We flatter ourselves with the idea that we make our own decisions, arrive at our own rational conclusions, etc.
If psychology has taught us about the unconscious influences that tend to control our thoughts and choices, the current social "science" of influence and persuasion addresses the external forces that control our minds. It is darn interesting, but depressing.
As a prof of Marketing, Berger surely knows how to sell us but gives us tools to see through it all too.
Recommended: Invisible Influence: The Hidden Forces that Shape Behavior