Chapter 5 considers evidence that disagreements about the jus ad bellum are linked to disagreements about between ‘pacificist’ and ‘interventionist’ strategic cultures ‘extra-legal’ politico-strategic and ethical principles. The chapter describes extra-legal reasoning, particularly in evaluating facts, in UK government statements and writings by eight legal scholars about the lawfulness of military action in Kosovo (1999), Afghanistan (2001) and Iraq (2003), judges’ opinions in the ICJ cases Nicaragua (1986), Wall (2004), and Congo (2005), and in interviews and a survey with thirty-one UK-based international lawyers. The chapter concludes that lawyers’ extra-legal reasoning and views on lawfulness of force broadly align, on a continuum between pacificists preferring a restrictive jus ad bellum, and interventionists favouring an expansionist approach. But again, there are caveats. Most interventionists accept some legal prohibitions they believe are politically or ethically wrong. Most pacificists accept some justifications they politically or ethically condemn. This suggests most lawyers’ politico-strategic and ethical intuitions act as forms of cognitive biases, shaping but not wholly determining opinions about legal interpretation and the jus ad bellum.

Chapter 8 concludes the book by reviewing its arguments and conclusions, identifying weaknesses in the methods used, and proposing ways in which these might be addressed and the research developed further, for example by involving participants in other countries. The chapter importantly notes that uncertainty and contestation remain marginal problems in the jus ad bellum, as in most areas of international law. In most cases, the requirements of international law governing resort to military force are clear and uncontested. There are many reasons to believe that the contemporary jus ad bellum has contributed to global peace and stability. This book’s examination of legal and factual uncertainty and extra-legal intuitions seeks to support and assist lawyers and states in their mission to uphold and apply this crucial area of international law, not to encourage lawyers or states to undermine or abandon it.

Culture has enormous influence on military organizations. One can broadly define organizational culture as the assumptions, ideas, norms, and beliefs, expressed or reflected in symbols, rituals, myths, and practices, that shape how an organization functions and adapts to external stimuli and that give meaning to its members. Except in unique circumstances, culture grows slowly, embedding itself so deeply that members often act unconsciously according to its dictates. Because culture lies hidden under more visible organizational doctrine and symbols, one can easily overlook its power. Culture creates organizational identity and establishes expectations of how group members will act. Three important external factors impact military culture: geography, history, and the environment in which navies, armies, and air forces exist. Of all the factors involved in military effectiveness, culture is perhaps the most important. Yet it also remains the most difficult to understand, because it involves so many external factors that distort its formation and continuities, even in different military organizations within the same nation. Organizational culture will shape how military organizations respond to challenges. The hardship is that changing military culture represents an extraordinarily difficult task that may require years, if not decades, to accomplish.

Culture is a key determinant in organizational effectiveness and plays an enormous role in the lives of military organizations. Cultural biases often result in unstated assumptions that have a deep impact on strategy, operational planning, doctrinal creation, and organization and training of armed forces. The impact of culture on military affairs often remains opaque for years, if not decades, after the events it has affected. Leadership is essential to creating and maintaining organizational culture. Leaders who can shape an organization’s culture from its inception have an outsized influence on its future orientation. Leaders, therefore, must be discriminating when establishing the initial culture of an organization, for once embedded, that culture will prove extraordinarily difficult to change. But even superb leaders are limited. Selection of the right subordinate leaders is critical if an organization’s culture is to survive a leadership transition. Some military organizations do change, assisted by cultures that embrace innovation and a reasonable degree of risk-taking. Organizational culture takes on the characteristics of wider societal culture, but when the military becomes a caste apart, the result can be the degradation of its ethical foundations. Military organizations often have subcultures with significant influence on the larger organization. Technology-centric forces must not allow a culture focused on technological excellence to turn into one centered on technological determinism. Professional military education is critical in sustaining organizational culture.

Strategic culture drives patterns of national statecraft, which in turn drive military strategy. Grand strategy also derives from strategic culture, which emerges from geographical, economic, and historical circumstances. A nation’s circumstances give rise to a distinctive manner of perceiving national power – including the use of military force. Strategic culture is ethnically and nationally driven, derived from a combination of factors. It may be national or subnational, and it may be based on real or imagined traits. It tends to be both enduring and unexamined. It involves intersectionality between national, subnational, and organizational cultures, and it may invoke fictive and contingent identities. It manifests in how individuals and organizations make sense of reality. Individuals and subgroups are presumed to self-ascribe to a certain identity, to absorb distinctive attitudes about force, and thus to adopt a “way of war.” Organizational and ethnic cultures coexist, and any military unit may have multiple subcultures. But strategic culture, since it derives from ethnic and national characteristics, precedes and supersedes organizational culture. Strategic culture influences the organizational culture of a national military, with ethnic and historical factors setting the parameters within which organizational culture and individual initiative operate. Ethnic culture frames strategic culture, which in turn interacts with organizational structure, institutional form, and individual incentives to create military organizational culture.