Locke and Natural Kinds

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Locke and Natural Kinds

• PHIL 2130

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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).

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Examples of natural kinds
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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).

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More Natural Kinds
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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.

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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.

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Whats 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 Aristotles 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.

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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 dont).

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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.

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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 characteristicseating habits, mating, or
  geneticson this basis?

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Too many names

• Lockes 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).

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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 understoodthe sound I makeexcites in another
  Mans Mindthe Idea I apply it to in mine (III,
  iii, 3).

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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).

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Aristotelian Real Definition

• Genus
• Species
• Difference
• Properties

• Animal
• Man
• Rationality
• Laughter, Language, Hands

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Meanings of Essence

• the real internal, but generally in Substances,
  unknown Constitution of Things
• Essence has almost lost its primary
  signification and insteadhas been almost wholly
  applied to the artificial Constitution of Genus
  and Species
• there must be some real Constitution.
  ButThings are ranked under Names into sorts or
  Species, only as they agree to certain abstract
  Ideasthe Essence of each Genus, or Sort, comes
  to be nothing but that abstract Idea, which the
  Generalname stands for (III, iii, 15).

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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

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Nominal Essence

• Themore 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).

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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!