Is there any way to interpret Greg Mankiw's Sunday New York Times other than as an elbow to Chtistie's ribs while he thinks the ref's eye is elsewhere? Christie certainly does not believe that tax multipliers are twice the size of spending multipliers.
Greg Mankiw is now citing Gary Becker as one who thinks any increase in public infrastructure will have almost no aggregate demand effect ala crowding out but let’s review the portions of Gary’s statement that Greg left out:
If the government increased its spending on infrastructure when the economy has full employment, its main impact would likely be to draw labor, capital, and raw materials away from various other activities. In effect, increased government spending under these employment conditions would "crowd out" private spending ... Of course, the present situation is not one of full employment but of underemployment and excess unemployment, and employment is still falling. How does one adjust the full employment analysis in the first paragraph to account for the presence of unemployed labor and capital? One extreme assumes no crowding out of other private spending when governments increase their spending with significant underemployment in the economy. Increased government spending through a stimulus package under these conditions might even have a "multiplier" effect that would greatly increase, not crowd out, other private spending. The reason is that the recipients of the government spending in turn would increase their spending, and thereby stimulate other activities. Intermediate assumptions assume partial crowding out of other private activities, so a stimulus package would still increase employment and GDP.
Gary presents us the standard reasoning and then asks us to apply it to the current situation. It is true that Gary makes the following argument:
For another thing, with unemployment at 7% to 8% of the labor force, it is impossible to target effective spending programs that primarily utilize unemployed workers, or underemployed capital. Spending on infrastructure, and especially on health, energy, and education, will mainly attract employed persons from other activities to the activities stimulated by the government spending.
In other words, he starts with the intermediate position and then tilts towards the full employment view but my reading of Romer-Bernstein suggests we are likely closer to the view held by the no crowding-out crowd.
We should welcome a real debate on this issue but cherry picking quotes is not exactly the best way to make a point.