The realist science of politics: the art of understanding political practice

Classical Realism represents a science of politics that is distinct from the conventional understanding of science in International Relations. The object of Realist science is the art of politics, which is the development of a sensibility based on practical knowledge to balance values and interests and to make judgments. Realism’s science and its object led to its tagging as “wisdom literature.” This article illustrates that reading Hans Morgenthau’s and Raymond Aron’s work shows how their hermeneutic form of enquiry provides insights into the character of international politics, which conventional understandings do not. Following the example of Morgenthau, the article, first, illustrates how Realism, rather than providing a theory of practice, builds on a science with the purpose to judge knowledge. Realism’s science analyzes the objective conditions of politics, theorizes them, and takes into account the requirements of political practice under contingencies and considerations of morality. The article, second, examines Aron’s take on political practice in the context of the Cold War and politics that built on knowledge without experience to judge knowledge. Morgenthau and Aron’s science helps to capture Realism’s take on politics as an art, how to explicate Realism’s epistemological foundation and value in studying international politics. Doing so, the article, third, contributes to practice theory by clarifying several aspects of Realism’s science. In particular, it shows how Realism captures the art of politics by conceptualizing practice as a form of human conduct thereby offering a more coherent notion of practice than current practice theory.

Classical 20th-century political Realists conceptualized politics as an art (Morgenthau, 1946b: 10). Mastering politics, they argued, requires wisdom and moral strength, rather than mere knowledge. Focusing on the art of politics, Realism's theoretical reflection "always stemmed from, and was rooted in, a practical context" (Beardsworth, 2017: 101), rather than deducing practice from theory (Carr, 1964: 12-20). For Realism, the art of politics is the development of a sensibility based on practical knowledge to balance values and interests and to make value judgments. However, Realist conceptualizations of politics as an art and the science to understand it never gained traction (e.g. Behnegar, 2003;Brown, 2012) and remains tagged as "wisdom literature." Realism's claim to be "based on science," yet advocating an anti-scientific argument (Koskenniemi, 2002: 470) perplexes. Invoking everything of Realist by name, Guzzini (2004), for example, claims "Realism's" dilemma as one of either updating its take on practical knowledge but then losing its "scientific credibility, or reaching for logical persuasiveness," casting its "maxims in a scientific mould, but end up distorting their practical knowledge" (p. 546).
The object of Realist science is the art of politics because Realism understands science as the systematic study of political practice, to create knowledge prior to theorizing practice or the knowledge of it (Morgenthau, 1972a;Rösch, 2016). Realism's science of the "art of politics" takes two fundamental dimensions of human life into consideration: power and morality. Politics, Hans Morgenthau (1954) contends, is an art because of the consequence of the real-life quagmire of "political man" and "moral man" (p. 12). 1 How else could Realists applaud the political art of Lincoln and Churchill other than pointing out the moral merits of their judgments? Certainly, Henry Kissinger (2013) articulated the art of politics as the "attempt to reconcile what is considered just with what is considered possible" (p. 5). Yet this common reference to the art of politics as a perspective, rather than an objective of science, captures only partially Realism's science of the art of politics.
To conceptually grasp this art, we need to acknowledge that Realism's science assumes a "form of knowledge of the human condition conceptually distinct from that embodied in the natural sciences" (Kuklick, 2007: 73). That means choosing practical wisdom over rationalism (Hanley, 2004) yet not over rigorous scientific thinking. Practical wisdom acknowledges the facts available but does not rely on rationalism, that is reducing the understanding of politics to "questions of fact" (Williams, 2006: 95). Realism denies the assumption that "an adequate understanding of the nature of empirical knowledge can be directly equated with the nature of political knowledge." In other words, "knowledge of objects in general and knowledge of the political object are not the same thing" (Williams, 2006: 102). Accordingly, the eminent target of Realism has been positivism, if the term is equated with the study of the laws of nature by methods of the natural sciences (e.g. Aron, 1961;Bull, 1966;Morgenthau, 1946b). Realism has been particularly hostile "to the idea that politics could be understood and controlled by utilizing methods modeled on those used in the natural sciences" (Bell, 2009: 12). To be sure, Realism does not oppose science understood as an "attempt to make experiences conscious in reason in a theoretically valid, systematic way" (Morgenthau, 1972a: 1) or empiricism. Yet Realism worries that "we put too much stock in science," overlooking "the distinctiveness of the political and social world" (Jackson, 2009a: 4) by reductionism and quantification.
Rather than reinforcing reductive claims about "Realism," I argue for the importance of exploring what classical Realism's art of politics is, how its science studies it, and what that implies for International Relations. 2 I delineate the understanding and science of politics as an art of theorizing politics based on rational assumptions without abandoning the conceptualization of political practice built on experience and practical knowledge. Exploring this aspect of Realism's intellectual history is relevant regarding studying political practices and the theory-practice gap. Realism's science points out the delusions of the dichotomy between knowledge and judgment. Judgment means evaluation and, for Realism, this includes a moral aspect. For example, practice theory and attempts to bridge the theory-practice gap suffer from a lack of analytical potential that is conscious of contingencies, yet systematically studies value judgments. Realist conceptions of the practice of the art of politics offer a science of politics and for politicians. Realist science does not abandon a critical stance because its purpose "is to judge the value of knowledge" and the "ultimate questions which confront the scientific enterprise are moral in nature" (Bain, 2000: 454). "The refusal to make morally relevant use of that intellectual ability is the real deficiency of scientific man" (Morgenthau, 1972a: 10) and political practitioners (Morgenthau, 1972b: 369). A definite distinction between knowledge and judgment is thus not possible. Rather, to navigate between them is an art, made accessible by Realist science.
