logic, grammar, philosophy, mathematicsthe rainbow, and theology under Jesuit instructionformulated a precursor of the nebular hypothesis of the origin of the solar system. [[CiteRef::Hatfield (2016)]]|Historical Context=The [[Scientific Mosaic|scientific mosaic ]] of the late sixteenth and early seventeenth centuries was based primarily on the works of [[Aristotle ]] and some later Hellenistic natural philosophers, . This was reconciled in various ways with Christian theology by scholars in the high middle agesHigh Middle Ages. It This '''Aristotelian-scholastic mosaic''' included elements such as Christian theologyPtolemaic astronomy, astrology, humoral physiology, astrology, Ptolemean astronomy, and Christian (Catholic, in many but not all communities contemporaneous with Descartes) theology.[[CiteRef::Haldane (1905)]] Descartes was well educated in this tradition through his attendance at the prestigious Jesuit La Fleche College between the ages of ten and eighteen. He studied a traditional scholastic curriculum of logic, grammar, philosophy, mathematics, and theology. Natural philosophy was taught from the works of Aristotle as interpreted by Christian scholars. Descartes also received an education in mathematics that was unusual for the Aristotelian tradition, and excelled at math. [[CiteRef::Gaukroger (1995)|pp. 38-61]][[CiteRef::Rodis-Lewis (1992)]][[CiteRef::Garber (1992)]]

Notably, Descartes’ major writings are either contemporaneous with or shortly successive to periods came in a time of significant social and intellectual upheaval in Europe. Descartes Before writing his major works, he was a participant in the Thirty Years War before writing his major works and . He travelled extensively around Europe at a time when the continent was embroiled in both reformation and counter-reformation, both of which were both a wellspring of new thought in theology and philosophy. Philosophically, Descartes The community of the time was immediately preceded by Bacon, whose contributions to epistemology helped engaged with major challenges to weaken the foundations of the ScholasticAristotelian-Aristotelian mosaic scholastic tradition. ScientificallyThese came from varied sources, including varieties of Platonism, Hermeticism, a number and the chemical philosophy of Paracelsus, among other movements.[[CiteRef::Garber (1992)]] There were new advancements had been made developments in optics, astronomy, and physiology during or shortly prior to Descartes’ lifetime; he commented on .[[CiteRef::Cottingham (1992)]] Aristotle's earth-centered cosmology had been challenged by the trial of Galileo and was familiar with the works work of Nicolaus Copernicus and (1473-1543), Johannes Kepler(1571-1630), the latter of whose work was already celebrated at La Fleche College when Descartes was attending. Although Descartes was critical of Galileo’s methodology it is clear that he nevertheless had read and was familiar with his workGalileo Galilei(1564-1642), which Descartes was instrumental in weakening the various communities’ confidence in the salience of the Aristotelian mosaic . Also notable is that Descartes’ most prominent teacher was the Calvinist natural philosopher Isaac Beeckman, whose work directly conflicted familiar with the Aristotelian tradition by positing atomism and by rejecting plenism. These and other factors place Descartes in a historical context rife with revolutionary change and immense scholarly interest in the changing landscape of academic inquiry.[[CiteRef::Hatfield (2016)]][[CiteRef::Rodis-Lewis (1992)]][[CiteRef::Ariew (1986)]]

In terms of his methodology After leaving La Fleche, in 1618,Descartes was largely responding to what he perceived as the dogmatism and marked lack of progress he perceived became involved in a collaboration with the Scholastic tradition within which he was schooled at La Fleche. His motivations Dutch Calvinist natural philosopher Isaac Beeckman (1588-1687), who valued him for undertaking his investigations mathematical skills. They worked together on several mathematical problems in natural philosophy. [[CiteRef::Gaukroger (1995)|p. 68]] Beeckman was a supporter of the way he did are well documented in his writings '''mechanical natural philosophy'''. This was a [[Theory Pursuit|pursued]] radical alternative to Aristotelian cosmology, embraced by some supporters of Copernican heliocentrism.