This is an important book that, as its subtitle suggests, integrates the study of international security and domestic politics.For Brian Rathbun, trust is the belief that cooperation will be reciprocated and generalized trust is the belief that others are typically trustworthy. Generalized trusters, at least in the first instance, do not depend on specific information about the behavior, character, or motives of others. Instead, they trust others with the belief that people behave morally in their social interactions. “Strategic” trusters, by contrast, will not trust others without specific information that those individuals have interests that encapsulate their own. If the standard formula for strategic trust is A trusts B to do X, the formula for generalized trust is “A trusts or A is trusting” (p. 24).

Unsurprisingly, generalized trust also differs from generalized distrust, the view that people are generally untrustworthy partners, both in its assumptions about the willingness of others to reciprocate cooperation faithfully and in the identity of its adherents. In Trust in International Cooperation, Rathbun's thesis is that efforts to establish the League of Nations, the United Nations, and the North Atlantic Treaty Organization, were shaped by domestic political contests in the United States between generalized trusters in the Democratic Party and generalized distrusters in the Republican Party. Multilateral organizations require states to place their interests in one another’s hands, meaning that joiners are exposed to the risks of opportunism. Trusting leaders, like Woodrow Wilson, who had a strong belief in the essential goodness of people, felt comfortable committing the United States to these arrangements despite the risks because he believed the country would not pay the consequences. On the other hand, distrustful leaders, like Henry Cabot Lodge, the powerful Senate leader, could not tolerate the idea that the United States might cede some control over its fate to others. Similar controversies between generalized trusters and distrusters over these institutions played out in England.

Rathbun argues that rationalist theories of international relations, whether they take account of strategic trust or not, cannot explain domestic-level variation in support for multilateral institutions among politicians. Rationalist theories imply that actors embedded in the same structural conditions should evaluate and respond to those conditions in similar ways. Yet Rathbun’s studies of the disagreements among U.S. policymakers about the wisdom of entrusting the country’s interests to others in the context of multilateral institutions make a compelling case that leaders did not assess the trustworthiness of states the same way. Instead, what we find is that assumptions about the general trustworthiness of others ran deep in the political philosophies of liberal and conservative politicians.

In 2005, when I published Building Trust: Overcoming Suspicion in International Conflict, I was aware of work in psychology and political science on generalized trust, but I was skeptical of its value for understanding international politics. Rathbun has persuaded me that thinking about generalized trust alerts us to significant variation in the domestic politics of multilateralism. By itself, this is an important contribution to the study of trust in international affairs and to the field of international relations more generally. I am less persuaded that Rathbun’s work enables to him explain things about the demand for multilateral institutions that rationalism cannot. He argues that leaders defaulted to their basic assumptions about the trustworthiness of others in response to their fundamental uncertainty about the future. Rationalist theories, however, make the same general prediction. As James Morrow (1994) points out in Game Theory for Political Scientists (pp. 28–29), under conditions of uncertainty (situations in which possible outcomes and their probability of occurring are unknown), actors may asses the probability of the same outcomes differently based on their prior beliefs about how the world works. It is under conditions of risk that actors are supposed to assess the world the same way. Seen in this light, Rathbun’s work complements rationalism by fleshing out the worldviews that leaders rely on when they have nothing else to help them see what the future holds.

This work also raises several questions for future research. First, to what extent does the assumption that others are trustworthy operate when state survival is at issue? Rathbun argues that the cases he examines are important because real interests were at stake and misjudgments about the intentions of others would prove costly. He is right about this, but either no one or very few of those involved in the U.S. domestic debate over the League, UN, or NATO thought the immediate consequences of joining these organizations were dire. Indeed, situations of multilateral cooperation may mitigate the costs associated with trust violations by spreading the consequences across many members. James Lebovic’s (2013) fine book, Flawed Logics: Strategic Nuclear Arms Control from Truman to Obama suggests that generalized trust operates even in high-stakes bilateral rivalries, but research that assesses alternative explanations for the attitudes leaders held during these episodes is needed to confirm this observation.

Second, why do foreign policy elites rely on assumptions about the trustworthiness of leaders they ostensibly know? The strongest support for generalized trust derives from laboratory studies showing that a set of people who play prisoner’s dilemma games with people they do not know use their first move to cooperate (e.g., Nahoko Hayashi et al., “Reciprocity, Trust, and the Sense of Control: A Cross-Societal Study,” Rationality and Society 11 [February 1999]: 27–46.). Yet the leaders Rathbun studied were not operating behind a veil of ignorance like the volunteers in laboratories. Woodrow Wilson and Henry Cabot Lodge, for example, were deeply involved in foreign policy issues—Wilson as president and Lodge as a member of the Senate Committee on Foreign Relations—for years before coming to loggerheads over the League. These individuals knew a lot about the people the United States would be relying on, but both still relied on their assumptions about human nature rather than the information they possessed.

Complicating matters, it is clear that the very leaders who rely on assumptions about the trustworthiness of their potential partners sometimes abandon those assumptions in favor of an analysis of the historical record. During the effort to establish the UN, for example, U.S. support for giving Security Council members a veto hardened in response to Soviet actions that made American leaders question their intentions (p. 147). The research on generalized trust does not suggest that people only rely on assumptions about others, but the conditions under which people replace their assumptions with information about the behavior of others is unclear.

Finally, are policies that are rooted in the generalized trust of leaders successful at promoting the interests of states over the long run? Blind trust of any kind is not normally considered wise strategy, but there is certainly a case to be made that generalized trust made the efficacious NATO alliance possible. On the other hand, the Wilson administration’s conviction that other states could be trusted was so strong that it failed to appreciate the challenges associated with getting the League Charter passed by the Senate. It is easy to imagine that Wilson also could have misjudged the rectitude of other leaders. Hasty judgments, after all, are often erroneous.

In summary, Trust in International Cooperation is a noteworthy contribution to the field of international relations. Rathbun’s thesis about generalized trust enables him to explain things about the formation of multilateral institutions that other theories overlook. It appears that the book’s biggest weakness is an inability to explain the conditions under which generalized trusters and distrusters become attentive to information about the actions and intentions of their counterparts. Nevertheless, the framework offered is rich enough and sophisticated enough to support future investigations into these and other subjects.