People arguing about slavery in the US did have the ability to observe that other societies had abolished it and been successful. And we today have the ability to observe other societies that don't have a stable monopoly of force and taxing power and see them in perpetual chaos, where competing groups with different sources of revenue struggle to become governments. It doesn't make any sense to say nobody has ever tried anarchy, because (a) it's all over the place, and manifestly involves poverty and misery, and (b) it was the original state of humankind, so we know it is possible and that government as we know it develops from it.