[[CiteRef::Luthy, Murdoch, and correspondencesNewman (2001b)]][[CiteRef::Chalmers (2014)]][[CiteRef::Gaukroger (1995)|p. He was unsatisfied with 69-73]] It rejected the education he received in college Aristotelian fundamentals of form, substance, and teleology, and frustrated with the conservatism of his instructorsidea that matter is continuous. In part one Instead of explaining the Discourse on properties of visible bodies in terms of form, it maintained that the Method he writes “there is nothing at stake for the scholar except perhaps world consisted of invisibly tiny particles of matter and that all the further his conclusions are from common sense the prouder he will be observable properties of visible bodies were a consequence of them because he will have had these particles and their interactions. The particles were held to use so much more skill interact mechanically, by contact, and ingenuity it was often supposed that this rendered natural phenomena potentially explainable in trying geometrical and mathematical terms. It can be traced to make them plausible!” His weariness with the largely dialectical scholastic method is what led him to develop the highly systematized epistemology Ancient Greek '''atomism''' of Democritus (circa 460-370 BCE) and metaphysics for which he would come to be knownlater Epicurean philosophers.|Major Contributions=Descartes Atomism was instrumental reintroduced into European thought in revolutionizing the mosaic of seventeenth-fifteenth century Europe by proposing a new methodology, new core scientific theories in physics and mathematics, and new understandings with the rediscovery of epistemology and metaphysics.===the Roman poet Lucretius's ''Cartesian MethodDe rerum natura'''===The most notable . Part of Descartes’ contributions was his introduction of a new method for pursuing knowledge its appeal lay in the science fact that unlike Aristotle's physics, the mechanical philosophy was distinct from the previously accepted method inherited from Aristotlecompatible with a moving planetary Earth. Descartes had become frustrated with In the previous method of the Scholastic European tradition and its dialectical approach to knowledgeearly seventeenth century, it was championed by Giordano Bruno (1548-1600), Nicolas Hill (1570-1610?), Sebastian Basso (1573-1625?), Francis Bacon (1561-seeking1626), which he charged with plunging him into sceptical doubts whereby he could never be sure what was true and what was notGalileo Galilei. He writes in Discourse on the Method[[CiteRef::Garber (1992)]][[CiteRef::Klein (2012)]][[CiteRef::Gatti (2001)]][[CiteRef::Luthy, Murdoch, and Newman (2001b)]]

“But no sooner had I completed Descartes and Beeckman worked together on several mathematical problems in natural philosophy. Beeckman is almost certainly the whole course first person in Europe to attempt to explain macro-geometrical regularities in terms of study that normally takes one straight into micro-mechanical models. [[CiteRef::Gaukroger (1995)|p. 70]] For the ranks most part, applying mathematics to physical problems was not part of the ‘learned’ than I completely changed my mind about what this education could do for meAristotelian tradition. Descartes adopted Beeckman's mathematical corpuscularism and became part of a community of corpuscularist thinkers which besides Beeckman and Descartes included Marin Mersenne (1588-1648), Thomas Hobbes (1588-1679), Pierre Gassendi (1592-1655), Sir Kenelm Digby (1603-1665), and Walter Charleston (1620-1707). For I found myself tangled in so many doubts They all knew each other and errors that I came reacted to think that my attempts to become educated had done me no good except to give me a steadily widening view each other's work.[[CiteRef::Osler (2001)]] The decade after Descartes met Beeckman was the most philosophically productive of my ignorance!” his life. [[CiteRef::Garber (1992)]]

In terms of his methodology Descartes concluded that if his goal was largely responding to attain certain knowledge about what he perceived as the world then dogmatism and marked lack of progress he saw in the presently accepted method was insufficient Scholastic tradition, and that a his excitement with the new one would be required to satisfy his aimsmechanical natural philosophy. Method was a central theme in Descartes’ writing and held a central place in Descartes’ epistemology; in fact, one of Descartes’ criticisms of Galileo was that he failed to produce a fully developed His weariness with the largely dialectical scholastic method is what led him to justify his discoveries. To that end he embraced his sceptical doubts develop the highly systematized epistemology and devised a method based on methodological scepticism; a method whereby he rejects all knowledge that he cannot be certain of, accepts only those propositions metaphysics for which he can accept as certain, and proceed deductively from those axioms according would come to reasonbe known. By this method The Aristotelian-scholastic mosaic continued to be [[Theory Acceptance|accepted]] throughout Descartes hoped to produce a kind 's life, with acceptance of systematized knowledge that could be universally acceptablehis views coming later. As it happened the sole indubitable proposition upon which he would build the entire rest |Major Contributions=Descartes new methodology and mechanical natural philosophy were of his philosophical system was his famous ‘Cogitorevolutionary importance. They became accepted at Cambridge University in England by 1680, Ergo Sum’ [[CiteRef::Barseghyan (also styled ‘Dubito, Ergo Cogito, Ergo Sum’ or simply as ‘the Cogito’2015); “I think, therefore I am|p.” From this foundation Descartes deduced his being a created thing, his requiring a creator211]] and in France by about 1700, displacing the Aristotelian-medieval system of theories that creator being God, the nature had been central elements of God, and the reliability of his senses [[Scientific Mosaic|scientific mosaic]] for centuries. These theories were ultimately fully displaced throughout Europe by Descartes' theories and reason, all of which would form by the broader foundation later theories of his systematized scientific worldview[[Isaac Newton]] (1642-1726).[[CiteRef::Barseghyan (2015)|p. 167]]

