Chapter 1: Introduction and Overview

Overview

When one admits that nothing is certain one must, I think, also add that some things are more nearly certain than others.

—Bertrand Russell

It is not certain that everything is uncertain.

—Blaise Pascal

Uncertainty is a fundamental—and unavoidable—feature of daily life. In order to deal with uncertainty intelligently, we need to be able to represent it and reason about it. How to do that is what this book is about.

Reasoning about uncertainty can be subtle. If it weren't, this book would be much shorter. The puzzles and problems described in the next section hint at some of the subtleties.