Another example is the reliability of the senses and how they can deceive a person and so cannot be relied on sight for example. A prime example that Descartes used was that the sun looks very small to the human eye maybe the size of a bright orange and yet in reality it is hundreds of thousands of miles in diameter many times larger then the earth, showing that the sense of sight cannot be relied on with absoloute certainty.
Descartes then progressed his argument by saying that other senses could not be true. While he is writing this meditation he is sitting by a fire in a warm room and argues that for all he knows he may not be sitting in that warm room by the fire. In a similar idea to the matrix (popular movie about how humans are controlled in a matrix or computer system and are led to believe they are living one life when in fact they are being used as energy sources for a robot population that has taken over the earth) That he may not be in that room at all but it may be that an evil demon his misguiding him into beliving this world he is living in is true and that he everything around him might not exist. There is no reason why anything else should exist or that colours are the same as Descartes imagines them to be for example red could resemble green or it might be part of a whole different spectrum that exists but the evil demon is just tricking Descartes into beliving that it dosent.
After considering all of the above ideas Descartes was capable of reaching the conclusion that there is only one thing that cannot be doubted and that is conciousness (being asleep and awake are both forms of conciousness). The reason Descartes believes that conciousness cannot be doubted is that to doubt oneselfs conciousness would mean that one would have to be conscious in the first place to doubt it so it cannot be doubted at all because to doubt it would be a contradiction. Information like this is called analytical truth or “a posteriori”
The only thing that Descartes could not doubt at this point would be his own knowledge not even mathematics could be taken as a certainty which up until this point had been seen as a dead certain of true and undoubtable knowledge. Statements such as 3+7=10 or the angles of a square no matter what size must add up to exactly 360 degrees were seen as impossible to doubt using logic. In true fashion Descartes did not accept the validity of claims such as this because he pointed out that the statement could only be true if the symbols and numbers that were used to form this statement were impossible to doubt. Descartes formed the idea that Empirical knowledge was possible to doubt if the meanings of the numbers and symbals in equations changed which would then make a statement invalid. If the numbers were not worth the values believed by Descartes yet the evil demon was making descarte believe so for example 3 may actually be worth 5 then the statement would be wrong because 5+7 does not add up to 10 but to 12.
I will now look at how Descartes method of systematic doubt can be critisiced. The first point that I will critsice of Descartes is that how legitimate the idea of doubting absoloutly everything is. Is it really sensible more then anything else to doubt certainties like the fact that he was sitting in the room he believed to be sitting in when he wrote his meditation and that there was not after all an evil demon tricking Descartes into beliving that he was. To take away anything that can be doubted reduces ones knowledge of the world to only one statement (the fact that one is aware of ones conciousness) meaning that nothing can be achieved because it would be impossible to be certain that it had actually be achieved and was not just trickery or misbelief.
Descartes seems to be to in awe of maths and this seems to have made his opinions and way of thinking so logical that it has become illogical he has taken all the facts to literally and is not willing to accept that some things are just unlikely and illogical to such an extent that it is illogical not to accept them as certainties for example the fact that the moon is not made of cheese. People know it is not made of cheese because they have visited the moon and examined the surface material Descartes would doubt this statement because there is still a chance our senses are deciving us even though the chance of this not being right is so small when all the facts point to the fact that it is.
The point I am trying to put forward, is that synthetic statements have to be examined in a different way to analytical truths not with what would be seen as in Descartes eyes as absoloute certainty but with what can be seen as absoloute certainty. To doubt something there must be good grounds to doubt something with it is just unprogressive and to dismissive to be able to doubt almost any statement just on the bare possibility that the external world which we live in does not exist. This is not an effective ground for doubt and, statements which have only ideas like this to suggest that they are wrong, and also can be doubted must be accepted on the grounds of reasanble doubt.
Another way at looking at Descartes argument is by pointing out the fact that if Descartes must doubt everything that can be doubted whether that doubt bares grounds or not then Descartes must doubt the words he is using to doubt facts with. If doubt does not have to have reasanoble grounds then the words he is using could just be trickery from this evil demon meaning that they do not exist and are just random sounds that have been merged together and so hold no meaning.
In conclusion I do not believe that Descartes idea of doubting everything that can be doubted on reasonable grounds or not, is effective because it takes almost all knowledge away is unproductive and is just progressing an idea to an extent that it becomes useless and cannot be taken seriously. Doubt needs to be backed up with reason in the same way as truth does.
