Syllogism validity structural rules – UGC NET Question

A is correct as a valid categorical syllogism uses exactly three distinct terms: major, minor and middle. B is true because the middle term must be distributed at least once to connect the extremes properly. C is correct since two negative premises provide no positive linkage, and D is true because two particular premises cannot logically support a universal conclusion. E is false because these are necessary but not sufficient conditions; a syllogism can meet them yet still be invalid for other reasons. Hence A, B, C and D only are correct.

Option A:
Option A omits D and thus fails to mention the important constraint on drawing universal conclusions from particular premises. While A, B and C are true, the omission of D makes the set incomplete.

Option B:
Option B ignores A, so it does not mention the three-term requirement; although B, C and D are true, this omission leaves out a central structural rule for syllogisms.

Option C:
Option C drops B and therefore fails to highlight the distribution requirement of the middle term, which is crucial for testing validity. Even with A, C and D present, missing B leaves the account incomplete.

Option D:
Option D is correct because it collects all the true structural rules while excluding E, which overstates their sufficiency. This matches how NET questions test necessary conditions for syllogistic validity.