Carefully explain Descartes’ cogito and his attempt to build his knowledge structure from the ground up. (Be as succinct as possible.) Does Descartes succeed or fail in that attempt? Justify your answer in full. Descartes’ Epistemology.

This essay attempts to explain Descartes’ epistemology of his knowledge, his “Cogito, Ergo Sum” concept (found in the Meditations), and why he used it [the cogito concept] as a foundation when building his structure of knowledge. After explaining the concept I give a brief evaluation of his success in introducing and using this cogito as a foundation.

Finally, I provide reasons why I think Descartes succeeded in his epistemology.

The First Meditation began with Descartes deciding to employ radical scepticism in his quest of acquiring true knowledge and this lead him to conclude that he could not be sure of anything except that he knew nothing (Descartes, 1984:12-15). Meaning that Descartes discarded all his knowledge whether it was knowing that he had fingers, knowing that the physical world existed, knowledge of his studies etc.

he began by acknowledging how everything that constituted his preconceived knowledge could be doubt worthy. This climax of doubt was rooted in one fact:

Descartes felt that there was good reason to believe that a higher power could have deceived him into believing that his empirical and a priori knowledge was plausible. Since God is a higher power that Descartes believed to be all good and never deceptive, he named his deceiver the “Evil Demon” a complete opposite to his wholesome observation of God (Blackburn, 2001:19).

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Descartes established that the “Evil Demon” argument could wipe away any assurance of his prior knowledge except for one: his existence (Descartes, 1984:17).

This was a good argument because it presented a well thought out reason to question his knowledge. Descartes argued that if an “Evil Demon” truly existed and is only focused on deceiving him then this proves that he [Descartes] exists… “If he is deceiving me; and let him deceive me as much as he can, he will never bring about that I am nothing so long as I think that I am something… I am, I exist, is necessarily true whenever it is…conceived in my mind” (Blackburn, 2001:20).

It is possible to refute this definition of existence in the form of: Do we suppose that a thinking thing exists because it has experienced thoughts? According to the Second Meditation Descartes’ response would be that ‘I am, I exist’ stands only for a thing that is doing the thinking now and if it were to cease thinking it would cease to exist altogether (Descartes, 1984:18). In addition it is not the thinking that lead to existence, but the existence lead to the thinking.

Descartes was willing to be questioned about his knowledge of the world and to prove that he truly sought the correct answer to any objection that may be raised; he overlooked everything he knew and started to build an argument from scratch to assert the knowledge he would later accept as accurate. Thus, Descartes chose the cogito concept as a foundation that he could begin to enlarge his territory of understanding on.

From observation it is clear that Descartes only began his Meditations to build a foundation of understanding and since he had discarded all his prior knowledge he needed a solid base to begin reconstructing on, hence the cogito concept emanates. “Cogito, Ergo Sum” is Latin for “I think, therefore I am”. The cogito argument is as follows:

1. An evil demon might be deceiving me into believing that I don’t exist.

2. If I believe that I don’t exist, then I exist.

3. I exist.

This argument states that, “if I convinced myself of something then I certainly existed” (Descartes, 1984:17). This simply means that anyone doubting his or her own existence or presence indeed exists because in order for doubt to take place there has to be someone to do it. A proper understanding of the cogito concept means recognizing specifically the classification in which this ‘someone’ that is existing fits into and whether it is accurate to say that he or she exists.

The argument, as Descartes presented, does not give a valid reason for the existence of the body or anything else in the physical world, so we cannot accept that bodies exist. Neither does the cogito account for the existence of other minds as that would entail knowledge of the physical world where other things exist. The cogito concept does however; give a valid argument for the existence of the mind or a thinking thing that exists independently of the body.

In his novel Think, Blackburn explains the cogito concept as a means of justifying the core of one’s existence as thinking, we accept that thought exists not a ‘self’ (Blackburn, 2001:20). I agree with Blackburn because his [Descartes’] concept serves well to prove that we exist as thinking things and even if we were to discard any a priori or a posteriori knowledge, we can still endorse the cogito.

