To accommodate its undiminishing appetite, Congress has raised its "limit" of the national debt to a fourteen-digit sum.
The fact that the latest reason for the credit limit increase is the housing mortgage debacle doesn't really help us see the cause of it all. Yes, bailing out financial institutions that facilitated bad loan decisions in the context of a scheme to turn a quick buck syndicating loans to buyers unwilling to consider their increasing financial risks might be a foolish idea, and it might be important to prevent loss of confidence in the financial markets, but it's still business as usual in Congress: it's not really their money, so they don't hesitate very long spending it, especially if there's a near-term political angle.
And there always is. One can pick one's evils and rail against spending in Congress -- regardless what political bent you might have; both major parties have Treasury printing-press ink on their fingers. You're a dove? Rail against decades of foreign wars, arms races, occupation expenses in places like Germany which aren't seriously likely to be invaded, and various forts and bases all over the country where it's unlikely the US will be invaded. You're a neo-con? Rail against the public assistance programs that hand food stamps to pimps, pushers, madams, and hookers all over the country while they claim to be unable to find gainful employment or to be too disabled to work. You're a Libertarian? Rail against the federalization of every imaginable criminal offense and the attendant enforcement and penal overhead of a level of domestic regulatory micromanagement that would shock the Constitution's authors to know.
And, regardless what spending most offends you, you get -- as a free bonus -- to gasp in shock at the size of each annual budget that must be committed to interest payments on debt incurred through prior years' overspending. The fact some politicians hope to cast government as more efficient flies in the face of the numbers, unfortunately: the debt keeps rising and there seems to be no effective political force to bring overspending in line with likely future capacity to make interest payments. You can look at various federal budgets at a dedicated federal web site, maintained through funds raised under threat of prison and seizure from citizens living peacefully as they work honest jobs.
In case you're interested just what the debt is, helpful civil servants have made it easy to learn.
If anyone has theories that might explain what forces will lead Congress to turn from the path to national insolvency, I'm keen to hear them. I simply don't see any point of leverage for controlling a Congress perpetually bent on spending its way into re-election.