One of the fears in the larger fiscal debate, which largely goes unstated in polite company, is that one side of the argument just doesn’t have its facts straight. A shared reality is the foundation for any policy debate, and there are credible concerns that some of the key players — most notably, those calling for entitlement “reforms” and austerity measures — just don’t know what they’re talking about.

If those helping drive the discussion are themselves ignorant, not only does the discourse suffer, but the policy outcome will be shaped, at least in part, by confusion and misunderstanding. It’s no way for sensible political system to operate.

With that in mind, Ryan Grimm caught up with former Sen. Alan Simpson (R-Wyo.), perhaps best known for his role leading a bipartisan deficit reduction commission last year. It’s Simpson’s preferred vision that’s helping serve as the basis for other policymakers.

After Simpson made some bizarre remarks about retirement ages and the history of Social Security, Grimm pressed the former senator on his understanding of the basics.

HuffPost suggested to Simpson during a telephone interview that his claim about life expectancy was misleading because his data include people who died in childhood of diseases that are now largely preventable. Incorporating such early deaths skews the average life expectancy number downward, making it appear as if people live dramatically longer today than they did half a century ago. According to the Social Security Administration’s actuaries, women who lived to 65 in 1940 had a life expectancy of 79.7 years and men were expected to live 77.7 years.

“If that is the case — and I don’t think it is — then that means they put in peanuts,” said Simpson.

Simpson speculated that the data presented to him by HuffPost had been furnished by “the Catfood Commission people” — a reference to progressive critics of the deficit commission who gave the president’s panel that label.

Told that the data came directly from the Social Security Administration, Simpson continued to insist it was inaccurate, while misstating the nature of a statistical average: “If you’re telling me that a guy who got to be 65 in 1940 — that all of them lived to be 77 — that is just not correct. Just because a guy gets to be 65, he’s gonna live to be 77? Hell, that’s my genre. That’s not true,” said Simpson, who will turn 80 in September.

Understanding life expectancy rates at age 65 in 1940 is central to understanding Social Security itself.

Look, I realize these issues can be confusing, but Alan Simpson isn’t just some random retiree flubbing relevant details. He led a bipartisan deficit commission that studied entitlement programs in minute detail. The media and political establishment considers Simpson an expert.

But when pressed on some of the basics — stuff anyone with a serious interest in these issues would learn on the first day — Simpson’s ignorance is just breathtaking. He’s making sweeping recommendations about the future of programs millions of Americans rely on, and yet, Simpson just doesn’t have his facts straight.

This isn’t some minor error of arithmetic. Simpson is lost on the entry-level details. It’s scandalous, or at least should be.

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Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.