Some notable economists argue that technological innovations in the future won't raise our living standards as much as they have in the past, dooming the economy to slow growth.

But Harvard economist Martin Feldstein begs to differ.

While GDP growth per worker has shrunk markedly since 1972, "the official statistics on GDP growth fail to capture most of the gains in our standard of living that come from new and improved goods and services," he writes on Project Syndicate.

So the depressed numbers don't account for air conditioning, new surgical procedures etc.

The economy has grown only 2.1 percent a year since the Great Recession ended in June 2009, compared to a rate of 3 percent from 1960 to now. But that doesn't mean we're doomed to poverty, Feldstein says.

"There is simply no reason for the view . . . that the children of today will not enjoy a standard of living as high as their parents’." To guarantee a bright future, we need to improve education, boost savings and investment and reform taxes and entitlements, Feldstein says.

Meanwhile, the recent turmoil in financial markets and China's economy has led some commentators to warn of a global crisis, but Ambrose Evans-Pritchard, international business editor of The London Telegraph isn't so sure.

"It has been a frightening summer," he acknowledges. China's economic growth has slowed to 3 to 5 percent, economists estimate; its stocks have dropped 40 percent since June 12; and its currency has fallen 2.7 percent since the government's devaluation three weeks ago.

Here in the United States, the S&P 500 index plunged 11 percent from Aug. 17 to Aug. 25.

But, "in the end you have to make a judgment call on whether this tangle of cross-currents in the world economy really is the start of another wrenching global crisis, or just a tremor," Evans-Pritchard writes. "This time I refuse to join the pessimists."

He says U.S. economic growth is accelerating. It registered 3.7 percent in the second quarter. And "Germany is rock solid."

Of course things also looked good prior to the downfall of Lehman Brothers in 2008, Evans-Pritchard notes. "But this feels nothing like the prelude to the Lehman crisis, when the monetary data was flashing red warnings on both sides of the Atlantic, and US commercial lending was contracting at the fastest rate since records began."

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