Recent history has seen a rapid growth in the involvement of private parties in war conflicts. In 2020, there were almost twice as many private contractors as US soldiers in Afghanistan.1 In the ongoing war in Ukraine, private actors are allegedly deployed by both parties in the conflict.2 Originally hired by states to provide support services from catering to logistics, private military firms (PMFs) have progressively taken on functions, including combat tasks, that were deemed, at least in the last century, inherently governmental.3 The phenomenon amounts to an unprecedented form of corporatized mercenarism.4
The condemnation of mercenarism has an illustrious history. While Machiavelli famously deprecated mercenaries' lack of loyalty and tendency to corrupt the state,5 Rousseau worried that hiring mercenaries, rather than having citizens fight wars, would lead the latter to value comfort more than republican freedom. Recent critics argue, among other things, that fighting for profit is inherently wrong;6 that the privatization of war leads to an unjust distribution of access to security;7 that it allows both states and private parties to escape democratic accountability;8 and that it provides incentives to escalate conflicts and to increase the use of violence in the battlefield.9 Some contemporary philosophers have, on the other side, shown a friendlier face towards mercenarism. Most prominently, Cécile Fabre argues that, at least under ideal circumstances, private parties have a right to sell their soldiering services to states, for the purpose of just defensive killing, and states are at liberty to buy those services from them.10
Departing from Fabre's (qualified) defense of mercenarism, my goal is to provide an account of the wrong of privatized war, which neither rests on the controversial claim that fighting for profit is inherently wrong, nor assumes that privatization leads to unjust distributive outcomes, a lack of accountability, or the disproportionate use of force (although it may). I argue that, even in the absence of such problems, the privatization of (at least some) military tasks would amount to a condition of double domination, whereby both those exposed to the mercenary's use of force and, perhaps more surprisingly, the mercenary themself is dominated: that is to say, subject to the arbitrary will of another. This can occur even within the context of a just war.
To make my case, I will first argue that the state's outsourcing of certain military tasks to private parties, including most combat tasks, consists of a system of contracts between states and such parties that contain either invalid (not binding) or seriously problematic promises. Either the mercenary's promissory offer to perform those tasks entails the alienation of certain rights that cannot be so alienated, in which case the promise is invalid, or, if limited to the mere waiving of those rights, then the state is generall