笔记：SEP“Disagreement”词条

1. Disagreement and Belief

Disagreement: Two individuals disagree about a proposition when they adopt different doxastic attitudes (or credence) toward the same (factive) proposition.

2. Questions about Disagreement

Response Question: Suppose you realize that some people disagree with your belief B. How must you respond to the realization in order for that response to be epistemically rational (or perhaps wise)?

Belief Question: Suppose you realize that some people disagree with your belief B. How must you respond to the realization in order for your subsequent position on B to be epistemically rational?

Here are the questions for agreement/disagreement plus levels of conviction:

Response Question*: Suppose you realize that some people have a confidence level in B that is different from yours. How must you respond to the realization in order for that response to be epistemically rational (or perhaps wise)?

Belief Question*: Suppose you realize that some people have a confidence level in B that is different from yours. How must you respond to the realization in order for your subsequent position on B to be epistemically rational?

3. Response to Disagreement vs. Subsequent Level of Confidence

接受新证据后改变我们的信念是很重要的：One can start out with an irrational belief, obtain some new relevant evidence, respond to that new evidence in a completely reasonable way, and yet end up with an irrational belief. This fact is particularly important when it comes to posing the central questions regarding the epistemology of disagreement (Christensen 2011).

Action of maintaining his confidence in his belief as a result of his new knowledge is reasonable even though his retained belief itself is unreasonable.

Two questions about the acquisition of new information:

• Intellectual Action Question: After you acquire some new information relevant to a certain belief B of yours, what should your new level of confidence in B be in order for your new level of confidence regarding B to be rational?
• Subsequent Level of Confidence Question: After you acquire some new information relevant to a certain belief B of yours, what should your new level of confidence in B be in order for your response to the new information to be rational?

4. Disagreement with Superiors, Inferiors, Peers, and Unknowns

Disagreement Factors (Frances 2014):

• cognitive ability had while answering the question
• evidence brought to bear in answering the question
• relevant background knowledge
• time devoted to answering the question
• distractions encountered in answering the question
• relevant biases
• attentiveness when answering the question
• intellectual virtues possessed

Two peers need not be equal on each Disagreement Factor.

If I have the view that if it turns out that she really thinks B is false then the odds that I’m right and she’s wrong are 95%, then in some sense my view is that she’s not “fully” my peer on B, as I think that when it comes to the possibility of disagreement I’m very confident that I will be in the right and she won’t be.

Better Position Question: Are the people who disagree with B in a better epistemic position to correctly judge the truth-value of the belief than the people who agree with B?

Better Position Question*: Are the people who have a confidence level in B that is different from yours in a better epistemic position to correctly judge the truth-value of the belief than the people who have the same confidence level as yours?

The Better Position Question is often not easy to answer. For the majority of cases of disagreement, with X realizing she disagrees with Y, X will not have much evidence to think Y is her peer, superior, or inferior when it comes to correctly judging B.（这就是我之前说的，是不是peer这件事本身就很难确定。）

5. Peer Disagreements

Two fools could be peers. However, the literature on peer disagreement has instead focused on disagreement between competent epistemic peers.

5.1 The Equal Weight View

The Equal Weight View is a combination of three claims:

1. Defeat: Learning that a peer disagrees with you about P gives you a reason to believe you are mistaken about P.

2. Equal Weight: The reason to think you are mistaken about P coming from your peer’s opinion about P is just as strong as the reason to think you are correct about P coming from your opinion about P.

3. Independence: Reasons to discount your peer’s opinion about P must be independent of the disagreement itself.

Three broad kinds of support for EWV:

(1) The central case that has been used to motivate the Equal Weight View is Christensen’s Restaurant Check Case.

(2) Theoretical support for the Equal Weight View comes from first thinking about ordinary cases of testimony.

This helps motivate Defeat, since a reason to believe the proposition when you disbelieve it amounts to a reason to believe that you have made a mistake regarding that proposition.

Equal Weight is also motivated by considerations regarding testimonial evidence. The weight of a piece of testimonial evidence is proportional to the epistemic position of the testifier (or what the hearer’s evidence supports about the epistemic position of the testifier).

Finally, Independence has been theoretically motivated by examining what kind of reasoning its denial would permit. In particular, a denial of independence has been thought to permit a problematic kind of question-begging by allowing one to use one’s own reasoning to come to the conclusion that their peer is mistaken.

The Equal Weight View has also been motivated by way of analogies (thermometers).

5.2 The Steadfast View

5.2.1 Denying Defeat

Defeat has been rejected by defenders of the Steadfast View in a number of ways. First, Defeat has been denied with an appeal to private evidence. Peter van Inwagen (1996) has defended the Steadfast View by maintaining that in cases of peer disagreement one can appeal to having an incommunicable insight or special evidence that the other party lacks.

