Question

In each of the questions below, two statements are given followed by two conclusions numbered I and II. Consider the two given statements to be true even if they seem to be at variance with commonly known facts, and decide which of the given conclusions logically follow(s) from the statements.

Statements: All bulbs are birds. Some birds are butterflies.
Conclusions:
I. All butterflies are bulbs.
II. Some bulbs are butterflies.

• A. if only conclusion II follows
• B. if only conclusion I follows
• C. if either conclusion I or II follows
• D. if neither conclusion I nor II follows

Hint:

Test the syllogism with a Venn diagram - watch for the undistributed middle term "birds".

Answer 1

The Correct Option is D

Statements: All bulbs are birds. Some birds are butterflies. Treat both statements as true and check whether each conclusion is forced in every possible arrangement (Venn diagram) that fits them.

1. Conclusion I (All butterflies are bulbs): The statements only place bulbs entirely inside birds and say some birds overlap with butterflies. Nothing restricts butterflies to lie inside the much smaller bulb circle. Most butterflies could easily lie in the part of the bird circle that has nothing to do with bulbs at all. So this conclusion does not follow.
2. Conclusion II (Some bulbs are butterflies): The middle term "birds" is not fully used up (not distributed) in either statement, since "all bulbs are birds" only tells us where bulbs sit inside birds, and "some birds are butterflies" does not say which part of birds overlaps butterflies. It is entirely possible to draw the birds-butterflies overlap in the part of birds that excludes bulbs altogether, so that bulbs and butterflies share no members. Since this arrangement also fits both statements, "some bulbs are butterflies" is not guaranteed. So this conclusion does not follow either.

Since neither conclusion is true in every diagram consistent with the statements, the correct answer is (D), neither conclusion follows. This is a classic "fallacy of the undistributed middle" case.

Note on discrepancy: The Cracku reference PDF's answer key shows "B" in this slot, but the explanation printed there is actually a duplicate of the next question's (coin/dollar/red token) explanation, not a genuine explanation for this bulbs/birds/butterflies syllogism, which points to a page-formatting slip in the source. Careful Venn-diagram verification of this specific syllogism shows neither conclusion is validly forced, so (D) is used here instead of the source's printed letter.