Kenneth Boulding’s classic book on Stable Peace (1978) provides one of the most powerful and straightforward expositions of the view that a pair or more grouping of states can enjoy vastly different levels of peace. The continuum from war to peace ranges from active warfare to a high degree of cooperation where violence is not even considered as an option for decision-makers in moments of disagreement and conflict; that is, a condition of ‘stable peace.’ Stable peace is not, however, a utopian condition; there is no need for a total harmony of interests between or among the parties involved. The main point is that political and other conflicts that arise between or among states or other actors are consistently resolved without resorting to military means. Thus, war and other types of violence or threats of war are no longer acceptable rational or legitimate means to settle domestic and international conflicts.

Almost fifty years later, despite many global changes and tectonic geopolitical shifts, Boulding’s relevance remains paramount to making sense of the state of war and peace throughout the world. Moreover, Boulding’s work has superb heuristic and pedagogical characteristics as an accessible, short textbook to introduce students to the different gradations and dimensions of peace, which transcends the mere absence of war. Thus, Boulding masterly breaks simplistic stereotypes about the characteristics of peace. Besides the intellectual rigor of the book, its plain and understandable language makes the challenges of established positions on sustainable peace easier to grasp.

The book is based on a series of talks that Boulding delivered in 1976-1977 where he attempted to answer the question: “If we had a policy for stable peace, what would it look like?” (Boulding 1978, ix). While recognizing that political developments confront “the human race with a quite unprecedented problem” (ibid., 26), Boulding emboldens the reader with a set of possibilities built upon a rational and economic approach to reach stable peace, and not just a quixotic, idealistic, and utopian quest.

It is said that Kenneth Boulding was one of the few people nominated for both the Nobel Prize in Economics as well as in Peace (Mott 2000). While he was both past president of the American Economic Association and of the International Studies Association, Boulding’s (1989, 392) self-assessment was that “I think I might like to claim that peace and conflict is the most important part of my work.” A lifelong pacifist and Quaker, the subject of peace and conflict appears particularly central to Boulding’s (1962, vii) personal and intellectual identity from an early age: “a passionate conviction of my youth that war was the major moral and intellectual problem of our age.” From his standpoint, there was a clear synergy and overlapping between his economic and rational approach, and his theory and explanations of stable peace.

Boulding’s contributions have been paramount to the field of peace studies, sustainable peace, conflict management, and conflict resolution. He is considered one of the founders of the Journal of Conflict Resolution, and later on he established, with Elise Boulding, the International Peace Research Association. Thus, Boulding can be listed as a trailblazer in Western scholarly discussions of peace and conflict studies in the post-World War II era along with other scholars such as Emily Greene Balch, Elise Boulding, John Burton, Cynthia Enloe, Herbert Kelman, Johan Galtung, and Betty Reardon. While their focuses and approaches were very different, they broadly highlighted the multifaceted and complex nature of peace (Richmond 2014; Barash and Webel 2014). Hence, Boulding’s work with the refined and sophisticated concept of stable peace is particularly important here.

The issue of defining peace has never been a merely academic debate and has real practical consequences, including for UN agencies and operations. For example, Jo (2019) highlights that competing definitions of peace within UNESCO, since its establishment, have resulted in changes in what programs received more allocations from the budget. For Boulding (1978, 136), research on peace was particularly crucial “in the modern era where failure to solve the problem of negative peace may result in an enormous worsening of the human condition and a very large diminution of positive peace in any sense of the word.” The concept of peace, then, has different dimensions, aspects, and gradations. It has both ‘negative’ (“the absence of something—the absence of turmoil, tension, conflict, and war”) and ‘positive’ aspects (“a condition of good management, orderly resolution of conflict, harmony associated with mature relationships, gentleness, and love”) (ibid., 3). Positive peace, at the highest level of the continuum in an ideal(istic) direction, has long been associated with the elimination of structural violence, i.e., “any structure in society which produced expectations of life below the normal expectation” (ibid., 135), or in other words, “cooperation, development, pluralism, dynamism, justice, and freedom” (Galtung 1975, 226).