A related argument is made by Huemer (2011), who argues for an agent-centered account of evidence. On this account, an experience being your own evidentially counts for more than someone else’s experience. So, with this conception of evidence in hand there will be an important evidential asymmetry even in cases where both parties share all their evidence.

Defenders of the Equal Weight View have noted that these considerations cut both ways (see Feldman 2006). 大意：如果有asymmetry那就不是peer了。

Second, Defeat has been denied by focusing on how things seem to the subject. Plantinga (2000a) has argued that there is a sense of justification that is simply doing the best that one can. There is an important phenomenological difference between the two peers—different things seem true to them. Plantinga claims we can do no better than believe in accordance with what seems true to us.

Third, Defeat has been denied by denying that peer opinions about P are evidence that pertains to P. Kelly (2005) distinguishes the following three claims:

1. Proposition P is true.

2. Body of evidence E is good evidence that P is true.

3. A competent peer believes P on the basis of E.

Kelly (2005) argues that while 3 is evidence for 2 it is not evidence for 1. If 3 is not evidence for 1, then in learning 3 (by discovering the peer disagreement) one does not gain any evidence relevant to the disputed proposition.

Why think that 3 is not evidence for 1? First, when people cite their justification for their beliefs, they do not typically cite things like 3. We typically treat the fact that someone believes a proposition as the result of the evidence for that proposition, not as another piece of evidence for that proposition. Second, since people form beliefs on the basis of a body of evidence, to count their belief as yet another piece of evidence would amount to double-counting that original body of evidence.

Finally, Defeat has been denied by appealing to epistemic permissiveness.

Defenses of the Equal Weight View either defend the Uniqueness Thesis (see Dogramici and Horowitz 2016, Greco and Hedden 2016, Matheson 2011, White 2005, White 2013) or argue that the Equal Weight View is not actually committed to evidential uniqueness (see Christensen 2009, Christensen 2016, Cohen 2013, Lee 2003, Levinstein 2017, Peels and Booth 2014, and Henderson et al 2017).

5.2.2 Denying Equal Weight

The Steadfast View has also been motivated by denying Equal Weight. A related and more plausible defense comes from appealing to self-trust.

Opponents have rejected the epistemic importance of the first-person perspective (see Bogardus 2013b and Rattan 2014). While the first-person perspective is ineliminable, it is not infallible. Further, there are reasons from the first-person perspective to make doxastic conciliation. It is my evidence the supports that my interlocutor is my peer and my evidence about what she believes which call for doxastic change. So, conciliation can be seen to be called for from within the first-person perspective. Besides, most maintain that when the novice learns that the expert disagrees he should make some doxastic movement if not completely defer.

5.2.3 The Right Reasons View

First-Order Evidence: First-order evidence for P is evidence that directly pertains to P.

Higher-Order Evidence: Higher-order evidence for P is evidence about one’s evidence for P.

The Right Reasons View is a steadfast view of peer disagreement that emphasizes the role of the shared first-order evidence in peer disagreements.

Following Kelly (2005) we can represent the discovery of a peer disagreement as follows:

• At t, my body of evidence consists of E (the original first-order evidence for P).
• At t′, having discovered the peer disagreement, my body of evidence consists of the following:

i. E (the original first-order evidence for P).

ii. The fact that I am competent and believe P on the basis of E.

iii. The fact that my peer is competent and believes not-P on the basis of E.

According to the Right Reasons View, the two pieces of higher-order evidence (ii) and (iii) are to be accorded equal weight. Having weighed (ii) and (iii) equally, they neutralize in my total body of evidence at t’. However, with (ii) and (iii) neutralized, I am left with (i) and am justified in believing what (i) supports.

Responses to Right Reasons View: 1. Kelly (2010) has since rejected the argument, claiming that when a greater proportion of one’s evidence supports suspending judgment some conciliation will be called for. 2. (ii) and (iii) can be seen to together call for a suspension of judgment over whether E supports P.

A more recent defense of the Right Reasons View is found in Titelbaum 2015. On this view a false belief about what attitude is rational does not ‘trickle down’ to affect the rationality of the lower-level belief.

5.3 The Justificationist View

The Justificationist View lies somewhere in between the Equal Weight View and the Steadfast View.

Jennifer Lackey agrees with the Equal Weight View’s verdicts in cases like the Restaurant Check Case, but thinks that not all cases should be handled in this way. Along these lines she gives the following:

Elementary Math. （关于2+2是否等于4的分歧）

In Elementary Math, Lackey finds it implausible that she should become less confident that 2+2=4. The Equal Weight Views gives the wrong verdicts in what we might call cases of ‘extreme disagreement’. If prior to discovering the peer disagreement you are highly justified in believing the soon to be disputed proposition, then upon discovering the peer disagreement little to no conciliation is called for.

