LANGUAGE LAWS

Tom Wier suggested that conlangs are "subject to the same laws that have
governed language since the dawn of time," and I suggested that "even
computer programming languages" are subject to those same laws.  The
purpose of this thread is to discuss what those "laws" might be.  In
other words, we're looking for "laws" that apply equally to all sorts of
languages (natural languages, constructed languages, computer
languages).

To get this discussion started, I'll propose one such law.  We can call
it "Tommie's Law".  Here it is: "What is permitted depends on what is
required."

Partly, that means that presenting certain types of information is
always a prerequisite for presenting certain other types of
information.  But that also means that a language won't let you present
any information at all -- it won't even let you present the types of
information that are a prerequisite for presenting the other types of
information -- unless you let the language specify what sorts of
information shall be required in any particular type of expression.

In other words, an expression (a sentence, phrase, compound sentence, or
whatever) must contain some information about its own nature (which
indicates what sorts of information the expression must contain), plus
it must contain all the sorts of information which its own nature
requires it to contain; and then it must permit the option of containing
certain other sorts of information that those sorts of information are
prerequisites for.

-- Tommie