Following the publication of this piece in the NY Times, I’ve had a string of email exchanges with Hal Varian, cc:ing Brad DeLong in the role of interested onlooker. I was surprised by the NY Times article since it included both a correct statement of the way in which Stern treats discounting and income redistribution (roughly speaking a 1 per cent change in income has the same value whenever it is incurred and whoever receives it) with a lot of statements that were either misleading or downright wrong, implying that the near-zero rate of pure time preference in the Stern Review implied a near-zero discount rate for cash flows.
Since Varian is one of the brightest and most technically careful people in the economics profession, I was unsurprised by the correct statement, but very surprised to see errors I’d already refuted when put forward by Arnold Kling, Bjorn Lomborg, Megan McArdle and others. Email revealed that the main problems arose from editorial attempts to ‘simplify’ things for readers, but we still have a lot of disagreements about the justifiability or otherwise of inherent discounting.
In any case, all this has spurred me on to produce my long-promised review of Stern on discounting, at least in draft form. Read, enjoy and criticise.