Most Americans don’t spend a lot of time worrying about how much income other people have, or how much others pay in taxes. At least they don’t unless they are encouraged to do so by a president who has made class envy the centerpiece of his reelection campaign.

President Obama’s frequent complaint that the wealthy don’t pay their fair share of taxes may have triggered the Occupy movement, but it doesn’t withstand scrutiny, and his proposal to increase taxes on this group is the progressive version of strangling the goose that does most of the country’s saving and investing.

Progressives complain that the wealthy have been collecting a growing share of taxable income. The observation is correct, although it is only part of the story.

The disparity in income shares has been growing in the U.S., and in the majority of other developed countries, for decades for a variety of reasons.

For example, the returns to education in general and to certain skills in particular have increased sharply over time, and advances in technology have further leveraged these returns. What the president and the Occupy crowd ignore is that while the income gap has widened, so has the disparity in tax shares.

A recent compilation of IRS data by the Tax Foundation shows that between 1987 and 2007, the share of taxable income collected by the top 10 percent of taxpayers rose from 37 percent to 48 percent. At the same time, the share of taxes paid by this group rose from 56 percent to 70 percent.

The income share collected by the top 1 percent rose even faster, from 12 percent to 23 percent, but their share of taxes also rose from 25 percent to 40 percent.

During the same period the share of taxes paid by the bottom 50 percent of tax filers fell from 6 percent to slightly less than 3 percent.

It is difficult to know what the president considers a “ fair share” in a tax system that is already the most progressive among developed countries.

Furthermore, a focus on income shares at any specific point can be misleading because it ignores the considerable amount of income mobility within the U.S. economy. A study by the Treasury Department in 2007 found that roughly half the taxpayers who were in the bottom 20 percent in 1996 had moved to a higher income group by 2005.

The composition of the highest income groups tends to change even more dramatically over time. Only about 40 percent of those in the top 1 percent in 1996 were still there in 2005.

As an example of how volatile the incomes of high earners can be, the income share of the top 10 percent declined from 48 percent to 43 percent from 2007 to 2009 because of the effects of the recession, while the share of the bottom 50 percent rose slightly.

The Treasury study also found that the real ( after inflation) incomes of two-thirds of all taxpayers increased from 1996 to 2005, and most importantly that the median incomes of those initially in the lowest income groups increased faster than those in the higher income groups. This again points to the danger of focusing on the performance of static income categories instead of the changes that take place in the circumstances of individual households over time.

None of this is to suggest that narrowing the income disparity between groups is not a legitimate goal. The hard question is how to do it.

President Obama’s way is to raise taxes on those who do most of the investing in ventures that create jobs so that the government can redistribute the income in ways that often do nothing for those who are the lowest earners.

The other way to close the gap is to increase the incomes of those in the lower brackets. Among other things this would involve improving the rigor and relevance of our education system.

Lowering business taxes and the regulatory burden would increase both the number of jobs at all income levels and the amount of income employers could afford to pay.

Policy reform is harder than raising taxes, but in the long run would be more productive. Teddy Roosevelt made class warfare the centerpiece of his run for the presidency as a Progressive in 1912. He lost, but at least Teddy was boisterous and colorful. The current president is merely grim, and it remains to be seen if class warfare can be a successful campaign strategy.

MARTIN JONES of Freeport is an economic and financial analyst and a former senior managing director in the investment division of US Bank.