limits of knowledge Flashcards
what is the differences between philosophical scepticism and normal incredulity
-in our everyday lives we doubt things all the time. eg, a friends birthday, wether its going to rain, this is ‘ordinary doubt’.
- philosophical doubt goes beyond ordinary doubt and questions everything we know.
1) it is extreme
philosophers doubt things which are near impossible to doubt in ordinary life eg. wether or not your hands really exist
2) is is not sensitive to evidence
in ordinary doubt we might consult a textbook, or the internet. but philosophical doubt would say that all textbooks are wrong. the doubt is immune to evidence.
3) it remains theoretical
in ordinary life doubts have a real implication, eg. if you doubt a friend will be on time you may leave later. but when philosophers doubt they may still hold the belief to be true. when a philosopher doubts the existence of physical objects it doesn’t imply that they don’t think they are real.
what is the role of philosophical scepticism
- the role of philosophical scepticism is to determine what, if anything, we can know
- its used to test the strength of our knowledge claims
- used to understand what underlies our most fundamental beliefs
- by defeating sceptical arguments, people have tried to clarify what we can and can’t know and to establish the certainty to which we can claim knowledge
what is local and global scepticism
local scepticism concerns some particular and restricted domain of knowledge but does not raise doubts about knowledge as a whole.
global scepticism are radical arguments that lead to ‘universal’ scepticism, they threaten to undermine the whole of our belief system.
what are descartes three waves of doubt
1) illusion - my senses have deceived me before, so I can doubt the reliability of them. the possibility of perceptual error is sufficient to lead him to doubt the whole of sense experience
2) dreaming - we can have dreams which are just like being awake. so if I can have dreams in which I think I am awake, how can I be sure I am not dreaming right now? this possibility means that any belief drawn from what he is perceiving around him may be false.
3) deception - the evil demon argument. an evil demon may be controlling my entire experience, using all his energies to deceive us about the existence of the physical world. there is no way I would be able to tell the difference if the evil demon scenario is true, therefore casting doubt on everything I know.
global scepticism
what is descartes own response to scepticism?
Descartes attempts to prove the external world by showing that his sensations of objects must be caused by the external world
Cogito - ‘I think therefore i am’ proves he exists
Trademark/ontological/cosmological - proves god exist
- his first argument says that sensations come from outside him because a will is apart of my essence and sensations are not subject to my will, showing they are external
- the second part of his argument says that sensations originate from matter because the origin of sensation can only come from either god or matter, and I have a natural strong inclination to believe they come from matter, so if their origin were god, god would be a deceiver. but god is not a deceiver, so sensation originates in matter
what is Lockes empiricist response of the external world to scepticism
- he also provides arguments for the coherence of our senses, and that perception is involuntary
- our senses are coherant and back each other up, e.g. touch backs up sound when knocking on a table, like two witnesses giving the same description of someone, would be extremly coincidental if the different senses of touch and sound agreed about the geometric properties of non-existent external world
- my sensory experience is involuntary, we cannot control what we see or hear e.g. if someone is talking to you, you have to listen to them. the fact that i cannot control what sensations i experience suggests that they must be made by some exterior cause
what is Russells response to scepticism
- russel recognises that we cannot demonstrate the existence of the external world
- however he noted that we cannot prove that it doesn’t exist either
- we are presented with a choice - that we accept that it does exist or it doesn’t
- russel says the physical world is the best hypothesis
- the existence of a physical world can explain why our sense experience behaves in regular and predictable ways eg. an apple left in a drawer will rot because it physically exists and has undergone a transformation whilst not being perceived
- on the other hand, the alternative hypothesis provides no explanation for my experience
what is berkleys response to scepticism
- berkleys idealism rejects mind-independent objects right off the bat
- so sceptical scenarios where mind-independent objects don’t exist aren’t possible
- the evil demon argument doesn’t work for idealism because idealism doesn’t make a distinction between perceptions and reality and the evil demon argument is based on the fact that the demon is intercepting reality and perceptions
- Berkley argues that his perceptions must be caused by something outside of him, and because of the complexity of these perceptions that thing must be god
- god is causing our perceptions, but rather than being a deception, it is just exactly what reality is like
explain the reliabilism response to spepticism
- knowledge is a true belief formed by a reliable method
- assuming I’m not being deceived by an evil demon, my perception counts as a reliable method of forming knowledge
- I can’t prove that im being deceived by an evil demon, but that does not matter - you don’t need to justify your knowledge
- I don’t have to know my perception is reliable in order for it to count as as a reliable method
- reliabilism denies that we need justification for our beliefs, so scepticism cannot get off the ground
- what about a brain in a vat scenario?
- as far as reliabilism is concerned, although I cannot tell whether I am a brain in a vat or not, this does not show that I do not have knowledge of the world
- if I am in a normal world, then my beliefs about the physical world are produced by a reliable process and so count as knowledge
- so reliabilism shows that we can have knowledge of the world, despite global scepticism
