The method of doubt that is used to attain certainty was formulated by famous Western philosopher Rene Descartes (Burnham & Fieser). It was initially formulated to be a method for religion, science, and epistemology (Burnham & Fieser).
He lived in the 16th to 17th century, and created works on mathematics and physics (Burnham & Fieser). His method of radical or hyperbolic doubt was a product of his being a radical skeptic. This position means that Descartes did not readily accept anything as true. Moreover, he did not immediately classify anything as knowledge. Thus, contrary to the inclinations of philosophers and thinkers of his time, he never believed in anything unless they passed his test of indubitability (Burnham & Fieser).
Descartes vehemently denied the prevailing concepts of his time, as put forward by the Aristotelian, Scholastic, and Medieval traditions (Burnham & Fieser). This gave birth to his determination to be a radical skeptic, which for him allowed him to start anew in his quest for a philosophical foundation (Burnham & Fieser). However, it is important to note that Descartes’ radical skepticism is different from the position of other skeptics, which is doubting for the sake of doubting.
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Being a radical skeptic, Descartes desperately searched for true knowledge (Burnham & Fieser). For him, knowledge is based on truth and indubitability (Burnham & Fieser). A certain proposition would only be accepted as knowledge if it were true and does not entertain doubt (Burnham & Fieser).
For example, one’s knowledge of a table is brought about by his belief that it is true and real. Descartes formulated a criteria of knowledge based on clarity and distinctness, which gives a person confidence in his determination of whether a statement is worthy of being accepted as true knowledge (Burnham & Fieser).
Descartes’ radical skepticism is characterized by his comprehensive rejection of the reliability of accepting ideas as truth or knowledge (Burnham & Fieser). He is known for the wide-ranging premise that truth is not represented by a person’s ideas (Burnham & Fieser).
For him, ideas cannot be automatically classified as truth (Burnham & Fieser). Quite the contrary, ideas obscure a person’s perception of the truth. (Burnham & Fieser). Thus Descartes rejected all ideas that are susceptible to doubt. In this connection, he likewise excluded mere wishes or opinions from real knowledge (Burnham & Fieser). For him, such dubitable ideas could not serve the purpose of determining the foundation for philosophy or knowledge (Burnham & Fieser).
Descartes’ method of hyperbolic doubt was explained in detail in his work published in 1641, entitled Meditations on First Philosophy, wherein he discussed issues regarding the existence of God and the distinction between mind and body (Burnham & Fieser). In this book, Descartes concluded that there is at least a doubting being whose existence is independent of its body; namely, himself (Burnham & Fieser, 2006).
Descartes’ method of hyperbolic doubt consists of several stages (Burnham & Fieser). First, it involves the identification of a class of knowledge that is unreliable because it is not credible (Burnham & Fieser). This class of knowledge refers to sensory information, or those gathered from sensory stimuli (Burnham & Fieser). Descartes’ choice of doubting sensory knowledge is based on his stand that sensory knowledge has been known for failing in the past (Burnham & Fieser).
Furthermore, Descartes claims that there is a distinct possibility that it will still fail in the future. Moreover, he referred to optical illusions, which are sensory knowledge that is based on deception. They make a person believe that his perceptions differ from what truly exists in the world (Burnham & Fieser. For Descartes, therefore, sensory knowledge cannot be trusted.
Descartes next subjected his own ideas to radical doubt (Burnham & Fieser). This he did by imagining that there exists a God who deceives him into thinking his thought, beliefs, and perceptions. (Burnham & Fieser, 2006). However, due to Descartes’ strong belief in God, he later replaced the idea of God as the deceiver to avoid disagreeing with his Christian belief, and conjured the idea of a malevolent demon who deceives him (Burnham & Fieser). Under this test, Descartes was able to conclude that even his own ideas cannot be trusted because they can still be doubted, since they could have been implanted in his mind by the malevolent demon (Burnham & Fieser).
Finally, Descartes settled with the conclusion that he exists (Burnham & Fieser). This conclusion he reached through mental intuition, because he noticed that there were statements that are presented to his mind with sufficient clarity and distinctness that there is no reason to doubt them (Burnham & Fieser). This gave rise to his famous phrase, “I think therefore I am,” or “Cogito ergo sum (Burnham & Fieser).”
This cannot be doubted, because the fact that he doubts shows that there is an existing entity who performs the doubting (Burnham & Fieser). If he did not exist in the first place, then there is no being whom the malevolent demon would be deceiving (Burnham & Fieser). In sum, Descartes arrived at one conclusion using his method of radical doubt. This conclusion is that it is the indubitable truth that he is a thinking entity that exists (Burnham & Fieser).
Burnham, D. & Fieser, J. “René Descartes (1596-1650).” The Internet Encyclopedia of Philosophy. 2006. 1 Apr. 2007 <http://www.iep.utm.edu/d/descarte.htm>.