With Democrats becoming increasingly ambitious in their policy goals, Republicans believe they have a killer answer to any new proposal: How are you going to pay for it?

The fact that this question is asked in complete bad faith - the GOP is the party that recently passed a $1.5 trillion tax cut for corporations and the wealthy without bothering to pay for it - doesn't mean it can't be effective. And one reason is that it will likely also be asked by the Washington media, people who as a group are enthusiastic deficit scolds, at least when it comes to programs that actually benefit ordinary people.

Nowhere can we see this more clearly than on the idea of universal health coverage, usually shorthanded as "Medicare for all," which is fast becoming consensus among Democrats. If you're an advocate of that idea, you can be sure that whenever it comes up in an interview, you'll be pressed on how you're going to pay for it.

That happened last weekend to future congresswoman Alexandria Ocasio-Cortez when she appeared on CNN's "State of the Union." Jake Tapper asked her how she was going to come up with $40 trillion over 10 years to pay for it (a number from one estimate of one particular plan). She answered by saying that other countries manage to sustain universal systems, and it's an investment that will continue bringing dividends.

Tapper replied by saying, "You say it's not pie in the sky, but $40 trillion is quite a bit of money ..." to which she replied by talking about all the costs that come from having so many people with inadequate coverage or no coverage, to which he replied, "I'm assuming I'm not going to get an answer for the other $38 trillion." You get the idea.

In some quarters that kind of exchange is met with tut-tutting ("The $40 trillion question Alexandria Ocasio-Cortez couldn't answer" read one headline) or outright glee that the liberals' Achilles heel has been exposed. But the truth is that the people who think they're being hard-headed and asking for specifics are missing the point of a proposal like universal health coverage.

So let me suggest a different question that might be asked not to those advocating Medicare for all, but to those opposing it and those journalists assuming it's unrealistic:

How do you propose to come up with the $50 trillion you want to spend on health care over the next 10 years?

Because that's what the status quo is going to cost. The questions about the cost of Medicare for all seem to come from a bizarre alternate universe where we aren't spending anything now on health care, and we're going to have to come up with a shocking amount of new money to fund this crazy idea of giving everyone coverage.

This $50 trillion number comes from the most recent projections by the Centers for Medicare and Medicaid Services, which say that America will spend $3.7 trillion on health care this year, a figure that will increase by between 5 and 6 percent per year in the coming years. Their projections only go to 2026, so I extended them out two years, assuming a 6 percent increase per year, to reach a full decade from 2019-2028. When you add the numbers up, you get $50.3 trillion over the next 10 years. That's what we're going to spend if we change nothing.

Where will that money come from? Well, from all of us. It will come in the form of taxes that pay for Medicare, Medicaid, CHIP, and the VA. It'll come in the form of premiums taken out of paychecks, and co-pays, and deductibles. It'll be paid by the American people, one way or another.

So if Medicare for all actually costs $40 trillion, we'd save $10 trillion. Hooray!

Now of course, there's the matter of exactly how we're going to shift all that money around, which taxes would be raised, and how to counter the influence of those who could lose out (like insurance and drug companies), all of which are important questions. But saying that the people who want to save $10 trillion are the ones who are offering something unrealistically extravagant is bonkers. It's as though I said that since you're heating your house by burning $100 bills, maybe you should buy a gas furnace instead, and you replied, "Spend $5,000 on a furnace? That's crazy! What am I, a Rockefeller?"

And yes, it's not just relevant but vital to point out whenever this question comes up that we're already spending more on health care than every other country on earth. We spend twice as much as other developed countries, and they cover all their citizens.

I'm not going to go into all the varied reasons why universal coverage is a good thing, or into the many models of universal coverage, each of which has its own strengths and weaknesses. I happen to think that a hybrid system like they have in France - a basic, universal government program that covers everyone, along with supplemental private insurance for people who want more benefits - is both an effective system and something that we could reach from where we are now. But that's a discussion for another day.

What matters for the moment is this: If you're going to demand that advocates of Medicare for all explain how they're going to come up with $40 trillion, you have to immediately ask advocates of the status quo how they're going to come up with $50 trillion. Because that's what they're proposing to spend.

Paul Waldman is an opinion writer for the Plum Line blog.