Descartes vs. Berkeley 03/05/95In Descartes’ First Meditation, Descartes writes that he hascome to the conclusion that many of the opinions he held in hisyouth are doubtful, and consequently all ideas built upon thoseopinions are also doubtful. He deduces that he will have todisprove his current opinions and then construct a new foundationof knowledge if he wants to establish anything firm and lasting inthe sciences that is absolutely true. But rather than disproveeach of his opinions individually, Descartes attacks the principlesthat support everything he believes with his Method of Doubt.
TheMethod of Doubt is Descartes’ method of fundamental questioning inwhich he doubts everything that there is the slightest reason todoubt. It should be mentioned that Descartes does not necessarilybelieve that everything he doubts is true. He does believe,however, that whatever can not be doubted for the slightest reasonmust be true. Descartes spends Meditation One trying to disprove hisfundamental beliefs.
First, Descartes doubts that his senses aregenerally trustworthy because they are occasionally deceitful (eg. a square tower may look round from far away). Also, because herealizes that there are no definitive signs for him to distinguishbeing awake from being asleep, he concludes that he can not trusthis judgement to tell him whether he is awake or asleep. Butasleep or awake, arithmetic operations still yield the same answerand the self-preservation instinct still holds. To disprove these,Descartes abandons the idea of a supremely good God like he hasbelieved in all his life and supposes an evil genius, all-powerfuland all-clever, who has directed his entire effort at deceivingDescartes by putting ideas into Descartes’ head.
With these three main doubts, each progressively more broad,Descartes finally is satisfied that he has sufficiently disprovedhis previous opinions. He now is ready to build a new foundationof knowledge of a physical world (the real world) based on whatmust absolutely be true. Berkeley, however, would argue that Descartes is wasting histime by trying to discover what must be absolutely true in the realworld. In his Dialogue One, Berkeley argues that there is no realworld, and that all sensible objects (those which can beimmediately perceived) exist only in the mind. He starts byproving that secondary (extrinsic) qualities exist only in the mindby use of the Relativity of Perception Argument.
As an example,Berkeley writes that if you make one of your hands hot and theother cold, and put them into a vessel of water, the water willseem cold to one hand and warm to the other. Since the water cannot be warm and cold at the same time, it must follow that heat (asecondary quality) must only exist in the mind. Berkeley also usesthe qualities of taste, sound, and color as examples to prove thatall secondary qualities must reside in the mind. However, Berkeley also says the same argument can be appliedto primary (intrinsic) qualities. He writes that to a mite, hisown foot might seem a considerable dimension, but to smallercreatures, that same foot might seem very large.
Since an objectcan not be different sizes at the same time, it follows thatextension must exist only in the mind. Further, since all otherprimary characteristics can not be separated from extension, theytoo must exist only in the mind. An interesting aspect of Descartes’ Dualistic view andBerkeley’s Idealistic view is the necessity of God. Descartesneeds an all-good non-deceiving God to insure that the ideas ofprimary qualities of objects he perceives in his mind accuratelyrepresent those qualities of objects in the external world. In theThird Meditation, Descartes says that God is infinite and finite isthe lack of infinite.
Infinite, he says, is NOT the lack offinite. Since our concept of the infinite could not have come fromthe concept of the finite (since infinite is not the lack offinite), the idea of infinite could only have come from God. Thisproof is shaky at best. Berkeley, on the other hand, needs God to give us the ideas ofthe objects we see since there is no physical world to draw thoseideas from through the senses. But rather than proving God toprove his philosophy, Berkeley uses his philosophy as the proof ofGod’s existence. In his Second Dialogue, Berkeley says God mustexist to put the same real ideas into everybody’s minds becauseminds cannot interact directly.
However, if it were the case thatGod did not actually exist (or had used his infinite powers toremove his infinity after he created the universe because he was nolonger needed), both Descartes and Berkeley would find theirphilosophies in trouble.