Public and private communication are different: results on relative expressivity

Dynamic Epistemic Logic (DEL) is the study of how to reason about knowledge, belief, and communication. This paper studies the relative expressivity of certain fragments of the DEL language for public and private communication. It is shown that the language of public communication with common knowledge and the language of private communication with common knowledge are expressively incomparable for the class of all pointed Kripke models, which provides a formal proof that public and private communication are fundamentally different in the presence of common knowledge. It is also shown that single-recipient private communication does not add expressive power to the language of modal logic with common knowledge for any class of transitive pointed Kripke models. The latter result provides a sense in which positive introspection—believing our own beliefs—induces a kind of self-dialog.     

恶“德”——一种特殊的道德现象

人类竭尽所能 ,在最大的限度上去减少各种罪恶 ,其中 ,包括恶“德”的手段在内。为了更好地运用恶“德”这种手段 ,加强对它的研究和运用是十分必要的。     

Skeptical Parasitism and the Continuity Argument

Abstract: Recent literature on skepticism has raised a nearly univocal voice in condemning skeptical argumentation on the grounds that such argumentation necessarily involves our adopting some nonordinary or unnatural perspective. Were this really so, then skeptical conclusions would not speak to us in the way in which skeptics think they do; we would be “insulated” from any such conclusions. I argue that skeptical argumentation need not rely on any nonordinary or unnatural standards. Rather, the skeptic's procedure is to offer a critique from within. Having given my argument for this claim (which I call the Continuity Argument), I consider and respond to two important objections. I conclude that the skeptic has a powerful meta‐argument to be deployed in defending the legitimacy of his skeptical conclusions against the slings and arrows of (those I call) the half‐true theorists.     

The Pursuit of Epistemic Good

Pace Zagzebski, there is no route from the value of knowledge to a non–reliabilist virtue–theoretic epistemology. Her discussion of the value problem is marred by an uncritical and confused employment of the notion of a "state" of knowledge, an uncritical acceptance of a "knowledge–belief" identity thesis, and an incoherent presumption that the widely held thought that knowledge is more valuable than true belief amounts to the view that knowledge is a state of true belief having an intrinsic property which a state of 'mere" true belief lacks. Her arguments against a "machine–product" conception of knowledge are undermined by these flaws, while the alternative "agent–act" model she recommends is unattractive, at odds with the knowledge–belief identity thesis she favours, and no solution to the problem of the value of knowledge she poses. I end with the observation that her version of virtue–theoretic epistemology points in the direction of cognitive decision–theoretic norms, and I briefly discuss the bearing of this fact upon her viewpoint.     

Epistemic Presuppositions and their Consequences

Traditional epistemology has, in the main, presupposed that the primary task is to give a complete account of the concept knowledge and to state under what conditions it is possible to have it. In so doing, most accounts have been hierarchical, and all assume an idealized knower. The assumption of an idealized knower is essential for the traditional goal of generating an unassailable account of knowledge acquisition. Yet we, as individuals, fail to reach the ideal. Perhaps more important, we have epistemic goals not addressed in the traditional approach – among them, the ability to reach understanding in areas we deem important for our lives. Understanding is an epistemic concept. But how we obtain it has not traditionally been a focus. Developing an epistemic account that starts from a set of assumptions that differ from the traditional starting points will allow a different sort of epistemic theory, one on which generating understanding is a central goal and the idealized knower is replaced with an inquirer who is not merely fallible but working from a particular context with particular goals. Insight into how an epistemic account can include the particular concerns of an embedded inquirer can be found by examining the parallels between ethics and epistemology and, in particular, by examining the structure and starting points of virtue accounts. Here I develop several interrelated issues that contrast the goals and evaluative concepts that form the structure of both standard, traditional epistemological and ethical theories and virtue–centered theories. In the end, I sketch a virtue–centered epistemology that accords with who we are and how we gain understanding.     

Complete Axiomatizations for Reasoning about Knowledge and Branching Time

Sound and complete axiomatizations are provided for a number of different logics involving modalities for the knowledge of multiple agents and operators for branching time, extending previous work of Halpern, van der Meyden and Vardi [to appear, SIAM Journal on Computing] for logics of knowledge and linear time. The paper considers the system constraints of synchrony, perfect recall and unique initial states, which give rise to interaction axioms. The language is based on the temporal logic CTL*, interpreted with respect to a version of the bundle semantics.     

The Russian Cards Problem

Suppose we have a stack of cards that is divided over some players. For certain distributions of cards it is possible to communicate your hand of cards to another player by public announcements, without yet another player learning any of your cards. A solution to this problem consists of some sequence of announcements and is called an exchange. It is called a direct exchange if it consists of (the minimum of) two announcements only. The announcements in an exchange have a special form: they are safe communications, an interesting new form of update. Certain unsafe communications turn out to be unsuccessful updates. A communication is a public announcement that is known to be true. Each communication may be about a set of alternative card deals only, and even about a set of alternatives to the communicating player's own hand only. We list the direct exchanges for a deal of seven cards where the two players holding three cards communicate their hands to each other. Our work may be applicable to the design of cryptographic protocols.     

Nietzsche on taste: epistemic privilege and anti-realism

Abstract

The central aim of this article is to argue that Nietzsche takes his own taste, and those in the relevant sense similar to it, to enjoy a kind of epistemic privilege over their rivals. Section 2 will examine the textual evidence for an anti-realist reading of Nietzsche on taste. Section 3 will then provide an account of taste as an ‘affective evaluative sensibility’ (AES), asking whether taste so understood supports an anti-realist reading. I will argue that it does not and that we should resist construing the affects (Affeke), which constitute taste for Nietzsche, as no more than Humean subjective preferences. Section 4 will then consider passages in which Nietzsche makes a connection between taste and epistemic considerations, suggesting that he appears to situate the epistemic privilege of his taste in a more fundamental method of evaluative disclosure, namely pre-reflective affective responses. Finally, Section 5 will argue that we can make sense of how such affective responses could provide us with evaluative knowledge by narrowing the scope of the objects of Nietzsche’s taste to other affective-evaluative states, such that the affective responses are meta-affective evaluations. On the basis of this idea, I construct a theory of meta-affective responses providing their subjects with access to the intrinsic phenomenal value of other affective-evaluative states, and then go on to show how Nietzsche can be read as applying this theory in a number of passages.     

IS CRITICAL THINKING EPISTEMICALLY RESPONSIBLE?

Abstract: There are at least three strategies we might take in approaching controversial issues: (i) we might accept the conclusions of experts on their authority, (ii) we might evaluate the relevant evidence and arguments for ourselves, or (iii) we might give up on finding the answers. Students of “critical thinking” are regularly advised to follow strategy (ii). But strategies (i) and (iii) are usually superior to (ii), from the standpoint of the goal of gaining true beliefs and avoiding false ones.