Someone writes:

TO List Supervisor, Prof. Volokh: Mendacious, Fabrication, Falsity, Untrue.
These words used by Mr. Lambert to describe Mr. Kates’s arguments. Is it
permissible to call a list member a liar if you use a thesaurus?

No. The only people you are allowed to call liars are those not in a
position to defend themselves (that is, those people who are not list
members).

I was
unaware of this list rule. It seems to me that anyway you say them, these
words still mean liar,

No. “mendacious” and “fabrication” are the only ones that imply
deceit. I only used the word “mendacious” in a hypothetical statement that
mirrored one made by Mr Kates. My intent was to argue that these
statements were just as incorrect as those made by Mr Kates. The form
of the argument was this:

Kates: Schetky is a liar because she did X.
Lambert: But you did X, too. Would it be correct to state “Kates is
liar because he did X.”? Surely not.

I suggested that the word “fabrication” might be the best description
of Mr Kates’ claim that handguns were involved in less than half of
criminal firearm injuries. This was because he admitted that the
claim was without foundation. Normally I would just state the facts
and let the reader decide for themselves the best description of Mr
Kates’ claim. However, since he insisted on what I consider an
incorrect usage of the word, I thought it best to counter with an
example of correct usage. I apologize for any distress this has
caused list members.

which, Mr. Kates is not.

I do not believe that any of Kates, Schetky, Smith, Falk and Sloan are
liars. I believe that all of these people were presenting what they
honestly believed to be true. Just because they may have been
mistaken in some of their beliefs it does not follow that they were lying.
I did not accuse any of these people of lying. I apologize to
any list members if my writing was unclear and they were inadvertently
given the impression that I was suggesting Mr Kates was lying