Coup d'état is an interesting concept in political thought. The term is open to differing interpretations and meanings. Some would say coup d'état means simply the sudden overthrow of a government, and this is the sense in which the term is most often used today. However, it originally had a broader meaning. In 1639, Gabriel Naudé published a book called 'Considérations politiques sur les coups d'Etat', which was translated into English in 1711 as 'Political Considerations on Master-Strokes of State'. The Oxford English Dictionary's best definition is probably this one -
a. coup d'état (ku deta) [F. état state] : a sudden and decisive stroke of state policy; spec. a sudden and great change in the government carried out violently or illegally by the ruling power.
This meaning is more complex than an understanding of coup d'état that boils it down to a sudden seizure of power by a minority (were power transferred by a majority, we would call it a revolution). Edward Luttwak, author of Coup d'état: A practical handbook, sums up our modern, more simple understanding of the term when he writes -
A coup consists of the infiltration of a small but critical segment of the state apparatus, which is then used to displace the government from its control of the remainder.
Under this definition, a coup is carried out by sections of the state's infrastructure, usually the military. Military coups were especially common in the developing world between 1945 and the early 1980s, taking place in places such as Iran, Paraguay, South Vietnam, Thailand and Chile. The majority of these coups were executed by the military, who seem to get confused by the difference between force and legitimacy.
Coups have become a lot less common in most regions of the world recently, for a number of reasons. One is the entrenchment of autocratic states in those that have in the past experienced military coups, which has happened mostly in the Middle East. The states here have established complex security structures similar to those found in Nazi Germany or Soviet Russia which ensure a diffusion of power throughout the security apparatus, with the most power lying with the loyalist elements, such as the Fedayeen Saddam or the Peshdaran (Iranian Revolutionary Guards). In other regions, the belief in democracy as the only remaining force of political legitimacy has stopped coups from occuring.
Over the years, the changing nature of politics and the state have altered the exact definition of the coup d'état. If we accept the modern definition of a coup d'état as involving the take-over of the state apparatus by a portion thereof, the interpretation of past coups becomes more problematic. Julius Caesar cannot be said to have carried out a coup, because he changed the entire nature of the state apparatus rather than merely changing its leadership. Indeed, before the modern state it is not really possible to imagine a coup d'état in the strict sense being carried out; yet, paradoxically, it was coup d'états that brought about the advent of the modern state. To understand this we need to look at changing definitions of politics.
To the ancients, politics was action in the general interest of the polis according to a constitution. This is not because the ancients never suffered illegitimate violence or usurpation, but because their concept of the political did not encompass such action. For instance, to Plato the dictator was 'wolf in human form', and violence destroyed political life as the Greeks understood it. Tyranny existed for the good of the tyrant and not for the polis, whereas liberty consisted in communal action according to a constitution: hence why Plato's Republic can from this point of view be considered just, despite its restrictions on personal liberty. Hence, a coup d'état in this environment would mutate the republic beyond all recognition and make it a-political, the realm of force and not persuasion, the usual Greek way of doing politics.
When the everyday rule of politics is that it is agreement between men within republican institutions to prevent themselves from domestic tyranny and foreign dominance, neither the classical coup or the modern coup is possible. The classical coup, as has already been discussed, would merely turn the new rulers into tyrants, and a modern coup presupposes an abstract concept of the state as a 'thing' that exists independently from the rulers and the ruled.
Nowadays the sphere of the political is much wider than it once was, and modern democracies often consider nothing to be beyond the power of the central state, as it is conceptually believed to be identical with the people ruled. They have also developed a new concept of the state, seeing it as something which has an apparatus and a legitimacy which exists in the long-term regardless of particular rulers or citizens. This definition is so radically enlarged from the ancient one that it is clear something has happened along the way. This thing is coup d'état, the political exception.
When Machiavelli wrote The Prince, just one of the new concepts within was the idea of an abstract state which had a legitimacy of its own. This is because Machiavelli was mainly concerned with how princes who had newly acquired territories should govern them, which meant he was usually dealing with the actions of violent usurpers. As the first thinker to actively engage in this sort of 'political science', which was amoral, he was the first to speak of legitimacy as stemming not from everyday political rule as the ancients understood it (i.e., republican institutions as the foci of participation), but from political institutions which are agencies of power acting on a subject population.
When Machiavelli's prince tried to establish his dominion through violence, he unleashed all sort of consequences that would later come back to haunt him. His initial act of usurpation made it necessary to keep on making exceptions to politics-as-usual by extending his state in time and space, entrenching himself by creating a state apparatus which could stand the slings and arrows of Fortune and man; just like late twentieth century Middle Eastern dictators. Legitimacy no longer lay in ancient myths or participation, but in a state apparatus which had mastered the concept of coup d'état by making exceptional political moves to maintain itself when necessary. Thus coup d'état became the centrepiece of raison d'état.
This meant coup d'état became the prime engine of the growth of the sphere of politics. When a ruler makes exceptions, he does two things. Firstly, exceptions eventually become rules: if something is done often enough, then there is a supposed legitimacy in doing it again, taking the past exception as a precedent. Secondly, as noted already, he makes it necessary for the state to make further exceptions to cope with the unexpected effects of the first. As the state expanded the sphere of the political to control more of what went on within its borders, it made possible the modern concepts of totalitarianism and a complete identification of rulers with ruled in modern democraries, both of which are different outcomes of the never-ending extension of the political until it finally touches everything in human life.