The cogito concept stands regardless of empirical knowledge because it suggests the existence of thought without actually linking it to the body (which constitutes a sort of empirical way of acquiring knowledge through the senses). In addition, it can be accepted without any a priori knowledge since Descartes only introduced it after concluding that he knew nothing, and could only accept knowledge of his own existence as vindicated.

To assess Descartes choice of foundation I will raise some questions that implore an explanation regarding the cogito concept. Firstly, if we only exist when thinking and the “Evil Demon” is able to manipulate our knowledge of everything else, why are our thoughts not susceptible to his deception? In my perspective, the “Evil Demon” has the ability to deceive us to a certain point, that point is our existence, and we have established that our existence leads to thinking.

Descartes supposed that the ‘Evil Demon” may have influenced our thoughts but the thought he [Evil Demon] could not alter is the thought of us thinking. For example, if I were to throw a plastic ball into a recycle bin and it were melted and reshaped into a mug, although the state of the ball may have changed it is still plastic and even if we discard its previous state its present state shows that it is indeed existing and I cannot convince the plastic that it never existed just because it is in a different state.

This example explains how our definition of existence may have changed but the fact remains that we exist hence we think. My example is another way of stating Descartes’ wax example(Descartes,1984:20-21), which according to Blackburn, he [Descartes] uses to confirm that with the cogito we can solidify that our thoughts exist regardless of them being immaterial, various and not constrained to a physical body (Blackburn, 2001:21).

A second question could be, if we know(or supposedly accept) that we are being deceived by the “Evil Demon”… wouldn’t that mean that we were aware of when we were not being deceived by him and so before we established our foundation(using the cogito concept), we had already accepted some knowledge which lead to the foundation? I think Descartes would respond by saying that the fact that we can think of the “Evil Demon” and accept that he is deceiving us means that we already established the cogito before moving on to think of the actual idea of a deceiver, again we see that any thinking means something existed to do it(the thinking).

This response seems to present some equivocation but unfortunately I think that any of Descartes’ responses may shift the burden of proof to the person who raised the question. His argument, as I would render it, may be that the question is going in circles and only raises doubt of his [Descartes] means of acquiring knowledge and not actually any objection to the cogito. This last response seems to credit Descartes success in establishing that the cogito is a concept that gives us the best potential start to gaining any knowledge.

Even the knowledge of an “Evil Demon” would mean we have to start by accepting that we exist (cogito) in order to prove any of our knowledge as untrustworthy. A third and final question is, what form of knowledge is the cogito and what other knowledge can we build on this foundation? The cogito is a form of a priori knowledge because we do not need to prove its validity by explaining anything or drawing on a previous experience to prove it. Descartes further used the cogito when acquiring the knowledge of Cartesian Dualism, which is his next step of building knowledge that is rooted in the cogito.

Descartes said that Cartesian Dualism is justified by the cogito because we only have knowledge of an existing ‘thinking’ entity that has no body, hence the body and the mind should be viewed as separate and neither one has the ability to influence the other (Descartes, 1984:21). I think the cogito concept provokes a sense of identity that each of our thinking may contain and this identity entails that as much as the “Evil Demon” may try to take away our knowledge we still have that little something, as thinking beings, that can only be explained as an existence. This entity of our existence is immaterial, yes, but it leads us into thinking and thinking is our starting point of gaining new knowledge.

Therefore Descartes succeeded in his epistemology by choosing “Cogito, Ergo Sum” as a base for his future knowledge. Once the cogito is accepted Descartes can acquire new knowledge. In conclusion Descartes’ processes of building a knowledge structure foundation was fruitful and ultimately leads to a successful epistemology.


  1. Blackburn, S. 1999. Think: A Compelling Introduction to Philosophy. New York: Oxford University Press.
  2. Descartes, R. 1984. The Philosophical Writings of Descartes, Vol. II, Cottingham, Stoothoff and Murdoch (Translators).UK: Cambridge University Press.
  3. Lerm, J. 2013. [Descartes’ ‘Second Meditation’: The Cogito Argument] Lecture Slides.

[ 1 ]. J. Lerm [Rebulding Begins] lecture slide 2
[ 2 ]. Lerm [The Cogito Argument] lecture slide 7

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