The worst loophole is what Donald Trump has talked about: the tax deductibility of interest. If you let real estate owners or corporate raiders borrow the money to buy a property or company, and then pay interest to the bondholders, you'll load the company you take over with debt. But you don't have to pay taxes on the profits that you pay out in this way. You can deduct the interest from your tax liability.

Mr. Trump wants to turn the U.S. economy into the kind of real estate development that has made him so rich in New York. It will make his fellow developers rich, and it will make the banks that finance this infrastructure rich, but the people are going to have to pay for it in a much higher cost for transportation, much higher cost for all the infrastructure that he’s proposing. You could call Trump's plan "public investment to create private profit". That's really his plan in a summary.

I think something like three-quarters of American currency is held abroad, by drug dealers, by tax evaders, Russians and Chinese. Other people think that they want to protect themselves against their own currency going down. When you have 75% of the currency and even more of the high-denomination $100 bills held abroad, you wonder whether these are people we really want to pay. If you get rid of the $100 bills, its foreign holders will be the main losers.

The vast majority of $100 bills are abroad, not in the United States. So yes, of course there's a use here but nowhere near as much as there's a use for $100 bills abroad.

Deflation means a slowdown of income growth. Markets shrink, new capital investment and employment also taper off, so wages decline. That is what's happening as deliberate policy in Europe and the United States. Falling or stagnant prices are simply the result of having less income to spend.

People tend to think that paying a debt is like going out and buying a car, buying more food or buying more clothes. But it really isn't. When you pay a debt to the bank, the banks use this money to lend out to somebody else or to yourself. The interest charges to carry this debt go up and up as debt grows.

High prices can be the result of speculation, and maybe plunging prices can be attributed to the end of speculation, but low prices over time aren't caused by speculation. That's oversupply, mainly by Saudi Arabia flooding the market with low-priced oil to discourage rival oil producers, whether it's Russian oil or American fracking.