To elucidate Realism's science of the art of political practice, I examine Morgenthau's "science" and Raymond Aron's "praxeology." 3 Both understand the problem of politics as one of contingency upon which individuals act. For both, the art of politics is the analytical concept to recognize contingencies and "to develop sensibility required to do so" (Williams, 2019: 70). 4 Realist science, then, is a hermeneutic enterprise not built on a "spectator construction of knowledge" (Bain, 2000: 448; see also Morgenthau, 1944: 179) separating analysis, advice, and criticism. The science of the art of politics, by default, relies on an interpretative "insider" account, rather than an explanatory "outsider" account (Hollis and Smith, 1990). An "outsider" account stresses natural science methods and "explanation" to identify "laws" of the social and political realm. The "insider" account relies on hermeneutic interpretation prone to affect theory and practice because it is theoretical analysis, practical advice, and moral criticism at once. This aims at learning to "make sense of and to perform actions, taking place inside the contexts of distinctive practices. There is no external, social scientific way of learning such practice-dependent performances" (Frost and Lechner, 2016b: 313). Scientific thinking, in other words, is about "realizing the specifically human in human existence" (Morgenthau, 1972a: 1). Morgenthau's science illustrates how Realism theorizes the art of politics to make an orderly sense of the reaction to contingencies via an evaluation of value judgments. Aron's (2017) work as well resembles Realism's desire to fuse normative and empirical analysis of the art of politics to a science. He takes into account the requirements of political action under contingencies, analyzes objective conditions, and theorizes them. Aron's understanding of politics as an art illustrates a way of theorizing politics based on rational assumptions without abandoning the conceptualization of political practice built on experience. Aron assumes theorizing political practices without practical experience fruitless. He shares Realism's skepticism of theorizing international politics while pointing out a way of theoretically capturing them nonetheless. Like Morgenthau, Aron "advocated 'a science for the politician and a politics based on science'" (Davis, 2009: 2).
Sorting out the puzzle of Realism's science of the art of politics also contributes insights for International Relations more broadly. In particular, Realism's science of politics as an art offers a more coherent notion of practice. First, Realism's engagement with and intervention into political practice contributes to practice theory. The "practice turn" in the social sciences and in International Relations (e.g. Adler and Pouliot, 2011a;Lechner and Frost, 2018;Schatzki et al., 2001;Stern, 2003) propelled a renewed interest in Realism's methodological and philosophical assumptions of the importance of political practice. Yet practice theory does not offer a science of the art of political practice because it does not address questions of morality within practice and their influence on the judgments of knowledge. The theory of practices and how to communicate theory miss that "[a]dvice and criticism are not mutually exclusive" (Bessner, 2019(Bessner, : 1111. Second, questions about Realism's and practice theory's take on science and practice are questions of reflexivity (e.g. Hom and Steele, 2010;Molloy, 2020). These questions are relevant, particularly whether or not the discipline can or should bridge the theory-practice gap and how (e.g. Zambernardi, 2016). Realism is both interested in the practice of politics and theoretical interventions into political practice. Realism ever since has been plagued by the theory-practice gap (e.g. Morgenthau, 1958). Sorting out the puzzle how Realism's science captures the art of politics not only points out weak epistemological spots of practice theory. It also provides an outline of how to overcome the dichotomy between knowledge and judgment (e.g. Hamati-Ataya, 2010). In particular, this article illustrates how Realism's science normative spur that conveys the analysis of practice, its knowledge, and judgment back to the practitioner.
The article proceeds as follows. The first section traces Realism's science, illustrating how it studies the art of politics. It points out how Realism conceptualizes the purpose of science as judging the value of knowledge, qualifying politics as the practice of an art. Aron's praxeology complements Morgenthau's conceptual framework. It points out how Realism studies politics from a rational but not rationalist angle. The remainder of the article clarifies several aspects of Realism's take on science and practice theory, particularly tracing how Realism's conception of practice as a form of human conduct captures the art of politics.

Politics as an art and the study of its practice
Realists inevitably voiced many ambiguities (Jervis, 1994: 853). Classical Realists, however, emphasize that "[n]o study of politics and certainly no study of international politics in the mid-twentieth century can be disinterested in the sense that it is able to divorce knowledge from action and to pursue knowledge for its own sake" (Morgenthau, 1948a(Morgenthau, : 7, 1972a. Realists remained skeptical of International Relations' turn to formal and ahistorical models that value formal rigor over policy relevance, a tendency that eventually expedited to disconnect the discipline from decision makers (Desch, 2019;Haslam, 2002: 1). This is obvious in the historical episode how George Kennan thought about nuclear weapons.
At the beginning of the Cold War, U.S. Secretary of State Dean Acheson tasked Kennan and Paul Nitze to offer suggestions if the United States should develop thermonuclear weapons. What followed is telling for Realism's conceptualization of political practice. Supporting the thermonuclear option, Nitze "joined the Atomic Working group with the State Department." Kennan, who was against the thermonuclear option, "remained isolated in his office, identifying the appropriate Shakespeare quotation to support his cause" (Milne, 2015: 6): "Then every thing includes in power-Power into will, will into appetite, and appetite, a universal wolf, So doubly seconded with will and power, Must make perforce a universal prey And last eat up himself" (U.S. Department of State, 1950). Nitze (1993) derived his assessment from the natural sciences, evaluating costs and consequences. Kennan (1967: 471-476) built his case on political theory, diving into political and moral philosophy. He concluded that a "fusion device was morally repugnant and the whole idea of honing an 'atomic strategy' was diabolical-leading as it could to a war in which everyone loses" (Milne, 2015: 4).