While Boulding challenged the mere minimalistic view that it was enough to refer to peace as simply the absence of war (“negative peace”), he also shied away from the maximalist approach adopted by Galtung that regarded peace as the absence of conflict (absence of “structural violence”) in harmonic terms, “positive peace”. Boulding was aware that ‘negative peace’ was, and still remains, the predominant view in many academic and policy circles. At the same time, he warned against adding newer and unrealistic dimensions to the phenomenon of peace, stretching the concept into idealistic directions. In this sense, and having a substantial dialogue and argument with Galtung, he approvingly quoted a reviewer of Galtung’s work who suggested a proclivity “‘to define structural violence as anything that Galtung didn’t like’” (quoted in Boulding 1978, 135). Rather, for Boulding (ibid., 136), peace research remained a limited subset of a much broader area of study, which he called “normative science,” requiring attention to many other key dimensions in society, e.g., “poverty, oppression, the illegitimate use of power, defenses against abuses of power, distribution and equity.” In this sense, Boulding’s work of thinking about peace compartmentalized its focus on the required conceptions and practices, next to many other key issues that deserve attention in a broader sense, similar to the United Nations Sustainable Development Goals, which includes “Goal 16. Promote just, peaceful and inclusive societies” alongside separate goals in many other issue-areas, such as poverty, climate, and gender equality.

The concept of stable peace obviously lies at the heart of Boulding’s Stable Peace (1978). Boulding’s work has been particularly influential for his useful categorizations and taxonomy by depicting four different stages of relations in a continuum between war and peace: stable war, unstable war, unstable peace, and stable peace. Rather than thinking of peace in simplistic, binary terms, as being present or absent, Boulding highlights the different stages in the continuum in clear and heuristic terms. At one end of the continuum, in violent terms, we find stable war as the norm that regulates the violent relations among countries mired in an armed conflict. At the other end of the continuum, in peaceful terms, we find stable peace, which is defined as a “situation in which the probability of war is so small that it does not really enter into the calculations of any of the people involved” (ibid., 13). Thus, norms are paramount to making sense of Boulding’s argument, according to which “whether war or peace is regarded as the norm” (ibid., 12) becomes key to differentiating among the four different phases, including those located in the blurred zone at the center of the continuum, ‘unstable war’ and ‘unstable peace.’ Unstable war is “the situation in which war is regarded as the norm but is interrupted by periods of relative peace” (ibid., 12). Similarly, unstable peace is the “condition in which peace is regarded as the norm and war is regarded as a breakdown of peace, which will be restored when the war is over” (ibid., 12).

Boulding’s four phases continue to generate extensive consideration and scholarly analysis. Throughout the 2000s, it was possible to find many new typologies that were extending Boulding’s initial discussions with expanded labels and typologies: precarious, conditional, and stable peace (George 2000); negative, stable, and pluralistic security communities, leading to two stages in the framing of stable peace: stabilization and consolidation (Kacowicz and Bar-Siman-Tov 2000); hot war, cold war, cold peace, normal, and warm peace (Miller 2001, 2016); frozen, cold, and warm peace (Bayer 2010, 2024); rapprochement, pluralistic security community, and union (Kupchan 2010); rivalry (severe and lesser), negative peace, and positive peace (including warm peace and security community) (Goertz, Diehl, and Balas 2016); and finally, opposition, overt aggression, latent aggression, indifference, latent cooperation, overt cooperation, and mutuality (Davenport, Melander, and Regan 2018). While Boulding’s initial four categories inspired other peace scholars to continue thinking about new typologies and gradations of peace (Bayer 2017), there has not been a consensus regarding an agreed upon framework that might include all the possible gradations, from actual war to positive peace. Part of the reason for using a diversified array of alternative categories lies in the difficulty in clearly differentiating between the intermediate and blurred categories of ‘unstable war’ and ‘unstable peace’ initially suggested by Boulding. Interestingly, the emphasis on ‘stable’ peace might have been problematic for some scholars, such as Goertz, Diehl, and Balas (2016) who preferred not to emphasize ‘stability,’ itself an ambiguous concept, as a required ingredient of peace. More importantly, the various typologies make comparisons among the different gradations of peace utterly difficult (Tang 2011). In this regard, Boulding’s original assessment in Stable Peace that the study of peace is a work in progress remains relevant almost fifty years later.

KEYWORDS: Kenneth Boulding, Stable Peace, Positive Peace, Negative Peace, Norms on War and Conflict