Marco Rubio's new pro-life message rests on the argument that a human 'won't become a donkey or a cat'

Marco Rubio has crafted a compelling, if questionable, pro-life argument: "Human life won't become a cat." The Republican presidential contender and Florida senator tweeted out this assertion on Monday afternoon, along with a link to a petition to agree that all human life begins at conception. He also offered video of a recent interview with Chris Cuomo on CNN's New Day, in which he first used this curious logic to prove his claim that "science has decided" that life does, indeed, begin at conception.

"What else can it be?" Rubio asked of the fertilized egg. "It cannot turn into an animal. It can't turn into a donkey. The only thing that that can become is a human being." When Cuomo countered that biologists hold that a "fertilized egg is no more or less alive than a sperm or an unfertilized egg," Rubio remained steadfast. "Well, if they can't say it will be a human life, what does it become, then? Could it become a cat?"