When was the last time a politician used the phrase "reason of state"? I'm not sure, but it must be quite a while. Phrases such as "the national interest" displaced "reason of state" in leaders' vocabularies long ago. But a brief historical look at reason of state may be interesting, at least (if you'll pardon the tautology) to those who are interested in this sort of thing.
The statesman most associated with the notion of raison d'état is Richelieu,
who sided with Protestant princes/polities in the Thirty Years War, breaking the link between religion and foreign policy. Richelieu's main concern was to counter the Habsburgs, though not necessarily to defeat them: according to one historian, "French policy aimed to restore a balance in Germany, not to bring about a Protestant triumph" (R. Briggs, Early Modern France,
2d ed. 1998, pp.102-103). At any rate, as David Bell wrote last year in reviewing a recent biography of Richelieu, the Cardinal "was
hardly the first European statesman to place national interest above
moral or religious imperatives...." No doubt that's true, but by now
Richelieu's name is so firmly linked with reason of state that the
connection is probably unshakeable.
While Richelieu is the politician most associated with reason of state, the writer most associated with the notion is Machiavelli, even though he never used the phrase. As Michel Foucault observed in one of his 1978 lectures at the Collège de France, the sixteenth- and seventeenth-century debates about reason of state were "conducted through" Machiavelli; the invocation of his name became, to some extent, a signaling device. In the debates of the time, opponents of Richelieu used the accusation of Machiavellism to signal that the lodestar of policy was the ruler's (in this case Louis XIII's) "whims or interests," not -- what reason of state more properly should have denoted -- an "autonomous and specific art of government," as Foucault put it. Writers more favorable to raison d'état were divided, some distancing themselves from the charge of Machiavellism, others praising the author of The Prince (see Foucault, Security, Territory, Population, trans. G. Burchell, pp.243, 245).
Controversies and polemics invoking Machiavelli began not long after the posthumous publication of The Prince in 1532, five years after his death. In 1559 the Church put all of
Machiavelli's books on the Index of condemned works. Before that the
English cardinal Reginald Pole had concluded that The Prince was devilish; Pole "issued a warning against Machiavelli" in his Apology for Emperor Charles V,
which was "written in the late 1530s but not published for over two centuries" (R. Bireley,The Counter-Reformation Prince, 1990, p.15).
Protestant writers also fiercely criticized Machiavelli. A key event in
this connection was the St. Bartholomew's Day Massacre (August 1572) in which several thousand Protestants were killed in Paris (and
more in the following days in other parts of France). Many Protestants
blamed Catherine de Medici, an Italian and a Catholic and the French
king Charles lX's mother, for the massacre, though she intended
not a mass killing but "the elimination of a relatively small group" of
Protestant leaders (Briggs, Early Modern France, pp.21-22). However, Catherine's
intentions were probably unclear to everyone outside her inner circle.
The Huguenot lawyer and writer Innocent Gentillet penned a Contre-Machiavel or Discourse against Machiavelli
(the full title is longer; it was written in Latin in 1571 [thus actually before the St. Bartholomew Massacre], then published in French in 1576 and in English in 1602 [or 1608, depending on which catalog entry one goes with]). Gentillet linked Catherine
de Medici to "Italian statecraft" as allegedly exemplified by
Machiavelli. Gentillet's book, as Robert Bireley notes, "was the first
attempt at a systematic refutation of Machiavelli and was to have a
far-reaching influence on Catholic as well as Protestant authors."
Interestingly, Gentillet referred to The Prince as the "Koran of
the courtiers" (Bireley, Counter-Reformation Prince, p.17).
As mentioned above, Machiavelli did have defenders. There was an attempt or two to argue that his views were compatible with the Bible (see Foucault, Security, Territory, Population, p.245), and today at least a couple of scholars argue that Machiavelli was not hostile to Christianity (see C. Nederman's entry on Machiavelli in The Stanford Encyclopedia of Philosophy, here [with a good bibliography]). A considered view is that "Machiavelli's
whole work is based on the contrast between ordinary Christian ethics
and the ethics of statecraft...not an 'immoral' code of behavior, except
by Christian standards, but a different code of morality, which wills
the means to the noble end of civic survival" (S. Hoffmann, Duties Beyond Borders (1981), p.23). And "[r]ather than an abstract sovereign institution, the state, for Machiavelli, was nothing less -- or more -- than the government, the prince himself at home and abroad" (M. Doyle, Ways of War and Peace (1997), p.97).
One might argue that the notion of raison d'état lives on, albeit in sometimes very attenuated form, in two ways: first, through the mushy idea of the national interest; second, through the view, famously stated by Weber in "Politics as a Vocation," that politicians must always weigh the likely consequences of their actions rather than just acting in accord with a principle regardless of likely results -- though in this second case the connection to reason of state is debatable.
Following the Weberian line, various writers have argued that the ethics of statecraft is "situational." As Robert Jackson puts it (in The Global Covenant (2000), pp.135-36), "scholars of international ethics should...lay open the conduct of statespeople to appropriate moral standards" but also should take into account the circumstances in which that conduct occurs. Stated in this general way, the position leaves open the questions of which moral standards apply in a given case and which circumstances are the more or less relevant ones. But those questions are probably best debated and answered in the context of specific decisions. (Note: I don't entirely agree with R. Jackson that the ethics of statecraft is "conservative more than progressive" (ibid., p.139) but won't pursue this here.)
P.s. A post on this subject shouldn't neglect to mention Friedrich Meinecke's 1924 book The Idea of Reason of State in Modern History (later translated into English under the title Machiavellism).
Added later: The chronology in this post, I've sort of belatedly realized, goes in reverse: it starts with the 17th cent. (Thirty Years' War), then goes back to the 16th cent. (French Wars of Religion). That's probably not the best way to have organized it, but you know, you get what you pay for here... ;)