Can Trumponomics work?

Work for whom?

That's what Martin Sandbu (subscription required) asks in the Financial Times. In his view, it might. He cites Ken Rogoff -- of spreadsheet fame -- who also has said that it's a possibility. Sandbu cites Summers doubts on Trumponomics, which are all based on supply side factors, but has very little to say about that.* Like Rogoff, Sandbu thinks that what matters is private investment that matters, meaning demand, and, as it must be in these cases, the confidence fairy makes an appearance. In his words:

"What matters, of course, is whether business investment will increase under a Trump economic policy. If it does, it could be because regulations are made business-friendly, because fiscal stimulus boosts aggregate demand and expectations of future demand growth, simply because there is something about Trump that changes the "animal spirits" of investors and business decision makers."

Keynes' animal spirits, also valued by New Keynesians, become relevant. However, the really relevant stuff in there is the fiscal stimulus and how much in terms of actual spending rather than tax cuts for the wealthy, and on what he will spend (e.g. infrastructure). On that, by the way, Trumponomics remains a mystery. But he is right that if: "if a greater fiscal deficit would have boosted growth under a president Hillary Clinton, it should also boost growth under a president Trump."
But the important point Sandbu makes is that:

"Whether greater spending leads to greater (sustained) growth depends on, as Rogoff rightly points out, whether there is much spare capacity in the economy today, or more intriguingly, whether supply capacity itself responds with faster productivity increases in a 'high-pressure economy' of strong demand."

Note that Rogoff only makes the point about spare capacity, and the intriguing idea that the supply constraint responds to demand is Sandbu's own. In other words, he argues that some sort of Kaldor-Verdoorn Law might be at work in the economy. And yes, that's absolutely right.

So can it work? Sure, but for whom is the important question you should ask. And it will be for the few? A boost to infrastructure spending would certainly help, and even military spending (and I'm not discussing the foreign policy implications of a Trump presidency), which is the way the US promotes industrial policy, might stimulate growth. But I would expect after his choices for the economic positions in the cabinet, including his last very anti-union Labor Secretary (and his twitter rant against the Carrier union leader) that the benefits will not be very well distributed.

* Rogoff thinks the economy is not growing less because of secular stagnation, as Summers, meaning it's not a permanent supply-side problem (negative natural rate of interest, or whatever version of the argument you prefer), but the result of debt overhang (more on this for a later post).