It’s much more complicated than an age law… but without a reliable and easy test to determine if someone has reached cognitive maturity, an age law is the next best thing. We choose 18 because at the age of 18 the solid majority of people *should* have reached a cognitive maturity. A few will not have… and a few will have reached it by the age of 12-14 or so… but by 18 most should understand right and wrong and that their actions have consequences. Should a *cognitively mature* 16 year old who hooks up with a 19 year old cause a big fuss? Probably not… Should a conitivly mature 15 year old who hooks up with a not cognitively mature 9-year-old cause a big fuss? Probably so!!! ***BUT*** there’s no easy way to determine if the 16 or 15-year-old has reached cognitive maturity. The only time I can think of where we spend time trying to figure this sort of thing out is during murder trials when the murderer is under-age. So we say “18” and are done with it, not because we don’t understand that life is much more grey area than a hard number, but out of the need for the stability of a social constant. Is it unjust in some situations, all things considered? Sure. Is it an *EASY* concept that even the dumbest members of society can understand? YES… And because of that I support the later until there’s an easy and clear way to support the more accurate grey scale model.