At the beginning of last night's GOP primary debate, each of the 10 Republican candidates on stage was asked to name his or her biggest weakness. Most of them simply deflected the question. What none of them said, but at least a few should have, is that they are only tenuously in touch with policy reality.

Start with Mike Huckabee. In one of the debate's most galling moments, he declared that "we've lied to the American people" about old-age entitlements Social Security and Medicare, and insisted that there's something "we're not telling" them—that "it's their money." The programs are neither entitlements nor welfare, he insisted. Instead, "this is money that people have confiscated out of their paychecks. Every time they got a paycheck, the government reached in and took something out of it before they ever saw it."

It is true that the government takes money out of people's paychecks to fund these programs. But Huckabee seems to be insisting that they are savings programs, in which money is withheld from one's earnings and kept safely stored for retirement. That's not right. It's more accurate to describe both as transfer programs, in which money is taken from the paychecks of current earners to fund the program for today's beneficiaries; ultimately, as the Urban Institute has shown, a typical beneficiary gets far more out of the program than he or she puts in.

Meanwhile, the Supreme Court has ruled on multiple occasions that Americans are not entitled to any of the money they "put in" to Social Security at all. It's a tax and transfer program, not a government-run savings system. Mike Huckabee is the one who is lying to people here; legally speaking, at least, it's not "their money" that the government is holding safely for them until retirement.

Huckabee seemed to attempt to swat away these sorts of practical concerns by declaring that "this is a matter not of math, this is a matter of morality," as if the two are at odds. Apparently Huckabee's belief is that the only moral position on entitlements is to ignore the underlying reality of how they work.

And then there was Donald Trump, the current primary frontrunner who near the beginning of the night was asked a question about how he would deport 11 million undocumented immigrants, build a border wall while making Mexico pay for it, and cut taxes by $11 trillion without raising the deficit.

On his tax plan, Trump insisted that the economy would take off "dynamically" and thus wipe away the deficit—the idea being that lower taxes spur so much economic growth that the bigger economy provides enough new revenue to make up for what was lost in lowering taxes. There is no evidence or reason to believe that his barely-sketched plan would provide such a boost. Even conservative economists working for the Congressional Budget Office say that dynamic effects tend to be modest at best, and rarely pay for themselves entirely or even mostly. Lowering taxes without raising the deficit requires commensurate spending cuts; Trump offered fantasy of large tax cuts without significant spending cuts to compensate.

On his immigration plan, Trump offered even less to work with. He simply insisted that "we can do a wall" and that Mexico is going to pay for it. "People say, how will you get Mexico to pay? A politician other than the people in the states—I don't want to—a politician cannot get them to pay. I can." Trump was essentially insisting that political reality as it is widely understood would not apply to him, simply by virtue of him being Donald Trump.

Trump's rival for the top slot in the primary polls, neurosurgeon Ben Carson, was similarly careless regarding details of his flat tax plan.

When told that his barely-counts-as-a-plan "plan" for a (probably) 15 percent flat tax would leave a $1.1 trillion deficit, he essentially shrugged and waved the objection away, saying, "you also have to get rid of all the deductions and all the loopholes. You also have to some [sic] strategically cutting in several places."

Carson, of course, has never even attempted to outline the cuts that would be necessary to fill such a budget gap, and he seemed unconcerned about ever really doing so. Like Trump, he's peddling a fantasy of giant tax cuts with no other meaningful changes to the federal government.

Those who favor smaller government might just be pleased to see a candithis is a problem for those who would actually like to reduce government's size and scope. By refusing to be honest about the practical challenges and reality of policy reform, Carson and others make it harder to actually achieve those reforms. Making government smaller, leaner, and more efficient is not a matter of will or ego or magical powers of negotiation or just saying the right few words; it's a painstaking, time-consuming process that requires attention to detail and a willingness to grapple with the boring but important facts of public policy.

The casual dismissal of those details and the various challenges they represent suggests how unserious candidates like Trump and Carson—who currently poll at nearly 50 percent combined—are about policy, and, in turn, how unserious their many backers in the GOP base are as well. The candidates may not have chosen to explicitly state their own biggest weaknesses in last night's debate, but in treating the details of policy with such looseness, they inadvertently managed to reveal one of the party's.