Sceptical Arguments

Sceptical Arguments Philosophy

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  • Created by: Caoimhe
  • Created on: 17-04-12 14:12

The Argument from Perceptual Illusion.

The argument from illusion runs as follows: the direct realist argues that the objects of our perceptions are the real contents of the world, however it is a well known fact that our perceptions can be inaccurate or completely illusory, for example a straight stick may appear bent when placed in water, or we may suffer from hallucinations that have no basis in reality whatsoever. Since the object of these perceptions is clearly not part of the objectively real world direct realism contradicts our experience and should be discarded.

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The Argument from Perceptual Variation.

When picking a dress to wear in the morning I may pick a black one, under the conditions of my bedromm light it appears to be black. However when I step outside I realise in fact my dress is Navy. This is perceptual variation, certain condition can effect my perception. Some might say the dress was always Navy and just appeared to be black, whereas others might say a black dress exists independednt of my mind which never experience the alteration that I percieve.

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Evil Demon Argument

Cartesian Philosophy, Descartes.

The evil demon presents a complete illusion of an external world, including other minds, to Descartes' senses, where in fact there is no such external world in existence. The evil genius also presents to Descartes' senses a complete illusion of his own body, including all bodily sensations, when in fact Descartes has no body. Most Cartesian scholars opine that the evil demon is also omnipotent, and thus capable of altering mathematics and the fundamentals of logic.

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It is impossible, Descartes argues here, to distinguish waking experiences from those in dreams. Dreams can be vivid and convincing. Often, we do not realise that the experiences that we took to be real were dreamed until we wake up. Whatever experiences we are now having, then, might turn out to be dreams; we could wake up at any second. We could always be dreaming and wake up at any ssecond, how can we be sure that any of this is real.

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Time Lag Argument

How we can be sure is something is really there or not? A good example is stars. When we look up at the night sky we know that some stars are billions of miles away, we also know that the speed of light would take a while to travel this long distance. This means that the star we are looking up could have xploded or burnt out hundreds of years ago, but the speed of light still hasn't covered the distance to our perception so it looks as if the star is really there when it is not. We can never be sure what exists and what doesn't if we trust our perceptions.

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Scientific Descriptions

Sciene can explain many of the above arguments, the stick in the glass of water, sicence says, is due to the refraction and bending of the light. The time lag is due to the speed of light not being fast enough. Everythign takes up space so there can't be an external world where everything exists that does not exists independent of our minds. No such 'place' has been found. Sub atomic science can explain many philosophical questions.

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