Plato and Machiavelli can be considered theorists of the ideal state, and each gives a high position to the military and military arts in achieving and maintaining order in society. However, they do have different views of the ultimate place and purpose of the military. What each has to say about the military reflects on the nature of the rest of their philosophies as expressed by Plato in The Republic and by Machiavelli in The Prince.
In Plato's Republic, the philosopher uses Socrates to investigate the nature of the city-state and what the ideal city-state should be. The philosophical inquiry in this dialogue addresses two primary conceptions, conceptions which are linked under the heading of idealism, with one detailing Plato's epistemology and the other his political philosophy. The first is a metaphysical consideration of the nature of life and the world and how we can know what we know, while the second is the practical application of various concepts to the state to demonstrate the relationship between the individual and his or her society in a utopian city-state. Plato's Republic describes a society that is completely rational, based on Plato's concept of the good life and developed to create and protect that sort of life within the context of a civil state. What Plato seeks in this dialogue is a definition of the perfect life and the perfect state to promote and sustain that life, and in the broadest sense, the subject of the dialogue is justice.
Inherent in Plato's analysis if the view that relations among human beings are subject to conflict, and he seems to see war as a permanent feature in human affairs. The city-state he develops will be the target of other city-states, and so the needs of war have to be considered. Machiavelli's view of the state several centuries later has changed little, for he also sees the state as subject to constant warfare, though he may also see war as a legitimate tool of diplomacy so that the state itself may seek to annex territory and influence affairs through war. Both ideal states are ruled by a strong central authority, which for Machiavelli is the prince, the benevolent despot, while for Plato it is a professionalized class known as the Guardians, with the philosopher-king part of an oligarchy at the top.
The Guardians are the rulers and protectors, and they exist to prevent strife in the Republic. Minimizing the threat of or possibility of strife is an important component in the state envisioned by Plato, and he sees the avoidance of strife as deriving from unity in the community. Plato's city-state is based on a certain view of the relationship between the individual and society. There is a different way of thinking about the individual and his or her relation to society that has infused Western political thought in the last three or four centuries and that is embodied in our own political system. The individual who lives under Plato's system, on the other hand, is placing himself or herself completely under the domination of the Guardians and as accepting the idea that everything society does is right and beneficial for the individual as well as for the majority. Clearly, the thrust of political development since the time of Plato has been otherwise as people have sought a way to curtail the power of government and to gain a voice in deciding what government can and cannot do.
The ideal state projected by Plato is based on his concept of the good life, and it has been developed in a way that would protect that sort of life within the context of a civil state. Plato sets forth a definition of the perfect life and the perfect state. Much of what Plato embodies in the Ideal State is a reaction to imperfections in the government and society of his time, a time of turmoil and warfare, and he created a society that would be free of all such strife. One problem with this ideal society is that it would have to be made up of perfect people. Plato tries to create perfect people through education and other means, but it is not clear that this could ever be effective.
Education is especially important in the shaping of the Guardians, including their military education. Guardians are to be of both genders, with the best arrangement being "for our men and women to share a common education, to bring up their children in common and to have a common responsibility" (Republic, 466d). Women are to "take part in all the same occupations as men, both in peace within the city and on campaign in war" (Republic, 466d). Children are to be taken to war along with the parents "to let them see, as they do in other trades, the job they will have to do when they grow up" (Republic, 467a).
Socrates even delves into the conduct of war, making a distinction between war and civil strife, "the one internal and domestic, the other external and foreign; and we call a domestic dispute 'civil strife,' and an external one 'war'" (Republic, 470c). Socrates says further that all relations between Greeks even from different regions are internal, while all relations "between Greek and barbarian" are "foreign and external" (Republic, 470d). The way a good city-state conducts itself in civil strife might be called very civilized, for the people will not "devastate Greek lands or burn Greek dwellings; nor will they admit that the whole people of a state -- men, women, and children -- are their enemies, but only the hostile minority who are responsible for the quarrel" (Republic, 471b).
The army in Plato's conception is a professional organization, a standing army with a dual purpose -- to defend the city-state from external enemies, and to put down civil strife and punish those responsible. In the latter role, the Guardian army would be acting more like a police force or local militia. Interestingly, Plato depends on the essential goodness of human nature in his city-state, though at the same time he believes others are not necessarily so good, hence the need for a standing army and the concern that war is a continuing enterprise. Machiavelli differs from Plato in that he believes in the citizen soldier or citizen militia rather than a standing professional army, though he also sees war as an ongoing enterprise, in his case because of a basic mistrust of human nature.
Plato's description of the tyrant who must scheme to hold onto power has resonance when one reads The Prince, for Machiavelli gives advice to such a ruler on how to achieve and retain power. In The Prince, Machiavelli emphasized the strong king, or prince, as the individual charged with control of government and required to take whatever means he deemed necessary to accomplish his goals. As a humanist educator, Machiavelli details the nature, goals, and responsibilities of such a leader in The Prince. In examining this issue, Machiavelli took a basically amoral approach to the issue, considering what the record showed regarding the activities of the sovereign and using this as a basis for determining how the Prince would be most successful. Machiavelli wanted to provide the basis for the foundation of a new science of statesmanship. He looked to history in terms of the facts rather than theological or moral interpretations or implications. He accepts immoral behavior from the Prince if that behavior promotes the interests of the state, while he rejects moral behavior on the part of the Prince if that behavior does not further the interests of the state.
Machiavelli is thus above all a pragmatist in his approach to statecraft, and the essence of his argument rests on the way people are viewed by others in terms of their actions and the consequences of those actions. He notes that men are spoken about and marked for qualities that bring them either praise or censure. For every good attribute that can be attributed to someone, there is a bad attribute that is its opposite and that can be attributed to someone else. This is true of the Prince as it is of every other human being, and as with any human being, the mixture of qualities includes both the good and the bad. Machiavelli writes:
And I know that every one will confess that it would be most praiseworthy in a prince to exhibit all the above qualities that are considered good; but because they can neither be entirely possessed nor observed, for human conditions do not permit it, it is necessary for him to be sufficiently prudent that he may know how to avoid the reproach of those vices which would lose him his state; and also to keep himself, if it be possible, from those which would not lose him it; but this not being possible, he may with less hesitation abandon himself to them. And again, he need not make himself uneasy at incurring…