Although Descartes maintained some methodological aspects of ===Cartesian Methodology===Under the Scholastic-Aristotelian mosaic – namely the axiomatic-deductive, epistemic-foundationalist structure of investigation – one critical difference in Descartes’ scholastic [[Methodology|methodology was the shift in the method of theory choice. According to Barsegyen the accepted method of the Scholastic-Aristotelian method was that ]] a theory is acceptable “if it grasps the nature of a thing through intuition schooled by experience, or if it is deduced from general intuitive principlesprinciples”.” The keywords in [[CiteRef::Barseghyan (2015)|p. 144]] Descartes became frustrated with this formulation of the Scholastictradition and its dialectical approach to knowledge-Aristotelian method are intuition and experienceseeking, both of which are necessary conditions for one to he charged with plunging him into skeptical doubts whereby he could never be justified in accepting a proposition. Descartes’ methodology is notable in that it jettisons both of those conditions; a proposition need be neither experientially based nor intuited for it to be acceptable, and although his system as it ended up allowed for knowledge that sure what was both experiential true and intuited the ultimate justification for knowledge claims what was human reasonnot. In this way He writes in ''Discourse on Method'':[[CiteRef::Descartes is both a rationalist and an apriorist, in that his epistemology and metaphysics allows for the existence of synthetic a priori propositions.(2007)]]

==='''The Cartesian Revolution <blockquote>“But no sooner had I completed the whole course of study that normally takes one straight into the ranks of the ‘learned’ than I completely changed my mind about what this education could do for me. For I found myself tangled in Natural Philosophy'''===so many doubts and errors that I came to think that my attempts to become educated had done me no good except to give me a steadily widening view of my ignorance!”</blockquote>

Descartes played a pivotal role in concluded that if his goal was to attain certain knowledge about the transition away from world,the Scholastic-Aristotelian mosaicaccepted methodology for doing so must be rejected, and his physical, physiological, psychological, and biological theories are too numerous to be adequately treated herea new one formulated. That said, Methodology held a number of central place in his theories are worth exploring epistemology; in brieffact, in particular those that were fundamental departures from the accepted mosaic one of the early sixteenth century. The first and most dramatic of these is Descartes’ rejection criticisms of hylomorphism Galileo was that he failed to produce a fully developed methodology to justify his discoveries, and the form-matter distinction which would be the foundation for Descartes’ rejection of most of the prior physicshad simply explained particular physical phenomena. In place of the hylomorphic theory of substance Descartes proposed that there are in fact two kinds of substances that are entirely different from each other in composition and kind[[CiteRef:: mental substance Ariew (1986)]] Rather than experience and physical substance. intuition, Descartes equated the former with the rational soul of God and humans ' '''methodological skepticism''' was based on reason and on the latter with all physical matter, the fundamental feature of which he considered capacity to be extension. Descartes deduced his scientific theories about the natural world from this basically metaphysical foundation (all of which he deduces by application of his method). For example the central concept in Cartesian mechanics is that all material interactions are interactions between matter, which fills the universe (plenism also followed from Descartes’ position of matter as extension because if all matter is extended then there can be no space without extended matter, i.edoubt. The harder a vacuum). Descartes also considered the universe to be essentially mechanical in character except for mental substance – animals according to Descartes, as being constituted solely of material substance and without mental substance, are mere automata and cannot be said proposition was to think, feeldoubt, or love in the way that human beings or God cangreater its certainty. This was an epistemological innovation.