In retrospect, Acheson (1969) brought Realism's apparent dilemma with theory and practice to the point. As a political practitioner, he was after "communicable wisdom," not "educated hunches" (pp. 347-348). How to deal with the outcome in political practice, in this instance nuclear deterrence, is often interpreted in Realist conceptions of statecraft. Other than treating "statecraft" as an object in its own right (e.g. Goddard et al., 2019), Realist conceptions of statecraft rely on an understanding of politics as an art. As it turns out below, understanding the art of politics and scientifically capturing it, not only factors in scientific but also moral aspects. Like Realists, Acheson (1969) concluded, "government is an art, perhaps the most difficult of the arts. It cannot be learned from a textbook. No pamphlet of instructions comes with the Presidency" (p. 47). "Communicable wisdom," then, is the product of scientifically grasping of the art of politics. "Educated hunches," on the other side, rely on a theorized form of knowledge without judging its value and, likely, without experience.
The fascination with Realist conceptions of the art of politics is enduring. Former U.S. President Obama, for example, allegedly has been influenced by Reinhold Niebuhr's Realism (e.g. Brooks, 2009). While this instance is an allusion to Realism's ethical contribution, there remain several sweeping claims about Realism's elitist longing for "high politics" and the art of statecraft (Bessner, 2018). Kissinger's management of international political events, for example, was facilitated by his personal networks and relationships (Ferguson, 2017: 284-298;Isaacson, 1992: 13). Kennan's, Kissinger's, and Obama's allusions to Realism illustrate the problems of understanding politics as an art. Studies on the importance of individuals in international politics often draw on the Realist conception of "practicing" politics (e.g. Byman and Pollack, 2001). These examples and the historical episode outlined above illustrate that the art of politics is not a perspective for studying the world of politics but the object studied by the science of politics. Yet the practice of politics as an art remains inaccessible to an assessment of social sciences, even to those relying on a "practical turn." In the following, I illustrate how Realism's study of politics and focus on practice sets out with judgments of political and ethical standpoints as Realism sees the purpose of science to judge the value of theoretical and practical knowledge. These judgments mark the qualification of politics as the practice of an art, overlooked by current scholarship of practice and Realism's intellectual history. Realism is based on empirical observation and prescriptive, based on a broad engagement with intellectual traditions (McQueen, 2020). Most of all, Realism seeks to interpret what it sees as the art of politics, to use experience in order to make value judgments and to balance values and interests. This remained a background assumption of Realist scholars and practitioners (Carr, 1964;Stephanson, 1992). Drawing on Aristotle (Lang, 2004), Morgenthau (1946b) stated that "Politics is an art and not a science, and what is required for its mastery is not the rationality of the engineer but the wisdom and the moral strength of the statesman" (p. 10). Insisting on experience, morality is thus not only a component of practical political wisdom (Neacsu, 2010). Rather, morality is a fundamental pillar of "wisdom literature's" science, building on the distinction between rationalism and rationality to develop the conceptualization of politics as an art into an analytical principle. Morgenthau's (1944Morgenthau's ( , 1946b epistemology distinguishes between rationalism and rationality. The former misunderstands the nature of social knowledge, desiring "an order analogous to the order perceived in the natural world" (Molloy, 2004: 3). Scientific rationalism, which both Morgenthau and Aron (1972a: 304) criticize, is a progressive approach that "converts the world into a rationalist utopia" (Jackson, 2017: 297), believing that there are "'correct' answers to practical questions" (Nardin, 2020). This rationalist approach seeks to solve political problems with the rational solution of the engineer (Rengger, 2000: 765-768). Rather than relying on wisdom and moral strength, "the decadence of political art" results from "the mistaken belief, rooted in rationalism, that political problems are scientific problems for which the correct solution must be found" (Morgenthau, 1946b(Morgenthau, : 213-214, see also 1972a. This does not mean that Realism abandons rationality as a starting point to theorize. Political science has to start with a "rational outline" which "suggests to us the possible meanings of history" (Morgenthau, 1952: 965-966). However, it would be a mistake to end with such an approach, which ultimately leads to a rationalistic notion of politics, absconding judgment of knowledge. "Were it not for ignorance and emotions, reason would solve international conflicts as easily as rationally as it has solved so many problems in the field of the natural sciences" (Morgenthau, 1975: 21;Ross, 2013). Yet what "has defeated political action . . . throughout history has been the lack of factual knowledge, the sheer ignorance of what was going on, both in one's own and in the enemy camp" (Morgenthau, 1972a: 41).
For Morgenthau (2012), one quality of the art of practicing politics is to distinguish between disputes and tensions (Jütersonke, 2010). The former is accessible to legal solutions, the latter to political solutions. Hence, Morgenthau (1930) suggested during the Weimar era that German diplomats were especially capable of dynamic diplomacy within the League of Nations and on the world stage. They "sought international peace but at the same time understood that violence was inherent to human nature, could determine whether conflicts were legal disputes or political tension" (Greenberg, 2015: 223). The art of the political practitioner is thus "to see through the dichotomies of being either preoccupied with the lust for power or the urge for justice" (Greenberg, 2015: 234). Not surprisingly, the pantheon of Realism's heroes hosts politicians like Abraham Lincoln and Winston Churchill (e.g. Morgenthau, 1955: 286-292;Morgenthau and Hein, 1983). Their art of practicing politics was to accommodate principle and contingent facts, which is to judge their respective value based on experience. 5 A core epistemological assumption of Realism, then, lies in the balance between "morality and the quest for power" (Greenberg, 2015: 254). How to achieve this balance, Morgenthau (1946a) illustrates at the example of the failures of early 20th-century diplomacy where practitioners had forgotten the rules by which it operates. Blending misplaced idealism with misunderstood power politics, our statesmen vacillate between the old and the new, and each failure calls forth an ever stronger dose of an illusory remedy. Whether they swear by Wilson or follow Machiavelli, they are always Utopians pursuing either nothing but power or nothing but justice, yet never pausing to search for the rules of the political art which, in foreign affairs, is but another name for the traditional methods of diplomacy well understood. (p. 1080) Realists share a perspective on international politics as conducted by "high politics" of individuals, hence the fixation on the "traditional methods of diplomacy well understood." This means the capability and leadership of individuals who make choices based on rational assessment and experience but not equating empirical with political knowledge. Realists focus on the observation and interpretation of leadership that leads to practicing politics as an art. Certainly, there are shortcomings when applying this narrative to Realism and its elitist perspective. Constrained by democratic institutions or mass media, this ideal type was already outdated in 20th-century Realists' own time. Facing this dilemma, scholars argue that Realism's conservativism (e.g. Finlayson, 2017) undermines its radical ambitions and that Realism's tendency toward unmasking power relations can affirm the status quo.
