How is the outcome of crises determined? In particular, what can now be said on the relative importance of crisis decisions and diplomacy, on the one hand, and ‘structural’ and other long-term determinants, on the other? Many historians place the emphasis on the long-term, ‘underlying’ causes. Crises, it is suggested, resemble the tip of an iceberg: the visible tip is moved by the submerged bulk of the iceberg, responding to ocean currents invisible to the observer. Such images draw attention to the need for a thorough understanding of the background of any crisis, but the preceding analysis has shown that outcomes are not predetermined by underlying causes. A crisis is not, like the tip of an iceberg, an inert mass whose movements depend entirely on forces external to it. The question cannot be resolved so simply.

Contemporary historical scholarship amounts to an ongoing debate rather than a preferred answer to the question. This is well brought out in James Joll's reappraisal of the explanations of World War One. Some historians, he notes, favour the Marxist style of explanation in terms of ‘a comparatively small number of basic factors’, but this leaves a gap between the general analysis and the specific decisions taken in 1914.