Limits of knowledge Flashcards
What’s global scepticism
Scenarios in which everything you believe could be false and there’s no way of knowing, giving us reason to doubt any and all beliefs. e.g Brain in a vat, the matrix.
ordinary doubt vs Philosophical doubt
ordinary doubt/normal incredulity is doubting a specific claim or group of claims in everyday life e.g doubting your memory of a fact like ‘London is the capital of England’
Philosophical doubt is doubting basically everything we think we know because of global sceptic scenarios like brain in a vat or descartes evil demon.
whats the brain in the vat
Scenario of global scepticism where all your experiences could be just electrical signals interpreted by your brain. for example, you may think ‘I’m walking to the shop’ but in reality you’re just a brain in a vat being fed electrical signals making it feel like you’re walking to the shop, making this belief false.
Descartes evil demon- why can’t we solve global scepticism like we can with ordinary doubt
In ordinary doubt, you can resolve it by e.g searching the internet for the country England and seeing that the capital is London, you can then be confident that this belief is true. But global scepticism, descartes evil demon, can place uncertainty over basic propositions,going beyond ordinary doubt. If all my experience is an illusion an evil demon is creating, I cant trust the internet, visual perception, or even that England exists.
Descartes evil demon - why is any knowledge impossible
Any ordinary knowledge can be doubted - Saying I know 1+1=2 could be false - the evil demon is making you believe the answer is 2 when it’s actually 4.
The evil demon places doubt on anything we can count as knowledge, we could constantly be wrong and not know it meaning any knowledge is impossible.
whats Descartes own response to scepticism
after Descartes established that god exists (trademark argument) God would not allow him to be globally decieved as he’s perfect by defenition, meaning he can trust his perceptions. His perceptions justify his knowledge of ordinary propositions and so therefore can know his knowledge is true, overcoming global scepticism.
Russell’s response to scepticism
External world is the best hypothesis, adjusted to evil demon -
A: Either the external world exists is the cause of my perceptions
B: An evil demon exists and is the cause of my perceptions
I can’t prove A or B definitely and so I have to treat them as hypotheses
A is the better explaination for my experience and so mind-independent objects exist and is the cause of my perceptions.
Locke’s responses to scepticism
-Perception is involuntary and I can’t choose what I hear or see therefore the cause of my perceptions must be external
-Different perceptions are coherent (sight and touch) I can touch water with my hand to confirm what I see with my eyes, suggests a common reality that is the cause of both perceptions
whats Berkeley’s response to scepticism
Berekely doesnt believe there’s a distinction between reality and perceptions, the idea that you’re percieving something different to reality doesn’t work because ideas are reality.
However Berekely is aware his perceptions must be caused by something external and given the complexity of them it must be god. God cant be decieving his perceptions because these ideas are reality.
Reliablist response to scepticism - Brain in a vat
A true belief is formed by a reliable method and so assuming I’m not a brain in a vat, then my perceptions count as a reliable method to gaining knowledge whether we know it or not.
Reliablist response to scepticism - Brain in a vat scenario 1
Scenario 1: I am not a brain in a vat
- My perception is reliable because I’m in the real world and I’m correctly percieving it
- My perception gives me the belief ‘I have legs’
-My belief is true because this is scenario 1 and I’m not a brain in a vat
-So I’ve formed a true belief by a reliable method that ‘I have legs’
- So, I know I have legs in scenario 1
Reliablist response to scepticism - Brain in a vat scenario 2
I am a brain in vat
-My perception isn’t a reliable method because I’m a brain in a vat being fed electrical signals
-My perception gives me the belief ‘I have legs’
-But my belief is false because I’m a brain in a vat in scenario 2
-So I’ve formed a false belief from an unreliable method that I have legs
-So, I do not know I have legs in scenario 2
Reliablist response to scepticism - Brain in a vat conclusion
We don’t have to know if we’re in scenario 1 or 2, if we are in scenario 1, then we have knowledge of ordinary propositions like I have legs, because our perception is a reliable method. As long as we’re not in a scenario such as brain in a vat or the evil demon, then we dont have to know that we know of such propositions. Knowledge is true if it’s a justified belief formed by a reliable method.
