Howard Wainer points me to a thoughtful discussion by Moti Nissani on “Psychological, Historical, and Ethical Reflections on the Mendelian Paradox.”
The paradox, as Nissani defines it, is that Mendel’s data seem in many cases too good to be true, yet Mendel had a reputation for probity and it seems doubtful that he had a Mark-Hauser-style attitude toward reporting scientific data. Nissani writes:
Taken together, the situation seems paradoxical. On the one hand, we have evidence that “the data of most, if not all, of the experiments have been falsified so as to agree closely with Mendel’s expectations.” We also have good reasons to believe that Mendel encountered linkage but failed to report it and that he may have taken the somewhat unusual step of having his scientific records destroyed shortly after his death. On the other hand, everything else we know about him/in addition to his undisputed genius/suggests a man of unimpeachable integrity, fine observational powers, and a passion for science. In other words, Mendel was as unlikely a candidate for scientific misconduct as can be imagined.
Nissani suggests that Mendel may have known what he was doing and deliberately falsified some data to make his story more compelling:
He [Mendel] was most anxious to have his results replicated and expanded, for even self-possessed people (and he wasn’t) entertain occasional misgivings about the accuracy, originality, and significance of their work.
To achieve these goals, his work had to be understood. In comparison to his theories, of whose validity he was sure, the data were of no significance whatsoever. His task was not the one faced by the normal scientist addressing a sympathetic and competent audience, but that of a revolutionary who must break through the cognitive paradigms and social prejudices of his audience. If this larger goal could be best achieved by simplification/deliberately omitting some observations from his report and adjusting others to make them more palatable to his audience/could not such a step be justified on moral grounds?