The Justificationist View denies Independence. In cases where you first-order evidence strongly supports believing p, this fact can be used to reassess your interlocutor’s epistemic credentials. Independence only permitted information from ‘outside’ the disagreement to affect assessment of peerhood credentials, but here, the fact that your interlocutor disagrees with something you are highly justified in believing give you a reason to discount his opinion on the matter.

Lackey defends the legitimacy of such a demotion due to the existence of personal information. I will always be more aware of my alertness, sincerity, open-mindedness, and so forth, than I will be of my interlocutor. Since in extreme disagreements one party is severely malfunctioning, my personal information makes the best explanation of this fact that it is my peer who is malfunctioning.

The Justificationist View has been criticized in several ways. Some object that high antecedent justification for believing the target proposition can make the relevant difference. Even high antecedent justification can be defeated by new information. Others have agreed that personal information can act as symmetry breaker giving the subject some reason to privilege their own view but deny that such an advantage would be had in suitably idealized cases of peer disagreement (Matheson 2015a).

5.4 The Total Evidence View

The Total Evidence View lies somewhere between the Steadfast View and the Equal Weight View. The Total Evidence View claims that in cases of peer disagreement, one is justified in believing what one’s total evidence supports (Kelly 2010).

On the Equal Weight View, then, the attitude that you are justified in adopting toward the disputed proposition is entirely determined by the higher-order evidence.

According to the Total Evidence View, the first-order evidence must also factor in to what the peers are reasonable in believing.

Kelly gives the following case to motivate the view:

Bootstrapping. At time t0, each of us has access to a substantial, fairly complicated body of evidence. On the whole this evidence tells against hypothesis H: given our evidence, the uniquely rational credence for us to have in H is 0.3. However, as it happens, both of us badly mistake the import of this evidence: you adopt a 0.7 degree of belief toward H while I adopt a 0.9 degree of belief. At time t1, we meet and compare notes and we then split the difference and converge on a 0.8 degree of belief. (Kelly 2010, 125–126.)

While the Equal Weight View seems to be committed to the peers being justified in adopting the 0.8 degree of belief in H, Kelly finds such a consequence implausible.

One route of response is deny Kelly’s assessment of the cases (Matheson 2015a). According to this response, given that misleading evidence is evidence nevertheless, it can be argued that the individuals still correctly responded to their total body of evidence.

A second route of response is to emphasize the distinction between the Response Question and the Belief Question. According to this response, while there may be something epistemically defective about the final doxastic states of the individuals in Bootstrapping, they nevertheless had the rational response to the higher-order evidence (Christensen 2011).

5.5 Other Issues

5.5.1 Self-Defeat

A prominent objection to the Equal Weight View and other views that prescribe doxastic conciliation is that such views are self-defeating.

Defenders of these conciliatory views have responded in a number of ways. First, the consequences here for conciliatory views is that given certain contingent circumstances they cannot be reasonably believed, but such an inability to be reasonably believed does not demonstrate their falsity.

Another way such a consequence has been downplayed is by comparing it to other principles that share the same result. (e.g. Minimal Humility).

A final response argues that these principles about disagreement are themselves exempt from their conciliatory prescriptions.

5.5.2 Formal issues

There are difficulties in making precise the Equal Weight View along Bayesian lines. Gardiner (2014) and Wilson (2010) each raise an objection that Equal Weight View violates the principle of commutativity of evidence, which claims that the order of evidential acquisition should not make such a difference.

5.5.3 Actual Disagreement and Possible disagreement

One challenge is to distinguish the epistemic significance of actual peer disagreement from the significance of merely possible peer disagreement.

Christensen (2007) responds to this challenge by noting that while merely possible disagreement only shows that we are fallible, actual disagreement demonstrates that someone has in fact made a mistake. Since we are already aware that we are fallible epistemic agents, thinking about possible peer disagreements does not add any information that calls for (further) doxastic change. In contrast, discovering an actual peer disagreement gives us information that we lacked.

5.5.4 Irrelevance of Peer Disagreement

What are the odds that someone else is in precisely as good of an epistemic position as you on some matter—and even she was, would you know it?

There are several reasons to think about the significance of peer disagreement beyond its intrinsic appeal. First, considering the idealized cases of peer disagreement helps to isolate the epistemic significance of the disagreement itself. By controlling for other epistemic factors, cases of peer disagreement help us focus on what epistemic effects discovered disagreement has. Second, while peers may be quite rare, as we have noted above, it is often not clear which party is in the better epistemic position. These unknown cases may have the same epistemic significance as peer cases.

6. Disagreement By the Numbers

略。

7. Disagreement and Skepticism

So, the phenomenon of disagreement supplies a skeptical threat: for many of our cherished beliefs. It follows that our beliefs we recognize as controversial do not amount to knowledge.