You don't have to agree to it, because it doesn't matter. You don't have a choice so you are in slavery. In modern states, you don't have a lot of choices eith

You don't have to agree to it, because it doesn't matter. You don't have a choice so you are in slavery. In modern states, you don't have a lot of choices either. But at least, even though you are "forced" into a society, you eventually get the right to participate politically.