There are some professions that require a very high level of intelligence and others that merely require a higher-than-average level of intelligence. Furthermore, there is a great deal of variation in intelligence within the professions. (Statisticians would say that the variance in intelligence within a profession is greater than the variance in intelligence between professions.) This means that there are some lawyers of average intelligence and others of extremely high intelligence. (See: Are law school students more intelligent than most others? – Intelligence and IQ )
Similarly, there is a great deal of variance in intelligence among professors. Those in theoretical physics, mathematics and philosophy require a high level of intelligence to reach doctoral levels in these subjects, while others, in less challenging subjects can achieve the necessary credentials without exceptional intellectual skills. These observations are reflected in the graph below from the College Board showing the SAT scores (strongly correlated to IQ) by college major.
The variation in intelligence within each profession prevents us from attributing a low estimate of someone’s intelligence based on their profession, because even the least demanding profession may include some brilliant people. However, the fact that a person has a Ph.D. from a top university in a highly demanding profession like theoretical physics, strongly suggests that this person has a very high intelligence.