The details His strategy was, first, to reject all knowledge that he cannot be certain of, and accept only those propositions of which he is certain. He would deduce other knowledge from such axioms using reason. By this method Descartes hoped to produce a kind of systematized knowledge that could be universally accepted. In his ''Meditations on First Philosophy'', [[CiteRef::Descartes (2004)]] Descartes identified the Cartesian school sole indubitable proposition upon which he would build his entire philosophical system: he was certain of natural philosophy are not his own existence as important however a thinking being, or in Latin, '''''‘Cogito, Ergo Sum’''''' (also styled ''‘Dubito, Ergo Cogito, Ergo Sum’'' or simply as ''‘the Cogito’''); “I think, therefore I am.” From the impact foundation of his own existence, Descartes deduced that he must be a created being, that this requires a creator, that creator being God, the benevolent nature of God, and the consequent reliability of his senses and of the school would have on subsequent God-given ability of his reason to form clear and distinct ideas. It was therefore possible to use his senses and reason to gain knowledge of an external world. This reasoning formed the foundation of his systematized scientific inquiryworldview. The overthrow [[CiteRef::Newman (2014)]] Descartes maintained some aspects of the Scholastic-Aristotelian traditionmethodology – namely an axiomatic-deductive, even epistemic-foundationalist structure of investigation. But the critical difference in places where Cartesianism his methodology was the shift in the method of theory choice. He jettisoned the Aristotelian expectation that a theory must be experientially based and intuitively obvious for it to be acceptable, and although his system, as it ended up, allowed for knowledge that was rejected both experiential and the community maintained Aristotelianismintuited, forced [[CiteRef::Newman (2014)]] the academic community in Europe to reconsider ultimate justification for knowledge claims was human reason and defend the Aristotelian mosaic absence of doubt. Descartes was both a '''rationalist''' and an '''a priorist''', in ways that his epistemology and metaphysics allows for the existence of synthetic a priori propositions. Although an argument for God's existence was at the foundation of his system, Descartes' rationalism was nonetheless a formidable challenge to the accepted theological methodology which had never before been encounteredcomprehensively expressed by the Catholic saint, Thomas Aquinas (1225-1274) more than three hundred years earlier. Though Aquinas saw human reason as limited, and always to be exercised in the dialectical approach context of, and subject to scholarship throughout the medieval period saw scholars constantly questioning various aspects authority of , the Aristotelian worldview Descartes’ wholesale rejection divine revelation of huge swaths the Bible. Descartes, by contrast, sought to develop his epistemology and theology on the basis of human reason alone. [[CiteRef:: Hyman (2007)]] ===Cartesian Natural Philosophy===Descartes scientific theories about the mosaic and its central concepts natural world were unprecedentedgrounded in a metaphysical foundation, in turn deduced by the application of his rationalist methodology. Theories He wrote that "the whole of philosophy is like hylomorphisma tree. The roots are metaphysics, the trunk is physics, and the branches emerging from the trunk are all the other sciences, which had been may be reduced to three principle ones, namely medicine, mechanics, and morals".[[CiteRef::Clarke (1992)|p. 271]] One ought to construct a given metaphysics first, based on criteria independent of observation, and subsequently consider physical theories consistent with the metaphysical foundation. His natural philosophy was in stark contrast to the mosaic accepted Aristotelianism. In Aristotelian natural philosophy all objects were a compound of form and matter, a concept called hylomorphism. Form gives material bodies their distinctive properties, and makes them different from one another. It explains why fire rises and stones fall. Matter is what all material bodies share in common. All things have teleological goals or purposes. [[CiteRef::Shields (2016)]]  In Descartes' mechanical corpuscular natural philosophy, by contrast, there are just two kinds of substance that are entirely different from each other in kind: mental substance and physical substance. The fundamental property of '''mental substance''' was thought, and Descartes equated it with the sixteenth rational soul of God and early seventeenth centuries humans. The fundamental feature of '''physical substance''' was extension in space. He rejected Aristotle's distinction between form and had endured through multitudes matter, including Aristotle's four elements. [[CiteRef::Ariew (1992)]] Cartesian mechanics rejects the void posited by atomists; instead matter fills the universe as a plenum. If all matter is extended, Descartes reasoned that there can be no space without extended matter. Also