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Descartes Meditations - method of doubt and rebuilding knowledge

Updated on July 6, 2012
Descartes | Source


Rene Descartes lived in France in the 1600’s during a time of great change, when many intellectuals were debating over scientific and philosophical theory. New discoveries in science resulted in scientists disagreeing with one another over what was in fact true. Philosophers were growing more sceptical; doubting if it was actually possible to know anything for certain. Beliefs and institutes which could once be trusted were no longer reliable so Descartes wanted to find what was certain and discard what was false or unsure in the hope of restoring some order in these matters. He wanted to prove certain knowledge existed in order to both prove the sceptics wrong and to create a boundary for theories so as to prevent extremely strange ideas being considered possible truth. He aimed to create a basis of a new philosophical and scientific system. He realised that many things which he trusted as true relied on unstable foundations and so to discover certain truth he would first have to get rid of these ideas. He puts his reviewed beliefs into three categories of certain truth, beliefs which are not entirely certain and indubitable from which he will hold his assent and manifestly false beliefs which he fully believes are false. He recorded what he discovered in the form of his six meditations. These meditations covered a variety of topics including his views on the reliability of the sense, the existence of God, etc. Religion had a great influence on Descartes writings and so he tried to accommodate the principle of God in all of his thinking.

Descartes begins his meditations by questioning how it is that one can know something is real. After realising that he has accepted many things which have later been proved false he sets out to decipher what is certain truth and what can be doubted. He realises that;

“Everything that I accepted as being true up to now I acquired from the sense or through the senses. However, I have occasionally found that they deceive me”

He thinks that there must be some information gained from the senses which cannot be doubted but realises that if there is any inconsistence then he cannot trust the senses at all. It is also with his dream argument that Descartes is able to doubt the evidence given to us by our senses. He believes that even if we feel absolutely sure that we are doing something we may in fact be dreaming that it is happening. In dreams we receive the same sensory information as in reality and Descartes felt there was no way of proving whether we were sleeping of not. Descartes believes also that events in dreams are based on reality so no matter how abstract and unusual they may be they still have foundation in reality. By believing this he prevents physical entities from being considered certain and true but he still has logic left. He believes that obvious truths are contained within mathematical propositions which is external from any physical form and can thus be considered true in both dreams and reality. He also believes that the possibility of an external world of some kind remains certain and safe from the dream argument. There are problems with the dream argument though as people believe there are certain ways of testing whether it is a dream of reality. Firstly, dreams tend to be largely visual and in dreams we tend not to have a sense of touch. Dreams also have less continuity as waking experience does and tend to be short episodes rather than the prolonged experience of life. Strange elements exist within dreams as well and may be far removed from reality. Descartes makes a jump from mistaking some dreams for reality to believing it is not possible to tell the difference between the two thus causing him to believe he can't tell whether he is awake or asleep now. Norman Malcolm believes it is logically impossible to ask “am I dreaming?” unless you are conscious and while dreaming you ate not so you can only ask this question in reality. Nigel Warburton feels that it is easy to distinguish dreams from reality because dreams are full of weird ideas but he also acknowledges that some dreams do cause us to wake with a slight sense of doubt about whether it happened or not. Descartes also fears that truth may be being meddled with by an Evil Deceiver and so he cannot trust his logic fully and without question. He later brings the belief of God into his meditations which over powers the Evil Deceivers power. During his meditations Descartes formulates the idea of an evil deceiver who’s resolve was to deceive him. The evil demon is derived as a concept from the idea of God; the evil demon is omniscient and omnipotent like God but not benevolent and perfectly good as God would be. Descartes thinks of the evil demon, not as a factual thing but as something which he cannot yet disprove. The idea that God may have been deceiving us had been rejected by Descartes in favour of the evil demon idea as God is too kind and loving to willingly and purposefully deceive us. The evil demon idea causes the doubt of any possible knowledge to spring up in Descartes theories. If some evil demon is able to deceive us then how can we be certain that he is not deceiving us completely and that all we trust may be merely a façade and so nothing can be certain knowledge. Now that he has provided the sceptical idea of no certain knowledge Descartes must build his way up from it and prove that there is in fact a physical world in space and time and show that there is something upon which to base science.

To rebuild knowledge and get back on track towards his aim of a firm and permanent structure of the sciences Descartes must treat even the slightest doubt as if it were certainly false, resulting in a strong foundation being found on which all else could be based. So far Descartes has come up with three arguments about doubt; problems with the senses, the dream argument, and the demon hypothesis. These concepts force both sensory evidence (a posteriori) and evidence based on reason (a priori) knowledge to be brought into question and are thus put aside. Descartes looked to other philosophers such as Archimedes, the ancient Greek philosopher who was also searching for firm foundations on which to build all other beliefs around, for help in finding a true belief. It is in his second meditation that Descartes begins rebuilding knowledge; he starts with the premise that “…Nothing ever existed; I have no senses at all; body, shape, extension, motion and place are unreal. Perhaps that’s all there is, that there is nothing certain”. He seems to have bowed to the to the sceptics view that it is not possible to prove that anything is real and so therefore it may not be. He also doubts his own existence because he cannot trust evidence from either the senses or reason. The cogito is the view that the evil demon cannot deceive him into believing he exists because, it is a necessity condition for being deceived that you must first exist. The evil demon, if he does exist, must have limited power as he cannot deceive a non-existent being; “without doubt I exist if he deceives me”. This is the first foothold which he can use to rebuild any sense of certainty in the sciences. He also conceives the idea that you must exist if you are able to doubt, wish, detect, examine and imagine; he cannot do any of these self determined things if he does not exist. Therefore, “I think therefore I am”; ‘I think’ being the premise/evidence of the proposal being offered to back up the conclusion ‘I am’. He believes that the proposition is necessarily true whenever it is stated by himself or conceived in his own mind because that is him thinking he exists, which he could not do if he did not. His existence is now proven and is now a member of the certain true knowledge category and will be the foundation of the firm and permanent structure in the sciences.

