Via Don Boudreaux, Roger Garrison notes that one cannot choose to default.
As he wrote to Boudreaux:
You mention, though, that the government could “choose to default.” Well, if default means that you’re unable to pay, then “choosing to default” must mean that you “choose to be unable to pay.” Hey, that really does sound like government-speak. But I think a more accurate and more revealing term is “renege.”
Speaking for myself, reneging in this case would to some small extent liberate the taxpayers from an unchosen obligation, so it would not carry the moral taint that private reneging on debt obligations does