unlike atomism, matter is infinitely divisible, though visible things are composed of tiny corpuscles that interact with one another by physical contact. The corpuscular composition of adjustmentsa material body, reconciliations rather than its Aristotelian form, determines its properties. Since corpuscles are too small to be directly observed, their size and dialectic criticism had never before faced complete overhaul shape must be hypothesized, though observation can allow us to infer the plausibility of our guesswork. Our senses, Descartes maintained, do not inform us of the mechanical world as Descartes threatenedit is, but provide us with sensations which are mere signs of their objective causes. Only extended matter and motion exist apart from our minds. Although [[CiteRef::Clarke (1992)]] Descartes would eventually completed a manuscript that was to be supplanted by Newton he made a comprehensive expression of his mechanical natural philosophy, called ''The World''. He withdrew his plans to publish it upon learning of the condemnation of Galileo in Rome in 1633. The work never appeared during his lifetime, but two major fragments, the ''Treatise on Light'', and the critical ''Treatise on Man'' were published posthumously. The first steps to replacing dealt with physics, and the second put forward a theory of physiology, nervous system function, and the Scholastic-Aristotelian mosaicmind/brain relationship.[[CiteRef::Garber (1992)]][[CiteRef::Descartes (2003)]] |Criticism=Descartes’ ideas saw widespread criticism In Descartes cosmology, the universe is essentially mechanical in his time character. Copernican heliocentrism is accepted, and shortly after from all manner planetary motion is explained in terms of a swirling '''vortex''' of material particles around the central sun. Earth, as a moving planet, is the center of its own smaller vortex. The particles of sourcesthe vortex push larger bodies towards its center and this explains gravity without supposing, including Scholastic vanguardsas did Aristotle, religious authoritiesthat the sphere of earth was at rest in its natural place; the center of the universe. It also made it reasonable to suppose that other planets had their own attractive vorticies, and were thus other philosophersworlds. [[CiteRef::Garber (1992)]]  Descartes also challenged Aristotelian physiology. By 2016 almost all Aristotle's theory of physiology posited three souls or vital principles; the nutritive soul, responsible for nutrition and reproduction, comprised the entirety of Descartes’ ideas have been consigned the soul in plants. The sensitive soul, responsible for perception, locomotion, imagination, and desire, was added to the graveyard sensitive soul in animals. A third component, the intellectual soul, was found uniquely in human beings. [[CiteRef::Shields (2016b)]][[CiteRef::Van der Eijk (2000)]] Descartes rejected the nutritive and sensitive souls, supposing their functions were instead performed by corpuscular mechanisms, the nature of which he outlined in his ''Treatise on Man''. [[CiteRef::Descartes (2007)]] Descartes' mental substance served roughly the same role as Aristotle's intellectual soul. Animals, according to Descartes, are complex automata composed of ideasphysical substance only and cannot be said to think in the way that human beings or God can; these properties being made possible by mental substance. [[CiteRef::Des Chene (2001)]][[CiteRef::Clarke (1992)]][[CiteRef::Descartes (2007)]] Descartes posited a mental substance for theological, metaphysical, and scientific reasons. He supposed that thought could not be mechanized, since all the machines known to him were specialized to perform one particular function, but it human reason was a general purpose instrument.[[CiteRef::Hatfield (1992)]][[CiteRef::Cottingham (1992)]] Descartes mechanical natural philosophy fostered a radical change in how natural philosophers gained new knowledge. The Aristotelian-medieval methodology accorded a very limited role for experiments in scientific investigation. This is worth noting some criticisms Descartes faced because a strict distinction was made between natural and artificial things. Every natural thing behaved in his lifetime or shortly thereafter accordance with its nature; acorns grow on oak trees, because that is what their nature dictates. Artificial things have an external source of change. The cogs and springs of a clock are constructed so that they no longer behave according to their respective natures (which is simply to fall towards their natural place at the center of the universe, rather than function as parts of a machine that tells time for humans). A thing cannot reveal its true nature under the artificial conditions of experimentation, because the experimental set up necessarily puts things under artificial conditions. To gain knowledge, things must be observed in their natural undisturbed state. Descartes' mechanical natural philosophy rejected the natural/artificial distinction along with its rejection of forms and teleology. Matter always obeyed the same set of mechanical laws regardless of its situation. Thus,under the mechanical natural philosophy experimentation was often a good source of historical interestknowledge about nature, and its adherents often became practitioners.[[CiteRef::Barseghyan (2015)|p.181-182]]

