This may not be the most serious problem in the world, but it is a familiar one: How do you divide a piece of cake equally between two children and also make sure that each of them sees it as a fair division?

There is universal consensus among experts that the earth's atmosphere is heating up - and that we are responsible for it by putting carbon dioxide in the atmosphere. We also know that the consequences of global warming are catastrophic. But how do we make sure that all countries reduce greenhouse gases?

In an industry with highly sequential innovation, it may be better for society to scrap patents altogether than try to tighten them.

If banks anticipate government will come to the rescue should the credit market go badly awry, they may make loans that would otherwise be imprudent, e.g. subprime loans with little prospect of repayment.

I like to work on a number of things simultaneously. If you're working on a variety of projects and if you get stuck on one of them, you can move to another without grinding your gears indefinitely.

The real problem is deflation. That is the opposite of inflation but equally serious to the borrower.