|
INTRODUCTION
The aim of the present inquiry is not to
wash necessity of all controversy; rather,
it is to save it from a particular criticism
headed by Quine (1953). Saving necessity,
thus, lends confirmation, not affirmation.
Quine's complaint over necessity is that
the terms (or contexts) in which the putative
concept occurs are nonextensional and cannot, therefore, be appended to quantifier
logic. Assuredly, if necessity-contexts were
nonextensional, this would be a major blow
to the logic of necessity-terms (so-called
modal logic); for without the auxiliary resources of
quantification theory (including identity),
putatively permissible sentences, for instance,
'(x)(it is possible that x is a person -> it is possible that x is rational)', would not be well-formed
formulae in virtue of the fact that quantification
rules could not be applied to them. Perhaps
this latter charge indisputable or, at any
rate, plausible. The issue I wish to raise,
however, regards to the former objection
that necessity-contexts are nonextensional.
In particular, I wish to show that Quine's
grounds for this charge are unsound.
QUINE'S ARGUMENT FOR NECESSITY-CONTEXTS'
NONEXTENSIONALITY
The underlying principle for extensionality
of a context is the following:
(E) A context is extensional if and only if two identical terms (each of which transform the context
into a complete, declarative sentence S) can be substituted for each other without
changing the truth-value of S.
When a context fails to satisfy (E), it is
said to be referentially opaque. When a context, on the other hand, satisfies
(E), it is said to be purely referential (or referentially transparent). Quine introduces
(E) in order to account for failure of Leibniz's
law in certain contexts such as 'has eight
letters,' 'is so-called because,' 'believes
that,' 'sees that,' etc. Leibniz's law, in
its most unsophisticated form, states that
if a predicate is true of an object a, then whatever that object is identical
to, say, b, the predicate is also true of b.[1]
(LL) Fa
a = b
Thus, Fb
There are contexts (or predicates), however,
that, when conjoined with a name for an object
such that the atomic sentence is true, and
further conjoined with a true identity statement
of the name of the object, the resulting
sentence, given (LL), is false. Thus, (LL)
would appear to be an invalid rule of inference.
(E) is meant to sharpen (LL) in order to
preserve it against its putative counterexamples.
Take, for instance, the true statement
-
Weezer is so-called because of his asthma
condition.
Conjoined with the following true identity
statement:
-
Weezer = Rivers Cuomo,
the following false statement follows in
virtue of (LL):
-
Rivers Cuomo is so-called because of his
asthma condition.
Quine's response to such a failure of (LL)
regarding the two terms 'Weezer' and 'Rivers
Cuomo':
"[R]eveals merely that the occurrence
to be supplanted is not purely referential, that is, that the statement depends not
only on the object but on the form of the
name. For it is clear that whatever can be
affirmed about the object remains true when
we refer to the object by any other name"
(1953).
In other words, (1) is indeed true, but it
also depends on the form of the name, not
merely on the object in question which is
referred to by its name. The name 'Weezer'
was so chosen specifically because of a happenstance
linguistic feature of the object in question,
as (1) says; this gives us information not
only about the object, but the object's name as well. In such cases, (LL) is inapplicable.
In fact, not only (LL), but other logical
rules (or sets thereof) such as quantification
theory are equally inapplicable. The blameworthy
component is the context, not (LL) or quantification
theory. For these rules are to be applied
only to statements that ascribe properties
to their objects, not their names as well.
Having shown where (E) succeeds in cases
that we are fairly content with agreeing
with the results, Quine moves on to a more
controversial issue: necessity-contexts.
Consider the putatively true statement (in
modal logic):
-
9 is necessarily greater than 7.
When conjoined with the following true identity
statement:
-
The number of planets = 9,
The following statement follows:
-
The number of planets is necessarily greater
than 7,
an outright falsity (in modal logic).[2]
Following (E), Quine concludes that necessity-contexts
are nonextensional, just as the context 'is
so-called because' is.
THE PROBLEM WITH QUINE'S CRITERION OF EXTENSIONALITY
As suggested in the second footnote of this
essay, one could argue with Quine that (6)
is true insofar as what we mean by 'the number
of planets' is just '9', and nothing more.
