Binyamin Appelbaum had a good piece in the NYT presenting how mainstream economists assess the prospects for boosting growth with the sort of tax cuts proposed by the Trump administration. While the piece accurately conveys the range of views among the mainstream of the profession about the extent to which it is possible to boost GDP growth, it is worth noting that the mainstream of the profession has an absolutely horrible track record in this area. 

The piece tells us that the Federal Reserve Board puts the economy's potential growth rate at just 1.8 percent a year. It then presents views of several economists suggesting that a well-designed tax reform could raise this by 0.3 to 0.5 percentage points.

As recently as 2012, the Congressional Budget Office (CBO) projected that the economy could grow at a 2.5 percent annual rate for the period between 2018 and 2022 (see Summary Table 2). CBO's projections are usually near the center of the economic mainstream, so in the not distant past, many economists believed that the economy could sustain a 2.5 percent annual rate of growth.

It is also worth noting that there is enormous uncertainty about how low the unemployment rate can go without sparking inflation. CBO put the non-accelerating inflation rate of unemployment (NAIRU) in the 5.2–5.4 percent range five years ago. In the most recent month, the unemployment rate was 4.4 percent. There is no evidence in the data of any acceleration in the rate of inflation.

This is important background. While it is probably true that the sort of tax reform proposed by Trump (i.e. giving rich people more money and creating more opportunities to game the tax code) will not provide much boost to growth, economists really don't have much basis for confidence in their own projections of the economy's potential. They have repeatedly been wrong by huge amounts in the past, so unless they suddenly learned a great deal of economics, we should view current projections with considerable skepticism.