Source: Question 9b, p 61, Principles of Microeconomics, 7 Ed, 2014, by N Gregory Mankiw
= Question 8b in Principles of Microeconomics, 4 Ed, 2008
9. Are the following statements true or false? Explain in each case.
b. “Certain very talented people have a comparative advantage in everything they do.”
Answer: b. False; it is not true that some people have a comparative advantage in everything they do. In fact, no one can have a comparative advantage in everything. Comparative advantage reflects the opportunity cost of one good or activity in terms of another. If you have a comparative advantage in one thing, you must have a comparative disadvantage in the other thing.
This question of Mankiw recommends my own version: (Abbreviate comparative advantage as CA)
Can people have neither a comparative advantage nor a comparative disadvantage in everything they do?
My lay guess is: yes. For example, suppose in a 3-person economy: person A's CA is cooking and person B's foraging, and person C does nothing. Then person C exemplifies such a person?