There was nothing particularly surprising about the shrill skirmishing at the ideological edges of Thursday night’s Republican presidential debate in Iowa. What was shocking were the antics in the center.

In full public view, the party’s mainstream jumped the tracks of reality on issues of spending and taxes, brightly illustrating the ruinous magical thinking that has led to a downgrade of the nation’s credit and invited a double-dip recession. When asked if they would reject a deal to cut the deficit that had 10 times the amount of spending cuts as it had tax increases, the hands of all eight candidates went up. Even a tincture of new revenue, though mixed with huge cuts in government spending, would be too much for the modern Republican Party.

The raised hands included those of Jon Huntsman and Mitt Romney, two former governors who have proved that they know better. Mr. Huntsman was the only one on the stage who said he would have accepted last week’s budget deal and the only one to point out that Washington should never even consider defaulting.

Saying as much is already Tea Party heresy, so why not take the next logical step and admit that the nation’s finances are unsustainable in the long term without some tax increases? Even Mr. Huntsman was unwilling to take the slightest risk of offending the rigid and unforgiving Republican Party primary electorate.