the limits of knowledge

Question 1

difference between philosophical scepticism and normal incredulty

Answer 1

normal incredulity’ or ‘ordinary doubt’= unsure whether a friend’s birthday is the 17th or the 18th of August
philosophical doubt = casts uncertainty over pretty much everything we think we know, e.g descrates evil demon, brain in a vat etc

Question 2

what is ‘brain in a vat’

Answer 2

If all your experience is just electrical signals interpreted by your brain, then you wouldn’t be able to tell the difference if you were a disembodied brain in a vat being fed these same electrical signals artificially.

Question 3

what is descartes global scepticim

Answer 3

the evil demon

Question 4

the aim of descartes evill demon

Answer 4

undermines our usual justification
* I know that 2 + 2 = 4”
* Nope, the evil demon is messing with you again. 2 + 2 actually equals 5 and each time you add the two numbers together, the evil demon messes with your mind and makes you think the answer is 4

Question 5

what does the global sceptic believe

Answer 5

all knowledge is impossible

Question 6

descartes own response to the global sceptic [evil demon]

Answer 6

1. Descartes’ cogito argument shows that, even if he is being deceived by the evil demon, he can at least be certain of the proposition “I exist”.
2. Descartes then goes on to argue that he can also know that God exists
3. Having established that God exists, and that God would not allow him to be globally deceived, Descartes concludes that he can trust his perceptions and so he can trust that the external world exists.
   If Descartes can trust his perceptions, then his perceptions justify his knowledge of ordinary propositions, and thus Descartes has defeated global scepticism.

Question 7

russel’s response to the global sceptic [evil demon]

Answer 7

Either:
* A: the external world exists and causes my perceptions
* B: an evil demon exists and causes my perceptions
1. I can’t prove A or B definitively
2. So, I have to treat A and B as hypotheses
3. A is a better explanation of my experience than B
4. So, mind independent objects exist and cause my perceptions

Question 8

response to russels response

[descartes whole point]

Answer 8

We can respond, however, that the fact we can’t prove A or B definitively was Descartes’ whole point! Descartes wasn’t trying to prove the evil demon does exist, he was saying that it was possible – i.e. that it was a viable hypothesis – and so we can’t trust our ordinary knowledge.

Question 9

russell’s response to crit that ‘that was descrates whole point’

Answer 9

**the possibility of the evil demon hypothesis does not mean knowledge is impossible. **
Just because we can’t know for certain that we’re not being deceived by an evil demon, that does not mean we can’t have knowledge.
* Descartes is assuming an infallibilist definition of knowledge here – he’s assuming that we have to know we’re not being deceived by an evil demon in order to have knowledge.
* Russell could respond that certainty is not necessary: Sure, we might be being deceived by an evil demon and we can’t know either way, but as long as we’re not being deceived and our beliefs are true then our ordinary (uncertain) justifications are sufficient for knowledge.

Question 10

another crit of russells arg that the ext. wrld is the best hypothesis

Answer 10

dispute that the external world is the best hypothesis at all. If we are being deceived by an evil demon, or are in the matrix, or are brains in vats, then our experience would appear exactly the same to us as if it was caused by the external world. Thus, we have no grounds to prefer one hypothesis over the other: The available evidence supports both hypotheses equally.

Question 11

what are lockes responses to the sceptical challenge

Answer 11

1. perception is involuntary
2. perception is coherent

Question 12

explain perception is involuntary

Answer 12

unable to avoid having certain sense data produced in his mind when he looks at an object. By contrast, memory and imagination allows him to choose what he experiences. Locke concludes from this that whatever causes his perceptions must be something external to his mind as he is unable to control these perceptions.

Question 13

explain coherence of the senses

Answer 13

, Locke argues that the different senses confirm the information of one another. For example, you can write something on a piece of paper and see the words. Then, you can get someone to read the words out loud and thus hear the same information via a different source.

