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

Marx wrote how in communist society, 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 holds sway on the left, and Sanders is, accordingly, proposing to move from a 40-hour to a 32-hour workweek 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 days 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 is 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.

It’s certainly true that Americans work more than people in other countries. France has a much-vaunted 35-hour workweek, although that stricture only applies to blue-collar workers. Still, France works less than we do, and — in a sign that basic economic laws aren’t so easily suspended — its workers make less money. The average net disposable household income in France, according to The Week magazine, is $34,375 a year, whereas it is $51,147 in the U.S.

If Sanders were being honest and weren’t a socialist, he’d say he has a great deal for Americans — they can work less and become poorer. There probably wouldn’t be many takers.

Sanders complains that American workers are 400% more productive than they were in the 1940s, yet they are still working long hours. Over time, though, we have worked less. In 1830, the average working week was more than 70 hours, and over the course of the next century, it dropped by almost half.

If we were all content with 1940s living standards, maybe we could go all the way and adopt a two-day workweek. From a 21st century perspective, though, returning to 1940s-era housing, plumbing, technology, transportation and health care would feel like impoverishment, and it would be.

What Sanders misses, as economics writer David Bahnsen argues in his new book “Full Time: Work and the Meaning of Life,” is that work is good for us, indeed an inherent part of the human condition. Moreover, the problem isn’t that Americans work too much, but that too many Americans aren’t working at all. Noting the long-term decline in labor-force participation, Bahnsen points out that if the participation rate were the same as it was in 2000, an additional 10 million Americans would be working, with a concomitant increase in goods and services.

In short, the Sanders idea is a frank expression of economic illiteracy. Instead of working so hard to propose and publicize such baldly ludicrous ideas, it’d be better for everyone if the senator found more time for leisure pursuits and resolved to put in fewer hours on the job.

— Richard Lowry is an American writer who is the former editor and now editor-in-chief of National Review