The first 20 or so pages of Eric Hobsbawm's The Age of Extremes: A History of the World, 1914-1991 constitute probably the greatest summary of the 20th century I've ever read. It's the kind of thing that I hope I remember to print out and make my children read, once they're old enough; the kind of dizzying intellectual accomplishment that makes you stop and re-read every paragraph because there's just so much packed into every sentence. It's a performance, an expertly-maintained running gag of distilled analysis that, were it a comedy routine, would have you crying and red-faced but instead, just keeps making you think, "Wow."
He begins by breaking apart the Short Twentieth Century (1914-1991; important to note that the book was written in 1992-93) into three parts, "a sort of triptych or historical sandwich." First comes the Age of Catastrophe, 1914 to 1945, in which the world cannot stop being at war with itself. Then comes a Golden Age, lasting until the early 1970s, followed by "a new era of decomposition, uncertainty and crisis - and indeed, for large parts of the world such as Africa, the former USSR, and the formerly socialist parts of Europe, of catastrophe."*
This has the effect of declaring the "Golden Age" of the 50s and 60s to be the real anomaly of the 20th Century, instead of the mean to which Western society will inevitably revert. An interesting thought, for someone who grew up essentially in a post-Communist world, a second Golden Age of the 20th Century (for a middle-class American, anyway).
From there, Hobsbawm moves on to perhaps his trippiest argument: International Communism, which took root in countries that covered 1/6th of the world's land mass, and which contained 1/3rd of its people, was able to become so dominant only because of the failure of the Capitalist system in the Age of Catastrophe. And yet, Communism (which had been created by Marx and Engels in explicit contrast to bourgeois Capitalism, and which was now succeeding because of the failure of that system) would be what ensured the survival and dominance of the Capitalist system. After all, in 1939 the ultimate triumph of democratic Capitalism was by no means assured, as fascism and authoritarianism spread. But had the Red Army not fought against the fascists (not that Hitler gave the USSR much choice), it's far from certain that Germany would have lost the war.
In discussing the general impact of the Golden Age, Hobsbawm moves on to point out, literally as an aside, that "A ... case can be made for saying that the third quarter of the century marked the end of the seven or eight millenia of human history that began with the invention of agriculture in the stone age, if only because it ended the long era when the overwhelming majority of the human race lived by growing food and herding animals."
That, for me, was one of those "Wow." moments wherein a simple, straightforward, obvious-in-hindsight argument gets made for the first time and in a split second, completely alters the way one understands the world. To say that the 20th Century is "exceptional" is not, itself, an exceptional statement. To say that it overturned eight millenia of human history is, um, pretty amazing. And, as far as I can see, completely true.
Hobsbawm's final bit of knowledge-dropping is just how extreme the moral depravity of the 20th Century really was. He notes that, with 187 million people killed in war, or 10% of the world population in 1900, this was probably the bloodiest century in human history, as well as its most progressive. And how many of those victims were civilians, bombed or nuked or tortured or terrorized (all methods of killing that, basically, hadn't even been invented (and certainly not perfected) until the last century rolled around.)
*I think it was probably only possible to thusly describe the 20th Century this way in the early 90s (which is when Hobsbawm was writing this.) Brad DeLong has a pretty harsh review of the book, which I've only skimmed (since I haven't read the book itself yet) but I think it misses this key point. DeLong basically accuses Hobsbawm of being too pessimistic about the future, and the latter part of the 20th Cent., because he's too caught up in being sad about Communism's decline. DeLong finds reason for optimism at the extinguishing of the political philosophy that produced 2 of the 3 great mass murderers, of the 20th Century.
But the unique time at which Hobsbawm and DeLong were writing encompassed the largest transfer of arms in history, the swift descent into criminal anarchy of one of the world's two major powers and the vacuum in world affairs that resulted from the end of the Cold War, the invasion of Kuwait, the conditions immediately preceding the Rwandan genocide, a war and genocide in Bosnia... In other words, I think the thesis of a 3-part Short Twentieth Century is a little on the tidy side given the events of the final decade of the literal 20th Century, but I'd say there was ample reason for pessimism at the outset of the 90s, and given the story Hobsbawm wants to tell (which, at the time of writing, really was the whole story) his structure still makes sense.