I'd like opposing views on Descartes' belief that absolute certainty concerning the existence of material things is possible, that some properties of the ideas of material things are certainly...

I'd like opposing views on Descartes' belief that absolute certainty concerning the existence of material things is possible, that some properties of the ideas of material things are certainly true, and that one has to first prove God exist to have such certainty.

Expert Answers
Jamie Wheeler eNotes educator| Certified Educator

If you are looking for a clear refutation to Descartes’ (1596-1650) philosophy of material certainty, look no further than Charles Sanders Peirce.  Peirce (1838-1914) was an American philosopher who is often called the “father of pragmatism,” and his arguments were influential in American societal foundation.

Let’s begin, however, with Descartes beliefs so that Peirce’s contrasting viewpoints will be more clearly understood. The overwhelming concern of Descartes’ life was transcending doubt.  He wanted to know if there was a way, that is, a particular method that could be used in any situation, for anything at all.  He wanted to be sure that whatever method he employed could be verified with absolute certainty. This absolute certainty is called being “apodictic.” As he explored different ideas, he knew that in order for any resulting claims to be true, the foundation of those claims must be absolutely apodictic.  The methods he employed, Descartes argued, must be both logical and systematic.

This need for an unshakable foundation is key to his philosophy.  However, finding agreement between individuals is no easy task, as people come from various backgrounds. Additionally, they have different beliefs and they base their judgments on those beliefs. 

Descartes sought to overcome these belief disparities by crafting a method that would apply to anyone seeking agreement on truth. First, people must decide which principles are “correct.”  Then, the ability to formulate a process for a formal acquisition, one that is indisputable, can be created.

One of Descartes’ first “agreeable” claims is that people all have a modicum of good sense: “Good sense is the most evenly distributed commodity in the world,” he argues. Descartes also believed that humans share a “natural light.” This “natural light” is our innate capacity for knowledge; we use this light to reason.   We then use that “good sense” and “natural light” to come to a shared truth. For Descartes, the evidence of this combination is found in mathematics; for him, mathematics was the ultimate expression of knowledge.  He writes, “I took especially great pleasure in mathematics because of its certainty and the evidence of its arguments... I was astonished that, because its foundations were so solid and firm, no one had built anything more notable upon them."

To reach this level, Descartes argues that the philosophy is the most logical principle of knowledge, and this is the all-important foundation. From this foundation, proposition are either probable, and therefore false, or certain, and therefore true. Most knowledge, he further argues, has never been proven to any individual on his own testing; rather, most “knowledge” we think we have is really just what other people have told us is “true.” This is the basis of probability, not certainty, and therefore, it must be rejected.  If two words could convey Descartes’ admonition they might well be “Question Everything.”

One of the things that must be extensively questioned, according to Descartes, is our senses. They are not always accurate.  Our thoughts, too, are questionable, since almost everything we “know” is “learned” from outside the self. If we cannot trust our sense or our minds,

Clear ideas, however, can be trusted. For Descartes, these “clear” ideas come from God, and God, Descartes argues, CAN be trusted.  God exists in perfection; if he were not perfect, he would not exist.  When we reject all else, we must ask what, other than God, what IS real. Individuals must ask whether WE real. This question is the basis for Descartes’ most famous statement, “I think, therefore, I am.”  The rest of this statement reads: “- [thinking] assures me that I am uttering the truth, except that I see very clearly that, in order to think, one must exist.”

Two hundred years later, Charles Sanders Peirce examines Cartesian philosophy and comes to some very different conclusion.  In stark contrast to Descartes, Peirce claims that all knowledge comes by way of experience.  We know a stove is hot when we experience its heat. We know a chair will hold our weight when we experience a chair. Peirce asks us to “[c]onsider what effects that might conceivably have practical bearings we conceive the object of our conception to have. Then, our conception of these effects is the whole of our conception of the object.”

In order to get along in the world, Peirce argues, we have to leave doubt behind. Once you experience a chair, you do not doubt every chair you see. You know a chair will hold you because this has been proven true in the past. We overcome doubt many different ways once truths have been evident by way of experience. People can come together to compare experiences and agree upon a truth, and they do so, Peirce claims, in order to arrive at a “settlement of opinion.”  This helps groups make a distinction in what they personally believe to be true and knowing something is true because many others agree on the shared experience of a truth.

For Peirce, the scientific method should be used to arrive at a truth: inductions from the known and formation of a hypothesis. Unlike Descartes, Peirce does not attempt to arrive at an absolute truth.  He does not believe such a thing is possible; instead, he wishes to overcome doubt, a very different philosophical approach from Descartes.

For Descartes, experience should be distrusted; for Peirce, experience leads to trust. Peirce argues that Descartes foundation, for which he places so much emphasis, is fundamentally flawed because although Descartes insists on “clear and distinct” ideas, he never defines that clarity and distinctions. ." Arguments about God, to Peirce, therefore, are irrelevant because these doubts do not come to us naturally. Peirce argues that “the mere putting of a proposition into interrogative form does not stimulate the mind to a struggle after belief. There must be a real and living doubt, and without this, discussion is idle.

Peirce is concerned only with the practical. Theoretical, to Peirce, is not real and therefore, not important.  Beliefs, so important to Descartes, are dismissed by Peirce. There can never be absolute certainty in this arena. The only acceptable truths in life are ones that overcome doubt.