Transcript Locke and Natural Kinds - University of Hong Kong

Locke and Natural Kinds
PHIL 2130
What is a ‘natural kind’?





A natural kind has a real existence
independent of human cognition;
And is not simply an arbitrary category;
A natural kind ‘is determined by the
presence of a presumed underlying
common nature’;
Which may be unknown to us;
Natural kinds have been theorized in the
20th century by Putnam (1975) and
Kripke (1972).
Examples of ‘natural kinds’:
Why are they different?





They obviously look different, but what
factors are you going to say make them
essentially different?
morphological (form),
phylogenetic (race history) or
reproductive factors?
There are lively debates in biology and
philosophy about what factors determine
membership of a kind (species or genus).
More Natural Kinds
Periodic Table





The atomic number of a given element is
taken to be (at least) one good possibility
for the real essence of an element;
Can you think of any other possibilities?
What is real essence?
Real essence is the underlying
characteristic that defines a natural kind,
as contrasted with nominal essences that
are superficial, possibly even irrelevant;
Essentialism is the philosophical position
that holds that kinds have essences.
How can natural kinds be
unknown to us?



We may recognize the external
appearance of a thing or substance and
assume it belongs to a particular kind;
But we may be mistaken, as Putnam
argues in his water on Mars example;
There could be a substance on Mars that
appears in every respect to resemble
water, but for one very important reason
does not: it does not possess the
underlying chemical structure H2O.
What’s at stake?
Philosophers since Aristotle (384-322 BCE)
have studied the relation between words
and things;
 Aristotle developed an elaborate account
of the categories of being, definition and
predication;
 Locke continues this analysis, but rejects
many of Aristotle’s ideas, e.g. rules of
definition (III, iii, ¶ 10, 15);
 The ultimate goal for many students of
this problem, including Locke (the
scientist), is a classification of nature.
What is classification?





Classification organizes things, substances or
anything else you can think of into categories
According to some criterion (sing.) or criteria
(pl.)
So you may classify your stationary kit by
separating pens by color, pencils by presence
/absence of erasers, etc.
Try this and see how many different categories
of classification you can develop for the same
set of items! This will give you an idea of what a
complex task it is;
Biologists may categorize by presence/absence
of a particular gene, a particular external feature
(sheep have curly wool, while horses don’t).
Why is classification
important?





Classification enables us to organize our
knowledge about the world;
How? By creating groups of things to
which we can assign names;
Why are names important?
Because they enable us not only to retain
the category in our minds,
But also to communicate with others
about things in the world.
Imagine a different world
Where there are names only of
particular things: this horse, that
sheep, but not horse in general or
sheep in general;
 So each sheep and horse would
need its own particular name; how
could we study sheep or horse
characteristics—eating habits,
mating, or genetics—on this basis?

Too many names
Locke’s answers:
“it is beyond the Power of humane Capacity
to frame and retain distinct Ideas of all
the particular Things we meet with: every
Bird, and Beast Men saw; every Tree, and
Plant, that affected the Senses, could not
find a place in even the most capacious
[large] Understanding” (III, iii, ¶2).

Particular Names not useful

“If it were possible, it would yet be
useless; because it would not serve to the
chief end of Language. Men would in vain
heap up Names of particular Things, that
would not serve them to communicate
their Thoughts. Men learn Names, and
use them in Talk with others, only that
they may be understood…the sound I
make…excites in another Man’s Mind…the
Idea I apply it to in mine” (III, iii, ¶3).
Knowledge is founded
on Generalities

“…a distinct Name for every particular
Thing, would not be of any great use for
the improvement of Knowledge: which
though founded in particular Things,
enlarges it self by general Views; to
which, Things reduced into sorts
[categories] under general Names, are
properly subservient [subordinate]”
(III, iii, ¶4).
Aristotelian ‘Real Definition’




Genus
Species
Difference
Properties




Animal
Man
Rationality
Laughter,
Language, Hands
Meanings of ‘Essence’



the real internal, but generally in Substances,
unknown Constitution of Things’;
‘Essence has almost lost its primary
signification; and instead…has been almost
wholly applied to the artificial Constitution of
Genus and Species’;
‘there must be some real Constitution….
But…Things are ranked under Names into sorts
or Species, only as they agree to certain abstract
Ideas…the Essence of each Genus, or Sort,
comes to be nothing but that abstract Idea,
which the General…name stands for’ (III, iii, 15).
Real vs Nominal Essence




Locke rejects Aristotelian definition of
species by genus and difference; uses the
term ‘Sorts’ instead (III, vi, 1);
The real essence of a chemical or kind of
animal is not known (III, iii, 15).
So how are we going to sort things into
kinds so that we may speak about them
with mutual comprehension?
A name for a kind must excite in the Mind
of the hearer the same Idea as it does in
the mind of the speaker;
Nominal Essence



‘The…more rational Opinion, is of those,
who look on all natural things to have a
real, but unknown Constitution of their
insensible Parts, from which flow those
sensible Qualities, which serve us to
distinguish them from one another’
(emph. added; III, iii, 15);
Monsters (e.g. hermaphrodites) =
refutation of Forms of nature;
‘The doctrine of the Immutability of
Essences, proves them to be only
abstract Ideas’ (III, iii, 19; cf. Plato).
To be continued…





Is Locke an essentialist?
See Essay, Book III, chs. 3 and 6.
Note that when Locke refers to ‘the
Schools’ he is referring to the Aristotelian
logic and philosophy of language taught
in the medieval and early-modern
European universities.
Further reading: Ernst Mayr, “Species
Concepts and Their Application” (Dept.).
Try a classification exercise!