One of the new chapters for the third edition of The Machinery of Freedom discusses the question of how a stateless society might defend against a state, which I regard as the hardest problem for such a society. One of the possibilities I raise is having people voluntarily train and equip themselves for warfare for the fun (and patriotism) of it, as people now engage in paintball, medieval combat in the Society for Creative Anachronism, and various other military hobbies.