Another fine article by Arnold Kling.
Watts' book can be regarded as an extended argument in favor of what I might term Epistemological Skepticism about Social Phenomena, or ESSP. Those of us with ESSP believe that we should be skeptical about how much we can know with certainty in the fields known as the social sciences. We may learn things that are true for a majority of cases under specific circumstances. But we are less likely to find perfectly reliable, broadly applicable laws comparable to those found by physicists.
The opposite of believing in ESSP is what Friedrich Hayek termed "scientism." Scientism is a belief that social phenomena can be understood in a scientific manner. It is the belief that we should be able to explain and predict social outcomes on the basis of simple, powerful, verifiable universal principles.