Obama extensively castigates Donald Trump during Rutgers speech: 'Ignorance is not a virtue'

President Barack Obama took extensive aim at the presumptive Republican presidential nominee Sunday, criticizing Donald Trump's plans to build physical and metaphorical walls between the US and other nations.

Obama never said Trump's name. But during his commencement speech at Rutgers University, the president blasted Trump's isolationist economic and foreign-policy messages, including his proposals to bar Muslims from entering the US and to build a wall along the southern border.

"Isolating or disparaging Muslims, suggesting that they should be treated differently when it comes to entering this country," Obama said. "That is not just a betrayal of our values, that's not just a betrayal of who were are - it would alienate the communities at home and abroad who are our most important partners in the fight against violent extremism.

He added:

Suggesting that we can build an endless a wall along our borders and blame our challenges on immigrants - that doesn't just run counter to our history as the world's melting pot. It contradicts the evidence that our growth and our innovation and our dynamism has always been driven by our ability to attract strivers from other parts of the globe. That's how we became America - why would we want to stop it now?

Obama used much of Sunday's speech to what he cast as Trump's restrictionist proposals. He said some US trade deals that put have some US jobs and manufacturers at risk often also have enormous economic benefits that protect intellectual property laws and raise environmental standards.

The president also slammed the debate over "political correctness," warning the graduates against leaders who do not pay attention to nuance.

"If you were listening to the political debate, you might wonder where this strain of anti-intellectualism came from," Obama said. "Class of 2016, let me be as clear as I can be: In politics and in life, ignorance is not a virtue. It's not cool to not know what you're talking about. That's not 'keeping it real,' or 'telling it like it is.' That's not 'challenging political correctness.' It's just not knowing what you're talking about."

Obama began Sunday's speech by offering a critique of Trump's campaign slogan, "Make America Great Again." The president pointed out that by many economic metrics and measures of racial and gender equality, the US is far more fair and prosperous than in previous generations.

"When you hear someone longing for the good old days, take it with a grain of salt," Obama said. "I guess it's part of human nature, especially in times of change and uncertainty to want to look backwards and long for some imaginary past when everything worked, and the economy hummed, and all politicians were wise, and every child was well mannered, and America pretty much did whatever it wanted around the world."

He added: "Guess what? It ain't so. The good old days weren't all that good."