Descartes’ Skepticism: A Journey from Doubt to Existence

René Descartes is one of the greatest minds in human history, and one of his greatest contributions is the methodological skepticism established in his essay ‘Discourse of the Method’.

Nov 15, 2022By Igor Zanetti, Student of Philosophy

rene descartes skepticism doubt to existence


As rational beings, some of the most inherent questions that lie within our minds are concerning existence, be it our own or the existence of other beings and, going even further, the world itself. What is existence? Why do we exist? How can we know that we exist? It’s likely that most human beings have posed these questions at one point or another, even before the birth of Philosophy. Many religions have had their own answers to these questions for as long as human civilizations have existed, but ever since the first Greek philosophers took it upon themselves to come up with rational explanations for such matters, the area of knowledge known as Ontology was born.


While Metaphysics is the major branch of Philosophy that studies the nature of reality and all of its principles and rules, Ontology is the branch of Metaphysics that deals specifically with the concepts of being, becoming, existence and reality, and was deemed the “First Philosophy” by Aristotle. For the purposes of this article, we will be focusing on the concept of existence and how it was approached by Modern Philosophy and, in particular, by René Descartes.


The Origins of Descartes’ Skepticism: Ontology and the Definition of Existence

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Allegorical Figure Representing Metaphysics by Giovanni Battista Tiepolo,1760, via the Met Museum.


But what is existence? We can use the simple definition that existence is the property of a being to be able to interact with reality. Whenever something interacts with reality in any form, it exists. Reality, on the other hand, is the concept used for the things that exist prior and independently to any interaction or experience. As an example, dragons exist because they interact with reality as an idea or imaginary concept, they exist as a concept, however they are not real because they do not exist independently of that concept that lies within our imagination. That same thought process can be applied to any sort of fictional creature and many other things that exist solely on the imaginary sphere.


It was in the Modern period that Ontology consolidated itself as a separate area of knowledge inside Philosophy, with the many philosophical systems that each had their own approach to existence, being and reality, most notably those crafted by Immanuel Kant, Baruch Spinoza, Arthur Schopenhauer, and, the subject of this article, René Descartes, regarded by many as being the philosopher that made the bridge between Medieval Philosophy and Modern Philosophy.

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Ontology and Modern Philosophy

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The Alchemist by Pieter Bruegel the Elder, after 1558, via the Met Museum.


When we talk about the Modern period in Philosophy, we are talking about the 17th and 18th centuries in Europe, in which some of the most well known philosophers of all history released their works. The Medieval period, also known by many as the Dark Ages, established a very strong connection between Philosophy and the Christian religion and was very prolific in that, as that said connection was still very strong in the Modern period.


With the rapid increase in scientific developments over the 17th century, philosophers had the challenge to reconcile the philosophical tradition, now carrying the principles of Christian religion along with it, with the new scientific world view that was becoming ever so stronger by the day, especially after the works of Galileo. That means that they had to answer a very clear and constant question of how the Christian principles and the new scientific discoveries could coexist.


The newly established scientific world view brought forth a mechanistic understanding of natural laws and the advanced mathematical methods of proving its theories, posing a direct threat to the religious views in Metaphysics and Ontology concerning the universe, God and mankind. The concepts of being, existence and reality had to be approached in a new light. Perhaps that challenge was the very thing that propelled the genius minds of the period to go so far beyond with their Philosophy, developing some of the most important contributions to the philosophical tradition in all history.


René Descartes and Methodological Skepticism

Portrait René Descartes Frans Hal
Portrait of René Descartes by Frans Hals, ca. 1649-1700, via Wikimedia Commons.


When we talk about Modern Philosophy, it is inevitable to talk about Descartes. René Descartes was a French philosopher born in 1596, and he is credited by many as “the father of Modern Philosophy”, “the last Medieval philosopher” and “the first Modern philosopher”, and all of those claims make sense. It is very noticeable in his writings that he does make a bridge between the Medieval way of thinking and the Modern way of thinking, mainly through the introduction of advanced mathematics into a philosophical system that still holds the Christian religion in a very high regard, paving the way for future philosophers such as Leibniz and Spinoza.


Descartes made important contributions not only to Philosophy but to many areas of knowledge, being a brilliant scientist and mathematician, with notably relevant works in theology, epistemology, algebra and geometry (establishing what is now known as analytic geometry). Being heavily inspired by the philosophy of Aristotle and by the schools of Stoicism and Skepticism, Descartes developed a philosophical system centered around the concept of Methodological Skepticism, which resulted in the birth of Modern Rationalism.


The Methodological Skepticism of Descartes is, in fact, a very simple concept: any genuine knowledge can only be obtained through absolutely truthful claims. In order to achieve such knowledge, Descartes proposed a method which consists in doubting everything that can be doubted, to get rid of uncertain beliefs and establish a fundamental set of principles that we can know as true without any doubt.


