 The moral importance of burden sharing comes out most clearly when we consider certain highly privatized ways of organizing national defense.  Consider, for example, a market based approach. A political community might allow entrepreneurs to set up “protection agencies” that would act as firms, hiring mercenaries, buying weapons, and selling varying levels of protection to individual citizens based on their preferences and their ability to pay (see Nozick 1974). Even if it were possible to defend people’s constitutional liberties through a mechanism of this kind,[21] political morality seems to rule it out. One reason is that the market scheme would allow citizens who are wealthy enough to buy protection services for themselves, but then leave it to others to face the actual dangers of combat. This would violate the communal ideal that all citizens must share in some way in carrying the collective burden of defending the community (see Walzer 1983: 98–9 and 169).