The Varying Meanings of "Fair Share"

I had what may be a bit of an epiphany this morning about why I can never understand the arguments that the President and others make for the "rich" paying "their fair share."

When I hear those words, I always think of their fair share of the federal tax burden of the country.  Because I think of it that way, I tend to look at tax distribution tables as a way to think about the question of fairness.  Because of changes in income distribution, I don't look at the distribution directly but rather I look at the change in total effective tax rates over time.

Here are two views of the comparison between 1979 (the first time CBO did the analysis) and 2013 (post the ATRA).

So we can look at this two ways, either in terms of the change in effective tax rate in percentages or percentage points.  In percentage points, effective Federal tax rates have declined by 6.1 points at the bottom of the income distribution and 0.6 points at the top of the income distribution.

In percentage terms, the comparison is directionally the same but an even larger order of magnitude.  Yet, despite these numbers, many maintain that the "rich" aren't really paying their fair share.  So my thought this morning was that maybe those who make this claim are not referring to fair share of the total tax burden but instead to fair share of their income, regardless of how much others are paying.

This seems a rather odd way of discussing fair share but it's the only one that makes any sense in light of the underlying data.  Now if only they would let us in on what the magical fair share of income is....beyond "higher" I mean.