The most notable objection challenge to the Aristotelian tradition, even in places where Cartesianism was rejected and the community maintained Aristotelianism, forced the academic community in Europe to reconsider and defend the Aristotelian mosaic in ways that had never before been encountered. Though the dialectical approach to scholarship throughout the medieval period saw scholars constantly questioning various aspects of the Aristotelian worldview, Descartes’ wholesale rejection of huge swaths of the mosaic and its central concepts were unprecedented. Theories like hylomorphism (that being is a compound of matter and form), which had been a given in the mosaic of the sixteenth and early seventeenth centuries, and had endured through multitudes of adjustments, reconciliations, and dialectic criticism, but had never before faced complete overhaul that Descartes's mechanical natural philosophy threatened. Although Descartes ' theories would end up facing would eventually be supplanted by those of Newton, he made the critical first steps to replacing the Aristotelian-scholastic mosaic.[[CiteRef::Hatfield (2016)]]|Criticism=Descartes’ ideas saw widespread criticism in his time and shortly after from all manner of sources, including Scholastic vanguards, religious authorities, and other philosophers. One common early criticism was that his new views were threatening to the Catholic and Christian faith.[[CiteRef::Jolley (1992)]] In 1663, his works were placed on the Catholic Church's ''Index of Forbidden books'', and in 1671 his conception was officially banned from schools in the Catholic world. In the early modern period, theological propositions and natural philosophical propositions were not seen as belonging to separate domains, but rather formed parts of an integrated [[Scientific Mosaic|scientific mosaic]]. Aristotelian natural philosophy had been carefully adapted to render it consistent with Catholic faith. Descartes' novel natural philosophy introduced many inconsistencies that needed to be [[The Zeroth Law|reconciled]] before his theories could be [[Theory Acceptance|accepted]]. [[CiteRef::Barseghyan (2015)|p. 190-196]] One specific theological criticism of Cartesian natural philosophy had to do with the Catholic sacrament of the holy Eucharist, in which bread and wine are said to be transformed into the body and blood of Christ. The dogma of the ''Real Presence'' maintained that in this sacrament, Christ is really (as opposed to metaphorically or symbolically) present in the bread and wine. Thomas Aquinas had posited an Aristotelian explanation for the ''Real Presence'' which had become the accepted Catholic ''doctrine of transubstantiation''. The doctrine held that in the Eucharist, the Aristotelian substance of the bread and wine were replaced by the body and blood of Christ, while their forms (that of bread and wine) remaining unchanged. In Descartes' corpuscularism, bread and wine differed from flesh and blood because they had a different arrangement of corpuscles. There is no obvious way that one could appear as the other. The Anglican church, the state church of England following its break with the Catholic papacy in the 1530's did not accept the ''doctrine of transubstantiation''. Thus Cartesianism did not face objections based on it, and became accepted at Cambridge University by 1680. Catholic Paris didn't accept it until 1700. Many solutions reconciling Cartesianism and the more mathematically precise ''Real Presence'' had, by then, been proposed. Barseghyan speculates that the one accepted by the Parisian community was that proposed by Antoine Arnauld (1612-1694) in 1671, in which Christ's presence in the Eucharist was due to a miracle beyond human comprehension, and outside the ordinary course of nature described by Cartesianism.[[CiteRef::Barseghyan (2015)|p. 194]] Critics in Decartes' era were also concerned that corpuscular explanation involved hypothetical unobservable entities, and the supposition that this invisibly small world could be understood by analogy with larger objects. Descartes countered that "there is nothing more explanatorily powerful physical theory given in keeping with reason that we judge about those things that we do not perceive, because of their small size, by Newton half comparison and contrast with those that we see" [[CiteRef::Clarke (1992)|p. 267]] He felt that a century laterplausible model, though potentially incorrect due to the unobservability of its fundamental parts, but there existed objection was better than none at all. The role of unobservably small entities in the physical sciences was to Descartes even earlierremain a matter of prolonged debate. In modern science, it is an accepted and central practice. One particularly  Another notable objection came from Princess Elizabeth of Bohemia(1618-1680), who questioned Descartes’ theory