The Gallup question specifically stated "Do you regard the income tax you will have to pay this year is fair?" It did not ask if the system was fair.
If those who pay no income tax think their zero share is fair (and logically they should), then a mere 16% of those who do pay taxes think their share is fair.
Here is my math: 55% think their share is fair. Subtract the 46.4% who pay nothing (and logically should be happy about that), the net is 8.6 percentage points. (8.6 / 53.6) * 100 = 16%.
Full text: Mish's Economic Trend Analysis
