Can We Kill the "Young Invincibles" Once and For All?

Don't worry, I'm not advocating mass murder; I want to put to death a silly myth about Obamacare that keeps getting spread by people who should know better. The basic story is that Obamacare is dependent on getting large numbers of young and healthy people into the system. The premiums these people pay will help to cover the costs incurred by older and less healthy people.

The latest repetition of this myth appears in a NYT editorial urging Republicans not to destroy the Affordable Care Act (...