Quine objects to equating meaning with extension
(1951), however; but it nonetheless would
satisfy Quine's skepticism over abstract
entities meant to serve as 'meanings' of
terms, above-and-beyond their extensions.
Instead of taking such a route, I will instead
pursue an objection to (E), Quine's criterion
that, when conjoined with (4)?(6), implies
necessity-contexts are nonextensional (and
thus, unable to be appended to other logics,
including quantification theory). To show
this, it is only required that one context
independently established as extensional,
in conjunction with a true identity statement
(indeed, one that Quine explicitly uses to
show the nonextensionality of necessity-contexts),
implies a false (or meaningless) conclusion.
The counterexample to (E) that I wish to
focus on begins with the following sentence,
involving a purely referential context:
-
It is true that there are nine planets.
Indeed, such a context in (7) is purely referential.
(7) does not depend on the forms of its names
for its objects; it depends on the fact of
there being a number of planets equal to
nine?not on the special linguistic fashion
by which the objects in question are referred
to. As conspicuous as this seems, (7), conjoined
with (LL), and the true identity statement,
(5), 'the number of planets = 9', entails
the following statement:
-
It is true that there are the number of planets
planets,
which is worse off than being false: it is
meaningless. Such a sentence as (8) is as grammatically
perverse as is the sentence "There are
dogs dogs".
The problem that this counterexample unearths
is the following dilemma: either (i) (E)
is inadequate, in which case Quine's argument
against necessity isn't sound; or (ii) (5)
is false, in which case, Quine's argument
against necessity-contexts isn't sound. Therefore,
the counterexample destroys Quine's argument
against necessity-contexts, so long as it
is affirmed that (7) is a true sentence that
is formed out of replacing names for schemata
in a purely referential context, and (8)
is meaningless. Confessedly, however, this
dilemma is deceptive. It is surely less costly
for Quine to deny the truth of (5) than it
is for him to deal with (E) being an inadequate
criterion of extensionality. This is due
to the fact that Quine has other arguments
against necessity-contexts that involve true
identity statements, e.g. 'Morning Star =
Evening Star', that do not seem to lead to
the same type of counterexamples as above.
Quine can merely drop his planets-argument
and settle for others. But, this, I fear,
lets Quine off too easily. It is still unexplained
why (5) and (7) lead to a meaningless conclusion,
when (7) appears referentially transparent
and (5) appears to be true. Quineans skeptical
of necessity need to explain why at least
one of these appearances are delusive, thus,
preventing (LL) to successfully apply to
them.
NOTES:
[1] Here, we can treat "predicate"
and "context" as the same. Both
predicates and contexts do not express complete
sentences, but do so when the schemata or
variables are substituted for objects. To
avoid confusion, however, (LL) is given in
terms of predicates, as it usually is, and
not of contexts, though doing otherwise would
not commit anyone to any serious logical
error.
[2] Note, however, that (6) is only false
insofar as 'the number of planets' means
something over-and-above its extension. That
is to say, if a modal logician ascribes to
a theory of meaning that equates the meaning
of a term and its referent (or its extension),
then (6) is true since both 'the number of
planets' and '9' refer to the same abstract
mathematical object. If it be objected that
it is possible (to the modal logician) that
'the number of planets = 7', then this only
implies that 'the number of planets' can
have variant meanings in response to observed
data (outside the scope of mere behavioral
data of language users). Such a logician
would say that (6) is true insofar as what
is meant by 'the number of planets' is also
what is meant by '9'; if the 'the number
of planets' becomes '7', then we say 'the
number of planets' has changed its meaning,
and thus, as expected, the truth-value of
(6); something no logician would object to,
viz. changing the meaning of a term in a context
makes it vulnerable to truth-value change.
REFERENCES:
Carnap, Rudolf. Introduction to Semantics and Formalization
of Logic: Two Volumes in One.
1942. N.p.: Harvard University Press, 1943.
Quine, Willard Van Orman. "Two Dogmas
of Empiricism." The Philosophical Review 60
(1951): 20-43. Rpt. In From a Logical Point of View. 2nd ed. Cambridge: Harvard University Press,
1980.
---. "Reference and Modality".
1953. In From a Logical Point of View. 2nd ed. Cambridge:
Harvard University Press, 1980.
|