Message-Id: <199509252028.QAA10482@locke.ccil.org>
Date:         Mon, 25 Sep 1995 12:10:40 -0700
Reply-To: "John E. Clifford" <pcliffje@CRL.COM>
Sender: Lojban list <LOJBAN@CUVMB.BITNET>
From: "John E. Clifford" <pcliffje@CRL.COM>
Subject:      Re: Mu
To: John Cowan <cowan@LOCKE.CCIL.ORG>
In-Reply-To:  <199509251505.AA06440@mail.crl.com>
Status: OR

On Mon, 25 Sep 1995, Don Wiggins wrote:

> Aha!  To disprove ".i piro loi pavyseljirna cu blanu", one must needs to
> come up with a counterexample - where is this unicorn which is not blue? ;-)
>
> There is an inherent problem with proving assertions (hypotheses?) of this
> nature.  The Medieval example was "All swans are white".  The scholar would
> 'prove' this by reasoning that since no one had ever seen a swan that was not
> white, it was true that all swans are white.  Many years pass.  Australia
> is discovered, along with the orange beaked, black swans native to that
> continent.  The counter-example annihilates the assertion.
>
> The presupposition that I imagine goes with _piro loi pavyseljirna_ is that
> there is at one least one unicorn.
>
> co'o mi'e dn.
>
I do not see why talk about the massification of the class of all unicorns
needs to presuppose that that set is non-empty.  Empty *classes* are just
the sort of thing you do find yourself talking about when you talk of
classes and, for various reasons, talking about masses seems to involve
talking about classes (even if this is not essential, the empty mass is
also not a problematic concept).  So, I do not see why _piro loi
pavyseljirna_ has a presupposition.  It certainly does not *assert* that
there is at least one unicorn, as the top-level use of _ro da poi
pavyseljirna_ does.  That the claim that this mass is blue is false was,
admittedly, a guess.  We seem to be unable to decide in many cases
whether claims about familiar inhabited masses are true, so we have very
little to go on to project to odd cases like te empty mass.  The guess
was based on the (known to be horribly defective) rule of thumb about
summing up the constituents, where the sum of zero constituents seems
likely to be zero (since sum here is just disjunction, that would be the
rule that says that an particular quantifier evaluated in the empty set
is false).  But NONE of this noncontroversial, indeed all has been
controverted on this thread.  Scratch my remark about whether the claim
is true then.  But it is still presuppositionless (well, free of the
presupposition about the existence of unicorns anyhow).