From the Introduction to How to Know:

The so-called "Information Age" in which we are said to be living is notoriously a time of information explosion and overload. On the other hand, it is only occasionally noticed that this Information Age has not automatically made us all smarter. More information does not mean more knowledge, less error, better judgments. Those real benefits come only with effort and skill -- thinking, in other words, and thinking well....

How to Know is, then, about the practical business of what we think of as "knowing" in everyday life....

How to Know considers the question of how we come to believe that we know things. What is this stuff we call knowledge, and where does it come from? How far can we trust it? If it is less than entirely reliable, what then? Most important, it argues that knowledge doesn't just happen, but that each of us is actively involved in its construction and that we can do the work well or not well but will have to take responsibility for the outcome in either case.