Question 14

response to lockes arg that perception is involuntary

Answer 14

even though Locke succeeds in proving something external is causing his perceptions,he doesn’t succeed in proving that this perception is in any way an accurate representation of the external world. The external something that is causing his (involuntary) perceptions could be an evil demon that is deceiving him.

Question 15

response to lockes arg that perception is coherent

Answer 15

Just because our different senses are coherent, it doesn’t do much to prove they are representative of reality. An evil demon could create coherent experiences – e.g. he could deceive you into hearing dogs barking at the same time as seeing dogs – and there is no way you could tell otherwise. The evil could just be creating coherent sound and visual perceptions.

Question 16

why doesnt the evil demon present a threat to Berkelys idealism

Answer 16

• The evil demon argument never really gets going against idealism because idealism doesn’t make a distinction between perceptions and reality
• idealism rejects mind-independent objects right off the bat

Question 17

how does berkeley use idealism to respond to global scepticism

Answer 17

argues that his perceptions must be caused by something outside of him and, given the** complexity of these perceptions**, Berkeley concludes that this cause must be the mind of God. Berkeley’s theory of perception here is almost like a benevolent version of the evil demon: God is causing his perceptions but, rather than being a deception, those perceptions just are what reality is.

Question 18

what does reliablism say about knowledge [and how does this relate to the evil demon]

Answer 18

says that knowledge is true belief formed via a reliable method. Assuming I’m not being actually deceived by an evil demon, then my perception would count as a reliable method of gaining knowledge because my perceptions reliably cause me to form true beliefs.

Question 19

what does reliablism say about proving whether im being decieved by an evil demon

Answer 19

Of course, I can’t prove either way whether I’m being deceived by an evil demon – but that doesn’t matter. I don’t have to know my perception is reliable in order for it to count as a reliable method – it just is. Consider the following two scenarios: Scenario 1: I am not a brain in a vat, Scenario 2: I am a brain in a vat

Question 20

explain scenario 1 in reliablims

not a brain in a vat

Answer 20

1. My perception is a reliable method because I’m living in the real world and am perceiving it accurately
2. My perception leads me to the belief “I have hands”
3. My belief is true, because this is scenario 1 and I’m not a brain in a vat
4. So I have a true belief formed via a reliable method that “I have hands”
5. So, according to reliabilism, I know “I have hands” in scenario 1 (so, if you’re not actually a brain in a vat, you can know “I have hands”)

Question 21

explain scenario 2 in reliablims

i am a brain in a vat

Answer 21

1. My perception is not a reliable method because I’m a brain in a vat being fed artificial stimuli
2. My perception leads me to the belief “I have hands”
3. But my belief is false, because this is scenario 2 and I’m actually a brain in a vat
4. So I have a false belief formed via an unreliable method that “I have hands”
5. So, according to reliabilism, I do not know “I have hands” in scenario 2 (which would be correct – you don’t want a definition of knowledge that says you know you have hands when you don’t have hands)

Question 22

aim of scenario 1 and 2

brain in a vat, brain not in a vat

Answer 22

The point is: If we’re in scenario 1, then we can have knowledge of ordinary propositions such as “I have hands”.

Yes, we can’t know whether we’re in scenario 1 or 2, and so we can’t know that we know such propositions – but we don’t have to. You can know something without knowing that you know that thing.

Assuming we’re not in some weird sceptical scenario like the evil demon or brain in a vat, then knowledge is possible if ‘knowledge’ is defined as true belief formed via a reliable method. If I am not a brain in a vat, then my perception is as a reliable method and so I can know ordinary propositions such as “I have hands”.

Question 23

response to reliabilms as a reponse to global scepticism

other defs.

Answer 23

However, the sceptic can respond that reliabilism is not the correct definition of knowledge (e.g. because of fake barn county). If we go with some other definition of knowledge – such as infallibilism or justified true belief – then we can’t provide proper justification for ordinary knowledge because we can’t justify that we’re not in some sceptical scenario. So, if any of the other definitions of knowledge are correct, I cannot know “I have hands” without first defeating the sceptical challenge and we’re back to square 1.