“The ideas of economists and political philosophers, both when they are right and when they are wrong, are more powerful than is commonly understood. Indeed the world is ruled by little else,” wrote John Maynard Keynes (a man who should know) in 1936. “Madmen in authority, who hear voices in the air, are distilling their frenzy from some academic scribbler of a few years back.”

One such scribbler currently ruling the world is the Edwardian geographer Sir Halford Mackinder. Oxford professor, MP and imperialist, Sir Halford was the intellectual architect of modern geopolitics and the thinker who put the idea of “the Heartland” at the centre of global diplomacy.

Today, he is more relevant than ever. As Russia and Georgia continue their hot and cold war over South Ossetia, as the Kremlin attacks the European Union for its “eastern partnership” policy towards Ukraine, Moldova and Belarus, and as America and Russia tussle over influence in Turkmenistan and Kyrgyzstan, Mackinder’s realpolitik vision is at its most active for half a century. Few recall his name, but our foreign policy is now played out in his shadow.

Mackinder’s fame comes from a rather dry lecture delivered to the Royal Geographical Society in 1904, entitled The Geographical Pivot of History. In it he made two dynamite propositions. First, that the globalised world — crisscrossed by steam, telegram and train — had become a closed system. Since there was nowhere left to colonise, the world had become a unitary space with every strategic advance by one nation necessitating a rival power to retreat. In this closed geographical context, diplomacy was a zero-sum game and geopolitics meant successfully squaring political power with geographical setting.

Second, the key to world power lay in “the Heartland of the Old World”, the Eurasian land mass stretching from the mouth of the Elbe in Germany to the mouth of the Amur in Outer Manchuria. This vast land mass included the Iranian upland in the southwest and part of the Mongolian upland in the southeast, but its core was constituted by the Russian Empire. In centuries past this terrain had been the pivot of world history as the Huns, the Mongols and the Magyars swept into Europe. Ranged against this “Heartland” sat the representatives of the outer fringe, the sea powers — Great Britain, the United States and Japan. And what geopolitics came down to was an ongoing struggle between the Heartland and the sea powers. Mackinder, as a loyal servant of the British Empire, was desperately worried that an expansionist Russia would act to the detriment of British imperial interests.

He explored these themes further during the 1919 Versailles peace conference in his most significant work, Democratic Ideals and Reality (tellingly republished this summer under the Faber Find imprint of lost classics). In contrast to President Wilson’s visionary rhetoric of democracy and national self-determination, Mackinder argued that the First World War victors should base the new world order not on lofty ideals but the hard geopolitical realities underlying history. And the most pressing of those realities was the threat posed by a united Russia and Germany. Mackinder’s thesis was simple: “Who rules East Europe commands the Heartland; who rules the Heartland commands the World Island; who rules the World Island commands the world.”

To prevent just such a terrifying power bloc, he advocated a cordon sanitaire of independent states in Eastern Europe — Poland, Czechoslovakia, Hungary — to act as a bulwark between Germany and Russia.

Unfortunately, in Britain Mackinder was a prophet without power. But in Germany he was taken very seriously — most particularly by Major Karl Haushofer, Professor of Political Geography at the University of Munich. Haushofer had served as a military observer in Japan and had there concurred with Mackinder that space equalled power, leading him to propose a German-Russian-Japanese axis to take on the Anglo-Saxon powers. On returning to Weimar Germany, he publicised Democratic Ideals and Reality and then, through the patronage of his friend Rudolf Hess, is credited with influencing Nazi party policy. Haushofer even visited Adolf Hitler during his time in Landsberg fortress (after the abortive 1923 putsch) and, in the words of a recent scholar, “certain passages [of Mein Kampf] read as though they could have been written by a Haushofer — or even by a Mackinder”. Everything that Mackinder feared Haushofer now favoured: Germany had to dominate the Heartland and seize the Eurasian land mass if it was ever to defeat British sea power.

