Disclaimer: This is an example of a student written essay.
Click here for sample essays written by our professional writers.

Any opinions, findings, conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of UKEssays.com.

How Successful Was Descartes Attempt to Secure Certain Knowledge?

Paper Type: Free Essay Subject: Philosophy
Wordcount: 2764 words Published: 8th Feb 2020

Reference this

The schism in Christendom throughout the mid-17th century caused the previous source of authority, specifically the Roman Catholic Church in Europe, to be in serious contention. So long as there existed a “higher” knowledge i.e. a metaphysical truth, Philosophy would respect it, but given the breakdown of Christendom, and its authority waning, its negation birthed Modern Philosophy, Descartes, widely renown as the father of this radical shift; for him the source of all authority was reason; knowledge A priori. Throughout this essay I will consider if the methods Descartes used to secure knowledge were successful; first by analysing his conception of knowledge itself; acquiring knowledge through the policy of radical doubt arriving at the certitude of the thinking self: that which cannot be doubted, from this foundation, it will lead to the attainment of knowledge through the ontological argument for the existence of God. I will also look at Descartes arguments for innate knowledge; the doubt of the senses, on the policy of innate knowledge, in opposition, I will bring in the argument for empiricisms owed to John Locke, attempting to establish a dialectic, between the two thinkers. I will then aim to arrive at a final conclusion, demonstrating, ultimately, Descartes new foundations for knowledge was ultimately unsuccessful.

Method of Radical Doubt.

To begin with, Descartes, famously establishes knowledge in terms of doubt, while differentiating a rigorous knowledge, in his letter to Henricus Regius, he writes: “I distinguish the two as follows: there is conviction when there remains some reason which might lead us to doubt, but knowledge is based on a reason so strong that it can never be shaken by any stronger reason.” (Descartes, 1640). Knowledge then, for Descartes must be based on complete and utter certainty that it becomes impossible to doubt. As an individual’s certainty begins to increase, their doubt decreases, the contrary follows in the same fashion. For Descartes, what he believes to be central, is to test everything of certainty, what is already established as a truth; Descartes felt that it would be too difficult a task to question each belief independently, instead he referred to the foundations; in the first mediation, this is where he embarked on his methodical approach of radical doubt consisting of several arguments. He begins by affirming, in the past he has been deceived by the senses, In the first mediation he assesses: “Everything that I accepted as being most true up to now I acquired from the senses or through the senses. However, I have occasionally found that they deceive me, and it is prudent never to trust those who have deceived us, even if only once” (Descartes, 1641). As the first mediation progresses, he seeks that which cannot be doubted, it seemed clear to him that he was sat in his dressing gown, by the fire with a piece of paper before him: “the fact I am here, sitting by the fire, wearing a dressing gown, holding this page in my hand…indeed how could I deny these hands or that this body is mine.” (Descartes, 19 1641). The first argument in the first meditation, is the dream argument, followed by the deceiving Demon. The reason he necessitates these arguments, is he needs to be certain of what he Is perceiving, the foundation, needs to be free from all doubt. Nothing can remain, no matter how clear or evident it may appear. The dream argument then, is to suggest the universal possibility of dreaming, to propose the senses aren’t always reliable. The deceiving Demon shows that even after the establishment of a perceived certainty, for all he knows he is being led astray. The arguments made are characteristically hyperbolic; however, the main point Descartes is trying to demonstrate; our faculties can be deceived, and if we are unable to trust our faculties to transmit data of the world, then we can’t trust the assumptions we’ve made via sense perception. The one thing he is certain of completely, is his own existence. For if one’s existence is doubtable, there has to be a functioning mind, contemplating – doubting in the first instance: “I am, therefore precisely only a thinking thing, that is, a mind, soul, intellect or reason – words the meaning of which was formerly unknown to me. But I am a genuine thing and I truly exist. But what kind of thing? I just said: a thinking thing.” (Descartes, 1641). Any knowledge system must be built upon this foundation, the one thing he can be certain of.

Securing Knowledge through the existence of God.

