JAMES TARANTO: ‘Parity’ or Parody? Optimistic economists have some funny ideas:

Subtract women’s earnings from men’s, and the smaller the number, the closer an economy is to “parity.” The reductio ad absurdum helps illuminate the problem: If there were no economic activity whatsoever, the formula would yield 0-0=0. Perfect parity!

In the real world, an economy in which men outearn women can come closer to parity in two ways: through rising female earnings and through declining male earnings. If parity is a desirable outcome in and of itself, we should stop hectoring young men to “man up,” stop playing videogames, and follow the example of their industrious female counterparts. The lads are doing their part to promote gender equality!

Joyce Jacobsen, the Wesleyan University economist who conducted the “Gender Inequality” study for Lomborg’s Copenhagen Consensus on Human Challenges, acknowledges that women’s rising earnings and men’s falling ones tend to move in tandem: “As women’s participation rise in the work force, men tend to work less, often starting work later in their lifespan and retiring earlier.” But her methodology does not account for that. Instead, it simply takes male earnings for granted and counts the earnings difference between the sexes as an economic “loss.”

That’s problematic for another reason: It assumes that in a society with more traditional sex roles, women contribute nothing of value. Gross domestic product measures only commercial work, not unpaid domestic (in the sense of household) work. It doesn’t capture the reality that a traditional marriage–or, for that matter, its reverse, a union between a working woman and a “house husband”–is an economic unit to which the homemaking spouse makes a vital contribution.

As we’ve noted, Scandinavian countries have promoted “gender equality” by employing armies of child-care workers, most of them female. That is, they get paid to take care of other women’s children. That counts toward the GDP figures, whereas it does not when mothers care for their own children at home. It’s not immediately obvious that the Scandinavian way leaves society as a whole better off.

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