Nations that are serious about defence relentlessly question assumptions about capability. Besides reducing the chances of mishap, self-examination enhances deterrence.

No one understood this better than Richard Burdon Haldane, secretary of state for war and architect of army reform in the decade before 1914. Trained in philosophy at Edinburgh and Göttingen, his intellectual engagement was prodigious. Once, in despair at yet more questioning, senior officers asked him, “What sort of an army do you want, minister?”, to which he replied, “An Hegelian one.”

They discovered that what he meant was persistent analysis — thesis, antithesis, synthesis, to reach a greater unity or a new thesis.

Analysis in the Ministry of Defence has of late been driven by immediate operational needs and declining resources. There has