2015 CSAT, all questions
UPSC Prelims 2015 · CSAT
Question 55: Logical Reasoning and Mental Ability
Consider the following statements followed by two conclusions :
- StatementsSome men are great. Some men are wise.
- Conclusion IMen are either great or wise.
- Conclusion IISome men are neither great nor wise.
Which one of the following is correct ?
aOnly conclusion I is valid
bOnly conclusion II is valid
cBoth the conclusions are valid
dNeither of the conclusions is valid
AnswerUPSC’s answer is (d).
Draw circles: 'some men are great' and 'some men are wise' tell us only that each group overlaps with men. Conclusion I says every man is great or wise; the statements allow men who are neither, so it does not follow. Conclusion II says some men are neither; the statements do not force that either, since great and wise men could make up all men. Neither conclusion is certain, so neither is valid.
- I. The statements do not say that every man is great or wise.
- II. The statements do not require any man to be neither; all men could be great or wise.
Why each option is right or wrong
- (a) Wrong: conclusion I is not forced; the statements leave room for men who are neither great nor wise.
- (b) Wrong: conclusion II is not forced either.
- (c) Wrong: neither conclusion is valid.
- (d) Right: each conclusion can be true or false with the given statements.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2015, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.