You may find this hard to believe, but Hillary Rodham Clinton was once a conservative. At the age of a sixteen, she campaigned for Barry Goldwater. As an undergraduate at Wellesley she was president of the Young Republicans. In 1968 she even attended the Republican convention.

There is therefore a considerable irony that, as America prepares to re-enact one or other of those elections, Hillary Clinton is the Democratic candidate.

“The history of all hitherto existing society is the history of class struggles,” Marx and Engels famously declared in their Communist Manifesto. A century and a half later, with communism seemingly buried under the rubble of the Soviet Union, Samuel Huntington predicted a clash of civilizations.

But what if the great struggle of our time turns out to be between the generations?

In “Notes from Underground,’’ Dostoevsky fired a broadside against all the Victorian do-gooders who dreamt of a perfectly rational society. “You seem certain that man himself will give up erring of his own free will,” he fulminated. He foresaw a ghastly future in which “all human acts will be listed in something like logarithm tables . . . and transferred to a timetable . . . [that] will carry detailed calculations and exact forecasts of everything to come.” In such a world, his utilitarian contemporaries believed, there would be no wrongdoing. It would have been planned, legislated, and regulated out of existence.

I am not going to underestimate him again.

Back in January, in a moment of weakness, I believed the assurance of a supposed expert that Donald Trump’s campaign for the Republican nomination would fizzle out when “real voting in real primaries” began.

“You like tomayto, and I like tomahto,” crooned Fred Astaire to Ginger Rogers in the 1937 caper “Shall We Dance.’’

The routine begins with an argument about the pronunciation not of “tomato” but of “either.” Also at issue are the words “neither,” “pyjamas,” “laughter,” “after,” “Havana,” “banana,” and “oysters.” As a middle-class Scotsman who has spent roughly half his adult life in the United States, I no longer have any idea what the “right” way to pronounce these words is.

But imagine all those words being uttered by Her Majesty the Queen. And then imagine them coming from the mouth of President Barack Obama. Never mind hearing them — merely to see the two heads of state together is to be reminded how very different the United Kingdom and the United States are.

When I was a little boy, my mother liked to quote the following quatrain (sometimes attributed to the New York wit Dorothy Parker):

See the happy moron,

He doesn’t give a damn,

I wish I were a moron,

My God! perhaps I am!

I often think of the happy moron when I settle down to the read the International Monetary Fund’s semiannual publication, the World Economic Outlook. Almost without fail, this publication acknowledges that its previous projections were too optimistic and need to be revised downwards. The Fund’s economists then proceed to make new projections, surely knowing that they too will soon need to be revised downwards.

I cannot imagine Ted Cruz as president of the United States. Despite his emphatic defeat of Donald Trump in the Wisconsin primary. Despite the ever-louder chorus of voices saying he is the only man who can deny Trump the Republican nomination.

I have to admit that DeepMind’s AlphaGo computer had me worried when it trounced the world champion at the Chinese board game Go last month.

The word of the week has been “network.” I have lost track of the number of times I have read that a terrorist network carried out last Tuesday’s lethal attacks in Brussels. The same is now being said about Sunday’s massacre in Lahore. Terrorists used to belong to “groups” and “organizations.” Increasingly, however, we say they belong to networks.

There is a powerful symbolism in the impending collapse of Iraq’s Mosul dam. Built on the cheap by Saddam Hussein in the early 1980s, it holds back up to 2.9 trillion gallons, roughly twice as much as Lake Pontchartrain in New Orleans. We all know what happened when Hurricane Katrina breached the levees around Pontchartrain’s south shore in 2005.

No hurricane is needed to breach the Mosul dam. Built on a weak foundation of soluble gypsum, its stability has always depended on continuous grouting. In 2007 the US Army Corps of Engineers, alarmed by what they had found after the invasion of Iraq, carried out repairs. But since the withdrawal of American forces, the dam has deteriorated. For several weeks in 2014 it came under the control of the Islamic State. Fighting between ISIS and Kurdish Peshmerga forces is just one of the reasons the dam has fallen into disrepair. A contract with an Italian engineering company to overhaul the dam has only just been signed by the Iraqi government.