Descartes’ Discourse on the Method

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Title page of the first edition of René Descartes’ Discourse on Method, via Wikimedia Commons.


The Discourse on the Method of Rightly Conducting One’s Reason and of Seeking Truth in the Sciences, or simply Discourse on the Method for short, is one of the fundamental works of Descartes and one of the most influential philosophical writings in all history, along with his other famous writing Meditations on First Philosophy.


It is in the Discourse on the Method that Descartes first addresses the subject of skepticism, which was a very prominent philosophical approach during the hellenistic period. Therefore, it is important for us to understand what skepticism means in Philosophy before anything else.


Skepticism is an ancient school of thought that we can trace the roots of all the way back to the Eleatic philosophers in Ancient Greece and even find many similarities between the Skeptics and Socrates. The Skepticism Philosophy is based around the core concept of questioning and challenging the reliability of any claim and assumption. Skeptics believe that most, if not all, premises are not reliable because every premise is based on another set of premises, and so on and so forth. Following that line of thought, the skeptics have a very firm doubt in any sort of knowledge that goes beyond our empirical and direct experiences.


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Caravaggio’s The Incredulity of Saint Thomas, 1601-2, via the Web Gallery of Art.


If we understand Skepticism, it is very easy to observe the similarities between the skeptics and what we have mentioned before about the Philosophy of René Descartes and his Methodological Skepticism. However, while the skeptics tend towards empiricism with their belief in the reliability of direct physical experiences, Descartes was a rationalist, and decided to take the core concept of Skepticism even further beyond in the Discourse on the Method, challenging the reliability of the empirical experiences that most skeptics had so much faith on up until that point.


The perspective that Descartes had when crafting his philosophical system was that he wanted to create something from scratch, rather than using the foundations that were laid by previous philosophers. That means that Descartes had the task to create his own foundations and establish principles from which his philosophical system would be built upon. That would be the very essence of the Cartesian method: to take Skepticism to a new level that goes far beyond the belief in empirical experiences, doubting everything in order to establish absolute truths and completely reliable principles that would be the foundation to his Philosophy.


Hyperbolic Doubt

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Senses, Appearance, Essence and Existence by Eleonor Art, via the artist’s Behance.


Hyperbolic Doubt, sometimes also called Cartesian Doubt, is the method used by Descartes in order to establish reliable principles and truths. It means that we have to always push the doubt further, which is why it’s dubbed as “hyperbolic”, for only then, after doubting everything in every manner, will we be able to recognize truths that cannot be doubted.


This approach is very methodical indeed, as Descartes gradually expands the limits of doubt in a very intuitive and almost playful manner. The first step is something we have already discussed before: to doubt all premises, just like the skeptics did, for all premises are based on other premises and therefore we cannot ascertain their truthfulness.


We then move on to the second step, in which we must doubt our own senses, for our senses are not completely reliable. All of us have been tricked by our senses at one point or another, be it by seeing something that wasn’t there or hearing someone speak and understanding something completely different to what was spoken. That means that we cannot trust our empirical experiences, since we experience the world through our senses and they are not reliable.


Finally, we must try to doubt reason itself. If all of our senses are unreliable, what is the justification to believe that our own reasoning is?


It is on that point of the Hyperbolic Doubt that Descartes finally reaches the first three truths that cannot be doubted. First, if we are able to doubt everything, that means that there must be something that doubts, and therefore we must exist. The method of the doubt cannot doubt reason itself, for it is through reason that we are able to doubt; and there must exist a God that created and guides our reason. And it is through these three principles that Descartes built the foundation of his Philosophy.


The Legacy of Descartes’ Skepticism

Portrait René Descartes Jan Baptist
Portrait of René Descartes by Jan Baptist Weenix, circa 1647-1649, via Wikimedia Commons.


There is one more thing that cannot be doubted, and that is the fact that the work of René Descartes has an immeasurable important legacy to Philosophy and to human knowledge as a whole, in all of its areas and branches. His approach to Skepticism was revolutionary and paved the way for future rationalist philosophers. It is truly amazing how he was able to take the process of doubt to extreme lengths while also establishing reliable principles and absolute truths at the same time.


The Cartesian method is a purposeful method that doesn’t wish only to disprove false premises, but to reach truthful premises in order to craft a well polished system on how to attain reliable knowledge. René Descartes succeeds in doing just that, taking us through a journey from doubt to existence, answering one of the most ancient questions of mankind and proving without a doubt that we do in fact exist.

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By Igor ZanettiStudent of PhilosophyIgor is a contributing writer and student of Philosophy at the Federal University of Juiz de Fora (Brazil). He has a long-standing passion for philosophy and all forms of art, from literature to modern genres.