Picture a skinny 18-year-old with a high metabolism. He can eat anything he wants -- doughnuts, ice cream, pizza -- with virtually no harm. His weight stays the same, his blood pressure remains low, and he faces no immediate risk of heart disease. So he keeps on gorging. Why change when the food tastes this good?

Later in life, this catches up with him, and he puts on a few pounds. Unsettled, he tries dieting and exercises more. His growing waistline now serves as an incentive to change habits.

Then, in his 60s, he has a heart attack. He survives, but he's terrified. He hires a nutritionist and a personal trainer, and downs a daily cocktail of pills to keep his heart ticking. His near-death experience is a powerful incentive to drastically change behavior. His life depends on it.

This is an appropriate analogy to understand why the fiscal cliff debate has dragged on so long. America's finances are not the 60-year-old heart attack victim, highly incentivized to change behavior. We are the 18-year-old with the fast metabolism, loving our bacon cheeseburgers with no current incentive to do anything differently.

Two events -- and only two events -- will prod legislators into wide-reaching, permanent budget reform: Rising interest rates, or the threat of not being re-elected. Both are (for now) completely out of sight. 

Take interest rates. They're currently at all-time lows. The impact this has on financing government deficits is massive. In 1995, the national debt was $4.8 trillion and interest payments were about $230 billion. In 2011, the national debt was $15 trillion and interest payments were about ... $230 billion. We tripled the national debt without paying a penny more in annual interest. Interest payments on the national debt as a percent of GDP are at multidecade lows.

And interest rates on Treasuries are now below the rate of inflation, so in real terms, creditors are actually paying the government to borrow. Why would any congressman choose to stop spoiling their constituents with borrowed money when there is no (current) cost of doing so? As long as the market is this friendly, the odds of comprehensive budget reform are extremely low.

Next, consider this statistic from Campaign for Primary Accountability: "During the past decade, House incumbents were as likely to die in office as to lose a primary election." Despite record-low approval ratings, the reelection rate of politicians is off the charts. According to Bloomberg, "90 percent of House members and 91 percent of senators who sought reelection in 2012 were successful." That wasn't a fluke. Re-election rates have rarely dipped below 70% or 80% for the last half-century. Long-term deficit deals could get done with low interest rates if the mechanism for keeping politicians in line -- elections -- enforced discipline. Alas, they rarely do.

The last time we had comprehensive budget reform was 1993, when taxes were raised by $240 billion, and spending cut by $250 billion. The political climate then was no more friendly than it is today. The key difference was that interest rates were rising, with yields on 10-year Treasury bonds jumping by 3 percentage points in just over a year. That prodded legislators into action. Former Clinton advisor James Carville quipped at the time:

I used to think that if there was reincarnation, I wanted to come back as the president or the pope or as a .400 baseball hitter. But now I would like to come back as the bond market. You can intimidate everybody.

It's totally different today. The U.S. bond market hasn't intimidated anyone in more than a decade. If anything, it is begging legislatures to keep borrowing. 

Someday that will change. Interest rates will rise, markets will protest, and then -- and only then -- will there be comprehensive budget reform. No one knows when that day will come. It could be tomorrow or decades off. When it does, it will likely be the equivalent of weight gain or even heart attack, prompting quick action -- a reality that actually makes me optimistic. Until then, expect more symbolic, short-term budget deals, more bickering, and more fiscal cliffs. There is no incentive for anything else.

As Charlie Munger put it: "Never, ever, think about something else when you should be thinking about the power of incentives."

Check back every Tuesday and Friday for Morgan Housel's columns on finance and economics. 

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