Technological change, for instance, is an emergent process reflecting the decisions of thousands of engineers and entrepreneurs. Growth slows when the pace of innovation falls below historical norms. Inequality rises when the innovations that do occur are used by skilled workers and replace unskilled workers. Such skill-biased technological change, as economists call it, is widely considered a leading cause of the increasing inequality the United States has experienced in recent decades.

The rich don’t pay much in taxes.

In an era of great inequality, it is natural for politicians to demonize the rich. And some top earners don’t pay enough in taxes, such as the hedge fund and private equity crowd that benefits from the tax treatment of carried interest.

But don’t confuse these exceptions, even if they are glaring ones, with the general rule. The Congressional Budget Office estimates that under the 2013 tax law, which is still in effect today, the top 1 percent pays 33 percent of its income in federal taxes. By contrast, the middle class (defined here as the middle three-fifths of the income distribution) pays only 13 percent of its income in federal taxes.

Tax cuts will unleash stupendous growth.

While Democratic candidates like to talk about making the rich pay their fair share, Republican candidates like to mimic Ronald Reagan’s call for lower taxes. Too often they act as if there were no problem that a tax cut couldn’t solve. According to the Tax Policy Center, Mr. Trump’s tax plan would reduce federal tax revenue by 29 percent.

This number is most likely an overestimate, because some of the lost revenue may be recouped with the somewhat faster economic growth that tax cuts can actually help promote. But no serious economist believes that this growth by itself would be sufficient to prevent large budget deficits. Mr. Trump’s assertion that he can easily fill the hole in the budget by eliminating “waste, fraud and abuse” is one of the least credible claims of the election year.

The next president can quickly fix all of our problems.

All candidates like to offer themselves as panaceas. “Vote for me and the economy will skyrocket, the poor will see riches without bound and that annoying wart on your foot will finally disappear.” Yet the power of the president — or even the entire government — is more limited than is often acknowledged.

Yes, there are things that can be done. A better education system, for example, would both promote growth and ameliorate inequality. But there is no magic bullet to improve our schools, and even if we succeeded, the economic impact would be felt slowly over many years.