Q. Why do marketers of a range of products spend as much money as they do on advertising? A. Becau se they want to sell more products. You don't have to be Don Draper to figure that one out. Q. But why does it increase the demand for the advertised products? Let's focus on broadcast commercials, and on competition within a particular industry: how does the radio/TV exposure cause people to want brand X rather than brand Y, assuming that they want the generic type of product to which both X and Y belong? A. The marketers of X try to persuade people that X is better. Q. Yes, I understand. But isn't the public long since jaded? How does persuasion work, if we assume that consumers are rational? [Rational consumers certainly would be jaded about the content of broadcast ads, would they not?] A. One possible answer to that is that rational consumers, regardless of the content of the ad, measure the likely expense of the advertising campaign. The amount of money that th...