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است). منابع اصلی مربوط به این فصل اینها هستند:
1-
Naming and Necessity, Kripke, lecture 3;
2-
Meaning and Reference, Putnam.
قسمت اول: مقدمه
Saul Kripke’s arguments
against description theories of names inaugurated a revolution in the philosophy
of language. One of the first acts of that revolution was an application of
similar arguments against a similarly descriptive theory of another sort of
expression – so-called natural-kind terms. Kripke himself claimed that
natural-kind terms are rigid designators. In this, he was
supported by the semi-independent work of Hilary Putnam. Kripke and Putnam
together are acknowledged as the creators of a new theory of such terms.
Natural-kind terms differ from proper names in this: whereas
proper names pick out individuals, natural-kind terms pick out kinds. Favorite examples are ‘tiger’ and
‘water’.
What makes a kind natural?
There are two based conceptions of nature which seem to be at play in the focus
on natural-kind terms:
(SRN) A natural kind is a
kind about which some natural science is authoritative.
What is natural science?
We will have a list – physics, chemistry, biology – and we will have in mind
certain contrasts – with art and with human sciences.
The other conception of
nature is perhaps more fundamental:
(RKN) A natural kind is a
kind whose identity as a kind is fixed by reality, and not by human interests
or concerns.
Someone may concern, of
course, link the two conceptions. Indeed, it might be held that the distinctive
point and value of natural sciences is that they tell us how reality is in
itself. This kind of view is often known as naturalism, and sometimes as
scientific realism.
One way the issue of
natural-kind terms is important is that it connects philosophy of language with
metaphysics.
قسمت دوم: دیدگاهی لاکی دربابِ ترم‌های انواع
طبیعی
Locke: “The nominal
Essence of Gold is that complex Idea the word Gold stands for, let it be, for
instance, a body yellow, of a certain weight, malleable, fusible, and fixed.”
This remark and others in the surrounding text has suggested that Locke himself held a
counterpart – for the case of natural-kind terms – of the description theory of
names which Kripke is concerned to undermine in the earlier of Naming and
necessity. But we can reasonably describe the view Kripke and Putnam attack
as broadly Lockean.
We can state the core of
a Lockean theory of natural-kind terms, as follows:
(LK) The meaning of a natural-kind term is determined by what is believed
to be definitive of the kind in question.
And we can lay out the
commitments of such a theory, as follows:
(LK1) If ‘K’ is a
natural-kind term, there is a family of things associated with ‘K’, an
appropriate part of which is believed to be true of members of K and only
members of K;
(LK2) If ‘K’ is a
natural-kind term, then if an appropriate part of what is believed to be true
of members of K is, in fact, true of
something, then that thing is indeed a member of K;
(LK3) If ‘K’ is a
natural-kind term, then it is a priori that an appropriate part of what
is believed to be true of members of K is, in fact, true of
members of K;
(LK4) If ‘K’ is
meaningful natural-kind term, then it is necessary true that an appropriate
part of what is believed to be true of members of K is indeed true of members of
K.
Locke seems generally to
endorse an individualist conception of language: each person is the authority
over the use of her own terms; a word in one person’s mouth can signify only
that person’s conception of things. It is this individualist theory which is
the target of the most direct of Kripke’s and Putnam’s criticism.
Take (LK1) first. Putnam
says that he cannot tell the difference between elms and beeches, and indeed
claims that there is no difference between his concept of an elm and his
concept of a beech. So (LK1) looks false.
(LK2) is similarly
doubtful. Suppose that what I think is definitive of tigers is just that they
are large carnivorous quadrupeds of cat-like appearance, tawny yellow in color
with blackish transverse stripes and white belly. Kripke claims, plausibly,
that there could be something of just this appearance which was of a different
species, and did not count as a tiger. The crucial thing here is that the
conception of members of a natural kind which ordinary speakers possess seems to
relate principally to relatively superficial appearances. What Kripke’s point
suggests is that, intuitively, we do not regard such superficial appearance as
really determining what counts as a genuine member of a natural kind. Instead, the job is done by something which we
might hope that a biologist would know, but most of us are ignorant of.
This is one of the points
of Putnam’s ‘Twin-Earth’ example. Putnam imagines that there is another planet somewhere
else in the universe, which he calls Twin Earth. Twin Earth is qualitatively
indistinguishable from earth, at least in relatively superficial appearance:
that is to say, if you were instantaneously transport there, you wouldn’t
notice the difference. Despite all this superficial similarity, there is a fundamental
difference between Earth and Twin Earth: whereas the chemical composition of
the stuff in Earth rain, Earth rivers, Earth lakes, which we call ‘water’, is H2O,
the chemical composition of the similar stuff on Twin Earth, which the Twin-Earthians
call by similar-sounding name, is something quite different – XYZ, let’s say.
