From R. Aaron Levine, Moral Issues of the Marketplace in Jewish Law, pp. 31-35:
Using Secondary Sources Without Attribution
I. Geneivat Da'at
The reasonableness criterion provides the starting point for analyzing the ethics of [Rabbi] Samson not disclosing to his audience that he made use of Berit Yehudah to prepare his lecture. Consider that thorough preparation combined with the knowledge of which sources to consult will assuredly generate goodwill for Samson for the lecture he delivers. There can be no doubt that this goodwill is his legitimate entitlement. Accordingly, if the audience generally presumes that Samson makes use of secondary sources and eclectic works to prepare his lecture, his failure to give attribution to Berit Yehudah does not project him as more scholarly and learned than he actually is. Does Halakhah give Samson a license to rely on his own intuition that this is in fact the case?...
What adverse consequences does Samson face in the event his assessment is wrong? Because punishing consequences do not follow on the heels of error, Samson’s intuition in the matter must be regarded as self-serving and hence unreliable.
Why is it wrong for Samson to rely on his intuition in this matter? The operative principle here is the mi’ut ha-matzui (small, but significant percentage) rule. This rule states that Halakhah concerns itself with a condition as prevailing even though it is not based on observed fact but, rather, only on a small, yet significant statistical probability...
The mi’ut ha-matzui rule tells us that there will certainly be some people in the audience who will gather an overly favorable impression of Samson’s scholarship on account of the rabbi’s failure to disclose that he used Berit Yehudah to prepare his lecture. Failure to make the disclosure hence puts Samson at risk of violating the geneivat da’at interdict. But, what of the principle, discussed earlier, that an individual is not responsible for disabusing others of a false impression when that impression is the product of self-deception? There must be a quantitive measure for mi’ut ha-matzui. If the percentage of people in the audience left with the misimpression falls below this threshold number, then, the judgment will be that these people were guilty of self-deception. If, on the other hand, the percentage of people left with the misimpression is higher than this benchmark, then Samson’s nondisclosure of his sources is not acceptable.
How is mi’ut ha-matzui translated into quantitative terms? Addressing himself to this issue, R. Jacob b. Aaron (Karlin, d. 1844) regards mi’ut ha-matzui as generally translating into a 10 percent benchmark. Disputing R. Jacob b. Aaron, R. Yosef Shalom Elyashiv (Israel, contemp.) feels that mi’ut ha-matzui translates into a 15–20 percent range...
Suppose that Samson conducts the necessary survey and the data confirm his intuition. What the outcome of the survey does is only to make Samson’s nondisclosure of Berit Yehudah free of a geneivat da’at violation. Not telling the audience of his debt to Berit Yehudah may, however, violate other ethical duties.
II. The Law of Attribution
One problem Samson’s nondisclosure entails is that his conduct falls short of the demands of the law of attribution. Repeating a saying in the name of the person who said it is counted by the Tanna in Avot as one of the 48 qualities necessary to acquire the Torah. The Tanna goes on to say: “Whoever repeats a thing in the name of the one who said it brings redemption to the world, as it is said: ‘And Esther said to the king in the name of Mordecai’ ’’(Avot 6:6). To be sure, Samson gives proper attribution to the originators of all of the concepts and rulings he mentions. But, he does not look up these sources in their original works, but instead relies on R. Bloi’s summaries [in Berit Yehudah] of these works. R. Bloi hence assumes the role of the first teacher in a chain of teachers. In this regard, the Talmud at Nazir 56b informs us that for a teaching reported in a chain of three or more teachers, we mention, in the attribution, the first and last conveyors of the law, but we need not mention the intermediate conveyors. Thus, R. Yehudah ha-Nassi presents in his Mishnah a teaching of R. Elazar in the name of R. Yehoshua b. Hananya; even though R. Elazar did not learn the dictum directly from R. Yehoshua b. Hananya, but instead only from R. Yehoshua b. Mamal, who, in turn, learned it from R. Yehoshua b. Hananya. Since R. Bloi is for Rabbi Samson the first teacher in a chain of teachers, the law of attribution requires Samson to mention R. Bloi.
A variation of this case occurs when Samson looks up all the sources R. Bloi quotes and studies them in the original. Because Samson is now in a position to directly report on what these authorities have to say, these authorities now become Samson’s first teachers in a chain of teachers and the role R. Bloi plays here is reduced to someone who made Samson aware of their teachings. In the latter scenario, the law of attribution does not require Samson to make mention of R. Bloi. Samson’s failure to acknowledge R. Bloi not only violates the law of attribution, but also bespeaks of ingratitude and disrespect for someone who has effectively become his teacher of Torah. We need only take note of the dictum of the Tanna in Avot (6:3): “He who learns from his fellow a single chapter, a single Halakhah, a single verse, a single Torah statement, or even a single letter, must treat him with honor . . .”
The upshot of the above analysis is that without a validating survey to confirm his intuition that the audience is well aware without being explicitly told that he uses secondary sources to prepare the lecture, Samson’s silence on the role Berit Yehudah played in preparing his lecture violates geneivat da’at law. Moreover, even if Samson has this validating survey in hand, not to acknowledge R. Bloi does injustice to the law of attribution and bespeaks of ingratitude and disrespect to someone who has effectively become his teacher of Torah. The extent to which Samson should acknowledge R. Bloi will depend on the degree to which Samson relied on Berit Yehudah in preparing his lecture. Greatest acknowledgment will be owed if Berit Yehudah both laid out his lecture for him and made him aware for the first time of the issues he spoke about.