Huntington argues this 'professional ethic' differentiates 'officers' from amateur groups engaged in violence (reservists, mercenaries, technical specialists, etc.). Huntington stresses that 'professionalism' entails a mutually binding relationship between society and its 'professionals.' The military profession requires that military officers fulfill its duties to its country by compliance with political officials running the state and government. It is the responsibility of the military to provide the public good of common defense since it acts as an agent to the principal government and citizenry. However, each step up in the hierarchy within the military profession demands more responsibility and skill because they are authorized to make more strategic decisions. In the case of the officer corps, officers are entrusted with evaluating the security of the state and providing expert advice to its leaders, and society in turn must afford a measure of deference to their professional expertise and institutions. (Huntington highlights the fact that the President cannot usurp the military hierarchy and appoint a lieutenant to serve on the Joint Chiefs of Staff). Additionally Huntington argues the officership displays a decidedly 'corporate character' as the officers tend to: live apart from general society, delineate hierarchy by specific uniforms and insignia, and maintain a strict separation (within the Department of Defense) from lay people who merely 'administer violence' (reservists). Corporateness refers to the distinct and unique features specific to a profession that which separate it from other professions. Entrance to the profession is restricted with high standards and fulfillment, military academia, and ranks.