There are however problems with the cogito. A.J. Ayer argues that just because there is thinking going on does not mean that there is necessarily someone doing the thinking; there could be a mind but not a body. We are merely making the assumption that the effect-thought has a cause-thinker. He blames language for the confusion as it could be the structure of our language which implies that thoughts must have a thinker. If language is the cause of our believing every thought has a thinker then it is very difficult to prove otherwise as it would be somewhat incomprehensible without altering because “I think therefore I am” must be extended to “All thinking things exist” but this cannot be done due to Descartes distrust of reason and logic which is required to make this conclusion. According to Descartes, the evil demon could be deceiving us into believing that all thinking things exist when it cannot be extended to another unless they themselves think it and so it doesn’t cover animals and the like, you are only able to prove to yourself that you yourself exist. Another general problem with the theory is that nothing really follows on from it. Descartes cannot prove that this thinker which definitely exist has a body or that there is any external world or even that there is anything out with the mind. This means that this certain and permanent discovery is irrelevant a it stands alone. Descartes does realise this and identifies the principle rules which make the cogito certain and attempts to apply it to other beliefs in order to find if they are certain or not.

It now becomes necessary for Descartes to introduce God into his argument as otherwise his argument would have nowhere to go. So far he has proved that he himself certainly exists but now he attempts to regain trust of the senses through God. The God which he is trying to prove is omniscient, omnipotent and benevolent. Descartes makes the assumption that “what is more perfect cannot arise from what is less perfect”; this is referred to as the causal adequacy principle. There are four steps of thought in this. Step one: we all have an idea of a perfect being which we compare ourselves to in order to grasp our own imperfections. Step two: the idea of a perfect being must have a cause. Step three: if a perfect thing exists then it must be caused by something perfect. Step four: this idea of a perfect being must have a perfect cause which cannot be ourselves as we are so imperfect. So, there must be a perfect being who placed this idea in our minds. Descartes follows this with the idea of clear and distinct perceptions. These are simple truths which are “[resent and accessible to the attentive mind”. He reasons that ‘I am’ cannot be doubted because it is clear and distinct therefore whatever is clearly and distinctly perceived in the mind must be true. Descartes says that he can trust clear and distinct perceptions because God would not deceive him and God exists. Descartes is not able to use this truth rule in order to arrive at his firm and permanent structure in the sciences. What is clearly and distinctly known cannot be doubted and so can be categorised as certain knowledge. This is the trademark argument; “…the mark of the craftsman stamped on the work”. Proof of Gods existence is crucially important because the perfect being will not be a deceiver; will not be the evil genius. The perfect being (God) must be omnipotent and so must be able to control the evil genius thus meaning the evil genius cannot be omnipotent as he is under the control of God. God will also be omniscient and so will know everything the evil genius is up to in trying to deceive us and because God is benevolent he would not allow us to be deceived. Now the idea of the veil genius can be dropped and reason can again be restored as a reliable foundational belief. God is now a guarantor of all discoveries of reason and logic; of all clear and distinct perceptions. Descartes now has a basis for his structure of the science which he can build on due to Gods benevolence as long as he uses his reason carefully. Two problems arise from this. Firstly, Descartes is making the assumption that God exists. Despite Descartes attempt to proves the existence of God you don’t believe the argument, thus his whole clear and distinct argument can be questioned and so can any arguments built on top of this now unstable foundation. Secondly, the meaning of clear and distinct is not certain or obvious enough as it is only described as that which gives you a sense of complete certainty but it is the case that we may believe something false to be extremely true. Alan Gewirth tries to explain that something is clear if it is present in the mind and shows us the essence of the object and the something is distinct if it excludes everything which is not essential to it.

Descartes is now on the path to rebuilding our knowledge with what he has found to be certain truth. He regains the reliability of the sense and gives them back some of their importance through God. God is not a deceiver and God gave us the sense organs so they can't be totally unreliable. The dream argument is rebuilt as Descartes now believes that he can tell between waking states, which are largely coherent and form a continuous story. and dreams, which are weird and incoherent. To banish the idea of the evil demon Descartes again relies on God who would not allow such a being to interfere with our knowledge. This rebuilding of knowledge is partially successful but Descartes relies too fully on God.


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    • jadesmg profile image

      jadesmg 5 years ago from United Kingdom

      Thanks for the comment. The world can be a woderful and mysterious place. completely agree it's sometimes more like a dream.

    • jadesmg profile image

      jadesmg 5 years ago from United Kingdom

      his rational mind is qite good, but does seem to fail, at least scientifically, after 'i think therefore i am' as he begins to rel wholly on God. This being fair enough but not really undeniable which is what he was seeking. A good start though lol.

    • jadesmg profile image

      jadesmg 5 years ago from United Kingdom

      lol thanks, it is a very versitile phrase.

    • Pamela-anne profile image

      Pamela-anne 5 years ago from Kitchener, Ontario

      Most interesting hub I really enjoyed the read keep them coming am I awake or am I dreaming sometimes I wonder thanks for sharing! take care pam.

    • Jewels profile image

      Jewels 5 years ago from Australia

      His rational mind is something isn't it. But I disagree with his theory "I think therefore I am." I prefer "I am, therefore I think."

      And so OldWitchcraft "You exist, therefore you drink." Cheers!

    • OldWitchcraft profile image

      OldWitchcraft 5 years ago from The Atmosphere

      Very nice article!

      I never think of Descartes without remembering the Philosophy Dept. of Wallamaloo, Australia... "I drink therefore I am!"