Here's a little diversion to pass the time as you endure Washington's policy debates. Listen for phrases like “All we have to do” or “We need just a small tweak” or “There’s a really simple fix.” Then watch to see what happens. Whatever that person is proposing will prove to be really, really costly -- politically or fiscally or both.

On some endless panel discussion, I once pointed out that fixing Social Security’s funding problem would probably involve some combination of tax increases and benefit cuts for future recipients. A very indignant left-wing commentator of some note got up and lambasted me, saying “All we have to do is raise the payroll tax cap.”

I was a trifle astonished. Mathematically, he was correct. But to say that's "all" we have to do? He made it sound as if this were a minor technical correction on par with getting the wheels realigned on your car. In fact, this amounts to slapping a12 percent surtax on all income above $118,500 a year. This would pretty much exhaust our fiscal capacity to tax the more affluent to fund new spending or existing programs, and it would all be funneled to a single program that is not even our biggest underfunded entitlement (that honor goes to Medicare). Doing this would be extremely politically costly (it would hit affluent professionals, who tend to both support the Democratic Party and run it), and it would also be the biggest single tax increase in living memory. This is rather like saying that “all we have to do to fix climate change is perfect cold fusion.”

But of course he was hardly the only offender. All we have to do to fix American health care is to pay our providers and suppliers low European prices instead of high American ones. All we need to do to make Republican tax plans work is to get economic growth up to 4 percent. All that was needed to make Iraq a better place was for America to depose Saddam Hussein and for Iraqis create a liberal democracy. There is always a devil in the details behind those innocuous “all” statements, and he has his pitchfork ready.

So beware when liberals today start saying that maybe Obamacare has a few problems, but all we need to do is …

They’re saying it a lot.

These things are not easy, simple fixes. Do you know how we know this? They weren’t done when the law was passed.

Why? Because Democrats couldn’t assemble a political coalition to do this. Mind you, at the time they had 60 votes in the Senate, and control of the House, and the presidency -- a level of historical dominance they hadn’t managed in decades. Either these simple fixes would have pushed the price tag of the bill too high, making it difficult to find even more taxes or program cuts to pay for it, or they would have damaged the popularity of a bill that was already really unpopular.

And this is true of every idea that starts with “All we need to do.” If “All we need to do” to fix some substantial problem were cheap and politically popular, it would already have been done, and we wouldn’t be talking about it. The stuff we argue about is, almost by definition, the stuff that’s hard.

Needless to say, Republicans are not going to be eager to do something hard and unpopular largely in order to save a program that was passed over their strenuous objections and is now hurting their political opponents. So if all we need to do is persuade Republicans to abandon their objections to Obamacare, and possibly their own electoral futures, in order to bail Democrats out of the mess they created, then we’re all going to be living with these problems for a very long time.

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

Megan McArdle is a Bloomberg View columnist who writes on economics, business and public policy. To read more of her blogs, Click HERE.