Interchanging the words ‘Islamic’ and ‘Islamist’ in the context of terrorism is often a tactic used by politicians to suit their moderate or hardline views, but when U.S. President Donald Trump mixed them up in Riyadh this week, it was not deliberate. The written draft said Islamist, which refers to the political use of Islam, but he read it as Islamic, which refers to religious aspects. The White House later clarified that the President was too exhausted and this led to the mistake.

Mr. Trump’s limited vocabulary and haphazard syntax compare in sharp contrast with his predecessor Barack Obama. Added to that is Mr. Trump’s proclivity to use foul language. But the degradation of political discussions in America is not limited to the President. In Congressional and media debates and in political comedies, the boundaries of decency are being pushed. Mr. Trump’s critics are not particularly role models. TV comedian Stephen Colbert — a strong critic of Mr. Trump and consequently a liberal hero — sketched an imagery of oral sex between the President and Russian President Vladimir Putin in a recent show, causing widespread outrage. Not so much for abusing the President, but for using a homophobic metaphor — which is a strict no-go area for progressive politics.

In other recent examples, Democratic National Committee chairman Thomas Perez and CNN primetime anchor Anderson Cooper used words that would be normally not used in public debates. While Mr. Trump gets the blame for triggering this general fall, the degradation preceded him, a 2012 study by non-profit Sunlight Foundation found. The entire Congressional debates starting from the 1990s were put into a searchable database and analysed for choice of words and grammatical accuracy. The result? “In 2005, Congress spoke at an 11.5 grade level... Now, it’s 10.6. In other words, Congress dropped from talking like juniors to talking like sophomores,” said a 2012 report by the National Public Radio.

Last year, Carnegie Mellon University linguists analysed the vocabulary and grammar of presidential candidates, and found that they averaged eighth grade levels. Mr. Trump was below average on vocabulary, at seventh grade, while Bernie Sanders stood highest at 10th grade levels. In terms of grammar, the President stood at sixth grade levels. But he is not the worst in history. That honour goes to George W. Bush, whose grammar is fifth grade. Of all American Presidents through history, Abraham Lincoln had the best grip over English grammar.

Positive side

But Trumpian English has a positive side, Wired reported in March. Several English study groups for beginners on Facebook are using Mr. Trump’s speeches as a resource. The repeated use of the simplest of words in the same speech — stupid, horrible, weak, winning, bad, lose, etc. — apparently help these learners familiarise themselves with basic concepts. And the message to the new English learners is that to be successful in America — even to be President — you don’t need any mastery over the language.

Mr. Trump’s self perception of his language skills is quite different from this reality. “I know words, I have the best words,” he had said during the campaign. Recently, he claimed he coined the phrase ‘pump priming’, which refers to the Keynesian economic principle of bumping up public expenditure to accelerate the economy. “Have you heard that expression used before?... I just… I came up with it a couple of days ago and I thought it was good,” Mr. Trump told his incredulous interviewers from The Economist of a phrase that has existed for two centuries.