There was a windstorm of hasty excuses in recent weeks after Kansas reported that it took in $338 million less than expected in the 2014 fiscal year and would have to dip heavily into a reserve fund. Spending wasn’t cut enough, said conservatives. Too many rich people sold off stock in the previous year, state officials said. It’s the price of creating jobs, said Gov. Sam Brownback.

None of those reasons were correct. There was only one reason for the state’s plummeting revenues, and that was the spectacularly ill-advised income tax cuts that Mr. Brownback and his fellow Republicans engineered in 2012 and 2013. The cuts, which largely benefited the wealthy, cost the state 8 percent of the revenue it needs for schools and other government services. As the Center on Budget and Policy Priorities noted, that’s about the same as the effect of a midsize recession. Moody’s cut the state’s debt rating in April for the first time in at least 13 years, citing the cuts and a lack of confidence in the state’s fiscal management.

The 2012 cuts were among the largest ever enacted by a state, reducing the top tax bracket by 25 percent and eliminating all taxes on business profits that are reported on individual income returns. (No other state has ever eliminated all taxes on these pass-through businesses.) The cuts were arrogantly promoted by Mr. Brownback with the same disproven theory that Republicans have employed for decades: There will be no loss of revenue because of all the economic growth!

“Our new pro-growth tax policy will be like a shot of adrenaline into the heart of the Kansas economy,” he wrote in 2012. “It will pave the way to the creation of tens of thousands of new jobs, bring tens of thousands of people to Kansas, and help make our state the best place in America to start and grow a small business.”