Three Statements followed by three Conclusions are given below. You have to take the Statements to be true even if they seem to be at variance from the commonly known facts. Read all the Conclusions and then decide which of the given Conclusions logically follows/follow from the Statements, disregarding the commonly known facts : Statement-1 : Some doctors are teachers. Statement-2 : All teachers are engineers. Statement-3 : All engineers are scientists. Conclusion-I : Some scientists are doctors. Conclusion-II : All engineers are doctors. Conclusion-III : Some engineers are doctors. Which one of the following is correct?
- (a) Only Conclusion-I
- (b) Only Conclusion-II
- (c) Both Conclusion-I and Conclusion-III ✓ UPSC's answer
- (d) Both Conclusion-I and Conclusion-II
Why the answer is (c)
• From Statement-1, some doctors are teachers, meaning there is an overlap between the set of doctors and the set of teachers.
• From Statement-2, all teachers are engineers, so the overlapping doctors who are teachers must also be engineers.
• From Statement-3, all engineers are scientists, so those specific doctors (who are teachers and engineers) must also be scientists.
• Therefore, some doctors are scientists, which logically implies that some scientists are doctors (Conclusion-I is valid).
• Similarly, since some doctors are teachers and all teachers are engineers, it follows that some engineers are doctors (Conclusion-III is valid).
• Conclusion-II is invalid because the relationship is only partial (some doctors are engineers), not universal (all engineers are doctors).
Why the other options are wrong
- (a) Only Conclusion-I
- Conclusion-III is also valid because some doctors are teachers, and all teachers are engineers, making some engineers doctors.
- (b) Only Conclusion-II
- Conclusion-II is invalid because only some doctors are engineers, not all engineers are doctors.
- (d) Both Conclusion-I and Conclusion-II
- Conclusion-II is invalid because the statements do not support the claim that all engineers are doctors.
Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2022, held on 5 June 2022. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.