Which form is universal affirmative?

• A. Some S are not P
• B. No S are P
• C. Some S are P
• D. All S are P

Answer: (D)

Universal affirmative means every member of the subject class is included in the predicate class, expressing a total, positive inclusion. It uses the word “All” to claim that there are no exceptions among S for being P. That is why “All S are P” fits this form: it asserts that the entire set of S lies within P, so the statement is only true if nothing in S falls outside P.

Think of it as a complete inclusion: if any S were outside P, the universal affirmative would be false. The other forms are weaker or different: “Some S are P” merely says there exists at least one S that is in P; “Some S are not P” asserts existence of an S outside P; and “No S are P” claims there is no overlap between S and P.