One of the claims i have seen being used in a number of debates of why anarchy couldnt work is related to having an army.
For example, if a country tommorow has a major revolution, rejects any form of goverment and authority mainly (statism) and maybe capitalism also.
What would stop another imperialistic country invading?
I have heard options like voluntary army and maybe professional army.
I would like to hear more about this topic.