Locke vs Modern Biological Classification

PHIL 2130

Essences = our ideas

Ordinary essences are merely sorts, our ordinary names for things:

‘The ranking of Things into Species, which is nothing but sorting them under several Titles, is done by us, according to the Ideas we have of them’ (III, vi, 13);

Take an individual human for example: There is nothing essential to an individual human That cannot be altered: Color, Shape can change;

memory loss, loss of locomotion can all result e.g. from illness.

What’s at stake in Naming in the 17th century?

Same names for different things (III, vi, 8): Locke cites example of Chemistry Different names for the same things: Example of Ice vs Water, liquid vs solid gold (III, vi, 13); A big issue in 17th century natural history: Many different names for the same organisms: birds,

plants (from 1,000 to 18,000 species between 1500 and 1700), animals.

Species not founded on essences

We would need to know if Nature has established regular ‘Models of all Things to be produced’;

Nature always attains that Essence Monsters (meaning?) are a distinct species Real Essence is knowable, which it is not (III,

vi, 15-20).

Does propagation prove species?

No Example of Hybrids Flowers (tulip at right) Mules (mating of Donkey

and Mare; see III, vi, 23)

Locke’s Influence on Taxonomy

Some claimed it was possible to create a system of classification that would reflect natural order;

Locke = a founder of a skeptical tradition in biological systematics (taxonomy) of the reality of taxonomical divisions, e.g. of an alleged ‘natural’ system of classification;

Also inspires programme of improving classification schemes, not on the basis of a purported natural classification, but rather on an orderly system of nomenclature, such that one name stands for one thing/group of things.

Why did Locke think Essences are unknowable?

His mechanistic philosophy, the ‘New Philosophy’ of the 17th century;

Matter has a substance and ‘constitutes everything in creation’ (Ayers 1981, 250).;

All matter is a continuum: ‘in all the corporeal World, we see no Chasms, or Gaps…the descent is by easy steps, and a continued series of Things, that in each remove, differ very little one from the other’ (III, vi, 12);

‘no need to postulate other universal natures’ (Ayers 1981, 250).

Locke’s Idea of Matter

There are just different configurations (shapes) of that matter, so that gold differs from a tree not in substance but in structure;

All matter is subject to laws of motion (same era as Newton)

Some philosophers like Descartes asserted they knew the structure of matter;

‘Locke believed that Boyle’s version of corpuscularianism–solid particles clashing in the void—was the best inadequate theory available and that the unknown truth must be something like it’ (Ayers 1981, 250)

‘A certain Chinese encyclopædia’

Borges quoted by Foucault, The Order of Things:‘…animals are divided into: (a) belonging to the Emperor,

(b) embalmed, (c) tame, (d) sucking pigs, (e) sirens, (f) fabulous, (g) stray dogs, (h) included in the present classification, (i) frenzied, (j) innumerable, (k) drawn with a very fine camelhair brush, (l) et cetera, (m) having just broken the water pitcher, (n) that from a long way off look like “flies”. In the wonderment of this taxonomy, the thing we apprehend…as the exotic charm of another system of thought, is the limitation of our own, the stark impossibility of thinking that’.

What is Borges’s/Foucault’s point?

There are many possible classifications of things: animals, library books, pens, etc.

They may differ culturally, as suggested by the descriptive phrase—’a chinese encyclopædia’

May be based on very different criteria of differentiation: are there any clear criteria of differentiation in the quote?

Is modern biological classification based on the species concept (Mayr) a special case?

Is it universally accepted and understood?

Essentialism/Typology

Aristotelian definition: essence (man=rational animal), definition, name (man)

explicitly informed biological classification up to the nineteenth century when Darwin and Mendel made their discoveries;

Hull (1992) argues Aristotelian definition still informs some taxonomists’ species definitions today.

Modern Typology

Three essentialist tenets of biological typology: -ontological assertion that forms exist; -methodological assertion that taxonomy

should discern the essences of species; -logical assertion concerning definition.According to Hull (1992), these all add up to

typology still being basically an Aristotelian exercise.

Aristotelian definition in modern terms

Properties severally necessary And jointly sufficient ‘For example, being a three-sided closed plane figure

is necessary and sufficient for a triangle.’ This was the only kind of species definition permitted

until recently by the international codes agreed by taxonomists;

Yet, ‘seldom is a property of any taxonomic value distributed both universally and exclusively among the members of a taxon [a biological grouping]’.

Eighteenth-century Taxonomy

Carolus Linnaeus of Sweden (1707-1778) reformed taxonomy, providing

Binomial nomenclature (2-word Latin name), and An artificial sexual system of classification (see next

slide) for plants, one of his major contributions; Based on morphological and reproductive

characteristics:– The number and position of stamens (male) and pistils (female),

the reproductive organs in flowers.

The goal for 18th c. naturalists, was a natural basis for classification that was not achievable at the time.

Linnaean Plant Taxonomy

Biological species concept

Darwin (evolution) and Mendel (genetics) formulated their theories in the mid-nineteenth century

This led to the development of the modern biological species concept described by Mayr:

Species consist of populations Have ‘reality’ and ‘an internal genetic program’ ‘The development of the biological concept of the species

is one of the earliest manifestations of the emancipation of biology from an inappropriate philosophy…’ (Mayr, 17).

Philosophical Holdovers

But, argues Hull (1992), a static species concept is still adhered to by many biologists;

Why? Even some evolutionary taxonomists (called ‘classificationists’)

prefer typology Because taxonomists’ job is easier if they call certain properties

or characteristics ‘essential’ and treat them as fixed in time and space;

Why easier? Evolutionary taxonomy entails making the unit of evolution the unit of classification (HINT: ‘evolution’ refers to change over time)

How is this done, according to Mayr?

Biological Species Concept

Members of species = reproductive community(Do you recall what Locke said about this? Example of the

mule; is Locke wrong?) An ecological unit, interacting as a unit w/ other species in

same environment, but protected from these other units by ‘isolating mechanisms’;

A genetic unit, comprising an intercommunicating gene pool of coadapted genes;

The evolutionary taxonomist seeks to assign populations to the correct rank or category in the taxonomic hierarchy, most difficult when populations exchange genes.

Taxonomic Hierarchy

Assignment of taxa

Higher taxa (phylum, genus, etc.) are defined by intrinsic characteristics (e.g bird = feathered vertebrate; any feathered vertebrate fits class of birds)

Species are unique in the hierarchy: they are defined by relational properties, i.e. interbreeding or lack of it;

See Mayr, p. 19 on species-specific bird songs as indications of relation.

Is this a universally applicable/acceptable concept?

Summary Table of Species Concepts

Essentialist Nominalist Biological

Forms/Ideas/ universals?

Yes No No or N/A

Why?

Cause of

Variation

Imperfect realization of

the idea

N/A Adaptation to Environment/Nat. Selec.

Role of Morphology

Very

Important

N/A Used w/ genetic info

Further reading:

D.L. Hull, ‘The Effect of Essentialism on Taxonomy: Two Thousand Years of Stasis’, in M. Ereshefsky, ed.,The Units of Evolution (1992), pp. 199-225 (book on reserve in Main Library).