Some commentators have noted that the Democratic and Republican conventions were "infomercials" for the two political aprties. Such criticism fails to understand not only the purpose of the Democratic and Republican conventions but also conventions generally. According to the Oxford English Dictionary, a convention "is the action of coming together, meeting, or assembling." Exactly! Both conventions do all three. Meetings take place during the day, and at nights, they assemble in the Pepsi Center (where they probably wish they could be drinking Coca-Cola).
What the speeches do is aid the first function of "convening"--coming together. It is notable that the dictionary lists coming together as a separate function from assembling. In other words, if coming together does not mean to assemble, it must have emotional function (the Oxford does not waste words). As any convention goer can tell you, most conventions are supposed to have an emotional effect as well. You attend them not only to gather information but also to become renewed within your field. When one does not feel that renewal, she or he is probably in the wrong field.
When commentators perform their cynicism about the function of conventions, it is at least somewhat warranted, just as any convention goer may later question the time and expense he or she spent on a few days where all anyone seemed to do is talk. But when Hilary Clinton and all the rest of the speakers get up there, their performance is geared toward renewing the fever and commitment of Democrats. That's why people go to conventions--to recommit to something they are already committed to.
But because there are spectators, the function of the convention goes beyond the attendees. In a sense, we are all attending the convention if we want to. Last week, Bill Clinton, Joe Biden, and Barack Obama reached out to all possible attendees, both at the convention and in their living rooms --which is one reason why Obama has symbolically set himself down in living rooms to watch the convention--he's attending the convention the same way we are. This week, the Republicans did the same. That the conventions were televised and performative didn't make them any less conventions.