Hitler attempted just that with his Nazi-Soviet pact, and when the alliance with Stalin had run its course, Hitler launched Operation Barbarossa to claim the Heartland for the Fatherland by force. Yet history was not on Hitler’s side and as the Second World War moved toward its endgame it became apparent that it was the Soviet Union, not the Third Reich, that would enclose the Heartland behind an Iron Curtain. The elderly Mackinder now came out of retirement to warn that “the territory of the USSR is equivalent to the Heartland” and that “if the Soviet Union emerges from this war as conqueror of Germany, she must rank as the greatest land power on the globe”. To secure the maritime democracies from Eurasian aggression, Mackinder proposed a North Atlantic alliance to provide a “bridgehead in France, a moated aerodrome in Britain, and a reserve of trained manpower, agriculture and industries in the eastern United States and Canada”.

Mackinder’s vision of geopolitics now suffused American postwar defence strategy. Widely publicised by the Yale international relations expert Nicholas Spykman, Mackinder’s influence was palpable in US plans to counter Soviet expansion — from the establishment of Nato to the Marshall Plan to intervention in Turkey, Malaya, even Korea. “The policy of containment or encirclement of the USSR was evolved as a direct response to the threat seen to arise from Soviet domination of the Heartland”, as one of Mackinder’s biographers puts it.

But then Mackinder fell out of fashion. In the wake of containment excess in Vietnam and the political demise of those arch-global strategists Henry Kissinger and Richard Nixon, geopolitics was regarded as a bloody and arguably amoral approach. Until, that is, the Soviets invaded Afghanistan and suddenly geography was back. President Carter’s national security adviser Zbigniew Brzezinski — raised on the northern edges of the Heartland in Poland — had studied Mackinder. Brzezinski had a reputation for controversial methods that he solidified by funnelling arms to the Mujahidin as the Americans and the Soviets fought another proxy war over hegemony in the Heartland. In the 1980s Mackinder’s belief in reality over idealism continued to hold sway in Washington and London as both administrations dropped détente to confront head-on the “Evil Empire”. President Reagan’s nuclear proliferation adviser, Colin Gray, was himself a leading scholar of Mackinder. And it is no surprise that many of those who worked in the Nixon and Reagan White Houses — Donald Rumsfeld and Dick Cheney among them — brought their geopolitics back to bear as part of the Bush Administration in 2000. With hundreds of US military bases stretching from Iraq to Afghanistan to Kyrgyzstan, critics have seen a bid for the Heartland underpinning much 21stcentury Pentagon thinking.

But the difference today is that geopolitics is now discussed in the Heartland itself. As Russian securocrats work to block Nato and US expansion into the former Soviet republics they are reaching for their Mackinder. In 2000 Geopolitics: A Textbook was published in Moscow with much of Mackinder’s work translated into Russian for the first time. Aleksandr Dugin, one of the leading ideologists of Russian nationalism, extensively cites Mackinder in his work championing a Heartland to oppose US “Atlanticist” dominance. And in Uzbekistan and Kazakhstan, think-tanks and diplomats are now surprisingly au fait with Sir Halford’s philosophy.

Today, in Georgia, Chechnya, Afghanistan and even Iran, an overt and covert battle for the Heartland grinds on. As in the 1930s, 1950s and 1980s, the tensions of our own times have brought back to life the musings of one of the most influential academics of the 20th century. The problem, as always, lies not with the academic scribbler but the madmen in authority.

Tristram Hunt’s new Radio 3 series, Ideas: The British Version, begins on Sept 27. Halford J. Mackinder’s Democratic Ideals and Reality is published by Faber and Faber at £15. To order it for £13.50 inc p&p call 0845 2712134 or visit timesonline.co.uk/booksfirst

Times Recommends

• Should Knox’s trial even have reached the courtroom?
• All that glitters is not sold in Wright’s world
• Believe it or not, Big Brother is your friend