Donald Trump (Birther-N.Y.) is at it again. In double-barrelled interviews on NBC’s “Today Show” and MSNBC’s “Morning Joe,” Trump continued his disgusting and dangerous dabbling in the disproved conspiracy theory that President Obama was not born in the United States. This might be good for the ratings of his television show. This might even be good for his business. But it is terrible for the nation and public discourse that someone who claims to be so smart is so willing to perpetuate a lie.

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Alex Koppelman snipped this strand of the conspiracy in Dec. 2008 and again in July 2009. And he’ll most likely have to do it again now that Trump has embraced the fallacy with both hands. This all stemmed from a interview of Sarah Obama, the second wife of the president’s grandfather, by Ron McRae, a street preacher, through a translator over the phone. As Koppelman reported in 2009, “Sarah Obama is not the president’s biological grandmother, but he calls her ‘Granny Sarah.’”

In a clear lost-in-translation moment (and over an international phone line), which you can listen to in full here, Mrs. Obama said she was there for her grandson’s birth. When McRae asks where in Mombassa the president was born, the translator, Vitalis Akech Ogombe, repeatedly corrected him.

MCRAE: When I come in December. I would like to come by the place, the hospital, where he was born. Could you tell me where he was born? Was he born in Mombasa?
OGOMBE: No, Obama was not born in Mombasa. He was born in America.
MCRAE: Whereabouts was he born? I thought he was born in Kenya.
OGOMBE: No, he was born in America, not in Mombasa.
MCRAE: Do you know where he was born? I thought he was born in Kenya. I was going to go by and see where he was born.
OGOMBE: Hawaii. Hawaii. Sir, she says he was born in Hawaii. In the state of Hawaii, where his father was also learning, there. The state of Hawaii.

That Trump is peddling the “grandmother” lie shows that he relies on the grapevine rather than even a cursory and critical Google search. And I’ve already banged the gong on the birth certificate nonsense. But I’ll keep doing it until Trump stops — which won’t happen anytime soon. He is now tied for second (with former Arkansas Gov. Mike Huckabee) among Republican primary voters, according to the latest Wall Street Journal-NBC News poll. And Trump comes in second to former Massachusetts governor Mitt Romney in the latest survey of New Hampshire Republican primary voters from Public Policy Polling. But Trump trumps Romney with Tea Partyers and birthers. The number of Republican primary voters in PPP poll who firmly don’t believe Obama was born in the United States is 42 percent.

Trump erroneously said that the Certification of Live Birth that Obama released in 2008 was not the same as a birth certificate. That may be the case in New York. But not in Hawaii. When the St. Petersburg Times’s Pulitzer Prize-winning site received a copy of the certification, it e-mailed a copy of it to the Hawaii Department of Health. Here was the response.

“It’s a valid Hawaii state birth certificate,” spokesman Janice Okubo told us.

Relying on the grapevine again, Trump also erroneously declared to Meredith Vieira, “A certificate of live birth is not even signed by anybody. I saw his. I read it very carefully. It doesn't have a serial number,  doesn't have a signature. There's not even a signature.” The Donald is wrong on all counts.

In the copy that was sent to, the serial number — 151 1961 - 010641 — is there for all to see. It is indeed signed by the state registrar, Alvin T. Onaka, who, reported, “uses a signature stamp rather than signing individual birth certificates.” To top it all off, the document is embossed with the Hawaii state seal.

"There's no amount of evidence or data that will change somebody's mind,” Michael Shermer, the publisher of Skeptic magazine, told Slate’s Koppelman back in 2008 in explaining why conspiracy theories never die. “The more data you present a person, the more they doubt it." Trump is now Exhibit A.