It was to change this dynamic, presumably, that Romney’s campaign decided to have him come out for the first time with a big tax reform plan of his own, which he unveiled last week in a speech at Ford Field. In its broadest strokes, the plan isn’t terrible: It promises lower rates and a broader base, which is the goal of just about every sensible tax reform proposal, and it cuts rates for most taxpayers, not just businesses and the rich. But the Romney campaign has declined to explain exactly how the cuts will be paid for, offering vague promises of loophole closing and spending cuts that suggest a return to supply-side irresponsibility.