Let's say you're a huge investment company that is considering a series of stock purchases that are pretty big and kind of risky. That's classic capitalism in its modern form. People take risks. If they lose, they take a loss. If they win, we cheer their good fortune. We cheer because people play the game honestly, and we cheer because they win while obeying the rules.

But we also cheer because measured risk taking promotes growth. Goods and services are produced because of investment. Warehouses are filled because someone decided that anticipatory production was a worthwhile risk. People who could have faced severe financial hardship are employed because someone took a chance on the future of the American economy.

So, as a huge investment company, you carefully read the key indicators on each purchase. You survey the economy for whatever growth can be reasonably anticipated. You look at the prospects of the portions of the market that applies to each corporation you want to invest in. How realistic is the risk? What is the return if things play out well? You perform due diligence because either you or your clientele will be winning or losing real money on the basis of your judgment. You are willing to make educated guesses, but you won't take blind chances.

Sometimes you win, and sometimes you lose, but you hope that with vigorous homework, years of experience, and luck, you will win more often than you lose. The faith is that you or your investors will come out ahead in the aggregate. But there are no guarantees.

But if, instead of an investment house, you are a bank, you still risk your own money and that of investors. But you also have access to deposits. There are some restrictions, but not too many.

You'll still perform every aspect of due diligence, of course. You'll look over key indicators. You'll survey the economy. You'll analyze the market. But you now have freedom that goes way beyond that of the typical investment firm. You can take risks you would never have taken with your own funds.

Because if you win, you will have all the rewards that classic capitalism can offer. And if you lose, the money you risked belonged to depositors. As long as their deposits are below regulatory thresholds, they can't lose either. Their deposits are guaranteed by the Federal Deposit Insurance Corporation. Only taxpayers can lose and, of course, they don't count.

It's called proprietary trading. That's when banks can use insured deposits to bankroll their own risky bets.

President Obama has proposed a new regulation limiting the risks banks can take with money belonging to depositors and insured by the government. Republicans are skeptical. They are holding things up in the Senate. After all, Republican theology teaches that regulation is an instrument of Satan.