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===Cartesian MethodMethodology===

Descartes concluded that if his goal was to attain certain knowledge about the world,the accepted method methodology must be rejected and a new one would be required. Method Methodology held a central place in his epistemology; in fact, one of Descartes’ criticisms of Galileo was that he failed to produce a fully developed method methodology to justify his discoveries, and had simply explained particular physical phenomena.[[CiteRef::Ariew (1986)]] To that end he embraced his skeptical doubts and devised a method methodology based on '''methodological skepticism'''; a method methodology whereby he rejects all knowledge that he cannot be certain of, accepts only those propositions which he can accept as certain, and proceed deductively from those axioms according to reason. By this method Descartes hoped to produce a kind of systematized knowledge that, he believed, could be universally acceptable. In his 'Meditations on First Philosophy', [[CiteRef::Descartes (2004)]] Descartes identified the sole indubitable proposition upon which he would build the entire rest of his philosophical system as his famous '''‘Cogito, Ergo Sum’''' (also styled ‘Dubito, Ergo Cogito, Ergo Sum’ or simply as ‘the Cogito’); “I think, therefore I am.” From this foundation Descartes deduced that he was a created thing, his requiring a creator, that creator being God, the benevolent nature of God, and the consequent reliability of his God-given senses and reason, all of which formed the broader foundation of his systematized scientific worldview.[[CiteRef::Newman (2014)]]

Descartes deduced his scientific theories about the natural world from a metaphysical foundation, in turn deduced by the application of his rationalist methodmethodology. He wrote that "the whole of philosophy is like a tree. The roots are metaphysics, the trunk is physics, and the branches emerging from the trunk are all the other sciences, which may be reduced to three principle ones, namely medicine, mechanics, and morals".[[CiteRef::Clarke (1992)|p. 271]] One ought to construct a 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 accepted Aristotelianism, which emphasizes experience and intuition are as routes to knowledge, rather than reason. 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 cosmology, the universe is essentially mechanical in character. Copernican heliocentrism is accepted, and planetary motion is explained in terms of a swirling '''vortex''' of material particles. Earth, as a moving planet, is the center of its own smaller vortex. This explains gravity without supposing, as did Aristotle, that 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 worlds. [[CiteRef::Garber (1992)]] Animals, according to Descartes, are complex automata composed of physical substance only and cannot be said to think, feel, or love in the way that human beings or God can; these properties being made possible by mental substance [[CiteRef::Clarke (1992)]][[CiteRef::Descartes (2007)]]. All 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 Descartes him were specialized to perform just one particular function, but human reason was a general purpose instrument. Thus, Descartes supposed, thought could not be mechanized. [[CiteRef::Hatfield (1992)]][[CiteRef::Cottingham (1992)]]

Descartes maintained that our senses do not inform us of the mechanical world as it is, but provide us with sensations which are mere signs of their objective cause. Only extended matter and motion exist apart from our minds. Secondary qualities, such as colors, are created in our minds in response to mechanical stimuli. [[CiteRef::Clarke (1992)]] Descartes completed a manuscript that was to be 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 ''Treatise on Man'' where were published posthumously. The first dealt with physics, and the second put forward a theory of physiology, nervous system function, and the mind/brain relationship. [[CiteRef::Garber (1992)]][[CiteRef::Descartes (2003)]]

|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 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 early modern period, theological propositions and natural philosophical propositions both formed part of the same scientific mosaic, and thus [[The First Law|one needed reconciliation with the other]]. [[CiteRef::Barseghyan (2015)|p. 190-196]] One specific theological criticism of Descartes was that his mechanistic corpuscular natural philosophy could not be easily reconciled with the Catholic ''doctrine of transubstantiation''. This doctrine had been proposed by Thomas Aquinas as an Aristotelian explanation for the Christian dogma of the ''Real Presence''. The dogma maintained that in the sacrament of the Eucharist, Christ is really (as opposed to metaphorically or symbolically) present in the bread and wine. Aquinas had posited that the Aristotelian substance of the bread and wine were replaced with 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. Anglican Christians did not accept the ''doctrine of transubstantiation'' and thus Cartesianism became accepted at Cambridge University by 1680. Catholic Paris didn't accept it until 1700. Many solutions reconciling Cartesianism and the ''Real Presence'' were proposed. Barseghyan speculates that the one accepted by the Parisian community was that proposed by Antoine Arnauld in 1671, in which Christ's presence in the Eucharist was due to a miracle beyond human comprehension.[[CiteRef::Barseghyan (2015)|p. 194]]Another sort of objection raised in commentaries on Descartes had to do with the fact 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 in keeping with reason that we judge about those things that we do not perceive, because of their small size, by comparison and contrast with those that we see" [[CiteRef::Clarke (1992)|p. 267]]

The most notable Another sort of objection raised in commentaries on Descartes would end up facing would be had to do with the more mathematically precise fact 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, but there existed objection though potentially incorrect due to Descartes even earlierthe unobservability of its fundamental parts, was better than none at all.  One particularly 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::La Mettrie (1996)]]. In the nineteenth century, Princess Elizabeth's objection became far more poignant with the formulation of the single example highlights how troubling 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 of the most Descartes' physical natural philosophy did not fare nearly so well. Within fifty years, Issac Newton (1642-1726) formulated a more mathematically precise and explanatorily powerful objections to arise after Descartes’ death in 1650 came a generation later with physical theory, which became the emergence accepted theory of the philosophy physical world. It rejected a major tenet of John Locke and the British EmpiricistsDescartes' corpuscularism by positing a gravitational force that acted at a distance. Locke, despite being an admirer Newton's laws of Descartesmotion, was highly critical of his methodology and in particular was critical of his methodological skepticismhowever, which Locke regarded as a non-starterbore important similarities to those formulated earlier by Descartes.[[CiteRef::Uzgalis Clarke (20161992)]]

Other One of the most powerful objections were politicalto arise after Descartes’ death in 1650 came a generation later with the emergence of the philosophy of John Locke and the British Empiricists. The empiricists argued for experience, theologicalrather than a priori reason, and personal objections brought by various interest groups who had some stake in as the academic status quobasis for human knowledge. In many places Descartes’ work was bannedLocke, in more even discussion despite being an admirer of Descartes’ work Descartes, was banned. Official condemnations came down from universities highly critical of his methodology and Church authoritiesin particular was critical of his methodological skepticism, none of which were effective at stopping the spread of Cartesian ideasLocke regarded as a non-starter.[[CiteRef::Jolley Uzgalis (19922016)]]