I'm not sure I can provide a full account of Descartes' philosophy, but perhaps I can get the ball rolling.
Rene Descartes was an 18th Century French philosopher, who is best known for his Essay, Meditations on First Philosophy, in which he essentially laid out the problem of the justification of knowledge. Tradtionally, until the comparatively recent (and dubious) work of Edmund Gettier, knowledge has been loosely defined as justified, true belief. This means that in order for something to count as genuine knowledge, it must meet at least 3 conditions: 1) it must be a belief (I cannot know that the earth is round unless I believe it). 2) it must be true (I cannot have knowledge that the Earth is flat, because it is in fact round). 3) the belief must be justified (I need to have a sufficiently good reason for my belief that the Earth is round in order for it to count as knowledge).
Modern Cartesian Epistemology has been primarily dedicated to trying to provide justification for belief. Descartes founded a doctrine called Skepticism, the idea that our beliefs have no sufficient justification. None. We have no genuine knowledge that anything exists outside our minds.
In his first Meditation, Descartes argues that the only tools we have to provide evidence that there is an external world are our 5 senses. He then states that our senses can and sometimes do deceive us, and it is not prudent to fully trust anything that has deceived us even once. Thus, he concludes that our senses are not to be trusted, and that we can therefore not prove that there is a world outside our minds.
Descartes offers several scenarios which are possible and which, in virtue of their own nature, cannot be disproved. For instance, you could be dreaming right now, and it could be the case that you have been dreaming your entire life. Sometimes dreams seem just as real as reality, and there is no way to deductively prove that you aren't dreaming at this very moment. Another possibility is the "evil demon" scenario, in which an evil demon has tricked you into believing everything you believe, including your belief that you exist in a world full of people with whom you can communicate. These skeptical scenarios cannot be disproved by means of using our senses, lest they beg the question. Thus, Descartes sets out to provide an internalist foundationalist account of justification. Namely, he tries to prove the existence of the world, as well as validate his knowledge using only pure reason and knowledge gained through what he cryptically calls "clear and distinct perception."
In subsequent Meditations, Descartes argues for his own existence (I think, therefore I am), then on the basis that he exists, he proves the existence of God, and finally, arguing that God exists and isn't a deceiver, and thus would not lie to us about reality, he thinks he proves that our knowledge is justified, and the world around us is a real one.
To sum up, Descartes founded Skepticism, and went on to try to disprove it. He seems to have failed in this second objective, and Cartesian epistemology is the branch of philosophy surrounding this alleged problem.
As I said above, not nearly a full acount of Descartes' philosophy, but enough to get you started.
His famous phrase: "I think therefore I am."
father of philosophy -SOCRATES father of modern philosophy - RENE DESCARTES
Rene Descartes is regarded as the father of Western philosophy. His writings influence most of the subsequent writings in Western philosophy.
Descartes is considered to be the father of modern philosophy.
Rene Descartes invented the famous Cartesian coordinate system.He worked in the field of analytic geometry.
Philosophy
Rene desscartes was the father of mathematics.
He is the "Father of Modern Philosophy".
Rene Descartes
Meditations on First Philosophy
René Descartes was a French philosopher, mathematician, and writer who spent most of his adult life in the Dutch Republic. He has been dubbed the 'Father of Modern Philosophy', and much subsequent Western philosophy is a response to his writings, which are studied closely to this day. In particular, his Meditations on First Philosophy continues to be a standard text at most university philosophy departments. Descartes' influence in mathematics is equally apparent; the Cartesian coordinate system - allowing algebraic equations to be expressed as geometric shapes, in a 2D coordinate system - was named after him. He is credited as the father of analytical geometry, the bridge between algebra and geometry, crucial to the discovery of infinitesimal calculus and analysis. Descartes was also one of the key figures in the Scientific Revolution.
René Descartes is considered the "Father of Modern Philosophy."
Rene Descartes was a Philosopher.philosopher (a person whose primary area of research and study is philosophy)