Hartley considered the passages in question to be the best possible expressions of the ideas they contain. Hartley could not have written the new book without the passages in question. A book on moral philosophy should contain only material representing the author's own convictions. Lawrence did not get the ideas in the passages in question or did not get their formulations originally from Hartley.
Professor Hartley' s new book on moral philosophy contains numerous passages that can be found verbatim in an earlier published work by Hartley' s colleague, Professor Lawrence. Ttherefore, in view of the fact that these passages were unattributed in Hartley' s book, Hartley has been dishonest in not acknowledging the intellectual debt owed to Lawrence.
Which one of the following is an assumption on which the argument is based?