Dismal and useless

This from Nobel-prize winning economist Paul Krugman:

And nobody knows the secret of raising productivity growth. In general, any economist talking about potential growth should start from a position of modesty: nothing in what we know or have experienced in the past justifies making big promises. By all means we should try everything we can think of — but our policies should make sense even if it turns out that the effects on long-run growth are modest.