This Post Is Underinclusive

I am really, really, really tired of law professors complaining about rule X on the grounds that it’s “underinclusive” or “overinclusive” or both. These arguments are typically followed by whatever is the printed-page equivalent of sitting back in one’s chair with a self-satisfied smirk.

So the rule you hate is underinclusive? So what? Most rules are. Your proposed alternative probably has exactly the same problems. All of life is underinclusive, and overinclusive, too.

To make a successful inclusiveness argument, you have to pair it with an example that would be included/excluded but shouldn’t be. The question then is whether you modify your rule or accept the “error.” (You could also explain the “error” away, I guess.)

While I understand your frustration, I think that inclusiveness arguments are at the core of legal reasoning. Arguments about precedents almost always take that form: e.g., “your argument would also require a different result in such-and-such case, and so it’s overinclusive.” And it’s also a key feature of moral reasoning, as the trolley hypotheticals show.