Alec Baldwin as Donald Trump: When extremism flourishes, liberal jokes fall flat (©NBC)

“Are you not entertained?” boomed Alec Baldwin as he played Donald Trump on the US comedy show Saturday Night Live. We ought to have been. Baldwin’s Trump was a puffy-eyed pervert. He loomed over the actress playing Hillary Clinton like a rapist stalking a victim. He was entitled, bigoted and stupid. Baldwin’s satire appeared so good that the real Donald Trump tweeted: “Time to retire the boring and unfunny show. Alec Baldwin portrayal stinks. Media rigging election!”

It seemed the ultimate compliment at a time when comedians appear to have replaced poets to become Shelley’s unacknowledged legislators of the world. No novelist, let alone a mere poet, can fill stadiums as he or she delivers a take on current affairs. After a scandal breaks no one thinks, “I must hear what Zadie Smith has to say.” Not the way they think, “I can’t wait to see how John Oliver or Have I Got News for You exposes these bastards.”

The Trump candidacy ought to have been political comedy’s apotheosis. Yet rather than affirm the power of satire, Trump has demonstrated its limits. It turns out that political comedy works in democracies that undoubtedly can be sinister, corrupt, stupid, incompetent and unequal, but are not, when you get down to it, so bad after all.

If we are talking about the unacknowledged, the most unacknowledged limit on satire is the power of its targets to retaliate. Russia and Saudi Arabia do not have the equivalent of John Oliver. Any television executive who tried to put one on air would be fired, and the Russian or Saudi Oliver would be lucky to stay out of jail. You can roar along with the audiences at The Book of Mormon. But the only reason it is on stage is because its authors know that, however bad members of the Church of the Latter Day Saints are, they are not so terrible they would try to kill them.

You cannot, after Salman Rushdie and Charlie Hebdo, roar along with satires of Islam anywhere, because in that instance, producers and writers fear that they would be putting their lives on the line.

It tells you all you need to know about Trump, that he tried to intimidate his critics by threatening to sue them. But the First Amendment to the US Constitution means public figures have no chance of winning a libel case. It is a frightening thought that a candidate in Britain backed by a plutocratic demagogue could limit criticism from artists, comedians and journalists by deploying libel lawyers. In America, however, legal threats are hollow gestures.

The real trouble Trump should force liberal satirists to face is that when extremism flourishes their jokes die. They live by pushing caricatures to extremes. All conservative leaders since Thatcher and Reagan have been likened to dictators. Tony Blair was a war criminal. The Daily Mail is Der Stürmer. And so on. But if Western leaders were really dictators, war criminals and monsters, they would have had the comedians shot. Having exaggerated so much in the past, when an actual monster confronts them, they have no words left.