However, Realism does not conserve the status quo. It rather seeks "to use classical thought to overcome [modernity's] dehumanizing tendencies and encourage people to become life world-creating individuals who take responsibility for their actions" (Rösch, 2017: 86). In order to do so, Realism seeks to bridge the gap between theory and policy without becoming technocratic and accommodating itself "to the world as it actually is" (Bessner, 2019(Bessner, : 1110Morgenthau, 1972a), exerting influence ignorant of the status quo (Karkour and Giese, 2020). The critical potential of Realism to call out overtly idealistic driven international interventionism, for example, is motivated by Realism's desire to balance morality and power. Realism, as outlined at the example of Morgenthau's praise of Weimar diplomats, seeks to see through the dichotomy of both, pursuing power or justice and finding a balance between the two. Neither does Realism perceive its epistemological concept of the "national interest" as an instrumental matter to secure national survival (Morgenthau et al., 2012: 39). Certainly, the undogmatic, pragmatic, and critical potential of Realism (Luke, 2016;Molloy, 2014) makes its empirical evaluations and judgments of political practice often unintelligible (Guzzini, 2004). "Judgment" is different under different circumstances and thus often "unrealistic" (Oren, 2009).
Morgenthau and Kennan, for example, took outspoken positions in their opposition to the U.S. involvement in Vietnam which divided Realists (e.g. Hixson, 1988;Klusmeyer, 2011;See, 2001;Zambernardi, 2011). Morgenthau, a famous critic, based his criticism on his invocation of the national interest which was "first and foremost concerned with values; that is those things and ideas in which human beings invest moral value" (Bain, 2000: 461; see also Morgenthau, 1960). 6 Aron (1972c) seemed to accept and then reject the U.S. engagement in Vietnam and Kennan had his own way of thinking about it (United States Congress, 1966: 331-430). Vietnam showed that the wisdom of political leaders and politics as an art could be fallible ways of approaching international politics, particularly if distorting the object of the art of politics with a perspective. Aron, for example, elucidates that approaching international politics needs to take into account the wisdom of individual acts. At the same time, approaching international politics must also seek to make rational sense of particular actions in the face of contingencies (Behr, 2019). The task of the analyst is to recognize these contingencies but, as Aron stresses, the practitioner's perspective does not recognize them necessarily.

Raymond Aron: the rational in the art of politics
Aron remains a thinker that International Relations only reluctantly engages and its canon tends to remember him as a mere "Cold Warrior" (Schmitt, 2018: 1). Yet, like Morgenthau (1945), Aron placed particular emphasis on the persistence of "the political," the necessity to act under uncertain conditions and contingencies (Anderson, 1998). Certainly, Aron and Morgenthau had their difficulties. Aron worried that Morgenthau was too much influenced by the German strand of power politics, predisposed by Carl Schmitt (Steinmetz-Jenkins, 2018). Morgenthau (1967b), on the other side, charged Aron's work with the lack of a comprehensive theory. However, what is important here is that what "Aron developed was not a political theory but a political science, a way of thinking about politics attuned to the need for making specific decisions in a given set of circumstances" (Davis, 2009: 3), that is the art of politics. To develop a political science, Aron, like Morgenthau, assumed rational, but not rationalistic, actors. Aron (see also Aron and Sutton, 1981: 115) described himself as part of the school of "rational humanism" which remains aware of the animal impulses in man, and the passions of man in society. The rationalist has long since abandoned the illusion that men, alone or in groups, are reasonable. He bets on the education of humanity, even if he is not sure he will win his wager (Aron 1994: 170).
Otherwise, any thinking about politics would be useless. Opposing rationalism, Aron's enterprise of studying international politics was one of building "'a science for the politician and a politics based on science'" (Davis, 2009: 2), not unlike Morgenthau's endeavor. Aron's (2017: Part Four) concept of "politics based on science" is best illustrated in his praxeology, that is, the "difficult, contentious area in which theory, ethics, and action converge" (Davis, 2009: 24). Tellingly, praxeology (Aron, 2017: 569) is a normative reflection that relates to the "understanding of objective conditions and the limits of historical knowledge to the requirements of action" (Aron, 1967: 204). Aron's praxeology seeks to untangle Realism's epistemological dilemma: understanding the problem of politics as one of contingency (Behr, 2019: 4-6) upon which individuals act (i.e. practice), while theorizing politics, which is to make an orderly sense of the reaction to contingencies. In other words, like Clausewitz, Aron (1972b) assumed theorizing necessary to "provide economical explanations for a wide array of phenomena" (Mearsheimer and Walt, 2013: 435), rather than only resorting to practice without taking values serious (Stewart, 2018). This is not to suggest that Aron sketched out a theory of international politics via the backdoor of political philosophy, prior to analyzing practice. "As long as each collectivity must think of its own safety at the same time as of that of the diplomatic system or of the human race, diplomatic-strategic behaviour will never be rationally determined, even in theory" (Aron, 2017: 17). Rather, Aron (2017) was after a conceptual framework without transforming "the rational analysis of International Relations" into an "inclusive theory" (p. 17). 7 His praxeology does not involve a comprehensive theory of International Relations, a fact Morgenthau criticized. Aron's "substantive propositions," Morgenthau (1967b) charged, are "the result of the author's practical judgment; they owe little to the theoretical concepts and framework" (p. 1111).
