This excerpt originally appeared in Adam Thierer's Forbes.com column on January 23, 2012.

Since the days when Plato and Aristotle walked this Earth, philosophers have debated what constitutes the ideal state and, more specifically, what holds societies together. Why doesn’t society just fall apart? How does society function when you know you can’t possibly trust everyone in it? And why aren’t we living in what Thomas Hobbes memorably referred to as a state of constant “war of all against all”?

There is no single or simple answer, says security technologist Bruce Schneier in his enlightening new book, Liars & Outliers: Enabling the Trust that Society Needs to Thrive.