Historian: Leibniz, the seventeenth century philosopher, published his

OFFICIAL EXPLANATION

The conclusion of the argument asserts that Leibniz and Newton each independently discovered calculus, and in drawing the conclusion the author addresses the possibility Newton may have influenced Leibniz, and then rejects that possibility. A review of the argument does not reveal any conspicuous flaws, and so upon encountering the question stem, you should expect to see a Defender answer. As such, do not spend time trying to prephrase and answer - just make sure you know the facts of the argument.

Answer Choice (A): The argument is about the independent discovery of calculus; the author makes no assumption that Leibniz did not tell anyone else, and indeed the fact that Newton did tell Leibniz is not accepted by the author as undermining the conclusion.

Answer Choice (B): Negate the answer: "A third person independently discovered calculus prior to Newton and Leibniz." Would this negated answer attack the argument? No, the author would just assert that three different parties independently discovered calculus.

Answer Choice (C): The author cites Newton's letter as evidence that Newton felt he had disclosed ideas to Leibniz prior to Leibniz's publication date. No assumption is made that Newton felt that what was disclosed allowed Leibniz to learn something important. If you are uncertain of this answer, negate the choice to see if it weakens the argument.

Answer Choice (D): This is clearly not an assumption of the argument because the author discusses Newton's letter to Leibniz prior to Leibniz's publication date.

Answer Choice (E): This is the correct answer. The answer can be difficult because it is somewhat similar to answer choice (B), which many people already eliminated by the time they reached this answer. Answer (E) is different from answer (B) because it involves learning details from a third source. This is important because the conclusion references the independent discovery of calculus, and so the author must believe that neither Newton nor Leibniz learned anything substantial about calculus from other sources.