In philosophy

Philosophy

Philosophy is the study of general and fundamental problems, such as those connected with existence, knowledge, values, reason, mind, and language. Philosophy is distinguished from other ways of addressing such problems by its critical, generally systematic approach and its reliance on rational...

, a natural kind is a "natural" grouping, not an artificial one. Or, it is something that a set of things (objects, events, beings) has in common which distinguishes it from other things as a real set rather than as a group of things arbitrarily lumped together by a person or group of people.

If any natural kinds exist at all, good candidates might include each of the chemical element

Chemical element

A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. Familiar examples of elements include carbon, oxygen, aluminum, iron, copper, gold, mercury, and lead.As of November 2011, 118 elements...

s, like gold

Gold

Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...

 or potassium

Potassium

Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...

. Physical particles, like quark

Quark

A quark is an elementary particle and a fundamental constituent of matter. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei. Due to a phenomenon known as color confinement, quarks are never directly...

s, might also be natural kinds. That is, they would still be groups of things, distinct from other things as a group, even if there were no people around to say that they were members of the same group. The set of objects that weigh more than 50 pounds, on the other hand, almost certainly does not comprise a natural kind. A person might group those objects together for some purpose like shipping costs, but there is no particular reason that any other person should lump those objects together instead of placing them in some other grouping.

There is considerable debate in philosophy about whether there are any natural kinds at all, and if so, what they are. Philosophers of biology

Philosophy of biology

The philosophy of biology is a subfield of philosophy of science, which deals with epistemological, metaphysical, and ethical issues in the biological and biomedical sciences...

 argue about whether biological species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

, like the Bald Eagle

Bald Eagle

The Bald Eagle is a bird of prey found in North America. It is the national bird and symbol of the United States of America. This sea eagle has two known sub-species and forms a species pair with the White-tailed Eagle...

 (Haliaeetus leucocephalus), are natural kinds. Others debate whether races, sexes, or sexual orientations are natural kinds. Meteorologists

Meteorology

Meteorology is the interdisciplinary scientific study of the atmosphere. Studies in the field stretch back millennia, though significant progress in meteorology did not occur until the 18th century. The 19th century saw breakthroughs occur after observing networks developed across several countries...

 classify a number of different kinds of clouds, but it is not clear whether they are really different kinds, or whether those groups merely reflect the classifying interests of human beings.

A more formal definition has it that a natural kind is a family of "entities possessing properties bound by natural law

Natural law

Natural law, or the law of nature , is any system of law which is purportedly determined by nature, and thus universal. Classically, natural law refers to the use of reason to analyze human nature and deduce binding rules of moral behavior. Natural law is contrasted with the positive law Natural...

; we know of natural kinds in the form of categories of minerals, plants, or animals, and we know that different human cultures classify natural realities that surround them in a completely analogous fashion" (Molino 2000, p.168). The term was brought into contemporary philosophy by W. V. Quine in his essay "Natural Kinds", where any set of objects forms a kind only if (and perhaps if) it is "projectable", meaning judgments made about some members of that set can plausibly be extended by scientific induction

Inductive reasoning

Inductive reasoning, also known as induction or inductive logic, is a kind of reasoning that constructs or evaluates propositions that are abstractions of observations. It is commonly construed as a form of reasoning that makes generalizations based on individual instances...

 to other members. Hence "raven

Raven

Raven is the common name given to several larger-bodied members of the genus Corvus—but in Europe and North America the Common Raven is normally implied...

" and "black

Black

Black is the color of objects that do not emit or reflect light in any part of the visible spectrum; they absorb all such frequencies of light...

" are natural kind terms, because any black raven constitutes at least some evidence that all ravens are black. But "nonblack" and "nonraven" are not, because a nonblack nonraven (say, a red herring

Red herring

A red herring is a deliberate attempt to divert attention.Red herring may refer to:* Red herring , the informal fallacy of presenting an argument that may in itself be valid, but does not address the issue in question....

) is not evidence that all nonblack things are nonravens. Nelson Goodman

Nelson Goodman

Henry Nelson Goodman was an American philosopher, known for his work on counterfactuals, mereology, the problem of induction, irrealism and aesthetics.-Career:...

