Directions: Each question consists of five statements followed by options consisting of three statements put together in a specific order. Choose the option which indicates a valid argument, that is, where the third statement is a conclusion drawn from the preceding two statements.
Example:
A. All cigarettes are hazardous to health.
B. Brand X is a cigarette.
C. Brand X is hazardous to health.
Here, ABC is a valid option, where statement C can be concluded from statements A and B.
A. Some towns in India are polluted.
B. All polluted towns should be destroyed.
C. Town Meghana should be destroyed.
D. Town Meghana is polluted.
E. Some towns in India should be destroyed.
Answer: B
(b) BAE is the correct answer choice, as it forms a valid syllogism.
PT = Polluted towns
SBD = Things that should be destroyed
IT = Indian towns or towns in India.
The shaded portion are those IT which are polluted (PT) and hence should be destroyed (SBD).
The premises state that polluted towns should be destroyed and that some towns in India are polluted.
The ‘some’ in statement E refers to the polluted Indian towns that should be destroyed.
(a) BDE is invalid, because with B and D as premises, the only valid conclusion that follows is C. Town Meghana should be destroyed. ‘Town Meghana’ cannot be simply replaced by ‘Some town in India,’ as in E.
(c) ADE is invalid, because the syllogism has more than 3 terms. The term SBD does not appear in the premises A and D, but appears in the conclusion E as a new and fourth term.
(d) CDB is invalid, because we can’t talk of all PT in the conclusion B, when we only have information about Town Meghana in both the premises C and D. In deductive reasoning, we cannot proceed from specific cases to general cases. It would, however, be valid to conclude that ‘some polluted towns should be destroyed.’