For example, Aron emphasizes that political means are rational whereas political ends are not necessarily so. War, Aron's (e.g. 1954Aron's (e.g. , 1972b: 608-609) persistent object of interest, serves a purpose, which is not intrinsic in the very act of war (Morgenthau, 1955). The option for war as an instrument of politics can be rational but not so its object. The plurality of interests, ideologies, and a host of other contingencies make it unrealistic to grasp the object of international politics in mere theoretical terms. Not even, as contemporary Realists claim, "survival" as the end of foreign policy can be "proved" to be a rational aim (Cozette, 2004: 443). In Clausewitz, Aron saw a preliminary advocate of his approach of rationally capturing political practice. "In Clausewitz's mind," much like for Aron, theory was connected to action only as preparation for it; strategic theory could not dictate solutions to the man of action but served instead to make action more rational by clarifying the range of choices that can be realistically pursued in a given situation. (Davis, 2009: 136; see also Morgenthau, 1944) However, what follows for theory if we assume in the nuclear age, as Aron holds with Clausewitz, that war is only an instrument of politics, a phase and not the end of politics? Only that theory can and must understand and approach "the political" and politics under the aspect of rationality. This is not to say that International Relations should understand politics under the aspect of rational choice that poses as an apolitical and non-ideological solution (Mirowski, 2019). After all, as Keohane (1984) points out, rationality is "a theoretically useful simplification of reality rather than a true reflection of it" (p. 108). For Aron (1963: 397-428), violence in the nuclear age remains a persistent pattern of politics. Violence is neither an ultimate end nor an exclusive means. War always overshadows the conduct of international politics but that is not to suggest that it is the only motive or interest (Morgenthau, 1955). For example, Aron criticizes the rational strategy of nuclear deterrence that builds on knowledge without experience. Strategists went from analysis to forecast and to doctrine. The advent of rational choice theory led to a nuclear strategy, "portrayed as a series of games played out on computers" (Erickson et al., 2013;Mirowski, 2019: 159). This kind of "producing reason" strips bare the human essence toward one that is no longer "defined by our bodies, our souls, our hopes or our dreams. We are defined by our choices" (Heyck, 2012: 99). Criticizing this development, Aron points out the extreme nature of violence that this train of development ignores. Once passion is inflamed and massacre unleashed, unthinkable terror, Aron (1980: 459) acknowledges, tends to turn into an appearance of normality. For example, the bombing of German cities caused horror in Great Britain, but only after the war. Reason and passion are thus not opposed: "It is passion that provokes the extremes of violence, and at the same time confers on war in its internal unity, its necessity, and its pure form" (Aron, 1972b: 606).
Political leaders, in this reading, are neither simply poker players who count on luck and bluffs, nor only calculating chess players. It is useless, in analytical terms, to grant individuals such an important power of decision. Historians, as Aron holds, warn of humans' affection to confuse personal patterns with the political process at which end a specific person or group of people come to a decision on war or peace. However, for Aron, those who abandon the fiction of rational acting condemn themselves to hopelessness. Similarly, as shown above, Morgenthau insists to start with a "rational outline." If we assume that we are toys of mysterious powers, what can we do other than awaiting the salvation from revolution or death due to nuclear apocalypse (Aron, 1980: 486-487)? Weapons, Aron (1980: 489) interjects, produce permanent risk, not permanent war. It is "man," not weapons, that causes war. If the use of nuclear weapons follows the same blind powers such as the back and forth of people, what hope remains, asks Aron. The possibility of boundless violence constrains actual violence. This is why Aron (1980: 495) thought of absolute war as a theoretical option. As shown above, a similar stream of thought led Kennan to oppose an "atomic strategy" in the first place for Aron and Morgenthau. politics, while being a struggle for power or survival, is also to be regarded as part of man's never ended attempt to implement what he regards as ethically right, even though is bound to fall short of the ethical ideal from which it arises. (Cozette, 2008: 678) Contemplating the nuclear apocalypse, Morgenthau thought about a world state to overcome the tensions of the time (Craig, 2007;McQueen, 2018). Facing the possibility of a nuclear apocalypse, Aron's bet was on reason, asking what to do in the government's place (Frost, 2007: 292). Similarly, Morgenthau (1952: 965-966), as he put the hypothesis of a "rational outline" to the test, gave in to John M. Keynes's proverb: "If the facts change, I change my mind. What do you do, Sir?" For Morgenthau and Aron, this approach was the rejection of idealism in favor of pragmatic Realism. Morgenthau realized "that power and politics cannot be constrained within a rational framework" (Molloy, 2004: 29). Morgenthau and Aron agree that studying political practice needs to set out with a rational approach. Yet for both it is not the kind of a rational approach understood as scientific rationalism. Morgenthau and Aron, when forced to choose between abstraction and reality, opted for reality, which suggests the enduring relevance of their "science" of international politics. It studies practice from a rational but not rationalist angle that takes into account the art of political practice of finding a balance between power and morality, an aspect of studying practice that practice theory glosses over.

From practice to conduct
From the beginnings, International Relation's scholars' intention has been "based upon their perceived contribution to better government" (Wallace, 1996: 301). During the consolidation phase of the discipline in the United States, the Rockefeller Foundation, for example, brought Realists and State Department officials together (Guilhot, 2011) who shared a common interest in how to theorize and influence practices. Studying "practices of one kind or another" is thus "what scholars always have studied" (Ringmar, 2014: 2). To grasp practices prior to theorizing them, scholars study politics in the field where politics is "made." Nonetheless, the "practice turn" only recently established a distinct branch of research in International Relations (e.g. Adler and Pouliot, 2011a;Lechner and Frost, 2018). This is not least because this "turn" developed distinct conceptions of practice, mainly borrowed from Pierre Bourdieu (1977). Lechner and Frost (2018) summarize that this particular take on practice theory assumes that "practices represent doings or actions, including patterned actions carried out by a multitude of agents" (p. 1). 8 According to two leading proponents of practice theory, " [b]y focusing on what practitioners do," practice theory zooms "in on the quotidian unfolding of international life and analyze the ongoing accomplishments that, put together, constitute the 'big picture' of world politics" (Adler and Pouliot, 2011b: 1). A practice is a performance that tends to be patterned across time, preformed competently or incompetently, rests on background knowledge, and weaves together discursive and material worlds (Adler and Pouliot, 2011c: 6-8). Practices, then, are "socially meaningful patterns of action" (Pouliot, 2016: 49). In other words, when "seen through these lenses, the concerns of other IR approaches . . . are bundles of individual and collective practices woven together and producing specific outcomes" (Cornut, 2017). Practice theory builds on reworking conceptions of practice by Aristotle and Bourdieu, on one hand (e.g. Adler and Pouliot, 2011a), and Wittgenstein, on the other hand (e.g. Lechner, 2016a, 2018;Navari, 2011).
