Online research in philosophy

How do reasons combine? How is it that several reasons taken together can have a combined weight which exceeds the weight of any one alone? I propose an answer in mereological terms: reasons combine by composing a further, complex reason of which they are parts. Their combined weight is the weight of their combination. I develop a mereological framework, and use this to investigate some structural views about reasons, the main two being "Atomism" and "Holism". Atomism is the view that atomic reasons are fundamental: all reasons reduce to atomic reasons. Holism is the view that whole reasons are fundamental. I argue for Holism, and against Atomism. I also consider whether reasons might be "context-sensitive".

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.

I develop a general framework with a rationality constraint that shows how coherently to represent and deal with second-order information about one's own judgmental reliability. It is a rejection of and generalization away from the typical Bayesian requirements of unconditional judgmental self-respect and perfect knowledge of one's own beliefs, and is defended by appeal to the Principal Principle. This yields consequences about maintaining unity of the self, about symmetries and asymmetries between the first- and third-person, and a principled way of knowing when to stop second-guessing oneself. Peer disagreement is treated as a special case where one doubts oneself because of news that an intellectual equal disagrees. This framework, and variants of it, imply that the typically stated belief that an equally reliably peer disagrees is incoherent, and thus that pure rationality constraints without further substantive information cannot give an answer as to what to do. The framework also shows that treating both ourselves and others as thermometers in the disagreement situation does not imply the Equal Weight view.

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.”.

Sue knows that, unaided, she cannot lift the 1,000 pound weight, but surely she can try. Can she not? For even if she believes it is impossible to succeed in lifting the weight, trying to lift the weight need not involve success. So surely, it would seem that nothing could be easier than for Sue to give lifting the weight a try. In this paper, I agrue that, appearances aside, it is not possible for someone to try to do what that person believes to be impossible. So, on this view, perhaps surprisingly, not only would it be impossible for Sue to lift the weight, but it would be impossible for her to try (as long as she believed her lifting it to be impossible). I defend this view in the context of a package of related claims and a functional accoung of trying and intentional action.

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.

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.

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.

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.

How should we respond to cases of disagreement where two epistemic agents have the same evidence but come to different conclusions? Adam Elga has provided a Bayesian framework for addressing this question. In this paper, I shall highlight two unfortunate consequences of this framework, which Elga does not anticipate. Both problems derive from a failure of commutativity between application of the equal weight view and updating in the light of other evidence.