UGC NET Questions (Paper – 1)

A valid categorical syllogism must contain exactly three terms: major, minor and middle. If ambiguous language or faulty structure introduces a fourth distinct term, the necessary linkage between major and minor via a single middle term is broken. This defect is known as the fallacy of four terms. Therefore the error described in the stem is correctly named four terms.

Option A:
Option A, undistributed middle, is a different fallacy where the middle term is not distributed in either premise, so it never refers to all members of its class. Although this also breaks the connection between major and minor terms, it does not involve adding an extra term.

Option B:
Option B is correct because the presence of four distinct terms means that the argument cannot be a proper syllogism, which by definition has only three. Often this happens due to equivocation, where a word is used with two different meanings.

Option C:
Option C, illicit major, occurs when the major term is distributed in the conclusion but not in the premise, which is a distribution error, not an increase in the number of terms.

Option D:
Option D, ambiguous conclusion, is not a standard named fallacy in traditional syllogistic logic, and ambiguity alone does not guarantee that exactly four terms are present.

The fallacy of undistributed middle occurs when the middle term in a syllogism is never taken to refer to all members of its class in any premise. As a result, the premises fail to establish a necessary connection between the major and minor terms. Without a properly distributed middle, the conclusion does not logically follow. Thus the situation described in the stem is the fallacy of undistributed middle.

Option A:
Option A is correct because the defining error is precisely that the middle term is left undistributed in both premises. This allows the argument to illegitimately treat partially overlapping sets as if they were fully connected. Recognising this flaw is essential to testing categorical syllogisms.

Option B:
Option B, illicit major, arises when the major term is undistributed in the premise but distributed in the conclusion, which is a different kind of distribution error. While serious, it is not the same problem as the middle term never being distributed.

Option C:
Option C, illicit minor, similarly involves the minor term being distributed in the conclusion without being distributed in the minor premise. Again, this concerns a different term than the one described in the stem.

Option D:
Option D, four terms, describes a fallacy where a syllogism effectively involves more than three distinct terms, often due to ambiguity. It does not depend on the distribution status of the middle term in the way indicated in the question.