The Aristotelian conception of practice rests on "an adequate description of ('practice') internal ends; that is, of the action itself" (Frost and Lechner, 2016a: 345). This assumes that "agents always act with some end in view." For Aristotle, the "end" of a particular action is to carry out the action in question. For Wittgenstein, however, "certain . . . ends of action are intelligible as 'parts' embedded within social 'wholes' or language-games (practices), where each practice is constituted as a more or less autonomous system of rules." The end of action, then, is not determined by what the agent wants but by the internal ends of a given language-game. 9 The Wittgensteinian approach of practice theory thus suggests that Realism's conceptualization of politics as an art discounts the constitutional set-up of social "wholes." "International society," for example, "is a realm of action as well as a realm of shared meanings." These meanings "can be interpreted, understood, and of course, also misunderstood" because the "internal ends of international society as a practice are specified by its own practice-defining rules" (Frost and Lechner, 2016a: 349) rather than only determined by what agents want.
Realist scholarship illustrates how and why practices matter and what a Realist perspective contributes to the "practice turn." Scientific Realism (as opposed to classical political Realism) invokes a philosophical tradition and its contribution to the study of practice (Joseph and Kurki, 2018), defending the autonomy of politics against ethics (Geuss, 2015;Williams, 2013). 10 There is also the above introduced Realist argument that associates the "practical turn" with the Aristotelian notion of phronesis and the Realist virtue of prudence (Brown, 2012;Lang, 2004). Phronesis and prudence are only accessible in the context of lived experience (Amoureux, 2016;Molloy, 2009), rather than by mere rationalist assumptions and epistemological approaches. Realist inspired interventions in the academic debate over practices, then, point out the weakness of existing approaches studying practices that looks at them without having a theory of them (Bueger and Gadinger, 2015).
Morgenthau and Aron's science of politics enforces this criticism. Both illustrate ways of apprehending international politics and practices without abandoning the practical impasse, not least because the art of politics is the object studied by the science of politics rather than a perspective on politics. Practice theory either focuses on macrosocial structures such as the balance of power or micro structures in formal terms such as diplomacy (e.g. Gould- Davies, 2013;Neumann, 2002;Pouliot and Cornut, 2015). A major predicament with both foci is the emphasis on these practices as dependent variables, which is at odds with a Realist analysis. The structure of practice, for instance diplomacy, is an intersubjective enterprise (Neumann, 2012). Not only do practitioners report different things, they also do things differently as outlined above at Morgenthau's conception of diplomatic practice. Realism does not frame practices (e.g. diplomacy) only as material representations of interests (Adler and Pouliot, 2011c: 3). For Realism, international theory evolves from the practice of prudent statecraft (Brown, 2012;Jackson, 2000). This is one reason why Realism, conceptualizing politics as an art, never clearly distinguished between explanation and prescription. Kennan and Costigliola (2014) echoed the practical driven sentiment that frames politics as an art in the spirit of "high politics," arguing, "there is no collective substitute for plain individual wisdom. The social science techniques may contribute to that type of wisdom, but they cannot replace it or improve upon it" (p. 248). International practices, then, are "understood as produced by inarticulate, practical, common-sense knowledge rather than by the application of theoretical knowledge" (Brown, 2012: 440). Political action, thus, "falls back on practical judgment that is not amenable to scientific precision: practical deliberation is an art" (Frost and Lechner, 2016a: 338). Asserting the experience-theory gap, Brown (2012) cuts into the problem when he concludes that One of the most attractive features of the scientific method is that, in principle at least, experience is of little importance; the newly minted graduate student can (again, in principle) undermine the work of the Nobel Laureate. On the other hand, exercising practical reason rests on experience of the world and of the practice in question, and this is not something that can be based on book learning alone-on this conception of knowledge, the newly minted graduate student is at a disadvantage when contesting the insight of an experienced practitioner. (p. 442)

Practice: behavior, habitus, or conduct?
