The late, great historian David Fromkin wrote a book called In the Time of the Americans, about the leaders - he focused on Roosevelt, Truman, Marshall and MacArthur - who created the American-led world order out of the ruins of World War II.
A future historian writing about today's world might title the book In the Time of the Authoritarians.
The post-Cold War "end of history" moment celebrated by Francis Fukuyama, when the entire world appeared to be converging on a liberal democratic model, appears almost as distant now as the pre-1914 Belle Époque.
This is the age of authoritarians and would-be authoritarians - of populists and nationalists.
Liberals, understood in the classic sense as the promoters of individual liberty, appear to be almost as embattled as they were in the 1930s. Freedom House reports that 2017 represented "the 12th consecutive year of decline in global freedom." Since 2016, 113 countries have seen a decline in freedom while only 62 have seen an improvement.
Everywhere you look, you see illiberal rulers gaining power and exercising that power ruthlessly and assertively.
You see Vladimir Putin annexing Crimea and occupying eastern Ukraine, projecting Russian power into the Middle East, trying to murder dissidents in Britain, and even meddling in the US election.
You see Xi Jinping accumulating absolute power while seizing military control of the South China Sea and consigning more than a million Uighurs to re-education camps.
You see Bashar al-Assad dropping barrel bombs and using poison gas to consolidate his rule in Syria.
You see Rodrigo Duterte sending out death squads in the Philippines ostensibly to combat a drug epidemic.
You see illiberal rulers undermining democracy in Poland, Hungary and Nicaragua - and soon perhaps in Brazil.
And you see Saudi Arabia's crown prince, Mohammed bin Salman, bombing Yemen indiscriminately, blockading Qatar, kidnapping the prime minister of Lebanon, locking up dissidents - and now allegedly murdering and dismembering Washington Post columnist Jamal Khashoggi.
This trend toward repression cannot be blamed entirely on the United States, but it cannot be entirely disconnected from the United States, either.
The greatest expansion of democracy around the world occurred in two waves - the first in the 1940s-1950s, the second in the 1980s-1990s - when the United States was at the height of its power and self-assertiveness.
American involvement was critical in the democratic transitions of countries from Poland to El Salvador. The US desire to fight for freedom began to wane when the Iraq War brought home the costs of nation-building by force. President Barack Obama still believed in promoting human rights but was more wary of intervening abroad than President George W. Bush had been.
Now President Donald Trump gives every indication that, far from fighting for freedom, he would rather fight against it.
This is the president who said it's "great" that Xi is declaring himself ruler for life, praised Duterte for the "unbelievable job" he was doing "on the drug problem," congratulated Recep Tayyip Erdogan for winning a rigged referendum that spelled the death of Turkish democracy, and declared his "love" for Kim Jong Un of North Korea.
When confronted by Lesley Stahl on 60 Minutes about Kim's catalogue of crime - "repression, gulags, starvation" - Trump was dismissive. "I get along with him really well," Trump said. "I have a good energy with him."
He was equally blasé when Stahl asked him about reports that Putin is involved in "assassinations" and "poisonings." He probably is, Trump conceded - but "it's not in our country," so who cares? Britain can deal with Russian hit teams on its own.
The only thing that matters to this intensely solipsistic president is how other rulers treat him; how they treat their own people or even their neighbours is irrelevant.
Thus, it is hardly surprising that Trump has shown so little outrage about the fate of Khashoggi, an American resident and a columnist for an American newspaper who was reportedly murdered in a Nato country.
Trump's threat of "severe punishment" is undercut by his willingness to accept at face value Saudi denials of complicity - just as he accepted Putin's denial of hacking the Democratic Party.
Trump even speculates, echoing a possible Saudi cover story designed to protect the crown prince, that "rogue killers" could be responsible.
How long before he claims that Khashoggi could have been killed by a 400-pound couch potato who somehow waddled into the heavily guarded Saudi Consulate?
If the Saudis carried out this grisly crime with high-level authorisation, as the evidence would indicate, they did so at least in part because they anticipated that the American president wouldn't care about the disappearance of another "enemy of the people".
Other dictatorships are equally emboldened by America's abdication of authority.
This is a good time to be a dictator - and a dangerous time to be a dissident.
Trump has given every despot on the planet a license to kill without worrying about the American reaction.
Because, in all likelihood, there will be none.