Rich Lowry writes for the New York Post about the latest bad idea from socialist Sen. Bernie Sanders.

Karl Marx would be proud: Bernie Sanders has urged taking another step toward the philosopher’s envisioned utopia by proposing to mandate a four-day work week.

In communist society, Marx wrote, workers would be liberated to “hunt in the morning, fish in the afternoon, raise cattle in the evening, criticize after dinner, just as I have in mind, without ever becoming hunter, fisherman, shepherd, or critic.”

Needless to say that’s not how communism turned out.

Yet the belief that work is basically a capitalist imposition that is unnatural and bad for people still hold sway on the left, and Sanders is, accordingly, proposing to move from a 40-hour to a 32-hour work week to make us healthy, wealthy and wise.

“It is time to reduce the stress level in our country and allow Americans to enjoy a better quality of life,” the Vermont socialist insists.

“It is time for a 32-hour workweek with no loss in pay.”

The last clause is the key one: If everyone can work less and produce and earn exactly the same, why not?

And if this is possible, why stop at four-days-a-week?

It’d be positively cruel to make someone work four days when they can work three with the same outcomes.

Of course, the promise that we can work less and make the same is the socialist equivalent of Mexico will pay for the border wall.

It’s not just promising a free lunch, but a free breakfast, lunch and dinner, with room service delivering a late-night snack gratis.

What we earn is not an arbitrary number, but linked to what we produce: To simplify, if everyone were to work 20% less without becoming any more productive, GDP would decline 20%.

The pie would shrink, even though Sanders is saying everyone’s slice would — impossibly — be just as big.