UPSC Prelims 2024·CSAT·Logical Reasoning·Deductive Logic

Two Statements followed by four 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: All pens are books. Statement- 2: No chair is a pen. Conclusion- I: All chairs are books. Conclusion- II: Some chairs are pens. Conclusion- III: All books are chairs. Conclusion- IV: No chair is a book. Which one of the following is correct?

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  1. AOnly Conclusion-I
  2. BOnly Conclusion-II
  3. CBoth Conclusion-III and Conclusion-IV
  4. DNone of the Conclusion followsCorrect

Explanation

Let's analyze each statement and conclusion: Statements: 1. All pens are books. (This means the set of pens is entirely contained within the set of books.) 2. No chair is a pen. (This means the set of chairs and the set of pens have no common elements; they are disjoint.) Now let's evaluate each conclusion: Conclusion I: All chairs are books. From Statement 1, pens are books. From Statement 2, chairs are not pens. This does not provide enough information to determine the relationship between chairs and books. Chairs could be books, not books, or partially books. For example, if pens are red objects, books are red objects, and chairs are blue objects, then chairs are not pens. But chairs could be blue books or blue non-books. Therefore, this conclusion does not logically follow. Conclusion II: Some chairs are pens. This directly contradicts Statement 2, which says "No chair is a pen." If no chair is a pen, then it's impossible for some chairs to be pens. Therefore, this conclusion does not logically follow. Conclusion III: All books are chairs. If all books are chairs, and we know from Statement 1 that all pens are books, then it would logically follow that all pens are chairs. However, Statement 2 clearly states "No chair is a pen," which means no pen is a chair. This creates a contradiction. Therefore, this conclusion does not logically follow. Conclusion IV: No chair is a book. From Statement 1, pens are books. From Statement 2, chairs are not pens. This does not mean chairs cannot be books. For example, if all pens are red objects, all books are red objects, and chairs are blue objects. Chairs are not pens, but chairs could still be books (e.g., blue books). There is no information to establish that chairs and books are disjoint. Therefore, this conclusion does not logically follow. Since none of the conclusions logically follow from the given statements, the correct option is D. The final answer is D) None of the Conclusion follows.
Logical Reasoning: Two Statements followed by four Conclusions are given below. You have to take the Statements to be true even if they see

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