Free Syllogisms MCQs with Answers

1. If all surgeons are doctors and some doctors are researchers, which conclusion definitely follows?

• A. All surgeons are researchers
• B. Some surgeons are researchers
• C. All researchers are doctors
• D. No conclusion about surgeons and researchers definitely follows

Explanation: The researchers who are doctors might all be non-surgeons, so nothing definite links surgeons to researchers. A conclusion is only valid if it holds in every arrangement the premises allow, not merely in the most natural looking one. The third option reverses the second premise, which said only that some doctors are researchers.

2. Statements: All roses are flowers. All flowers are plants. Conclusion: All roses are plants. This conclusion is

• A. valid
• B. invalid
• C. possibly true only
• D. contradictory

Explanation: Two universal affirmative premises that share a middle term chain together, placing roses inside flowers and flowers inside plants. This is the classic Barbara syllogism and it is always valid. Nesting three circles on paper confirms it in seconds.

3. Statements: All cats are mammals. All dogs are mammals. Conclusion: All cats are dogs. This conclusion is

• A. valid
• B. invalid
• C. certainly true
• D. partly true

Explanation: Both groups sit inside mammals, but nothing forces them to overlap each other, so they may be entirely separate as in fact they are. This error, in which the middle term is never distributed, is called the fallacy of the undistributed middle. Sharing a category does not make two groups identical.

4. Statements: Some pens are books. All books are papers. Which conclusion follows?

• A. Some pens are papers
• B. All pens are papers
• C. No pen is a paper
• D. All papers are pens

Explanation: The pens that are books must also be papers, so at least some pens are papers, while nothing is known about the rest. A particular premise can never support a universal conclusion. The final option reverses a universal statement, which is invalid.

5. Statements: No student is careless. Some careless people are drivers. Which conclusion follows?

• A. Some drivers are not students
• B. No driver is a student
• C. All drivers are careless
• D. Some students are drivers

Explanation: The drivers who are careless cannot be students, since no student is careless, so at least some drivers fall outside the student group. Extending this to all drivers is unwarranted, because the remaining drivers are unaccounted for. A negative premise always yields a negative conclusion.

6. Statements: Some doctors are writers. Some writers are poets. Which conclusion follows?

• A. Some doctors are poets
• B. No doctor is a poet
• C. All writers are doctors
• D. No definite conclusion follows

Explanation: Both premises are particular, and two particular premises can never yield a definite conclusion, because the two overlapping groups of writers may be completely different people. Some doctors being poets is possible but not guaranteed. Recognising this rule saves time on many syllogism questions.

7. Statements: All engineers are graduates. Some graduates are unemployed. Which conclusion follows?

• A. Some engineers are unemployed
• B. No engineer is unemployed
• C. No definite conclusion about engineers follows
• D. All unemployed people are graduates

Explanation: The unemployed graduates may all lie outside the engineer group, so nothing definite follows about engineers either way. The pattern of an all premise followed by a some premise on the wrong term is a standard trap. Only when the particular premise connects to the right term does a conclusion emerge.

8. Statements: All metals conduct electricity. Copper is a metal. Conclusion: Copper conducts electricity. This is an example of

• A. deductive reasoning that is valid
• B. inductive reasoning
• C. an invalid conclusion
• D. circular reasoning

Explanation: A general rule is applied to a specific case, which is deduction, and if the premises are true the conclusion cannot be false. Induction works the other way, generalising from particular observations to a rule. Deduction guarantees its conclusion while induction only makes it probable.

9. Statements: No fish can fly. All sharks are fish. Which conclusion follows?

• A. Some sharks can fly
• B. No shark can fly
• C. All flying things are fish
• D. Some fish are sharks only

Explanation: Sharks lie entirely within fish, and fish are entirely excluded from the flying category, so sharks are excluded too. This is the valid form no A is B, all C are A, therefore no C is B. The exclusion passes down to every subset.

10. Statements: Some teachers are singers. No singer is a dancer. Which conclusion follows?

• A. Some teachers are not dancers
• B. No teacher is a dancer
• C. All teachers are singers
• D. Some dancers are teachers

Explanation: The teachers who are singers cannot be dancers, which establishes that some teachers are not dancers. The other teachers might well be dancers, so the universal negative is too strong. Combining a particular affirmative with a universal negative always gives a particular negative.