There's a nice rhetorical trick in today's OpinionJournal - Featured Article:

More broadly, the critics want everyone to forget how steeply progressive the tax code already is. IRS data released late last year show that the top 1% of earners paid 37.4% of all federal income taxes in 2000. The top 5% paid 56.5% of federal taxes, and the top half of all earners paid 96.1%. In other words, even before President Bush started slashing taxes on the poor by increasing the child tax credit in 2001, the bottom 50% of filers had next to no federal income tax liability.[emphasis added]

Not quite. The figures show that the bottom 50% of filers contributed next to nothing to the total income tax revenue -- 3.9% of the total. But it's not the same thing to claim that these filers had "next to no federal income tax liability". Their federal income tax liability may well have been substantial, relative to their total income.

With an argument that's otherwise quite strong, there's no need to use silly rhetorical and mathematical tricks to make it appear stronger. It just annoys people like me, who would otherwise be in total agreement.