Building upon what knowledge is certain: the thinking self, Descartes follows by offering proof of the external word via the existence of God. In the third mediation, he seeks to find out if there is in fact a God. He tries to make sense of why we have this idea of God in our minds. As a finite being, God could not have originated from us, as he is an infinite being. Descartes employs a double rational principle, assuming something cannot come from nothing, and something perfect cannot have been innately produced by something less perfect, for Descartes writes: “I think of God, however, as actually infinite, so that nothing can be added to his perfection. Finally, I perceive that the intentional being of an idea can be produced not by a merely potential being.” (Descartes, 1641). Descartes has the notion that a cause, must have as much reality as its effect, a finite substance would be able to produce another finite substance however, it would not be able to cause an infinite substance only an infinite substance is able to produce it. The lesser cannot be derived from the greater, as Descartes writes: “But if I derived my existence from myself, there would be nothing that I would either doubt or wish for, nor would I lack absolutely anything. For I would have given myself every perfection of which I have some idea and thus I would be God himself.” (Descartes, 1641). From this, Descartes notes a finite substance which has a property, the infinite substance which caused it to exist must also be endowed with the same property. He writes: “Evidently it is not surprising if God, in creating me, endowed me with this idea so that it would be, as it were, the artisan’s trademark imprinted on his work. Nor is it necessary that the mark be distinct from the work itself. From the mere fact that God created me, however it is very probable that I was made in some way in his image and likeness.” (Descartes, 1641). What Descartes is denoting here is the Causal Adequacy principle, for he writes: “whence can the effect draw its reality if not from its cause? And how could the cause communicate to it this reality unless it possessed it in itself?” (Descartes, 1641). However, looking at the Casual adequacy principle in more detail we find that it does not stand up to the scrutiny of contemporary scientific procedure. For example, Helium, which is formed by fusion from Hydrogen consists of properties which are not contained within Hydrogen. However strong this objection is, it seems to be quite unfair to Descartes because modern chemistry had not been invented. Nevertheless, it is difficult to propose what kind of response he could offer as this seems to be a strong case against the causal adequacy principle. A contemporary objection can be attributed to Marin Mersenne, he had suggested the example of the emergence of life through “non-living forces” such as the effects of the Sun and rain. Animals are alive and are kept alive by these non-living forces. “‘it does happen that an effect may derive from its cause some reality, which is nevertheless not present in the cause.” (Cottingham, 1985). To make one final objection on securing knowledge through the existence of God, (underpinning the entirety of what I have just discussed) Descartes establishes the existence of himself, he had been recently doubting the reliability of reason, and in order to establish the existence of God, reason is required, however he does not explain how  reason works until his demonstration that reason can be relied upon via the existence of God: “Thus I see clearly that the certainty and truth of all knowledge depends on the knowledge  of the true God, before I knew him I was incapable of knowing anything else perfectly.” (Descartes, 1641). This is referred to as the Cartesian circle. Two major foundational steps could be taken to strengthen the argument: I exist, and reason can be trusted, then you can argue God exists based on reason. However, he fails to establish new foundational knowledge on account of this circular reason.

Innate Knowledge.

To take another approach, there are some things that Descartes believed that we can know independently of experience, through interactions with the senses. This is what is commonly known as Innate Knowledge; this is knowledge that is not acquired by experience but comes from within the subject. One common example of this innate knowledge is knowledge of Mathematics, as Descartes writes: “…but that arithmetic, geometry, and other such disciplines that discuss only very simple and general things and are not concerned with whether or not they exist in nature, contain something that is certain and beyond doubt.” (Descartes, 20, 1641). He thus suggests: “For whether I am awake or asleep, two and three added together make five and a quadrilateral figure has no more than four sides. It seems impossible that one could ever suspect that such clear truths are false.” (Descartes, 1641). There is no need to go out into the world in order to understand this through sensory data. Descartes also presumes that concepts of already empirical properties of objects such as colour and shape, are in fact innate, for Descartes writes, in relation to the wax he recalls in the Second Meditation: “But what should be noticed is that perceiving it is not a case of seeing, touching or imagining, nor was it ever such although it seemed that way earlier, but it is an inspection of the mind alone.” Only the faculty of being able to judge rests in the mind. The when in which Descartes describes this innate knowledge is very similar to what Noam Chomsky has called Poverty of Stimulus. This is the argument that the external worlds ability to stimulate does not have the ability to confer on the individual the idea that you’re getting something from it: “The poverty of Stimulus argument holds that children do not receive enough evidence to infer the existence to infer the existence  of core aspects of language such as the dependence of linguistic rules on hierarchical phrase structure.” (Perfors, Tenenbaum, Regier, 2006). This in turn suggests that those who learn language from development, make grammatical generalisations that do not appear justified by the evidence in the input (Chomsky, 1965, 1985). This would then suggest a type of inborn knowledge.  So, the case for Descartes then, there is no shape, or colour in the external world, there is only extended objects in motion. The properties of objects thus cannot come directly from the stimulus, as they do not possess these properties; so, then, they must come from the mind, Descartes writes with the example of the wax candle: “It is nothing but something that is extended, flexible and changeable.” (Descartes, 28, 1641).


