Bunuel
One approach to the question of which objects discussed by a science are real is to designate as real all and only those entities posited by the most explanatory powerful theory of the science. But since most scientific theories contain entities posited solely on theoretical grounds, this approach is flawed.
Which one of the following principles, if valid, most helps to justify the reasoning above?
(A) Any object that is posited by a scientific theory and that enhances the explanatory power of that theory should be designated as real.
(B) Objects posited for theoretical reasons only should never be designated as real.
(C) A scientific theory should not posit any entity that does no enhance the explanatory power of the theory.
(D) A scientific theory should sometimes posit entities on grounds other than theoretical ones.
(E) Only objects posited by explanatory powerful theories should be designated as real.
(A) Any object that is posited by a scientific theory and that enhances the explanatory power of that theory should be designated as real. - Mistaken reversal. Stem says
designate as real all and only those entities posited by the most explanatory powerful theory of the science. Option says object that is posited by a scientific theory and that enhances the explanatory power of that theory should be designated as real. You see the roles are reversed?
(B) Objects posited for theoretical reasons only should never be designated as real. - Correct [This can be properly inferred from the passage]
(C) A scientific theory should not posit any entity that does no enhance the explanatory power of the theory. - Passage does not talk about an entity enhancing the explanatory power of the theory.
Passage says designate as real all and only those entities posited by the most explanatory powerful theory of the science. This again is a case of reversal.
(D) A scientific theory should sometimes posit entities on grounds other than theoretical ones. - This gives alternative recommendation.
(E) Only objects posited by explanatorily powerful theories should be designated as real. - Trap answer. Powerful theories of what? Powerful theories of science would make this option correct.