Lockean Thesis Research Articles

Contemporary Epistemic Logic and the Lockean Thesis

This paper studies the Lockean thesis from the perspective of contemporary epistemic logic. The Lockean thesis states that belief can be defined as ‘sufficiently high degree of belief’. Its main problem is that it gives rise to a notion of belief which is not closed under conjunction. This problem is typical for classical epistemic logic: it is single-agent and static. I argue that from the perspective of contemporary epistemic logic, the Lockean thesis fares much better. I briefly mention that it can successfully be extended from single-agent to multi-agent settings. More importantly, I show that accepting the Lockean thesis (and a more sophisticated version for conditional beliefs) leads to a significant and unexpected unification in the dynamic behavior of (conditional) belief and high (conditional) probability with respect to public announcements. This constitutes a methodological argument in favor of the Lockean thesis. Furthermore, if one accepts Baltag’s Erlangen program for epistemology, this technical observation has even stronger philosophical implications: because belief and high probability display the same dynamic behavior, it is plausible that they are indeed one and the same epistemic notion.

A springboard for exploring the many approaches to degrees of belief

Degrees of Belief is a strong collection of essays distinguished by its inclusion of an unusually wide array of approaches to understanding its subject. The book consists mainly of recent works (growing out of a 2004 conference at the University of Konstanz) from perspectives as diverse as probabilism (the view that degrees of belief ought to be probabilities), Dempster-Shafer theory, possibility theory, ranking theory, AGM (Alchourron-Gardenfors-Makinson) belief-revision theory, and others. The essays are varied in focus, but many are concerned with outlining formal axiomatizations of degree of belief (variously understood), and several of them are surveys of their respective sub-fields. As one might expect, the discussion is often technical and sometimes dense, and so the book is best suited for formally proficient advanced students (graduate or upper-level undergraduate) or professionals seeking to explore other approaches to degree of belief than the ones in which they currently work. Some recurrent themes in the book include the relation of degree of belief to full belief, how degree of belief ought best to be understood (its purpose and function), and the formal laws (so understood) it ought to obey. There is limited reference in some articles to applications (e.g., in computer science), but the main focus of the book is theoretical. What follows is only a small sample of the rich content contained in the book. After a clear and concise preview of the book’s contents, written by one of the editors (Franz Huber), Part I of the book concentrates on how belief relates to degree of belief. The lottery paradox is key here (and also the related preface paradox), and accordingly, the section begins with one exposition of it, by Richard Foley (a revision of Chapter 4 of Foley 1993). The lottery paradox arises from the so-called Lockean thesis that belief is just sufficiently high degree of belief. For example, if I believe p just in case my degree of belief in it is at least 99%, then I’ll

Tolerancia, verdad y libertad de conciencia en el siglo XVIII

The 18th century defense of tolerance rests upon two lines of argument; lines that we can observe in thinkers such as Montesquieu and Rousseau, Diderot, Romilly and Voltaire. The first deconstructs the concept of absolute truth as it applies not only to the (orthodox) doctrine itself, as revealed by God, but also to the Catholic Church insofar as it is taken to be the only institution where truth resides uniquely. The second line of argument would run as follows: Once we acknowledge the rights of consciousness to every single religion, how can we possibly avoid a circular justification of intolerance? Romilly and Voltaire defend, without renouncing to the rights of consciousness (which are the base of individual liberties), the Lockean thesis of the separation Church-State. However, they assign to the State the ius circa sacra. It is only upon this foundation that the idea and the practice of tolerance, both religiously as well as universally and multiculturally speaking, can be constructed.

The preface, the lottery, and the logic of belief

John Locke proposed a straightforward relationship between qualitative and quantitative doxastic notions: belief corresponds to a sufficiently high degree of confidence. Richard Foley has further developed this Lockean thesis and applied it to an analysis of the preface and lottery paradoxes. Following Foley’s lead, we exploit various versions of these paradoxes to chart a precise relationship between belief and probabilistic degrees of confidence. The resolutions of these paradoxes emphasize distinct but complementary features of coherent belief. These features suggest principles that tie together qualitative and quantitative doxastic notions. We show how these principles may be employed to construct a quantitative model—in terms of degrees of confidence—of an agent’squalitative doxastic state. This analysis fleshes out the Lockean thesis and provides the foundation for a logic of belief that is responsive to the logic of degrees of confidence.