It is illogical to infer a second and different effect from a cause which is known only by one particular effect. This is incorrect because the inferred effect must necessarily be produced by some different characteristic of the cause than is the observed effect, which already serves entirely to describe the cause.
Which one of the following arguments makes the same logical error as the one described by the author in the passage?
(A) An anonymous donor gave a thousand dollars to our historical society. I would guess that that individual also volunteers at the children’s hospital.
(B) The radioactive material caused a genetic mutation, which, in turn, caused the birth defect. Therefore, the radioactive material caused the birth defect.
(C) The tiny, unseen atom is the source of immense power. It must be its highly complex structure that produces this power.
(D) The city orchestra received more funds from the local government this year than ever before. Clearly this administration is more civic-minded than previous ones.
(E) If I heat water, which is a liquid, it evaporates. If I heat hundreds of other liquids like water, they evaporate. Therefore, if I heat any liquid like water, it will evaporate.


Sven: Trade unions are traditionally regarded by governments and economists as restraints of trade, working against the complete freedom of the economy, but I believe that unions are indispensable since they are often the worker’s only protection against exploitation.
Ravi: I don’t agree. The exploitation of the workers and their work is a normal part of ordinary trade just like the exploitation of natural or other material resources.
Sven and Ravi will not be able to resolve their disagreement logically unless they
(A) define a key term
(B) rely on the opinions of established authorities
(C) question an unproved premise
(D) present supporting data
(E) distinguish fact from opinion