Lapident, argumentum ad 103
Reason is no guide; you must open your heart... and you will know.
(This is not terribly useful to outsiders looking for the truth of a thing,
comforting though it may be to those who know.)This fallacy occurs in a university setting far more than one might
suppose. It is often argued quite seriously in quasi-academic
circles that certain books should not be allowed on campus
because they propagate error. Speakers are quite frequently
shouted down because their audience know they are speaking
falsehoods, and do not need to hear the argument. Some stu-
dent unions actually make a policy of the ad lapidem, refusing to
allow a platform on campus for known error - a category which
can even include members of the elected government of the
country.
A charming version of the fallacy emerged from the pen of
Herbert Marcuse. Now forgotten, although he was a high priest
of student radicals in the 1960s, his Critique of Pure Tolerance
made the interesting point that tolerance can be repressive
because it permits the propagation of error. How could we
recognize error in order to stop it? Easy. Guess who was going to
tell us.
When you yourself employ the ad lapidem, you must do so
with a total assurance which suggests that the person who raised
the offending fact or argument is totally beyond the pale. Like
the judge who once convicted a jury for 'going against plain
evidence', you should make it clear that he is going against all
reason. Your opponent, by going beyond every received opinion
and every canon of decency, has rendered his opinion totally
unworthy of discussion.
Liberty of expression is one thing; but this is licence!
('Licence' means liberty you don't approve of.)