From a Politico article about the fiscal cliff:

“For many Republicans, a cliff dive means blaming President Barack Obama for a big tax hike in the short term and then voting to cut taxes for most Americans next month. That’s an easier sell back home in Republican-heavy districts than a pre-cliff deal that raises taxes on folks making over $250,000 or $400,000, extends unemployment benefits and does little if anything to curb entitlement spending. If they back a bad deal now, they run the risk of facing primary challenges in two years.

For Democrats, the cliff is better than setting a rich man’s cutoff in the million-dollar range — or worse yet, extending the Bush tax cuts for all earners — and slashing Medicare and Social Security to appease Republicans. They, too, see an advantage in negotiating with Republicans who will feel freed from their promise not to vote to raise taxes once the rates have already gone up….

Another analogy: It’s a Nash equilibrium. John Nash, subject of “A Beautiful Mind,” the Oscar-winning film that revolved around game theory, explained how players act in a multiplayer game. Put simply, if each player understands his adversaries’ strategies, no one will alter their own course. Right now, Obama, Boehner and Reid are locked in on a course for the cliff, and there’s no obvious solution that would make any of them switch directions.”
In the next story, they will superimpose electoral incentives on the Nash demand game!