Democrats have had trouble grasping the Republican diagnosis because they don’t have the same sense that the current model is collapsing around them. In his speech in Cleveland on Thursday, President Obama offered an entirely different account of where we are. In the Obama version, the welfare-state model was serving America well until it was distorted a decade ago by a Republican Party intent on serving the rich and shortchanging the middle class.

In his speech, Obama didn’t vow to reform the current governing model but to rebalance it. The rich would pay a little more and everyone else would get a little more. He’d “double down” on clean energy, revive the Grand Bargain from last summer’s budget talks, invest in infrastructure, job training and basic research…

This is what this election is about: Is the 20th-century model obsolete, or does it just need rebalancing? Is Obama oblivious to this historical moment or are Republicans overly radical, risky and impractical?

Republicans and Democrats have different perceptions about how much change is needed. I suspect the likely collapse of the European project will profoundly influence which perception the country buys this November.