How should one react when one has a belief, but knows that other people—who have roughly the same evidence as one has, and seem roughly as likely to react to it correctly—disagree? This paper argues that the disagreement of other competent inquirers often requires one to be much less confident in one’s opinions than one would otherwise be.

How should you take into account the opinions of an advisor? When you completely defer to the advisor's judgment, 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. (shrink)

I know various contingent truths about my environment by perception. For example, by looking, I know that there is a computer before me; by hearing, I know that someone is talking in the corridor; by tasting, I know that the coffee has no sugar. I know these things because I have some built-in mechanisms specialized for detecting the state of my environment. One of these mechanisms, for instance, is presently transducing electromagnetic radiation (in a narrow band of wavelengths) coming from (...) the computer and the desk on which it sits. How that mechanism works is a complicated story—to put it mildly—and of course much remains unknown. But we can at least produce more-or- less plausible sketches of how the mechanism can start from retinal irradiation, and go on to deliver knowledge of my surroundings. Moreover, in the sort of world we inhabit, specialized detection mechanisms that are causally affected by the things they detect have no serious competition—seeing the computer by seeing an idea of the computer in the divine mind, for example, is not a feasible alternative. (shrink)

My conclusion will be that, more often than we might have thought, suspension of judgment is the epistemically proper attitude. It follows that in such cases we lack reasonable belief and so, at least on standard conceptions, knowledge. This is a kind of contingent real-world skepticism that has not received the attention it deserves. I hope that this paper will help to bring this issue to life.