system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 what libertarianism is.
gpt
Every day, you go buy lunch in the school cafeteria and sit with all of your classmates. While you're at lunch, you can do whatever you want with your food. You can eat it all, or you can throw it all away. You can trade it with other kids. You can give some of it to another kid who forgot his lunch money, or you can tease him because he doesn't have any by eating it in front of him. Now, you can't do something that would hurt another kid or ruin something he owns; you can't throw food at him or steal his food, because if you do, you'll get put in detention by the hall monitors. But as long as you aren't being mean, you can do whatever you like. And these rules are the same for all the kids. Pretty great, right?

Now, what if you were in a school where many kids forgot their lunch money often, and didn't have a lunch to eat? A lot of kids would go hungry, and that wouldn't be good. So the hall monitors institute a new rule. Every kid must give up a third of their lunch money to the hall monitors. Then, hopefully, the hall monitors will fairly give it out to the kids who didn't bring their own, so they can buy a lunch. Maybe those kids didn't have any money, maybe they forgot it at home, or maybe they just stopped bringing money because they know they can get some from the hall monitors every day.

That's not fair! You bring your own lunch money every day! Under these rules, you have to give up part of your lunch every day just because some other kids can't take care of themselves. Now, to get the same amount of food, you now have to bring even more lunch money, which you might not have. If you were a nice kid, you'd surely help out someone who truly didn't mean to leave his lunch money at home. You don't need the hall monitor to be nice to someone. But because they took your lunch money from you, you have to hope that they're giving your money out fairly. And they don't always do the best job at it.