Washington may reach a deal to raise the debt ceiling by Aug. 2, ...... through accounting tricks.

But what happens if the $14.3 trillion debt ceiling, ....... which the U.S. actually hit on May 16 — isn't raised?

"Frankly, no one knows," says Matt Slaughter, a professor at Dartmouth's Tuck School of Business. "There's no historical precedent for what happens if the US defaults on part of its outstanding debt obligations."

But it's clear the outcome won't be good, .........