A workforce working 50 % fewer hours but doing 50 % more work per hour would only get 75 % of the original work done. The actual amount to cut work time by to compensate for a 50% productivity gain is ⅓ or 33.3̅ %.
Bertrand Russell was a mathematician and logician first and foremost. He wouldn’t allow such a slip-up.
I’m pressing 🅧 for doubt on you. The social critique is on point but let’s go over the numbers:
1 “+ 50 %” = 1.5 (productivity multiplier)
1 “− 50 %” = 0.5 (time multiplier)
1.5 × 0.5 = 0.75 ≠ 1
A workforce working 50 % fewer hours but doing 50 % more work per hour would only get 75 % of the original work done. The actual amount to cut work time by to compensate for a 50% productivity gain is ⅓ or 33.3̅ %.
Bertrand Russell was a mathematician and logician first and foremost. He wouldn’t allow such a slip-up.
Edit: indeed, see pages 16-17 of the archive.org copy of the essay, his multipliers are 2x and 0.5x, respectively.