of substance in a letter dated the tenth of May, 1643. In it, she asks “Given that the soul of a human being is only a thinking substance, how can it affect the bodily spirits, in order to bring about voluntary actions?” [[CiteRef::Descartes (2009)]] Descartes would never gives a satisfactory answer to this central question over the course of the correspondence. In 1747, in his ''L'Homme machine''(''Machine Man'') Julien Offray de La Mettrie (1709-1751) raised another simple, but devastating objection to Descartes' supposition that human reason must be due to an immaterial mental substance. He noted that reason can become impaired by material causes such as drunkenness and fever. [[CiteRef::De La Mettrie (1996)]]. In the single example highlights how troubling nineteenth century, Princess Elizabeth's objection became far more poignant with the formulation of the law of the conservation of energy, which implied causal closure of the issues left open physical world to influence by Descartes’ system are for a mental substance. In the early twentieth century, the integrity mathematician Alan Turing (1912-1954) showed that it was possible to construct a general purpose machine capable of performing any possible mathematical computation, thereby demonstrating that systema general purpose machine was possible and refuting Descartes' core argument against a mechanical understanding of human reason. Elizabeth’s objection raises reasonable (significantBy the end of the twentieth century, even) doubts about whether or not the theory relevant scientific communities of neuroscience and cognitive science had rejected the idea of a mental substance around which Descartes bases and sought a significant portion of his scientific theories can hold watermechanistic physical explanation for the mind [[CiteRef::Bechtel (2008)]], though there was still no agreement as to whether consciousness could be explained in this fashion. [[CiteRef::Chalmers (1996)]]

One Descartes' physical natural philosophy did not fare nearly so well. Within fifty years, Isaac Newton (1642-1726) formulated a more mathematically precise and explanatorily powerful physical theory, which became the accepted theory of the most powerful objections to arise after Descartes’ death in 1650 came physical world. It rejected a generation later with the emergence major tenet of the philosophy Descartes' corpuscularism by positing a gravitational force that acted at a distance. Newton's laws of John Locke motion, however, bore important similarities to those formulated earlier by Descartes. [[CiteRef::Clarke (1992)]] As practicing scientists, researchers like Newton and the British Empiricists. LockeRobert Boyle (1627-1691) did not, despite being an admirer of as did Descartes, was highly critical seek certain knowledge of his methodology and in particular was critical the real essences of his methodological scepticismmaterial objects. Instead, they sought an ordering of phenomenal experience which Locke regarded as a non-starterwould enable them to predict nature's course with the best available theory. [[CiteRef::Osler (1970)]]

Other objections were political, theologicalDescartes' method itself was criticized by two sympathetic figures; Antoine Arnauld and Marin Mersenne. Their criticism had to do with Descartes demonstration of the existence of God, which is the linchpin of his method. Descartes claimed that our belief in the reliability of the clear and personal objections brought by various interest groups who had some stake distinct perceptions of the human intellect depends on our knowledge of the existence of God as the source of that capacity. But how could that knowledge be established in the academic status quofirst place? If we answer that we can prove God's existence from premises we clearly and distinctly perceive, then the argument collapses into circularity. In many places Descartes’ work Descartes' argument that it is possible for us to have certain scientific knowledge of the world fails with it, since it depends on God to underwrite the reliability of our senses and intellect. This criticism, called the '''Cartesian Circle''', was bannednever successfully countered. Within a generation, Descartes quest for certainty in more even discussion scientific knowledge was widely recognized to have failed. [[CiteRef::Cottingham (1992)]] In 1650, [[John Locke]] and the British Empiricists brought forth a new conception of Descartes’ work scientific knowledge that was bannedmore modest than Descartes' failed quest for certainty. Official condemnations came down from Universities and Church authoritiesThe empiricists argued for experience, rather than a priori reason, none of which were effective at stopping as the spread basis for human knowledge, and sought a philosophy of science more in keeping with scientific practice. [[CiteRef::Uzgalis (2016)]][[CiteRef::Osler (1970)]]|Related Topics=Method, Methodology,|Page Status=Editor Approved}}{{YouTube Video|VideoID=yFH7i3Lx7IA|VideoDescription=Hakob Barseghyan's lecture on Cartesian ideas.Worldview|VideoEmbedSection=Major Contributions