's problem predicate "grue", meaning "observed before 1 January 2050 and blue or observed after 1 January 2050 and green", turns out to be inappropriate for science because it does not denote a natural kind. Quine argued that kind-hood was logically primitive: it could not be reduced non-trivially to any other relation among individuals.

Cultural artifact

Cultural artifact

A cultural artifact is a term used in the social sciences, particularly anthropology, ethnology, and sociology for anything created by humans which gives information about the culture of its creator and users...

s are not generally considered natural kinds. As one author puts it, "they never stop changing, and terms that designate them constitute only what Wittgenstein called 'family resemblance

Family resemblance

Family resemblance is a philosophical idea made popular by Ludwig Wittgenstein, with the best known exposition being given in the posthumously published book Philosophical Investigations It has been suggested that Wittgenstein picked the idea and the term from Nietzsche, who had been using it,...

 predicates'" (ibid, p.169). This point is more disputed; John McDowell

John McDowell

John Henry McDowell is a South African philosopher, formerly a fellow of University College, Oxford and now University Professor at the University of Pittsburgh. Although he has written extensively on metaphysics, epistemology, ancient philosophy, and meta-ethics, McDowell's most influential work...

 has extensively argued that this opposition between "culture" and "nature" cannot be clearly formulated, and that in any case it ought to lead us to construing cultural products not as unnatural, but as, adopting Aristotle

Aristotle

Aristotle was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology...

's terminology, a kind of "second nature."

Further reading

• Andreasen, Robin O. 2005. The Meaning of 'Race': Folk Conceptions and the New Biology of Race. Journal of Philosophy 102(2): 94-106.
• Collins, Harry M. 1975. The Seven Sexes: A Study in the Sociology of a Phenomenon, or the Replication of Experiments in Physics. Sociology 9(2): 205-224.
• Dupré, John. 2001. In Defence of Classification. Studies in History and Philosophy of Biological and Biomedical Sciences 32(2): 203-219.
• Fausto-Sterling, Anne. 2000. Essay Review: The Sex/Gender Perplex. Studies in History and Philosophy of Biological and Biomedical Sciences 31(4): 637-646.
• Hacking, Ian. 1990. Natural Kinds. in Robert B. Barrett and Roger Gibson, F., editors. Perspectives on Quine. Cambridge, Mass.: Blackwell.
• Hacking, Ian. 2002. How "Natural" Are "Kinds" of Sexual Orientation? Law and Philosophy 21(3): 335-347.
• Markman, Ellen. 1989. Categorization and Naming in Children. Cambridge, Mass.: MIT Press.
• McOuat, Gordon. 2001. From Cutting Nature at Its Joints to Measuring It: New Kinds and New Kinds of People in Biology. Studies in History and Philosophy of Science 32(4): 613-645.
• Putnam, Hilary. 1975. The Meaning of 'Meaning'. in Keith Gunderson, editor. Minnesota Studies in the Philosophy of Science, vol. VII. Minneapolis: University of Minnesota Press.
• Quine, Willard Van Orman. 1969. Natural Kinds. in Ontological Relativity and Other Essays: Columbia Univ. Press.
• Sokal, Robert R. 1974. Classification: Purposes, Principles, Progress, Prospects. Science 185(4157): 1115-1123.
• Waters, C. Kenneth. 1998. Causal Regularities in the Biological World of Contingent Distributions. Biology and Philosophy 13(1): 5-36.

External links

• Natural Kinds, by Alexander Bird and Emma Tobin, in the Stanford Encyclopedia of Philosophy
  Stanford Encyclopedia of Philosophy
  The Stanford Encyclopedia of Philosophy is a freely-accessible online encyclopedia of philosophy maintained by Stanford University. Each entry is written and maintained by an expert in the field, including professors from over 65 academic institutions worldwide...
  
  
• Natural Kind Terms, draft of an entry to the Encyclopedia of Language and Linguistics
  Encyclopedia of Language and Linguistics
  The Encyclopedia of Language and Linguistics, first published in 1994, with a 2nd edition in 2006, is an encyclopedia of all matters related to language and linguistics...
  
  , by Steven Gross, 2005-01-07. Accessed 2008-10-14.
• Project Cosmology Modern effort to produce a comprehensive list of major categories for natural kinds