The delegitimization of opposing views

R' J.J. Shachter has an article about history which illustrates how the Charedi world delegitimizes any viewpoint that it doesn't currently agree with. The quotes below are taken from R' J.J. Schachter's article Facing the Truths of History

"In its 24 Teves 5754 issue, the English edition of the Yated Ne’eman
published a brief biography of Rabbi Eliyahu Eliezer Dessler by one
of his most devoted disciples
...
During his childhood years, Rabbi Dessler
was taught at home and, wrote the author of this article, “true to the
principles of his rebbe, R’ Simcha Zissel, the boy’s father included
general studies in the curriculum. Among these were some classics of
world literature in Russian translation. One of them (so Rabbi Dessler
told me) was Uncle Tom’s Cabin. The reason for this choice is not far
to seek.”
...
Three weeks later, in its 16 Shvat 5754 issue, the Yated pub-
lished a letter to the editor which was extremely critical of that newspaper’s
decision to publish this information. Expressing his “amazement
and outrage,” the correspondent noted the enormous responsibility
which rests upon the editorial staff of the Yated to “maintain
a constant vigilance over every sentence and phrase that it publishes,
in order to ensure that emunah, Torah and yiras Shomayim
shall be strengthened by that phrase.” Since, he continued, “you will
surely admit that the references to ‘some classics of world literature in
Russian translation,’ etc. ‘including Uncle Tom’s Cabin,’ will not
strengthen emunah, Torah and yiras Shomayim in any one of your
readers,” a grievous error was committed by their having been published."
Then, in conclusion, the author of the letter wrote: “One of the
great features which distinguish the world of Bnei Torah from the
other sections of Orthodox Jewry, is the readiness on our part to be
‘modeh al ha’emess,’ to admit to the truth when we have made an
error, because ‘emess’—the truth, the seal of the Almighty—is our
greatest pride and possession. It should, therefore, be admitted, without
hesitation, that the publication of the aforementioned chapter was
an error, and special care should be taken to insure that such errors
shall not be repeated in the future.”2 In this final argument, the author
of this letter invoked truth as requiring the editors of the Yated to
honestly acknowledge that they had made a mistake."

R' J.J. Schacter then makes the following comment which I believe is right on and is at the heart of the Slifkin controversy as well. Suddenly we are now deciding that the Gedolim of yesteryear's opinions cannot be accepted. Their opinions have suddenly become delegitimized.

"What is problematic here, however, is that it was not R. Reuven
Dov himself, and certainly not “little Elia Laizer,” who decided that
the young boy should study “classics of world literature in Russian
translation.” Rather, by exposing his son to “general studies,” writes
the author of the article, R. Reuven Dov was simply being “true to
the principles of his rebbe, R. Simcha Zissel.” R. Simh. ah Zissel is the
one who wanted him to engage in these studies. Surely this great
gadol and talmid of R. Yisrael Salanter would never have done anything
other than to strengthen “emunah, Torah and yiras Shomayim”
in young yeshiva boys, and yet he obviously felt that such studies
were appropriate. On what authority, then, does the author of this
letter disagree with R. Simh. ah Zissel and maintain that such studies
indeed “will not strengthen emunah, Torah and yiras Shomayim?” It
would have been more appropriate for the author of the letter to
have acknowledged that while R. Simh. ah Zissel had one opinion,
times have changed and, therefore, “you will surely admit that the
references to ‘some classics of world literature . . .’ will no longer
strengthen emunah, Torah and yiras Shomayim. . . .”

This is what happened in the Slifkin affair as well. R' Slifkin did not make any thing up, he has many sources for the approach he takes. Suddenly, his sources are no longer legitimate because they contradict the in vogue thinking.