Online research in philosophy

How should you update your (degrees of ) belief about a proposition when you find out that someone else — as reliable as you are in these matters — disagrees with you about its truth value? There are now several different answers to this question — the question of ‘peer disagreement’ — in the literature, but none, I think, is plausible. Even more importantly, none of the answers in the literature places the peer-disagreement debate in its natural place among the most general traditional concerns of normative epistemology. In this paper I try to do better. I start by emphasizing how we cannot and should not treat ourselves as ‘truthometers’ — merely devices with a certain probability of tracking the truth. I argue that the truthometer view is the main motivation for the Equal Weight View in the context of peer disagreement. With this fact in mind, the discussion of peer disagreement becomes more complicated, sensitive to the justification of the relevant background degrees of belief (including the conditional ones), and to some of the most general points that arise in the context of discussions of scepticism. I argue that thus understood, peer disagreement is less special as an epistemic phenomenon than may be thought, and so that there is very little by way of positive theory that we can give about peer disagreement in general.

There is an ancient, yet still lively, debate in moral epistemology about the epistemic significance of disagreement. One of the important questions in that debate is whether, and to what extent, the prevalence and persistence of disagreement between our moral intuitions causes problems for those who seek to rely on intuitions in order to make moral decisions, issue moral judgments, and craft moral theories. Meanwhile, in general epistemology, there is a relatively young, and very lively, debate about the epistemic significance of disagreement. A central question in that debate concerns peer disagreement: When I am confronted with an epistemic peer with whom I disagree, how should my confidence in my beliefs change (if at all)? The disagreement debate in moral epistemology has not been brought into much contact with the disagreement debate in general epistemology (though McGrath [2007] is an important exception). A purpose of this paper is to increase the area of contact between these two debates. In Section 1, I try to clarify the question I want to ask in this paper – this is the question whether we have any reasons to believe what I shall call “anti-intuitivism.” In Section 2, I argue that anti-intuitivism cannot be supported solely by investigating the mechanisms that produce our intuitions. In Section 3, I discuss an anti-intuitivist argument from disagreement which relies on the so-called “Equal Weight View.” In Section 4, I pause to clarify the notion of epistemic parity and to explain how it ought to be understood in the epistemology of moral intuition. In Section 5, I return to the anti-intuitivist argument from disagreement and explain how an apparently-vulnerable premise of that argument may be quite resilient. In Section 6, I introduce a novel objection against the Equal Weight View in order to show how I think we can successfully resist the anti-intuitivist argument from disagreement.

This paper focuses on the question of how to resolve disagreement and uses the Lehrer-Wagner model as a formal tool for investigating consensual decision-making. The main result consists in a general definition of when agents treat each other as epistemic peers (Kelly 2005; Elga 2007), and a theorem vindicating the “equal weight view” to resolve disagreement among epistemic peers. We apply our findings to an analysis of the impact of social network structures on group deliberation processes, and we demonstrate their stability with the help of numerical simulations.

The proportional weight view in epistemology of disagreement generalizes the equal weight view and proposes that we assign to judgments of different people weights that are proportional to their epistemic qualifications. It is shown that if the resulting degrees of confidence are to constitute a probability function, they must be the weighted arithmetic means of individual degrees of confidence, while if the resulting degrees of confidence are to obey the Bayesian rule of conditionalization, they must be the weighted geometric means of individual degrees of confidence. The double bind entails that the proportional weight view (and its moderate adjustment in favor of one’s own judgment) is inconsistent with Bayesianism.

In this paper, I respond to recent attempts by philosophers to deny the existence of something that is both real and significant: reasonable disagreements between epistemic peers. In their arguments against the possibility of such disagreements, skeptical philosophers typically invoke one or more of the following: indifference reasoning , equal weight principles , and uniqueness theses . I take up each of these in turn, finding ample reason to resist them. The arguments for indifference reasoning and equal weight principles tend to overlook the possibility of a certain kind of agnostic credal state which I call deep agnosticism , the possibility of which derails the arguments. The arguments for uniqueness theses tend to invoke a flawed understanding of the evidential support relation. When these problems and misunderstandings are brought into the light and corrected, the threat to reasonable disagreement vanishes.

