What We Can't Not Know, A Guide
As all later Russian fiction came out of Gogol's The Overcoat, so Anglo-American moral philosophy in the 20th century came out of G. E. Moore's Principia Ethica, published in 1903. By inventing the "naturalistic fallacy," Moore made canonical the split between Is and Ought first suggested by Hume. The fact/value dichotomy became dogma. No more could one appeal to the features of a thing--the facts--to explain the commendation or condemnation of it: "good" and "bad" became unmoored from natural properties. Anything whatsoever could be called good, or bad, since such evaluations had nothing to do with what the things are.
So what, if anything, did "good" mean if not the natural properties of the good thing? The history of analytic moral philosophy could be told in terms of the successive answers to this question through the century. Despite Peter Geach's important reminder about attributive and predicative adjectives, the divorce of good from the things called good was not repaired. In the end, the dominant view, as Alasdair MacIntyre has said, was Emotivism. "Good" and "bad" signified the feelings I have when I evaluate, feelings which are not dictated by the inherent qualities of things I call good or bad. Condemning something was like admitting to a toothache. Calling something good was confessing that one enjoyed it.
Read the entire review on the Claremont Review of Books website.