The first thing I did was to make a "first pass" to remove titles for which a political slant would seem to matter little or find little platform.
Then Gordon winnows further:
Again, I had removed a large number of titles in my "first pass," but not surprisingly there still remained 55 titles that I then subsequently deemed to not have been relevant to the matter of ideological categorization; further, for another 47 of the books I found the authors too reticent about political ideology to enable a coding. Hence from the 494 titles that remained after my "first pass," only 392 were given an ideological coding corresponding to the list of nine categories above.
His bottom line:
The categories Communitarian, Tending communitarian, Left, and Centrist leaning left account for 55 percent, while the categories Classical liberal, Tending classical liberal, Conservative, and Centrist leaning conservative account for only 15 percent (the remainder being Centrist and the two neuter categories). Moreover, only eight of the titles (1.6 percent of the 494) can be counted as squarely Conservative or Classical liberal, while 198 of the titles (40 percent) can be counted as squarely Left or Communitarian.
This isn't too surprising, given my casual empiricism in noticing HUP titles over the years. What I did find a little surprising--refreshingly surprising because it saves prospective authors a lot of time--is how open the Senior Editor for Social Sciences, Michael Aronson is about his bias. He tells prospective authors:
I acquire books in economics, law, political science, and sociology. Although my interests are wide-ranging and eclectic, I am particularly interested in problems of capitalism, including distribution, inequality, market instability, resource depletion, and climate change.
Notice what's missing. He doesn't mention his interest in successes of capitalism, market stability, and how markets handle resource depletion (think Julian Simon). And--call it a hunch--I'm betting that he's not interested in books that say that climate change is not due to mankind or, if it is due to mankind, is good, not bad.