Difficulty: Medium
Correct Answer: Neither I nor II follows.
Explanation:
Introduction / Context:
This question involves three overlapping sets: children, adults, and old people. Two some type statements are given, and you are asked to decide which negative conclusions, if any, must follow. The task is to see whether the existence of some overlaps forces the existence of specific non overlapping elements, or whether such elements remain only possible and not certain.
Given Data / Assumptions:
- Statement 1: Some children are adults. At least one person belongs to both the children set and the adult set.
- Statement 2: Some adults are old. At least one adult is also old.
- There may be other children, adults, or old people, but they are not described explicitly.
- Conclusion I: Some children are not old.
- Conclusion II: Some adults are not old.
Concept / Approach:
The key idea is that some simply guarantees existence of at least one element with the stated property. It does not say anything about the rest of the set. The fact that some adults are old does not tell us whether other adults are or are not old. Similarly, knowing that some children are adults does not tell us whether those particular children are old or not old. Negative conclusions require clear information about the absence of overlap, which is not given here.
Step-by-Step Solution:
Step 1: From Statement 1, mark at least one person who is both a child and an adult. Call this person X. This shows that the sets children and adults overlap.
Step 2: From Statement 2, mark at least one adult who is old. Call this person Y. This shows that the sets adults and old people overlap.
Step 3: Notice that the problem does not say whether X and Y are the same person or different persons. Both possibilities are allowed. X may be old or not old, and Y may or may not be a child.
Step 4: Consider Conclusion II first: some adults are not old. For this to be necessarily true, there must be at least one adult who is definitely not old in every valid diagram. However, it is possible that every adult is old. In that scenario, the statement some adults are old is still true, but there is no adult who is not old. Since such a diagram is consistent with the statements, Conclusion II is not guaranteed.
Step 5: Now consider Conclusion I: some children are not old. It is possible that every child, including those who are adults, is old. That would satisfy both statements, because there could be at least one child who is an old adult and at least one adult who is old. In that case, there would be no child who is not old. So Conclusion I is also not guaranteed.
Step 6: Because we can construct valid diagrams where both conclusions fail, neither conclusion follows logically from the given statements.
Verification / Alternative check:
Construct a specific example. Suppose there are three people, all of whom are adults and all of whom are old. Two of them are also classified as children in this abstract setting. Then, some children are adults (true) and some adults are old (true). However, in this example, every child is old and every adult is old. There is no child who is not old and no adult who is not old. This concrete scenario shows that both conclusions can be false while the statements remain true, which proves that neither conclusion is logically forced.
Why Other Options Are Wrong:
- Any option that accepts Conclusion I assumes there must be at least one child outside the old group, which is not stated.
- Any option that accepts Conclusion II assumes there must be at least one adult outside the old group, which again is not stated.
- The option that says both conclusions follow is clearly incorrect, since the example above shows both can fail at the same time.
- The cannot be determined option is not appropriate here, because in syllogism we ask whether something must follow. Since these conclusions do not have to be true, the correct logical status is that neither follows.
Common Pitfalls:
Many candidates assume that some automatically implies some not, for example that if some adults are old then some adults are not old. This is not valid. It is always possible that every adult is old and the some statement still remains true. Another error is to bring in real world knowledge about the meanings of child and adult instead of treating them as abstract sets in this logical exercise.
Final Answer:
Thus, neither conclusion is logically compelled by the given statements. The correct answer is Neither I nor II follows.
Discussion & Comments