On immigration at least, Paul Krugman seems to have a better understanding of market economics than some conservatives (TimesSelect):

…Because Mexican immigrants have much less education than the average U.S. worker, they increase the supply of less-skilled labor, driving down the wages of the worst-paid Americans. The most authoritative recent study of this effect, by George Borjas and Lawrence Katz of Harvard, estimates that U.S. high school dropouts would earn as much as 8 percent more if it weren’t for Mexican immigration.
That’s why it’s intellectually dishonest to say, as President Bush does, that immigrants do ”jobs that Americans will not do.” The willingness of Americans to do a job depends on how much that job pays — and the reason some jobs pay too little to attract native-born Americans is competition from poorly paid immigrants.