Putnam claims that the stuff on Twin Earth, despite being superficially
indistinguishable from water is not really water. What Putnam is claiming here
is that what counts as water is not determined by what ordinary speakers know.
It is the knowledge of the scientist which is decisive, not the concepts which
ordinary speakers have.
Take (LK3). Kripke shows
how we can raise doubt this by considering two kinds of possibility: the
possibility that we might have been subject to some kind of illusion when we
encountered those members of the kind on which our conception of the kind is
based; and the possibility that the members of the kind we have encounter were
in fact abnormal.
Now take (LK4). We might
identify water as the liquid which falls in rain, which flows in rivers, and
which fills lakes and seas. This might be how we fix the reference of the term
‘water’, but it is surely not necessary that water does this.
Kripke and Putnam
themselves seems to be more interested in a Lockean claim which looks almost
the converse of (LK4). We might formulate it like this:
(LK5) If ‘K’ is a
natural-kind term, then nothing is necessarily true of members of K as members
of K other than appropriate part of what is believed to be true of members of
K, or what follows logically from that.
This claim derives from a
general trend in empiricism. A crucial commitment of empiricism is the view
that we cannot have any real knowledge of the world beyond what we can gain
from experience. Within this basic philosophical approach, Hume made the
following claim: we cannot literally perceive that something is necessary.
If necessary derives from
our way of thinking about things, rather than from the things themselves, it
seems that what is necessarily true of a natural kind can only derive from the
way we think of the kind. Kripke and Putnam are concerned to deny (LK5) and the
associated conception of necessity as being derived from our way of thinking of
things. Consider the following pair of sentences, for example:
(1)
Gold is the element with atomic number 79;
(2)
Water is H2O.
They claim that
statements like these are necessary – at least if they are true at all.
Although they are necessary, (1) & (2) are a posteriori. In
insisting that (1) and (2) are necessary, Kripke and Putnam are attacking the
empiricist conception of necessity which led people to conflate the epistemic
and the metaphysical in first place.
Take (1) for example. It
seems that (1) can only be necessary if both of the following are true:
(1a)The predicate ‘x is
the element with atomic number 79’ applies to that stuff in all possible
worlds;
(1b)The term ‘gold’ picks out that stuff in
all possible worlds.
If (1) is true, then it
seems that (1a) must be true. But (1b) is just the claim that ‘gold’ is a rigid
designator. What this show is that the claim that (1) and (2) are necessarily
true, depends on the claim that ordinary natural-kind terms are rigid
designators.
قسمت سوم: چگونه ترم‌های انواع طبیعی می‌توانند
نشانگرهای صلب باشند؟
According to the
Kripke-Putnam view, natural-kind terms like ‘gold’, ‘water’, and ‘tiger’ are
rigid designators: they designate the same kinds in all possible worlds. They
seem to offer an account of their rigidity which is parallel to Kripke’s
picture of how proper names work.
In the case of gold,
Kripke imagines a ‘hypothetical’, though ‘admittedly somewhat artificial’
baptism, carried out by means of some such declaration as this: ‘Gold is the
substance instantiated by the items over there, or at any rate, by almost all
of them’. Putnam imagines that I give what amounts to an ‘ostensive definition’
of water as something like ‘the liquid which has such and such superficial
properties in the actual world’. Kripke’s ‘baptism’ and Putnam’s ‘definition’
look just like the different ways in which Kripke imagined the reference of a
proper name might be fixed.
This might then be
thought to suggest that the later uses of natural-kind terms designate the
relevant kinds in virtue of being historically connected to the first,
introductory uses. That might suggest that natural-kind terms, like proper
names, are directly referential. And it might then seem that this
non-descriptive directness is what explains the rigidity of natural-kind terms,
just as it seems to in the case of proper names.
منابع بیشتر
1-
The meaning of ‘meaning’, H. Putnam;
2-
Natural Kinds, D. H. Mellor,
3-
Putnam’s Theory on the Reference of Substance Terms, E. Zemach;
4-
Natural Kind Terms and Recognitional capacities, J. Brown;
5-
Natural Kind Terms: A Neo-Lockean Theory, A. D. Smith;
6-
Beyond Rigidity, S. Soames.
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