In a series of articles and now a much anticipated book, Dale Copeland has built the case that realism and liberalism are interdependent, that international political economy and security studies are interdependent, and that most of the major and minor wars in modern history stem from interdependence. His basic insight has evolved into trade expectations theory (TET), which states that hopes of commercial and investment flows cause peace, while fears of blocked flows can lead to wars. The argument is more nuanced, of course, but it challenges a string of heavyweight champions: liberal theorists, economic realists, and scholars of domestic politics. Copeland’s gauntlet is forty periods of great power rivalry from 1790 to 1991. He reviews the quantitative literature, but the bulk of the book is comprised of in-depth qualitative studies. His central finding is that TET played a prominent or decisive role in 65 percent of the cases, compared to economic realism’s 28 percent and liberalism’s 7 percent (p. 431–432). A banner implication is that domestic politics “hardly ever” explains war (p. 14), but international factors often do.
Economic Interdependence and War is international relations on a gigantic scale. Copeland asks big questions, makes big arguments, engages big alternatives, and tests them all on big powers over a big timespan. And he does this in one of the most bustling, mature literatures in social science: the causes of war. Few have the ambition or ability to even attempt this, much less pull it off, but that is largely what Copeland has done. A work of this scope is bound to ruffle feathers—it did mine—but it is thoughtful, challenging, and there is undoubtedly truth to it. Grand tomes have gotten rarer as the division of labor has sharpened, and of course narrower books can be equally valuable. Yet books like this one are a healthy reminder that there remains trenchant things to say about the big picture.
Admirably, Copeland wants to move beyond the paradigmatic spats of yesteryear, and seeks to build bridges between theories. He designed his theory “to resolve the fundamental tension between liberalism and realism,” but it is “fundamentally realist” (p. 27). Nonetheless, the assumptions and the logic are largely realist, and the conclusions are crushingly realist. Liberals could be forgiven for thinking this bid for paradigmatic resolution is more hegemonic than hybrid. Moreover, this book is fearless in searching for empirical puzzles and contesting prevailing views, but it usually mounts a circumstantial case that decision-makers saw trade expectations as central. This may be consistent with structural theorizing, but it is unlikely to soothe diplomatic historians.
Theoretically, the work is a significant advance, but the argument is not always clear and convincing. One issue is whether bilateral or multilateral dynamics capture the essentials. For simplicity’s sake, Copeland focuses on bilateral relations (pp. 35–36) before adding third party complications. While potentially a sensible approach, a bilateral frame may seldom capture the core decisional dynamics of trade and war. States contemplating war must weigh a complex chain of factors: the probability of trade cuts, the extent of trade cuts, the duration of trade cuts, the adjustment costs of shifting to new trade patterns, how these shifts will affect other great powers’ relative standing, windows of vulnerability from any quarter, and the probability of sufficient outside support from any quarter. If states worry about relative gains, they should do so in war as in peace, and examine the structural implications of their policy options. Yet the pith of Copeland’s claims, though sensitive to strategic interaction, is less sensitive to systemic repercussions.
Furthermore, falsifying the argument is difficult. This is hardly the author’s fault, but it does pose problems for proving the explanation. Expectations vary dramatically across people and time, and they are hard to measure over individual politicians, much less across the “official mind” of a government. Worse, trade expectations may be caused by other factors. Psychologically, if leaders tend to believe bad things go together, then adverse shifts in security or ideology may prompt policymakers to paint a consistently dark picture of enemies to justify hawkish policies they favor on other grounds. Copeland does yeoman duty consulting the documentary record to try to correct for these issues, but they remain profound and successive researchers should remain alert to their dangers.
On a related note, Copeland appears to be understating the importance of domestic politics. It is true that he starts from neorealist origins, interprets much of the evidence from that perspective, and acknowledges that domestic political factors reinforce and facilitate structural pressures for war (pp. 430–431, 435). Although my sympathies skew realist, the theory (pp. 43–46) and evidence (esp. the Russo-Japanese War) seemed to grant more importance to domestic politics than initially advertised. However, this criticism should be kept in context: The argument has purchase regardless of the banner it marches under, and Copeland softens his position by the end of the work (p. 445).
Empirically, there are grounds to suspect that wars over trade are less common than Copeland asserts. For war to pay (or be the least bad option), the odds of victory have to be good, the spoils of war have to exceed the cost, and the opportunity cost has to be worse. But nothing is more expensive and uncertain than war. Perhaps for these reasons, war is more likely to cause decline than arrest it. The Franco-Prussian, Boer, Russo-Japanese, and First and Second World Wars mangled most of the states that blundered into them. Violence has sometimes been a useful tool of statecraft, but, for more than a century, preventive war has not. Rational, security-seeking states are not perfect, but they should be more cautious than Copeland contends.
Ultimately, Economic Interdependence and War is a work of passion, conviction, and erudition. If it does not achieve all it sets out to, that is no stain given how high it shoots. If it can account for at least some of the scourge of war, it is a worthy service. If the causes of war literature is crowded, they should push aside other arguments to make room for TET.
