It's a very tight and concise exposition, such that it has one the highest errors-to-sentences ratios I've ever observed.
Let's walk through it. 1/18


If people are paid less, they might not work as hard or as long. They might invest less in things that would increase their earnings by a fixed percent. 10/18




He is making basic, textbook errors.
Going forward, he should check his claims with people who are well informed in both fields. 18/18