673 "Alla hästhuvuden är djurhuvuden" -
Låter sig den verkliga innebörden av denna sats riktigt beskrivas
predikatlogiskt genom:
* ""x ($y(H(y) Ù G(x,y)) ® $y( D(y) Ù
G(x,y))"
[där H = häst, G(x,y) = x är huvud till y, D = djur. Se: ABC i symbolisk logik
/ D. Prawitz, vol. 2, s. 191.]
Utsäger vi med * inte bara den samtidiga existensen av hästhuvuden och
djurhuvuden? Hur ser vi att det faktiskt rör sig om exakt samma huvuden?
674 In
his “Notes on Existence and Necessity” [reprinted in “Semantics and the
Philosophy of Language”, ed. L Linsky, University of Illinois Press, 1972]
Quine discusses contexts in which names are used “indesignatively”. He imagines
some of his readers to be willing to rewrite the sentence
(s) “Philip is unaware that Tully denounced Catiline.”
thus
(s*) “Philip is unaware of ‘Tully denounced Catiline’.”
in order to make the indesignative use of the name ‘Tully’ explicit. But, Quine
remarks, “it is unnecessary to insist that every indesignative occurrence of a
name form part of the name of an expression.” - Yes, but is it only a question
of necessity or non-necessity? Wouldn’t it be even wrong to replace (s) by
(s*)? Are (s) and (s*) really logically equivalent? Couldn’t we imagine some
case where Philips would be aware of the sentence ‘Tully denounced Catiline,’
without being aware of the fact that Tully denounced Catiline?
675 [Till
FK 1:674] “Any expression formed by single quotes is a name of the expression
within quotes.” [Quine, ibid.] - But then, why shouldn’t “'x' contains six letters” mean simply “The
name of x contains six letters”, which would make the sentence
(10) $x('x' contains six
letters)
a true statement; that is, if x is really taken as a variable sign for any
singular term.With this interpretation (10) could be written thus:
(10*) $x$y ( Name of(y, x,) Ù Six-lettered(y))
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