> A circle of competence is the subject area which matches a person's skills or expertise. The concept was developed by Warren Buffett and Charlie Munger as what they call a mental model, a codified form of business acumen, concerning the investment strategy of limiting one's financial investments in areas where an individual may have limited understanding or experience, while concentrating in areas where one has the greatest familiarity. -Wikipedia
> I try to temper my tendency to believe the Halo effect with Warren Buffett's notion of the Circle of Competence; there is often a very narrow domain where any person can be significantly knowledgeable. (commenter above)
Putting aside Buffett in particular, I'm wary of claims like "there is often a very narrow domain where any person can be significantly knowledgeable". How often? How narrow of a domain? Doesn't it depend on arbitrary definitions of what qualifies as a category? Is this a testable theory? Is it a predictive theory? What does empirical research and careful analysis show?
Putting that aside, there are useful mathematical ways to get an idea of some of the backing concepts without making assumptions about people, culture, education, etc. I'll cook one up now...
Start with 70K balls split evenly across seven colors: red, orange, yellow, green, blue, indigo, and violet. 1,000 show up demanding balls. So we mix them up and randomly distribute 10 balls to every person. What does the distribution tend to look like? What particulars would you tune and/or definitions would you choose to make this problem "sort of" map to something sort of like assessing the diversity of human competence across different areas?
Note the colored balls example assumes independence between colors (subjects or skills or something). But in real life, there are often causally significant links between skills. For example, general reasoning ability improves performance in a lot of other subjects.
Then a goat exploded, because I don't know how to end this comment gracefully.