Beth referred me to a Slate article by Timothy Noah on disparities in income during past century.  My reply below illustrates an example of how economists and others push a political agenda by “bending” the data or, in some cases, simply leaving out any data which might detract from, lessen the impact of or refute the author’s point.  My reply follows:


This article has a decided “liberal” slant.  The graph showing disparities in income leaves out “transfers of income”.  In July 2010, the BEA reported that transfer payments were 1/6 of total personal income, or about 30% of what people got paid in wages and salaries.  Transfer payments include Social Security, unemployment insurance, back to work welfare programs, pell grants, etc, etc.  There is disparity of income but Paul Krugman and others who have a strong political agenda pick out the data that most strongly shows their case.  Income is income.  In the early part of the 20th century there were no social safety net programs and few transfer payments.  Now, they comprise a significant part of income for a growing part of the population and should be included for comparison.

A final note:  There will always be disparities in income, disparities in circumstance, disparities in ability.  James Madison, the primary architect of the Constitution, was well aware of this and wrote in Federalist #10:
 
The diversity in the faculties of men, from which the rights of property originate, is not less an insuperable obstacle to a uniformity of interests. The protection of these faculties is the first object of government. From the protection of different and unequal faculties of acquiring property, the possession of different degrees and kinds of property immediately results; and from the influence of these on the sentiments and views of the respective proprietors, ensues a division of the society into different interests and parties.

Those who hold and those who are without property have ever formed distinct interests in society. Those who are creditors, and those who are debtors, fall under a like discrimination. A landed interest, a manufacturing interest, a mercantile interest, a moneyed interest, with many lesser interests, grow up of necessity in civilized nations, and divide them into different classes, actuated by different sentiments and views. The regulation of these various and interfering interests forms the principal task of modern legislation, and involves the spirit of party and faction in the necessary and ordinary operations of the government.

The violence of factions had brought down previous republics like Greece and Rome.  What can remedy this natural tendency of people to form factions?

There are two methods of curing the mischiefs of faction: the one, by removing its causes; the other, by controlling its effects.
There are again two methods of removing the causes of faction: the one, by destroying the liberty which is essential to its existence; the other, by giving to every citizen the same opinions, the same passions, and the same interests.