Last week, I began discussing Robert Cialdini’s six approaches to persuasion or what he calls weapons of influence by covering reciprocation and commitment and consistency. This week, we’ll be exploring Cialdini’s third and fourth tools–social proof and authority. While people clearly go out and shop on Black Friday because there are great deals, there is also the desire to be a part of a community of people who are all doing something that is must be good and correct behavior....