The chat-o-sphere has been abuzz lately about a proposal by Slate columnist Reihan Salam: The childless should pay higher taxes so that lower- and middle-income parents can pay less.

"The willingness of parents to bear and nurture children saves us from becoming an economically moribund nation of hateful curmudgeons. The least we can do is offer them a bigger tax break," writes Salam, who has no children himself.

And by "we" he specifically means any nonparent who makes more than the U.S. median income of roughly $51,000. They should bear a heavier tax burden, he argues.

Related: Singles make up majority of tax filers

The idea lit off some biting retorts along the lines of "Sure, I'll pay more, but then I want more say in how you raise your kids and how many more you're allowed to have."

But it also raises an interesting question: Just how many tax breaks do parents get?

The answer: About $171 billion a year's worth, according to a 2013 estimate from the Tax Policy Center.

And that's a measure of just the five biggest child-related breaks: The earned income tax credit, child tax credit, child and dependent care tax credit, the dependent exemption and the head of household filing status for single parents.

The Tax Policy Center further estimates that the average tax benefit for parents exceeds $3,400. A married couple with two kids could get benefits of nearly $7,700, while a single parent with two children might receive more than $8,100.

As a result of the code's many child-related tax provisions, about half of households with kids -- many of them lower income -- won't owe any federal income taxes in 2013. Some in that group will even get a check from the government.

That's not surprising since the tax code is intended to impose the lightest burden on those who are most strapped.

Related: 7 surprising 2014 tax facts

There's no question raising kids has become an expensive venture and parenting is the hardest job in the world.

So there may be good arguments for expanding today's federal tax breaks for parents. And there should be a debate over how to pay for that.

But Salam's proposal to more heavily tax a select group of people simply because they don't have kids disregards some important realities.

For starters, some people physically can't have children or have a tough time adopting. Others have made a conscious choice not to have children because they can't afford them or because they think they can contribute to society in other ways.

And the truth is everyone in society -- not just the childless -- benefits from parents' work raising the next generation.

Salam's proposal also seems to assume that every nonparent making more than $51,000 can afford a bigger tax burden.

But maybe they're helping to support an elderly parent or have their own big medical expenses.

Or maybe they're just trying to pay down their student loan debt and save for children of their own some day.