Realism's predicament posed by its emphazis on practical reason nonetheless, for generalized theoretical output, that is for general propositions, there need to be "features of practices which are not specific to a single case and thus can be theorised" (Brown, 2012: 442). To theorize these features of practice, Realism interprets human conduct in particular contexts and contingencies as facts themselves "have no social meaning" (Morgenthau, 1962). "Interpreting human conduct," hence, does not involve discovering "true" motives or "real" intentions, and it does not involve explaining processes or forces that bring a particular state of affairs into being. The character of human conduct is disclosed, not in an unbroken chain of causes and effects, but in a particular context of activity; a context that conceives conduct "as actions and utterance, wise or foolish, which have reasons, adequate or inadequate, but not causes." (Bain, 2004: 9; see also Morgenthau, 1978: 4-15) For International Relations, interpreting human conduct means to study a wide range of contemporary and historical accounts; discover the conceptual cores of the actions and practices under scrutiny; and the study of literature on the effects of the agents' actions. The method required by such a framework is to "get the hands dirty" by digging in archives, looking at foreign office documents, memoirs, newsprints, and conducting interviews to grasp the notion of practice, self-conception, and the discourses of selfjustification of the actors involved (Navari, 2014: 213). Realism's study of human conduct contributes to International Relations debate what Kratochwil (2018) calls the need for "a closer engagement with the substantive issues characterizing political action, and the realm of praxis" (p. 1). Like Aron, Morgenthau (1973) advised for the conceptual analysis of the "statesmen's" practice: We look over his shoulder when he writes his dispatches; we listen in on his conversation with other statesmen; we read and anticipate his very thoughts. Thinking in terms of interest defined as power, we think as he does, and as disinterested observes we understand his thoughts and actions perhaps better than he, the actor on the political scene, does himself. (p. 5) The understanding of political practice as conduct and its interpretation are different from current International Relations studies of practice. Current notions of practice rest on a Bourdieuian (1977) explanation (e.g. Adler and Pouliot, 2011a;Adler-Nissen, 2013) focusing on habitus. Habitus "stands for an embodied, largely unconscious disposition to act" (Frost and Lechner, 2016a: 337). Practice, in this sense, is "the patterned outcome of habitual action of individuals or groups" (Frost and Lechner, 2016a: 338), yet action "absent meaning is mere behavior" (Barnett, 2018: 324). The endeavor to analyze politics where it is "made," by focusing on practices, led to several theoretical challenges and disputes within the broad Church of "practice turn" scholars. Relying on Wittgenstein, Lechner and Frost (2018) point out that the major drawback of the "practice turn" is that "those currently debating the character of social practices are prone to conflate the category of action (and interaction) with that of practice, social activity constituted by rules" (pp. [10][11]. In other words, the "practice turn" "categorizes practice under the rubric of Aristotle's praxis and because practice-turn scholars in IR adopt Bourdieu's apparatus, they tend to associate practice with praxis" (Lechner and Frost, 2018: 198).
The foregoing illustration of practice and political art makes it clear that for Realism it is human conduct, which constitutes practice. "Conduct (and misconduct) is exclusively a human activity that is judged by a moral or legal standard of some kind" (Jackson, 2000: 78) which provides meaning but not necessarily causes. Yet for Realism's science of the art of politics, this is only possible if it takes power and morality into its account of systematically studying political practice. The empirical reference and normative standard for human conduct, that is human relations in terms of normative standards (e.g. Jackson, 2009b), is the social (its conventions, processes, and contingencies), not the autonomous individual (its behavior or habitus). As illustrated above, the "practice turn" critique of Realist conceptions of practice and politics as an art falls short to account for Realism's "principles" and "laws." They are like maxims "that are intended to aid the judgment of the practitioner of international politics" (Bain, 2000: 462). 11 For Realists, the standard what is agreed or desirable in human conduct is practical knowledge and practical reason precisely because they did not accept a clear-cut distinction between behavior (e.g. in terms of interest) and ethics as deriving from two different principles (Lebow, 2009: 37;Williams, 2006: 95). Turning away from deliberate reflection, that is, a science of the art of politics that addresses moral questions related to structures of power, much of practice theory robs itself of a comprehensive picture of practice and how to theorize it (Hopf, 2018: 688).
For example, the practice of diplomacy is a form of conduct rather than a practice understood as behavior/action (Neumann, 2005). This understanding of practice is goaloriented and does not subscribe to a causal notion of practice which current practice theory seeks. However, both the "practice turn" and the idea of practical reason rest on notions of knowing how to go on in the world, and whether this ability is seen as resting on acquired dispositions or the ability to reason from experience, it cannot be learnt only from books. (Brown, 2012: 455) Rather, to "give meaning to the factual raw material of history," Morgenthau (1952) asserted, we must approach historical reality with a kind of rational outline, a map which suggests to us the possible meanings of history. In other words, we put ourselves in the position of a statesman who must meet a certain problem of foreign policy under certain circumstances and ask ourselves, what are the rational alternatives from which a statesman may choose who must meet this problem under these circumstances, presuming always that he acts in a rational manner, and which of these rational alternatives was this particular statesman, acting under these circumstances, likely to choose? It is the testing of this rational hypothesis against the actual facts and their consequences which gives meaning to the facts of history and makes the scientific writing of political history possible. (pp. 965-966) For example, for Morgenthau (1940), the mainstream narrative of "internationalists," driven by rationalism, fails to ask whether the devices were adequate to the problems which they were supposed to solve, it was the general attitude of the internationalists to take the appropriateness of the devices for granted and to blame the facts for the failure. When the facts behave otherwise than we have predicted, they seem to say, too bad for the facts. Not unlike the sorcerers of primitive ages, they attempt to exorcise social evils by the indefatigable repetition of magic formulae. (p. 260) The eminence of practice theory's understanding of practice as weaving together discursive and material worlds is reinforced by studies of political and international political theory, oscillating between the intellectual history of human rights and international governance (e.g. Barnett, 2018;Rosenboim, 2017). Those studies aim to deconstruct the mainstream narrative of human rights and global governance. This target narrative is one of framing ideas and instruments as a continuing progressive, that is, a rationalist development toward a rule-based international framework. Doing so, this progressive target narrative assumes controllable disputes (e.g. over morality) but not tensions, let alone an analytical focus on conduct and practical knowledge.