Locke’s Refutation and The Brain in a Vat.

 In contrast, it is often assumed that we have a strong inclination to agree with Locke’s assessment, Locke took it as apparent, that ideas of what he calls Sensible qualities must be derived from sense perception. Locke thus writes: “It would suffice to convince unprejudiced readers of the falseness of this supposition [innate ideas] if I should only show . . . how men, barely by the use of their natural faculties, may attain to all the knowledge they have without the help of any innate impressions; and may arrive at certainty without any such original notions and or principles.”(Locke, 1689).  It is evident for Locke that we get the idea of Green, by perceiving cases of Green objects. There is however an argument to support Descartes position in opposition to Locke’s empiricism. It is a contemporary Cartesian argument, similar to Descartes deceiving demon argument, originated by Gilbert Harman.  It is entirely possible for someone to have the sensations of Green without sense perception, it is known as: The Brain in a Vat argument. For all we know, we are a brain in a vat, nothing we experience is real: “The persons brain (your brain) has been removed from the body and placed in a vat of nutrients which keeps the brain alive. The nerve endings have been connected to a super scientific computer which causes the person whose brain it is to have the illusions that everything is perfectly normal.” (Putnam, 1981). Since then, the brain in the vat is giving and receiving the same impulses if it were in a human body, it is thus impossible to tell from its viewpoint, whether it is in a vat or a human body. It is then, entirely possible and reasonable, for such a brain to have sensations of Green through stimulation, without having an experience of it directly through the senses. It is no more unreasonable to suggest the brain in a vat from having sensations of pain. For if we look at what Descartes writes in his sixth mediation: “In countless other similar things I discovered that the judgments of the external senses were mistaken. And not only the judgments of the external senses, but also those of the internal senses. For what can be closer to me than pain? But once I heard from those who had a leg or arm amputated, that they still seemed to feel pain in the part of their body that was missing.” (Descartes, 1641). What Descartes is describing here is the phenomena of phantom pain.  We can see then, from these examples, the senses are not always reliable, so there is enough reason to doubt them entirely.

Find Out How UKEssays.com Can Help You!

Our academic experts are ready and waiting to assist with any writing project you may have. From simple essay plans, through to full dissertations, you can guarantee we have a service perfectly matched to your needs.

View our services

To conclude, throughout the body of this essay I have aimed to establish to what extent Rene Descartes was successful at securing certain knowledge. Descartes was quite successful at demonstrating the fact we can possess innate knowledge through the application of reason, he demonstrated quite clearly the senses can be unreliable, demonstrated by: Chomsky’s poverty of stimulus, the brain in a vat, and the phenomena of phantom pain. We also do not have to go out into the world and see via sense perception that simple mathematical calculations (such as two plus three equals five) work. However, having established this, looking in detail, at his foundations for knowledge (the securement of an external world) underpinned by the existence of God, is evidently a weak argument demonstrated by him contradicting himself, as denoted in reference to the Cartesian circle. This is ultimately, the fatal flaw in his ability to demonstrate a new foundation for knowledge. We can also look at another weakness in this argument, as shown by the artisan stamp causal adequacy principle. We know, through the example of Mersenne something doesn’t need to have the same properties as the thing it caused to exist.


  • Chomsky, Noam (1965). On Certain formal properties of grammars. Information and control, 2:137-167
  • Cottingham, John (1985). Philosophical Writings, vol. 2, p. 88.
  • Descartes, Rene (1661). Meditations and Other Metaphysical writings, Penguin Classics,Translation: Clarke, Desmond, 1998, pp. 19-61
  • Descartes, Rene (1640). Selected Correspondence of Descartes, Copyright: Bennett, Johnathan (2017). 
  • Locke, John, (1689) An Essay Concerning Human Understanding, Chapter 1
  • Putnam, Hillary (1981) Reason Truth and History, Chapter 1, pp.5-6
  • Tenenbaum, Joshua, Perfors, Amy, Regier (2006) Poverty of the Stimulus? A Rational Approach. Department of Brain and Cognitive Sciences, MIT. University of Chicago.


Cite This Work

To export a reference to this article please select a referencing stye below:

Reference Copied to Clipboard.
Reference Copied to Clipboard.
Reference Copied to Clipboard.
Reference Copied to Clipboard.
Reference Copied to Clipboard.
Reference Copied to Clipboard.
Reference Copied to Clipboard.

Related Services

View all

DMCA / Removal Request

If you are the original writer of this essay and no longer wish to have your work published on UKEssays.com then please: