Classification is a term used both about the process to classify (distinguishing and distribution kinds of "things" into different groups) and about the resulting set of classes, as well as the assignment of elements to pre-established classes. To classify in the broad meaning given above is a fundamental concept and a part of almost all kinds of activities, and it is an interdisciplinary field of study. Among the most important contributing disciplines are philosophy, biology, knowledge organization, psychology, statistics and mathematics.
Frederick Suppe[1] distinguished two senses of classification: a broad meaning, which he called "conceptual classification" and a narrow meaning, which he called "systematic classification".
About conceptual classification Suppe (1989, 292) wrote: "Classification is intrinsic to the use of language, hence to most if not all communication. Whenever we use nominative phrases we are classifying the designated subject as being importantly similar to other entities bearing the same designation; that is, we classify them together. Similarly the use of predicative phrases classifies actions or properties as being of a particular kind. We call this conceptual classification, since it refers to the classification involved in conceptualizing our experiences and surroundings"
About systematic classification Suppe (1989, 292) wrote: "A second, narrower sense of classification is the systematic classification involved in the design and utilization of taxonomic schemes such as the biological classification of animals and plants by genus and species.
During the history of science and philosophy many definitions and theories of classification have been put forward. A chronological list of definitions appears in Birger (2017).[2]
Hull (1998)[3] suggested "The fundamental elements of any classification are its theoretical commitments, basic units and the criteria for ordering these basic units into a classification".
The basic units in a classification system are classes (or sometimes clades or related terms, cf. Hjørland (2017, Section 2) [1].
There is a widespread opinion in knowledge organization and related fields that such classes corresponds to concepts. We can, for example, classify ‘waterfowls’ into the classes “ducks”, “geese”, and “swans”; we can also say, however, that the concept “waterfowl” is a generic broader term in relation to the concepts “ducks”, “geese”, and “swans”. This example demonstrates the close relationship between classification theory and concept theory. A main opponent of concepts as units is Barry Smith (cf. Smith 2004).[4] Arp, Smith and Spear (2015, 5ff)[5] discuss ontologies and criticize the conceptualist understanding. The book writes (7): “The code assigned to France, for example, is ISO 3166 – 2:FR and the code is assigned to France itself — to the country that is otherwise referred to as Frankreich or Ranska. It is not assigned to the concept of France (whatever that might be).” Smith's alternative to concepts as units is based on a realist orientation, when scientists make successful claims about the types of entities that exist in reality, they are referring to objectively existing entities which realist philosophers call universals or natural kinds. Smith's main argument - with which many followers of the concept theory agree - seems to be that classes cannot be determined by introspective methods, but must be based on scientific and scholarly research. Whether units are called concepts or universals, the problem is to decide when a thing (say a "blackbird") should be considered a natural class. In the case of blackbirds, for example, recent DNA analysis have reconsidered the concept (or universal) "blackbird" and found that what was formerly considered one species (with subspecies) are in reality many different species, which just have chosen similar characteristics to adopt to their ecological niches (Fjeldså 2013, 141).[6]
An important argument for considering concepts the basis of classification is that concepts are subject to change and that they changes when scientific revolutions occur. Our concepts of many birds, for example, have changed with recent development in DNA anal
About conceptual classification Suppe (1989, 292) wrote: "Classification is intrinsic to the use of language, hence to most if not all communication. Whenever we use nominative phrases we are classifying the designated subject as being importantly similar to other entities bearing the same designation; that is, we classify them together. Similarly the use of predicative phrases classifies actions or properties as being of a particular kind. We call this conceptual classification, since it refers to the classification involved in conceptualizing our experiences and surroundings"
About systematic classification Suppe (1989, 292) wrote: "A second, narrower sense of classification is the systematic classification involved in the design and utilization of taxonomic schemes such as the biological classification of animals and plants by genus and species.
During the history of science and philosophy many definitions and theories of classification have been put forward. A chronological list of definitions appears in Birger (2017).[2]
Hull (1998)[3] suggested "The fundamental elements of any classification are its theoretical commitments, basic units and the criteria for ordering these basic units into a classification".
The basic units in a classification system are classes (or sometimes clades or related terms, cf. Hjørland (2017, Section 2) [1].
There is a widespread opinion in knowledge organization and related fields that such cla
The basic units in a classification system are classes (or sometimes clades or related terms, cf. Hjørland (2017, Section 2) [1].
There is a widespread opinion in knowledge organization and related fields that such classes corresponds to concepts. We can, for example, classify ‘waterfowls’ into the classes “ducks”, “geese”, and “swans”; we can also say, however, that the concept “waterfowl” is a generic broader term in relation to the concepts “ducks”, “geese”, and “swans”. This example demonstrates the close relationship between classification theory and concept theory. A main opponent of concepts as units is Barry Smith (cf. Smith 2004).[4] Arp, Smith and Spear (2015, 5ff)[5] discuss ontologies and criticize the conceptualist understanding. The book writes (7): “The code assigned to France, for example, is ISO 3166 – 2:FR and the code is assigned to France itself — to the country that is otherwise referred to as Frankreich or Ranska. It is not assigned to the concept of France (whatever that might be).” Smith's alternative to concepts as units is based on a realist orientation, when scientists make successful claims about the types of entities that exist in reality, they are referring to objectively existing entities which realist philosophers call universals or natural kinds. Smith's main argument - with which many followers of the concept theory agree - seems to be that classes cannot be determined by introspective methods, but must be based on scientific and scholarly research. Whether units are called concepts or universals, the problem is to decide when a thing (say a "blackbird") should be considered a natural class. In the case of blackbirds, for example, recent DNA analysis have reconsidered the concept (or universal) "blackbird" and found that what was formerly considered one species (with subspecies) are in reality many different species, which just have chosen similar characteristics to adopt to their ecological niches (Fjeldså 2013, 141).[6]
An important argument for considering concepts the basis of classification is that concepts are subject to change and that they changes when scientific revolutions occur. Our concepts of many birds, for example, have changed with recent development in DNA analysis and the influence of the cladistic paradigm - and have demanded new classifications. Smith's example of France demands an explanation. First, France is not a general concept, but an individual concept. Next, the legal definition of France is determined by the conventions that France has made with other countries. It is still a concept, however, as Leclercq (1978) demonstrates with the corresponding concept Europe.[7]
Hull (1998) continued: "Two fundamentally different sorts of classification are those that reflect structural organization and those that are systematically related to historical development." What is referred to is that in biological classification the anatomical traits of organisms is one kind of classification, the classification in relation to the evolution of species is another (in the section below, we expand these two fundamental sorts of classification to four). Hull adds that in biological classification, evolution supplies the theoretical orientation.
Ereshefsky (2000)[8] presented and discussed three general philosophical schools of classification: "essentialism, cluster analysis, and historical classification. Essentialism sorts entities according to their essential natures. Cluster analysis divides entities into groups whose members share a cluster of similar traits, though none of those traits are essential. The historical approach classifies entities according, to their causal relations rather than their intrinsic qualitative features."
These three categories may, however, be considered parts of broader philosophies. Four main approaches to classification may be distinguished: (1) logical and rationalist approaches including "essentialism"; (2) empiricist approaches including cluster analysis (It is important to notice that empiricism is not the same as empirical study, but a certain ideal of doing e
These three categories may, however, be considered parts of broader philosophies. Four main approaches to classification may be distinguished: (1) logical and rationalist approaches including "essentialism"; (2) empiricist approaches including cluster analysis (It is important to notice that empiricism is not the same as empirical study, but a certain ideal of doing empirical studies. With the exception of the logical approaches they all are based on empirical studies, but are basing their studies on different philosophical principles). (3) Historical and hermeneutical approaches including Ereshefsky's "historical classification" and (4) Pragmatic, functionalist and teleological approaches (not covered by Ereshefsky). In addition there are combined approaches (e.g., the so-called evolutionary taxonomy", which mixes historical and empiricist principles).
"Empiricism alone is not enough: a healthy advance in taxonomy depends on a sound theoretical foundation" (Mayr 1968, 548)[12]
Ridley (1986,191)[21] wrote: "teleological classification. Classification of groups by their shared purposes, or functions, in life - where purpose can be identified with adaptation. An imperfectly worked-out, occasionally suggested, theoretically possible principle of classification that differs from the two main such principles, phenetic and phylogenetic classification".
One or more of the following terms are by some authors considered synonyms for classification while other authors have suggested various ways of differentiating these terms.
Is the classification of the chemical elements which is in particular associated with Dmitri Mendeleev (cf., History of the periodic table). Hubert Feger (2001, 1967–1968;[22] numbered listing added) wrote about it: A well-known, still used, and expanding classification is Mendelejew's Table of Elements. It can be viewed as a prototype of all taxonomies in that it satisfies the following evaluative criteria:
Bursten (2020)[23] wrote, however "Hepler-Smith, a historian of chemistry, and I, a philosopher whose work often draws on chemistry, found common ground in a shared frustration with our disciplines’ emphases on the chemical elements as the stereotypical example of a natural kind. The frustration we shared was that while the elements did display many hallmarks of paradigmatic kindhood, elements were not the kinds of kinds that generated interesting challenges for classification in chemistry, nor even were they the kinds of kinds that occupied much contemporary critical chemical thought. Compounds, complexes, reaction pathways, substrates, solutions – these were the kinds of the chemistry laboratory, and rarely if ever did they slot neatly into taxonomies in the orderly manner of classification suggested by the Periodic Table of Elements. A focus on the rational and historical basis of the development of the Periodic Table had made the received view of chemical classification appear far more pristine, and far less interesting, than either of us believed it to be."
Is the particular form of biological classification (taxonomy) set up by Carl Linnaeus, as set forth in his Systema Naturae (1735) and subsequent works. A major discussion in the scie
Bursten (2020)[23] wrote, however "Hepler-Smith, a historian of chemistry, and I, a philosopher whose work often draws on chemistry, found common ground in a shared frustration with our disciplines’ emphases on the chemical elements as the stereotypical example of a natural kind. The frustration we shared was that while the elements did display many hallmarks of paradigmatic kindhood, elements were not the kinds of kinds that generated interesting challenges for classification in chemistry, nor even were they the kinds of kinds that occupied much contemporary critical chemical thought. Compounds, complexes, reaction pathways, substrates, solutions – these were the kinds of the chemistry laboratory, and rarely if ever did they slot neatly into taxonomies in the orderly manner of classification suggested by the Periodic Table of Elements. A focus on the rational and historical basis of the development of the Periodic Table had made the received view of chemical classification appear far more pristine, and far less interesting, than either of us believed it to be."
Is the particular form of biological classification (taxonomy) set up by Carl Linnaeus, as set forth in his Systema Naturae (1735) and subsequent works. A major discussion in the
Is the particular form of biological classification (taxonomy) set up by Carl Linnaeus, as set forth in his Systema Naturae (1735) and subsequent works. A major discussion in the scientific literature is whether a system that was constructed before Charles Darwin's theory of evolution can still be fruitful and reflect the development of life. [24][25]