About a month ago, President Obama delivered a closely-watched speech on debt reduction, and emphasized early on the thread of the American tradition that says “we’re all connected, and that there are some things we can only do together, as a nation.”

Explaining that point in more depth, the president added, “We recognize that no matter how responsibly we live our lives, hard times or bad luck, a crippling illness or a layoff may strike any one of us. ‘There but for the grace of God go I,’ we say to ourselves. And so we contribute to programs like Medicare and Social Security…. We’re a better country because of these commitments. I’ll go further: we would not be a great country without those commitments.”

It was among the most progressive ideas Obama has articulated in a while — and a month later, it’s still bothering the hell out of Rick Santorum.

“We have a president who does not understand what American exceptionalism is,” he said. He faulted President Obama for telling an audience last month that America “would not be a great country” without the entitlement programs of Social Security and Medicare. “Stunning,” Santorum said. “America was born great. The president of the United States doesn’t understand who we are.” He spoke of how the British Empire faded because “they accepted the mediocrity of state control…. We face that moment right now.”

Putting aside Santorum’s limited understanding of British history — for that matter, if the failed former senator thinks we’re facing state control now, he needs to brush up on current events, too — there are two interesting angles to his little tirade.

The first is the notion that President Obama, unlike Santorum, “does not understand what American exceptionalism is.” The importance of this was fleshed out about a week ago by Slate‘s John Dickerson, who spoke at some length with the senator about this issue, and discovered that it’s Santorum who doesn’t understand what American exceptionalism is. Indeed, Dickerson pressed Santorum on the substantive qualities of the argument, and by the end of their interview, “Santorum had all but abandoned his textual analysis of Obama’s remarks.”

That’s the funny thing about too many conservative arguments: they only remain intact if they go unchallenged.

The second is the notion that the president said something outrageous — or “stunning,” as Santorum put it — when he said our commitments are integral to our greatness. The former senator’s worldview simply can’t tolerate such a concept. “America,” after all, “was born great.”

I’m fascinated by the shallow vacuity of the sentiment. It’s reminiscent of Michele Bachmann’s recent argument that “our founding documents … cannot be improved upon.”

This may come as a shock to Santorum, but he ought to take a moment to read the preamble to the Constitution: “We the People of the United States, in Order to form a more perfect Union, establish Justice, insure domestic Tranquility, provide for the common defence, promote the general Welfare, and secure the Blessings of Liberty to ourselves and our Posterity, do ordain and establish this Constitution for the United States of America.”

By Santorum’s reasoning, the Constitution’s framers lacked the necessary patriotism — after all, they intended to have us strive to be “more perfect,” which should apparently be considered impossible.

But they were right and Santorum is wrong. The United States has not only grown in size and power, it’s gotten fundamentally better. Part of our greatness, we can now safely say, comes from our commitments to one another. Medicare and Social Security may no longer popular in Republican circles, but they’re bedrocks of American society and they’re vital to making the nation more perfect.

The only thing “stunning” about this is seeing a Republican presidential candidate failing to understand the underlying principle.