It's not, though. The code was written with a certain emotional state. If Senator Jones of the Great State of Wherever's kids were kidnapped, we'd have the Jones amendment to the tax code saying that kids were dependents until they clearly weren't, because we were all sad for Senator Jones at the time we wrote the code. Ignoring that fact means that we treat the law as some piece of inviolable logic, as opposed to something we thought made sense at the time, and prevents us from seeing it as something we both can and ought to change should it not deliver the results we want.