The extension of the concept 'man' includes which of the following?

• A. All men who have ever lived, who are living, or will live
• B. The concept of man in the mind
• C. The properties that define man
• D. The set of individuals who are men

Answer: (A)

The extension of a term is the set of all individuals to which that term applies. For the word “man,” that means every person who is a man. To capture the full scope, this includes those who have lived in the past, those who are living now, and those who will live in the future. So the statement that names all men who have ever lived, who are living, or will live exactly expresses that complete set. The other ideas refer to what the term means in the mind or to its defining traits (intension), not to the actual group of individuals it denotes.