One reasonable principle is that laws ought to reduce harm.
That is a bit glib, but so is your bald assertion that states ought to be concerned only with principle. It is neither part of our legal tradition nor even a plausible interpretation of the foundational ideas of most currently constituted governments.
I see where you are coming from, but I don't know that, as humans currently understand things, your argument really has traction on reality.
Then consider my examples. If the role of the state is to reduce harm, why is alcohol legal? Why are people allowed to be mean online? Why can cars go over 15mph? Why aren't there facial recognition cameras on every corner? Why isn't everyone on mood stabilizers?
Pretty obviously because the role of the state isn't to reduce harm to the exclusion of everything else. It has multiple goals which it imperfectly pursues. Just like any human institution or individual.
That is a bit glib, but so is your bald assertion that states ought to be concerned only with principle. It is neither part of our legal tradition nor even a plausible interpretation of the foundational ideas of most currently constituted governments.
I see where you are coming from, but I don't know that, as humans currently understand things, your argument really has traction on reality.