Realists sought to meld philosophy, history, and science to a coherent understanding of politics (Smith, 1999: 61-83). Morgenthau and Aron pursued a project informing a "theory of action-a praxis overcoming the Weberian opposition between ethics of conviction and ethics of responsibility" (D'Appollonia, 2018: 175;Morgenthau, 1948b). Because of Realism's understanding of politics as art, it is weary of formal (reductivist) studies and categorizations of political practices and their (quantified) outcomes. Realism, in all its ambiguity, was fundamentally opposed to the "faith in the perfectibility of human society through reason and a brash optimism that all problems were susceptible to technical solution" (Jackson, 2017: 297; see also Morgenthau, 1946b). Yet it is precisely this what scholars of rationalism are after (e.g. Pinker, 2018). The opposition to rationalistic faith is present in Aron's work as well. Realism's take on political practice starts with rational assumptions about human conduct (Morgenthau, 1978: 4-15), that is, what is agreed and desirable under objective conditions. Realism assumes political practice as a form of human conduct, not as a practice that rejects rule-based theory (Frost and Lechner, 2016a) in order to circumvent rule-based restraint for the sake of decision in the realm of practice. Moreover, Realism avoids the temptation to focus on one aspect of knowledge, either technical (learnable) or practical knowledge (which cannot be learned). This is evident in Morgenthau's conception of politics as an art and Aron's work. As Aron illustrates, Realism opts out of a rationalistic approach to study politics that is "problem-solving in orientation and dependent on an account of knowledge . . . that elides the dual basis of skill, technical and practice" (Rengger, 2000: 768).
Such a conception is incapable of a rationalistic assessment. A rationalistic assessment confuses the requirements of practice as outlined by Michael Oakeshott (1962): technical knowledge of rules (theorizing that starts with a "rational outline") and "traditional" knowledge (i.e. practical knowledge). The latter is "not reflective and (unlike technique) cannot be formulated into rules" (Rengger, 2000: 766). In other words, traditional knowledge is "knowing how" rather than "knowing that" (Ryle, 1949). Realism, as illustrated here, is aware of this distinction as its tapping of politics as an "art" emphasizes practical (i.e. Oakeshott's "traditional") knowledge in practice. Realism's desire to theorize international politics, however, led to Morgenthau's take on science and to Aron's praxeology. Both take technical knowledge and practical knowledge into the account of understanding the practice of politics. The belief in rationalism ignores, as Realists warn, "that 'progress'" could be "both liberating and threatening" because "rationality is dangerous precisely because of how hugely it expands human power" (Davies, 2018) beyond practical experience. As charted throughout the article, Morgenthau's and Aron science is not one in the sense of the natural sciences (Brown, 2018: 51-54) understood as reductionism and quantification. It rather favors interpretation and assumes no separation between the theorist and the realm of human experience.

Conclusion
Dean Acheson (1969) drives home the point how for Realism the art of politics, which lies in judgment, requires "both mastery of precise information and apprehension of imponderables" (p. 141). On these grounds, the article shows that classical Realism, warning of the epistemological impasse of rationalism, is skeptical of practice theory without retorting to a science of the art of politics. Realism views theorizing international politics without practical experience fruitless. Aron shares Realism's skepticism of the possibilities theorizing International Relations. Nonetheless, like Morgenthau, he points out how to systematically conceptualize international politics. Doing so, both set out with rational assumptions without abandoning the practical impasse, culminating in the conception of politics as an art, yet accessible by a science of politics. Consolidating this Realist conceptual take, particularly regarding Realism's science, defies the verdict that "squaring the circle of practical knowledge in a scientific environment did not work" (Guzzini, 2013: 523).
Sorting out the puzzle of Realism's concept of politics as an art, accessible by its science, has implications for broader International Relations audiences. In particular, this article illustrates how Realism's engagement with and intervention into political practice contributes to current approaches of studying political practice. First, reducing meanings of actions to an instrumental character, practice theory does not sufficiently address questions of morality within practice and their influence on the judgments of knowledge. Scholars-turned-practitioners value Realism's practical wisdom (e.g. Nye, 2010), yet they rarely pick up on Realism's science whose point was to systematically capture that practical wisdom. Mapping how this aspect of practical wisdom leads to a scientific study of practice, the article, second, contributes conceptual insights to the theory-practice gap discussion. In particular, it shows how Realism's reflexive scientific study of the art of politics seeks to overcome the dichotomy between knowledge and judgment, a major predicament in the theory-practice gap discussion.
Certainly, the survival of Realism's take on science and the art of politics in the mid-20th century had also to do with its creation of abstract maps of the international divorced from policy concerns. Realism had replaced a subject matter that had been much more practical and diverse (Ashworth, 2013). However, it is also that aspect of Realism, which eventually drives its take on theory as a critical function (e.g. Behr and Williams, 2016;Finlayson, 2017;Wallace, 1996). As this article illustrates, this critical function rests on Realism's way of seeing knowledge and judgment inseparable, something practice theory seemingly glosses over (Leander, 2011).
International Relations only recently (e.g. Rathbun, 2012) took an interest in its own "inarticulate premises" (Wilson, 1949). In the case of Realism, those are often said to be conservativism and elitism, allegedly making them outdated approaches (e.g. Guzzini, 2004;Ish-Shalom, 2006). As this article illustrates, there needs to be more research on the "inarticulate premises" of International Relations theories, particularly regarding their take on practice, the art and science of politics, and the theory-policy nexus. This is not least because the focus on political conduct as presented here struggles with what is asked for today in academia and the policy-making world: problem-solving approaches (e.g. Cox, 1981;Rosenau, 1996). Theories, Morgenthau (1967a) warned, "provide a respectable protective shield not only for their practitioners but also for the official doctrine. By saying nothing against it, they imply that there is nothing to be said against it" (p. 214).
Realists, then, are also "problem solvers." Not because they oppose a rationalist framework or because they elude an explanatory theory. Realists are problem solvers because they help to solve how to think about international politics and its general problems (George, 1993: xxiv). Political inquiry as well as political action, therefore, "depends for its success not simply on the methods that enable us to solve problems, but also on the judgement that enables us to appreciate which questions remain most worth asking" (Hanley, 2004: 338; see also Morgenthau, 1972a). If this means that classical Realists unsuccessfully attempted to "square the circle" (Guzzini, 2013: 529) between the art of politics and a science to capture and judge it, it only illustrates that no science of politics is free from the imponderables and contingencies of its subject.