Here is a first-rate summation of the problem: Rep. Paul Ryan appears to have the answer

Given the predictable retirement of baby boomers, it was no secret that promised government benefits would overwhelm the existing tax base. This problem could have been fixed.

It hasn't because our political culture is so wedded to public opinion that it can't (or won't) govern. To govern is to choose, and our leaders recoil from unpopular choices. Americans want generous benefits and low taxes, so that's what the system -- led by either Democrats or Republicans -- provides.

President Obama continues this tradition. His administration's long-term budget projections show skyrocketing debt. In 2008, federal debt held by the public equaled 40 percent of the economy (gross domestic product). The administration has it rising to 77 percent of GDP in 2020, 99 percent in 2030 and 218 percent in 2050.

In reality, not choosing is a choice: to govern by crisis. Someday, the debt and associated interest payments (projected at $840 billion in 2020, a seventh of federal spending) may trigger a financial backlash. Lenders won't lend or will demand much higher rates. Congress would then be forced to cut benefits or raise taxes. The unstated hope is that the crisis occurs on someone else's watch.

Ryan rejects this consensus. He would make choices now.