Skepticism

what is skepticism

• The view that many/ most of the things that we take ourselves to know we do not in facts know 

what is a global skeptic

• A global skeptic will maintain that we do not know anything 

what is a local skeptic

• A local skeptic will maintain that we don't know any truths within some particular domain 

what do most arguments for skepticism appeal to

Most arguments for skepticism appeal to various possible skeptical scenarios 

examples of skeptical scenarios

• For example: Descartes imagined that he was being deceived by an evil demon and he believed that his experiences were manipulated by the demon so that they misrepresented reality  

• Or we might consider the possibility that instead of being embodied beings sitting in the room that we’re in, instead we’re brains in vats which are being stimulated so that it seems to us that we’re sitting in a room etc.

What is notable about skeptical scenarios

The first thing to note about these scenarios is that, in some sense, they seem possible 

• In principle nothing is stopping the scenarios from being possible 

• Certainly, while there aren’t in fact such brains in vats, there could be brains in vats that were stimulated so that they had experiences as of being embodied agents living in the world 

how do skeptics use skeptical scenarios

The skeptic starts from the thoughts that there are such possible skeptical scenarios and tires to use this fact to argue that we do not know certain facts

What is the structure of Skeptical Argument 1

• (P1) If in a situation S1 you have exactly the same evidence as in situation S2, then you know P in S1 just in case you know P in S2

  • If your evidence is the same then your knowledge is the same

• (P2) In the brain in a vat scenario (BIV) you have exactly the same evidence as the actual situation A

• (P3) In the BIV you do not know that you are sitting in a room 

  • Factivitity- attitudes that are truth entailing

  • As long as knowledge is factive P3 is true

• (C) In A you do not know that you are sitting in a room

The argument is valid. That is, if the premises are true then the conclusion is guaranteed to be true 

Is Skeptical Argument 1 sound? What is the first consideration?

• (P2) In the brain in a vat scenario (BIV) you have exactly the same evidence as the actual situation A

  • To reject P2, then, you must maintain that you do in fact have different evidence in (A) than you do in (BIV)

  • In the good case (A), there are propositions that are part of your evidence that aren’t part of your evidence in the bad case (BIV)

    • You should naturally have more evidence in the good case (A)

  • But this difference in your evidence is, in some sense, not something that you can tell when you’re in the bad case 

what is another consideration for the soundness of skeptical argument 1

• (P1) If in a situation S1 you have exactly the same evidence as in situation S2, then you know P in S1 just in case you know P in S2

  • You can have more knowledge in the good case because the world is cooperating on the basis of having the same body of evidence 

  • To deny P1 we would need to maintain that there is something, in addition to you evidence, that determines whether or not you know something 

what is Fallibilism

•  you can know P even if your evidence if your evidence is compatible with the falsity of P 

how is fallibilism related to skeptical argument 1

• Fallibilist denies P1

  • You can have two agents in the same evidential situation but one can get more knowledge than the other

  • They will allow you to have the same evidence in BIV and A. The evidence that you have is compatible with both scenarios

  • Thus the evidence that you have is compatible with the claim that you are sitting in the room and with the claim that you are a brain in a vat

  • Nonetheless, according to the fallibilist, the evidence suffices for knowing that we’re sitting in this room, when we have evidence and, in fact, we are sitting in this room 

what are two ways to resist the first skeptical argument

1. We can reject P2 by maintaining that we have different bodies of evidence in (BIV) and (A)

2. Or, we can reject P1 by maintaining that, although we have the same evidence in the tw scenarios, when we’re in the good case, we do have knowledge that we’re sitting in this room 

what are the two prima facie plausible ideas that are maintained that seem to lead to a skeptical conclusion

• (i) if two scenarios are subjectively indistinguishable, then one’s evidence is the same in both 

• (ii) if you have the same evidence in two scenarios then you know the same things in the two scenarios

what is skeptical argument 2

(P1) If you know P, and you know: if P then Q, then you know Q

-(P2) You know that if you have hands then you are not a brain in a vat 

-(P3) You do not know that you are not a brain in a vat 

(C) You do not know that you have hands 

why is premise 1 of skeptical argument 2 plausible

(P1) If you know P, and you know: if P then Q, then you know Q

- this seems quite plausible. Now we might worry about cases in which you haven’t done the appropriate deduction etc. But let’s assume that you have in this case

- Then this principle would seem to say that we can always extend our knowledge by deducing the known consequences of things that we know, That seems plausible

why is premise 2 of skeptical argument 2 plausible

(P2) You know that if you have hands then you are not a brain in a vat 

- The claim that: if you have hands, then you are not a brain in a vat, is just an obvious truth. Since we aren’t global skeptics, it wouldn’t seem like there’s any good reason to deny this 

- you know that you are an embodied creature 

why is premise 3 of skeptical argument 2 plausible

(P3) You do not know that you are not a brain in a vat 

• How would you know this? By looking around? But everything would look the same if you were a brain in a vat 

  • Trying to show that this isn’t a stable combination 

• We can bolster the case for P3 by appealing to the notion of epistemic sensitivity 

what is epistemic sensitivity

• We say that a belief that P is sensitive just in case were P not true you would not believe P 

• Counterfactual examples would have normal conditions and would retain normal everyday beliefs- so acquisition of knowledge would be the same 

what is sensitivity

Sensitivity: If A knows that P, then A’s belief that P is sensitive

How does the example of fake barn country relate to sensitivity

f I’m looking at a real barn it seems plausible that it doesn’t amount to knowledge 

• Belief that you are looking at a barn is not sensitive- even if it were false you would still have the belief that you are looking at a real barn- you know you are wrong but still have the belief 

how does sensitivity disprove that I am not a brain in a vat

ssuming sensitivity, it follows that I do not know that I/m not a brain in a vat 

• Suppose that if you were a brain in a vat what would you believe- you would have all the same beliefs- you don’t count as being sensitive- sensitivity is necessary for knowledge therefore you do not have knowledge 

• For if I were a brain in a vat, I would still believe (falsely) that I am not a brain in a vat 

• But note that even though this is true, I can still count as knowing that I have hands, since this belief is sensitive

why is denying P2 not a live option

If then we are to resist the skeptical argument we must either:

• (i) Allow that there are some cases in which A knows P and A knows that if P then Q and yet A does not know Q (even though A may competently deduce Q from P)

• (ii) Allow that you can rule out being a brain in a vat just by looking, despite the fact that that’s how things would look were you a brain in a vat 

what is the Moorean response

• How do I know I’m not a brain in a vat?

  • Well, look, here’s one hand, here’s another- since I have hands, it follows that I’m not a brain in a vat 

what is closure

• If A knows P, and A knows if P then Q and A competently deduces Q, then A knows Q

how does Moore appeal to the principle of closure

• While the skeptic appeals to this principle to argue that we don’t know that we have hands, Moore turns the argument on its head and uses this principle to argue that we do know that we are not brains in vats 

how do Moore and the Skeptic agree

They agree about the following: either (i) we know that we have hands and that we aren’t brains in vats, or (ii) we don’t know that we have hands, and we don’t know that we aren’t brains in vats

What does Moore think is obvious

• Moore though takes it as completely obvious that we know that we have hands 

  • No argument according to Moore should convince us that this isn’t true. For any such argument must appeal to premisses that are less plausible than the claim that we know that we have hands 

what are moorean propositions

•  like basic beliefs- propositions that other propositions appeal to- doesn’t stand in need of further justification