Just about every presidential campaign’s policy plans leave a lot of blanks and rhetorical placeholders, to be filled in later. They also straddle conflicting pressure points and dodge inevitable tradeoffs. The preference is to point in a general, and seemingly more popular, direction, without offering too many instructions for how to traverse the complicated path from here to there. On top of that, the limited attention spans of most voters, let alone candidates, cannot be taxed too much (unlike their incomes).