WSJ.com - The Real Causes of Income Inequality

This article is quite number-intensive, providing strong evidence for the excerpt below, which I think captures the point of all the numbers.  If liberals have an alternate explanation for the presented facts, I sure haven’t seen it.  

WSJ.com - Opinion: The Real Causesof Income Inequality

While income distribution has become a source of protest and political debate, any analysis of taxes paid in high tax-and-spend countries shows that the U.S. has the most progressive income tax system in the world. An inconvenient truth for the advocates of higher taxes on America's rich is that big governments in developed countries are funded not by taxing the rich more than the U.S. does, but by taxing everybody else more.

In an eternal irony unique to large welfare states, it is the expansion of government in the name of the poor and middle class that always costs poor and middle-class families the most.

If the U.S. spent and taxed like France and Sweden, it would hardly affect the top 10%, who would pay about what they pay now, but the bottom 90% would see their taxes double.

Since OECD members have significantly higher consumption taxes on average than the U.S., the total tax burden of bigger government is even more heavily borne by lower-income citizens in developed nations than these numbers suggest.

The real and alarming message in these OECD numbers is that there appear to be limits in the real world to how much tax blood can be extracted from rich turnips. With much higher marginal income-tax rates, countries that are clearly willing to soak the rich have proven to be incapable of doing so.

Proposals to raise taxes on high-income Americans in the name of "fairness" not only threaten economic growth. The experience of nations with large governments shows that this argument is simply a red herring for a massive tax increase on middle-income Americans.