The bull market in U.S. stocks, which started on March 9, 2009, gets little respect. Those who have been bullish, and right, are mocked as "perma-bulls," while "perma-bears," who have been repeatedly wrong, are quoted endlessly.

We don't have enough fingers and toes to count the number of times a recession has been predicted. Brexit, Grexit, adjustable rate mortgages, student loans, the election of Donald Trump, tapering, rate hikes, a 3% ten-year Treasury yield, Hindenberg Omens, Death Crosses, and two fiscal cliffs are just a few of the seemingly endless list of things that were going to end the bull market. (And the pouting pundits of pessimism are never held accountable for erroneously spreading fear.)

One staple of the bearish argument, and the one we want to discuss today, is that corporate profits have grown faster than GDP. This, the bears have claimed for years, can't last. The argument is that there will be a reversion to the mean, profit growth will slow sharply and an overvalued market will be exposed. A close cousin to this argument is that stock market capitalization has climbed above GDP, signaling over-valuation.

Both of these arguments make fundamental mistakes: first, about the relationship between GDP and profits; second, about the correct measurement of GDP.

The economy is a combination of the public sector and the private sector. Most people think direct government purchases of goods and services, which were 17.2% of GDP last quarter, represents the full impact of government on the economy. But total Federal, State and Local spending (which adds in entitlement spending, welfare, and government salaries), as well as the cost of complying with government regulations, raises the number to 45% of GDP. And because the private sector pays for every penny of government spending, resources directed by the government are significantly larger than just purchases.