In 1913, on the eve of World War I, the United States featured a State Department of some 213 employees in Washington, dc—manual labourers included—and an Army that was barely a fifth the size of Bulgaria’s. The Navy was another matter, but, however impressive, it lagged behind both Britain and Germany in technology and size. Thirty years later, the United States was well on its way to becoming the globalized military and political power it would be when Harry Truman left office in 1953 and that we know today. John Thompson’s A Sense of Power is an attempt to understand that great transformation from the unusual premise that it may not have been necessary. footnote1

The question, of course, is what one means by ‘necessary’. Thompson conforms to recent political parlance in seeing necessity as the opposite of choice—as in ‘wars of necessity, wars of choice’, though he himself does not invoke that well-known formula. As I write, the polarity of necessity and choice has been given unexpected relevance by a president-elect who says that many of the us engagements in the world are unnecessary and certainly bad choices from the national standpoint of ‘America’. It is a language that rejects, it seems, the basic frame in place since the 1940s, whereby the United States is ultimately responsible for world order—responsible for the whole. A Sense of Power is about the emergence of that conception in the first half of the twentieth century, more particularly about the policymaking debates and choices that created it as seen in relation to a certain set of actually existing necessities. A historian of the us at Cambridge, Thompson brings to the subject a lifetime’s study of these debates, focused above all on the Progressive era.

This, then, is a study of decisions in cases where, all things being equal, the possibilities run from the widest range of options to no choice at all. ‘Necessity’, on Thompson’s view, impinges on policymaking in two ways: ‘security’ and ‘economy’. Every polity must evaluate external threats and provide the resources to maintain its continuity, inside and outside; every polity must attend to the kind of economic interests inside that produce the wherewithal for population and state alike. The remainder, then, is ‘choice’. It was indeed one such policy decision, the Vietnam War, that originally moved Thompson to reflect on these problems. Clearly, no issue of ‘security’—whatever successive presidents insisted—was really at stake for the United States in Vietnam, nor any economic interests. Intervention, then, seemed a matter of choice, a bad one (Thompson implies) but a choice nonetheless. The task, accordingly, is to find out how the United States moved from the notion that virtually nothing is necessary to one in which virtually everything is. Thompson’s pitch here is that, strictly speaking, the historical shift was grounded in a mistake: necessity was a choice, so to speak. The United States was never subject to the kinds of systemic pressure that would have required the movement to globalism: hence the luxury of having the choice to make it. The question, then, is how and why it was actually made.

Security and economic interests correspond to the two main explanatory positions which do invoke systemic necessity and form A Sense of Power’s polemical counterpoints: realism on the one hand, economic determinism on the other. On empirical grounds, he thinks both are wrong, and sets out to show this by analysing the familiar shifts and pivots in us foreign relations during this transitional period: the War of 1898 and the imperial-colonial splurge that followed it; the entry into World War I in 1917 and its post-war, Wilsonian debacle; the relative retreat of the 1920s and 30s; the uneven but fairly consistent move from 1938 on towards involvement in the approaching World War II; the massive, ensuing war effort; and the final transition to full globalism in the early Cold War from 1947 onwards. This is not, Thompson underlines, a comprehensive history but an investigation of a particular thematic, and so by nature selective. Nevertheless, A Sense of Power sweeps across a great deal of territory, often in considerable, interesting detail. The reference to Vietnam indicates a problematic originating in the 1960s or 70s, when historiographic arguments were in every way sharper; Thompson is unusual in taking explanatory models more seriously than is typically the case after the cultural turn in the field.

The realist alternative centres on necessities of ‘security’, arguing variously that objective power capabilities lead inherently to the exercise of that power, that the international ‘system’ requires such exercise as inaction would mean insecurity, or that inaction would create instability in the hegemonic order of things. In due course, any gap between power and its exercise would tend to close. Historically, it is then argued, the United States did in fact come to calibrate objective power and ‘security’. Thompson agrees that the country had the means to implement a large, global policy, or at least a much more vigorously expansive one than was actually the case. The potential here was not in doubt. The United States, having already become the biggest manufacturer in the world by 1870, produced almost 40 per cent of all goods at the start of World War I. By 1945, when it had demonstrated its awesome military and economic power in another global conflagration, the figure had risen to 50 per cent; and this was a war during which domestic standards of living had actually risen. Yet, except for the two war efforts, there remained a discrepancy between what the United States could do and what it actually did. Only after 1945 did that divide close with the decisions surrounding the advent of the Cold War.