A lot of (but not all) right-libertarians and anarcho-capitalists believe in NAP or non-aggression principle. The non-aggression principle is deontological in that it is a universal commanding principle with no exceptions that states one should never initiate aggression. Of course it’s ok to use aggression in self-defense when someone has initiated aggression against you. Some people believe the non-aggression principle is the only moral dictum you need in your life.
There’s only one problem: the non-aggression principle isn’t an all encompassing ethical theory. Suppose you’re walking home from school and you see someone drowning. Naturally, if you’re an empathetic person, you’d want to do something to help. Well according to the non-aggression principle, by itself, there is no moral obligation to help. The drowning person isn’t harming you, no one is initiating aggression against the drowning person, no one is being aggressive towards you. It wouldn’t be a form of self-defense to help the drowning person. So what do you do? Well, the non-aggression principle essentially doesn’t tell you what to do. If you believe only in the NAP, then you can either just walk on by or proceed to try to help.
But there’s something really wrong with this picture of total supremacy of NAP. It seems like you’re morally obligated to help the drowning person or try to help. You don’t want to drown along with the other person while trying to save the drowning person obviously, so you grab a long stick and you tell the person to grab on. Or maybe it’s just a kid that weighs significantly less than so it would be easy to swim to the kid and save the kid without much risk of you both drowning. Or maybe yell for help or call for help if you can’t swim and there’s hardly any feasible way for you to help the person drowning.
Stoicism explains our gut feeling of why we feel we should save someone drowning. Stoicism says we have social ethical duties to help others when they’re in need if we can help. We are obligated to help people whether or not there is an issue of violence at hand. The NAP is simply too limited of an ethical principle to explain our gut feelings about how we should help others in need. It simply only cares about the need for aggression only in self-defense against a person who wrongly initiated the aggression.
Stoicism can do a lot more for us than what the NAP can accomplish. The NAP means you only care about aggression so you don’t necessarily care about types of behaviors that aren’t aggressive but what others would find wrong like lying. Lying isn’t a clear aggressive act so it seems like it’s permitted by the NAP. But most people do not like lying liars. They understand lying to help others but they don’t understand people who lie for themselves or their reputation. And the NAP could easily be interpreted to allow for self-interested forms of lying. You’re not actually initiating aggression by telling a falsehood purposely to trick someone. It’s just semantics and syntax at play.
If you had to choose between ethical theories, you would fair much better with Stoicism than the NAP by itself.