(CNN) Donald Trump has spent most of his adult life telling himself a story about a brave, ruthless and fearsome man named "Donald Trump."

The latest example: His pledge that had he been outside Stoneman Douglas High School 12 days ago, he would have rushed in to stop the shooter, who murdered 17 people.

"You don't know until you test it, but I think, I really believe I'd run in there, even if I didn't have a weapon, and I think most of the people in this room would have done that too," Trump said at a meeting of the nation's governors in Washington on Monday

Obviously, as Trump says, "you don't know until you test it." As in: None of us can know whether, put in a situation like security guard Scot Peterson during the shooting spree earlier this week, we would have rushed into the building to try to save lives. Peterson remained outside school for several minutes, and inside the shooter fired and fired. (Referring to Peterson and other Broward County Sheriff's deputies, the President said they "weren't exactly Medal of Honor winners," adding: "The way they performed was really a disgrace.")

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But even as the President is acknowledging you can't ever know how you would react in a situation like the one in Parkland, Trump is also making the case that he knows that he would have rushed in -- armed or not! -- to save kids' lives.