In this paper, we investigate various possible (Bayesian) precisifications of the (somewhat vague) statements of “the equal weight view” (EWV) that have appeared in the recent literature on disagreement. We will show that the renditions of (EWV) that immediately suggest themselves are untenable from a Bayesian point of view. In the end, we will propose some tenable (but not necessarily desirable) interpretations of (EWV). Our aim here will not be to defend any particular Bayesian precisification of (EWV), but rather to raise awareness about some of the difficulties inherent in formulating such precisifications.

This paper assesses the comparative reliability of two beliefrevision rules relevant to the epistemology of disagreement, the Equal Weight and Stay the Course rules. I use two measures of reliability for probabilistic belief-revision rules, Calibration and Brier Scoring, to give a precise account of epistemic peerhood and epistemic reliability. On the Calibration measure of reliability, epistemic peerhood is easy to come by, and employing the Equal Weight rule in the case of peer disagreement generally renders you less reliable than Staying the Course. On the Brier-Score measure of reliability, epistemic peerhood is much more difficult to come by, but employing the Equal Weight rule in the case of peer disagreement always renders you more reliable than Staying the Course. I conclude with some lessons we can draw from these formal results for the normative issue of rational belief-change in the face of peer disagreement, foreshadowing part II of my work on this topic, “On the Rationality of Belief-Invariance in Light of Peer Disagreement.”.

This paper considers two questions. First, what is the scope of the Equal Weight View? Is it the case that meeting halfway is the uniquely rational method of belief-revision in all cases of known peer disagreement? The answer is no. It is sometimes rational to maintain your own opinion in the face of peer disagreement. But this leaves open the possibility that the Equal Weight View is indeed sometimes the uniquely rational method of belief revision. Precisely what is the skeptical import of this fact; is it the case that some form of skepticism triumphs in such cases? The answer to this question is also no. As it turns out, the situations in which it is most plausible that the Equal Weight view is a rational requirement are the ones in which meeting halfway with a disagreeing peer brings you closer to, and not farther from, knowledge. I argue for these theses in a novel way; by looking at the comparative reliability of belief-invariance and meeting halfway using measures of reliability for degrees of belief, and by drawing normative conclusions from such results. The conclusions here can have the effect of reframing the entire debate in the epistemology of disagreement.

How should you take into account the opinions of an advisor? When you completely defer to the advisor's judgment (the manner in which she responds to her evidence), then you should treat the advisor as a guru. Roughly, that means you should believe what you expect she would believe, if supplied with your extra evidence. When the advisor is your own future self, the resulting principle amounts to a version of the Reflection Principle-a version amended to handle cases of information loss. When you count an advisor as an epistemic peer, you should give her conclusions the same weight as your own. Denying that view-call it the "equal weight view"-leads to absurdity: the absurdity that you could reasonably come to believe yourself to be an epistemic superior to an advisor simply by noting cases of disagreement with her, and taking it that she made most of the mistakes. Accepting the view seems to lead to another absurdity: that one should suspend judgment about everything that one's smart and well-informed friends disagree on, which means suspending judgment about almost everything interesting. But despite appearances, the equal weight view does not have this absurd consequence. Furthermore, the view can be generalized to handle cases involving not just epistemic peers, but also epistemic superiors and inferiors.

Some philosophers believe that when epistemic peers disagree, each has an obligation to accord the other's assessment the same weight as her own. I first make the antecedent of this Equal-Weight View more precise, and then I motivate the View by describing cases in which it gives the intuitively correct verdict. Next I introduce some apparent counterexamples – cases of apparent peer disagreement in which, intuitively, one should not give equal weight to the other party's assessment. To defuse these apparent counterexamples, an advocate of the View might try to explain how they are not genuine cases of peer disagreement. I examine David Christensen's and Adam Elga's explanations and find them wanting. I then offer a novel explanation, which turns on a distinction between knowledge from reports and knowledge from direct acquaintance. Finally, I extend my explanation to provide a handy and satisfying response to the charge of self-defeat.