For example, I think it would be nice if many of my friends and family paid more attention to stories about candidates’ rhetoric on Iran; I consider those stories very valuable and I certainly want them prominently featured in the national newspapers I read. But I hardly ever e-mail them those stories, because that just doesn’t seem like a useful way to get them interested in the subject or provide them with information. Not many people want to be given a reading list by their friends based on their friends’ abstract ideas about what is important to know about. (Instead, I talk to them about the Iran issue at what seem like appropriate points in our conversations.)

When I e-mail a story, it’s usually because the story is relevant to some personal connection between me and the e-mail recipient — a story about a school we both attended, or about some topic we recently happened to discuss, or that proves my side of a recent argument, or that seems amusing in a way that I think will appear to that friend’s specific sense of humor.

Another important factor is persona-construction: I’m sure I tend to e-mail stories when I have the sense that doing so makes me seem cool or interesting or perceptive or what you will. The set of such stories certainly overlaps with the set of stories I want to read, but there’s a pretty significant disjunction as well.