Today, as Wilson notes, middle names serve much the same purposes they always have: they're a way to keep family names going and thus preserve relationships; they're a way to try something new or “put old names out to grass” without cutting the cord entirely.

Is everyone supposed to have a middle name?

Today, some people don't even have middle names, some prefer to be called by their middle name, and some never even use theirs. But just be grateful that we don't trace our lineage back with multiple cognomina like some aristocratic families used to and end up with 38 names.

Why some people go by their middle names?

The best explanation seems to stem from Southerners' penchant for keeping a name going down the line, especially for males. You end up with John Smith Jr., III, and IV in one family, and calling a child by his middle name is an easy way to distinguish between him and his father.