The Law Is Not a Mathematical Treatise
We often find people saying something like, "If Americans can serve in the military at age 18, it is contradictory not to let them drink at 18 as well." ( An example of this sort of accusation.) But these complaints rest on a confusion. When we want to build up a system of mathematics, such as geometry, we state propositions (theorems, axioms, lemmas, etc.) and work out their consequences. We should worry about the consistency of our propositions, because if two of them are contradictory, anything at all can be proven in our system. But the law does not consist of propositions with logical consequences, from which we try to prove something further. It consists of rules of conduct, with consequences for the breaking thereof, which serve to help guide and improve our practical life. In general, the only important sort of proposition that laws contain is that X is illegal and Y is legal.* Therefore, in general, laws can be contradictory only in declaring X to be both l...