What role, if any, does formal logic play in characterizing epistemically rational belief? Traditionally, belief is seen in a binary way - either one believes a proposition, or one doesn't. Given this picture, it is attractive to impose certain deductive constraints on rational belief: that one's beliefs be logically consistent, and that one believe the logical consequences of one's beliefs. A less popular picture sees belief as a graded phenomenon. This picture (explored more bydecision-theorists and philosophers of science thatn by mainstream epistemologists) invites the use of probabilistic coherence to constrain rational belief. But this latter project has often involved defining graded beliefs in terms of preferences, which may seem to change the subject away fromepistemic rationality.Putting Logic in its Place explores the relations between these two ways of seeing beliefs. It argues that the binary conception, although it fits nicely with much of our commonsense thought and talk about belief, cannot in the end support the traditional deductive constraints on rational belief. Binary beliefs that obeyed these constraints could not answer to anything like our intuitive notion of epistemic rationality, and would end up having to be divorced from central aspects of ourcognitive, practical, and emotional lives.But this does not mean that logic plays no role in rationality. Probabilistic coherence should be viewed as using standard logic to constrain rational graded belief. This probabilistic constraint helps explain the appeal of the traditional deductive constraints, and even underlies the force of rationally persuasive deductive arguments. Graded belief cannot be defined in terms of preferences. But probabilistic coherence may be defended without positing definitional connections between beliefsand preferences. Like the traditional deductive constraints, coherence is a logical ideal that humans cannot fully attain. Nevertheless, it furnishes a compelling way of understanding a key dimension of epistemic rationality.

In everyday life we normally express our beliefs in all-or-nothing terms: I believe it is going to rain; I don't believe that my lottery ticket will win. In other cases, if possible, we resort to numerical probabilities: my degree of belief that it is going to rain is 80%; the probability that I assign to my ticket winning is one in a million. It is an open philosophical question how all-or-nothing belief and numerical belief relate to each other, and how we ought to reason with them simultaneously. The Stability of Belief develops a theory of rational belief that aims to answer this question. Hannes Leitgeb develops a joint normative theory of all-or-nothing belief and numerical degrees of belief. While rational all-or-nothing belief is studied in traditional epistemology and is usually assumed to obey logical norms, rational degrees of belief constitute the subject matter of Bayesian epistemology and are normally taken to conform to probabilistic norms. One of the central open questions in formal epistemology is what beliefs and degrees of belief have to be like in order for them to cohere with each other. The answer defended in this book is a stability account of belief: a rational agent believes a proposition just in case the agent assigns a stably high degree of belief to it. Leitgeb determines this theory's consequences for, and applications to, learning, suppositional reasoning, decision-making, assertion, acceptance, conditionals, and chance. The volume builds new bridges between logic and probability theory, traditional and formal epistemology, theoretical and practical rationality, and synchronic and diachronic norms for reasoning.

This anthology is the first book to give a balanced overview of the competing theories of degrees of belief. It also explicitly relates these debates to more traditional concerns of the philosophy of language and mind and epistemic logic.

Essays on the state of research investigating the relationship between conditionals and conditional probabilities.

Martin Smith explores a question central to philosophy—namely, what does it take for a belief to be justified or rational? According to a widespread view, whether one has justification for believing a proposition is determined by how probable that proposition is, given one's evidence. In the present book this view is rejected and replaced with another: in order for one to have justification for believing a proposition, one's evidence must normically support it—roughly, one's evidence must make the falsity of that proposition abnormal in the sense of calling for special, independent explanation. This conception of justification bears upon a range of topics in epistemology and beyond, including the relation between justification and knowledge, the force of statistical evidence, the problem of scepticism, the lottery and preface paradoxes, the viability of multiple premise closure, the internalist/externalist debate, the psychology of human reasoning, and the relation between belief and degrees of belief. Ultimately, this way of looking at justification guides us to a new, unfamiliar picture of how we should respond to our evidence and manage our own fallibility. This picture is developed here.

An introductory 2001 textbook on probability and induction written by a foremost philosopher of science.