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Infallible Justification

Markus Lammenranta

Humanistinen tiedekunta / Markus Lammenranta / Infallible Justification 1


• S may be justified in believing that p even if

• p is false.

• S’s evidence e does not entail p.

• P(p | e) ˂ 1.

• Three problems of fallibilism:

1. The Gettier problem: S has a justified belief that is true by mere luck.

‒ Knowledge = true and justified belief

2. The lottery paradox: I am justified in believing about each ticket that it will not win, but I am also justified in believing that one of them will win.

3. The Cartesian Problem: There are alternatives to p (error-possibilities) that e does not rule out.

2Humanistinen tiedekunta / Markus Lammenranta / Infallible Justification

Fallibilism


• S is justified in believing that p if and only if

• e entails p (e guarantees that p is true).

• P(p | e) = 1.

• Knowledge = justified belief.

• The problems of fallibilism are avoided.

1. If justification entails truth, there cannot be justified beliefs that are true by luck or accident.

2. I am not justified in believing about any of the tickets that it will not win (I don’t know that it will not win).

3. e rules out all alternatives to p (all possibilities of error).


Infallibilism


A Brain in a Vat



1. If I am justified in believing that I have hands, I am justified in believing that I am not a BIV.

2. I am not justified in believing that I am not a BIV.

3. So I am not justified in believing that I have hands.

• The Justification Closure: If S is justified in believing that p and S knows that p entails q, S is justified in believing that q.

• Paradox: {1, 2, ~3}

The skeptical paradox


• Internalism: S’s justification for believing that p is constituted solely by S’s (non-factive) mental states or by facts that S can know by reflection alone.

• The New Evil Demon Thesis: I have the same evidence in the good case (in which I have hands) and the bad case (in which I am BIV).

• BIV = 

• e = <it appears to me that I have hands>

1. BIV e

2. e

3. So BIV


Evidential Internalism (Fallibilism)

1. E = K: p is a part of S’s evidence if and only if S knows that p.

• T. Williamson

2. Evidence for perceptual beliefs consist of factive mental states.

• Seeing that p entails p.

• J. McDowell, R. Neta, (D. Pritchard)

• The New Evil Demon Thesis is false.

• The good case: e = (Williamson)

e = (McDowell)

• The bad case: e = <It appears to me that I have hands>

• In the good case, my evidence entails that I hands and that I am not a BIV.


Evidential Externalism (Infallibilism)


1. New evil demon intuition

2. Reflective access

3. The barn façade case

4. Skeptical intuitions

5. Inductive justification (knowledge)

Problems of evidential externalism



• The extent to which I am justified in believing that p is just the same as the extent to which my recently envatted internal twin is justified in believing that p.

1. We are equally responsible in our beliefs.

• It is equally understandable, excusable and blameless that we believe as we do.

2. We are equally rational in our beliefs.

• Only I am justified in believing what I do believe.

• How does justification differ from these other properties?


1. The New Evil Demon Intuition


• S is justified in believing that p if and only if S can answer appropriate challenges to p (by giving reasons for p).

• I am justified in believing that I have hands because I can give as my reason the fact that I see that I have hands.

• My envatted twin cannot give this as his reason because there are no such reason in the bad case. So he is not justified in believing that he has hands.

• Knowledge requires justification rather than just responsibility or rationality.

• E. Craig: the point of the concept of knowledge is pick out good informants.

• The question “How do you know?” presupposes that you can answer it by giving reasons.


The Dialectial Conception of Justification

• I have perceptual justification for believing that p if and only if my evidence for p is both factive and reflectively accessible to me.

• Neta, Pritchard, McDowell

• If I cannot know by introspection that I have hands, I cannot know by introspection that I see that I have hands.

• entails .

• Furthermore, the good case, in which I have such factive evidence, and the bad case, in which I have not, are introspectively indistinguishable.


Reflective Access


1. It appears to me that I have hands.

• I am introspectively aware of this.

2. If it appears to me that I have hands, I have hands.

• When I form the belief that I have hands on the basis of its appearing to me that I have hands, I presuppose this.

I can cite as my evidence not only that it appears to me that I have hands but that I see that I have hands.


Access and the Dialectical Conception of Justification


• When we form beliefs, defend them and challenge others to defend their beliefs, we typically presuppose that the relevant cognitive abilities are reliable and that they are used in favorable conditions.

• Reliability: My vision is reliable

• Safety: If it visually appeared to me that p, p would be true.

• The barn façade case

• What counts as evidence depends on what is presupposed in the context of attribution (of evidence).

• In the context, in which the BIV hypothesis is taken seriously, it is not presupposed that my vision is reliable. In that context, I do not have as my evidence that I see that I have hands. I have only the evidence that it appears to me that I have hands, and this evidence does not justify me in believing that I am not a BIV.

‒ This explains the skeptical intuition that I am not justified in believing that I am not a BIV: it is true in this skeptical context.


Presuppositions and Epistemic Contextualism


(1) Emerald 1 is green.

(2) Emerald 2 is green.

. . .

(n) Emerald n is green.

So all emerald are green.

• The argument shows that all emeralds are green.

• The presupposition: ‒ The uniformity of nature: The sample represents the population (the

unobserved cases resemble the observed cases).

‒ The reliability and safety of inductive reasoning

• Grue = green when observed before now but blue when not yet observed


Inductive Justification

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