Romney’s preposterous arguments for not telling you which tax breaks he’d abolish.

In Wednesday’s presidential debate, Mitt Romney said he would cut tax rates by 20 percent. He promised to do this without costing the government any revenue or forcing middle-class taxpayers to make up the difference. How would he make the math work? By eliminating tax loopholes and deductions.

No way, said President Obama: “If you are lowering the rates the way you described, Governor, then it is not possible to come up with enough deductions and loopholes that only affect high-income individuals to avoid either raising the deficit or burdening the middle class.”

Romney insisted he could make the numbers add up, but he wouldn’t say how. “I’m going to work together with Congress” to figure out “what are the various ways we could bring down deductions,” he asserted.

This preposterous dodge has been going on for weeks. Romney, Paul Ryan, and their surrogates have refused to say which deductions they’d eliminate. But their magic accounting, whatever it is, can’t be half as creative as the arguments they’ve concocted for hiding it. Here’s a catalogue of their excuses so far.

1. Specificity is for accountants. Last week on Meet the Press, David Gregory objected that Romney “has failed to enumerate any of the deductions that he would eliminate.” Romney’s representative on the show, Gov. Chris Christie, R-N.J., dismissed the objection: “Gov. Romney has laid out a direction and a vision for the direction of this country. He’s not an accountant. He is not going to go line by line, as much as you like him to do, through the budget.”

2. Specificity is for incumbents. George Stephanopoulos made the same point to Christie on This Week: “Gov. Romney has not been willing to lay out which deductions are going to go away for the wealthy.” Christie replied: “Well, listen, the president of the United States has an obligation after four years as being president to be the one who is the most specific.”

3. Specificity is presumptuous. On Sept. 16, David Brody of the Christian Broadcasting Network asked Ryan: “Is there a reason you guys aren’t naming specific tax loopholes?” Ryan humbly explained his reticence: “We don’t want to presume to say, ‘Here’s exactly our way or the highway. Take it or leave it, Congress.’”

4. Specificity is micromanagement. On Sept. 27, CNBC’s Andrew Ross Sorkin asked Sen. Rob Portman, R-Ohio, “I just want to know if we're going to get specifics by the time November rolls around.” Portman lectured him: “You don't dictate to Congress exactly how it's going to be done. You need to work with Congress to actually get it done. You know, this is a president in Barack Obama who has not been able to work with Congress on anything substantial … And so I think it does not make sense to lay out all the specifics.”

5. Vagueness is standard practice. On Sept. 16, CNN’s Candy Crowley asked whether Romney “needs to come out and say specifically, ‘Here is what I would do to reform the tax code. Here are the loopholes I would close.’” Romney’s surrogate, former New York Mayor Rudy Giuliani, responded that Romney was “running a perfectly fine campaign. This is the level of specificity that American candidates usually give in a campaign.”

6. Vagueness is leadership. In an interview for the Sept. 23 broadcast of 60 Minutes, Scott Pelley pressed Romney: “What are we talking about? The mortgage deduction? The charitable deduction?” Romney spurned the question. “To work together with people across the aisle,” Romney explained, “you don't hand them a complete document and say, ‘Here, take this or leave it.’ Look, leadership is not a take-it-or-leave-it thing. We've seen too much of that in Washington.”