Jeb Bush is banking on 4 percent. That's the annual rate of growth in gross domestic product that he's forecasting for a Bush presidency. “There is not a reason in the world why we cannot grow at a rate of 4 percent a year,” Bush said in June when he officially announced his campaign.

Actually, there are quite a few reasons, including a half-century of economic history and the improbability that productivity would grow sufficiently to create such a high rate of growth. (Though it isn't high compared with Mike Huckabee's robust pledge of 6 percent growth.)

Productivity isn't the only way to raise GDP. A rising population also works. And the surest, easiest way to increase population? Immigration.

Read the full article at Bloomberg View: Secret to Jeb's 4 Percent Growth Plan? Immigrants