Re: Do we need "Mission-Critical" software? Was: What to Do?

[Keith Thompson <kst@cts.com>]

Robert Dewar <robert_dewar@my-deja.com> writes:
> In article <93bv37$43b$1@nnrp1.deja.com>,
>   n_brunot@my-deja.com wrote:
[...]
> > And as usual, exceptions confirm the rule :-)
> > The percentage of companies non using Ada is high enough just
> > to make obvious the generalization.
> 
> Your generalization was about Ada programs as I read it, so I
> do not understand that (by the way, you have garbled the idiom
> here, it is "exceptions prove the rule", and the word prove
> here means "test" not "proof" as in mathematics. In other
> words, this idiom means that you test rules by looking for
> counterexamples -- well I will have to file this along with
> other entertaining "round-trip idioms" -- my favorite was
> someone from France announcing that a particular task was
> easy --- "a slice of pie" -- from that day on in Alsys, all
> sorts of simple tasks were referred to as a "slice of pie" :-)

Actually, that's not what the idiom means, or at least not what it
originally meant.  The origin of "The exception proves the rule" is an
old legal principle, "Exceptio figit regulam in non exceptis".  An
(explicitly stated) exception proves the *existence* of the rule, not
its general truth.

See <http://www.alt-usage-english.org/excerpts/fxtheexc.html> for more
details.  Here's an excerpt:

    As MEU says, "the original legal sense" of the "the exception
    proves the rule" is as follows: "'Special leave is given for men
    to be out of barracks tonight till 11.0 p.m.'; 'The exception
    proves the rule' means that this special leave implies a rule
    requiring men, except when an exception is made, to be in earlier.
    The value of this in interpreting statutes is plain."

-- 
Keith Thompson (The_Other_Keith) kst@cts.com  <http://www.ghoti.net/~kst>
San Diego Supercomputer Center           <*>  <http://www.sdsc.edu/~kst>
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