Sensu
Encyclopedia
Sensu is a Latin
word meaning "in the sense of".
It is used in a number of fields including biology
, geology
, linguistics
, and law
. Commonly it refers to how strictly or loosely an expression is used, but it also appears in expressions that indicate the convention or context of the usage.
word meaning "in the sense of".
The term is used in a number of fields including biology
, geology
, linguistics
, semiotics
, and law
as part of the phrases sensu stricto ("in the stricter sense") (abbr.: s.s.), and sensu lato ("in the wider sense") (abbr.: s.l.).
Sensu amplo might be translated as "in a relaxed, generous (or 'ample') sense", meaning much the same as sensu lato.
When appropriate, comparative
s and superlative
s also may be used:
These finer distinctions may well help in expressing intended meanings more flexibly, but they need not always be taken too seriously. An inspection of any collection of references will produce a range of very variable and dubious usages, and often a great deal of unnecessary fuss. In contrast, the glossary attached to the textbook on Biological Nomenclature produced by the Systematics Association expresses a very dismissive attitude to the question; the only relevant entries it presents are:
As far as they go, those are useful entries, but it all suggests that the Systematics Association is not much concerned with hair-splitting in the use of the Latin terms.
In informal or non-technical English, one might say: "strictly speaking" for Sensu stricto and "broadly speaking" for sensu lato and so on. There is however no need even in formal writing for anyone to use the Latin terms if he prefers the proper use of the vernacular
, or is more confident in using the vernacular.
Valid reasons for using the Latin words should have nothing to do with pretentiousness; they include:
. The author citation refers only to the type of the name, the specimen or specimens that one refers to in deciding whether other specimens are members of that species or not. Given that an author (such as Linnaeus, for example) was the first to supply a definite type specimen and to describe it, it is to be hoped that his description would stand the tests of time and criticism, but even it it does not, then whether his description was correct or not, or whether he had correctly identified its biological affinities
; as far as practical the name that he had assigned will apply, in preference to any subsequent names or descriptions that anyone proposes. This does not always happen of course; all sorts of errors occur in practice, such as a collector who scoops a netful of small fish and describes them as a new species, whereas it turns out that he had failed to see that there were several (possibly unrelated) species in the net. If it is not clear what he had named, then his name can hardly be taken seriously, either s.s. or s.l.
After a species has been established in this manner, specialist taxonomists
may work on the subject and make certain types of changes in the light of new information. In modern practice it is greatly preferred that the collector of the specimens immediately passes them to specialists for naming; it is rarely possible for non-specialists to tell whether their specimens are of new species or not, and not many publications or their referees would accept an amateur description.
In any event, the person who finally classifies and describes a species has the task of taxonomic circumscription
. Circumscription means in essence that anyone competent in the matter can tell which creatures are included in the species described, and which are excluded. It is in this process of Species description
that the question of the sense arises, because that is where the worker produces and argues his view of the proper circumscription. Equally, or perhaps even more strongly, the arguments for deciding the questions of higher taxa
such as families
or orders
, requires very difficult circumscription, where changing the sense applied could totally upset an entire scheme of classification, either constructively or disastrously.
might find it helpful first to think of everyday examples of the principles. When we deal with groups and parts of groups (subgroups) of different types of things, we sometimes wish to speak of the whole lot, and sometimes just a small part, but we almost always want to deal with some particular part; if we tell someone to poll the opinions of twenty-one members of the village community, we will not usually be satisfied if the pollster returns with the reactions of two heads of households, three infants, four dogs, five cats, six rats, and a tramcar. That would be taking sensu lato beyond good sense.
Instead we would generally tell someone which sense we had in mind, such as sensu stricto (or strictiore):
or sensu lato (or latiore):
The important thing is that in each example we circumscribed the people we had in mind; that means that we said which people were wanted and correspondingly, which were to be left out.
Our circumscription could be in terms of very specific criteria
:
or the criterion could be very casual, even vague:
However simple, even simple-minded, that may sound, it is supremely important, both in science and in everyday life. Such circumscription amounts to the way we tell things apart in everything we do. If we get that sort of thing wrong, we cannot expect to get anything right in dealing with the world about us.
In biological taxonomy, as you may see in the next section, the same principles are used, but they deal in various ways with circumscribing living things according to any relevant criterion
. In modern biology the criterion usually has something to do with which creature descended from which kind of ancestor, and in which ways it changed in the process, and by how much. However, in more general taxonomies
, although the principles of circumscription are fundamentally similar, the criteria we use could be largely different. In geology for example, taxonomy differs drastically from biological taxonomy.
of a given taxon
is meant, where more than one circumscription can be defined.
Examples:
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
word meaning "in the sense of".
It is used in a number of fields including biology
Biology
Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines...
, geology
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...
, linguistics
Linguistics
Linguistics is the scientific study of human language. Linguistics can be broadly broken into three categories or subfields of study: language form, language meaning, and language in context....
, and law
Law
Law is a system of rules and guidelines which are enforced through social institutions to govern behavior, wherever possible. It shapes politics, economics and society in numerous ways and serves as a social mediator of relations between people. Contract law regulates everything from buying a bus...
. Commonly it refers to how strictly or loosely an expression is used, but it also appears in expressions that indicate the convention or context of the usage.
Sensu and its common qualifiers
Sensu is a LatinLatin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
word meaning "in the sense of".
The term is used in a number of fields including biology
Biology
Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines...
, geology
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...
, linguistics
Linguistics
Linguistics is the scientific study of human language. Linguistics can be broadly broken into three categories or subfields of study: language form, language meaning, and language in context....
, semiotics
Semiotics
Semiotics, also called semiotic studies or semiology, is the study of signs and sign processes , indication, designation, likeness, analogy, metaphor, symbolism, signification, and communication...
, and law
Law
Law is a system of rules and guidelines which are enforced through social institutions to govern behavior, wherever possible. It shapes politics, economics and society in numerous ways and serves as a social mediator of relations between people. Contract law regulates everything from buying a bus...
as part of the phrases sensu stricto ("in the stricter sense") (abbr.: s.s.), and sensu lato ("in the wider sense") (abbr.: s.l.).
Sensu amplo might be translated as "in a relaxed, generous (or 'ample') sense", meaning much the same as sensu lato.
When appropriate, comparative
Comparative
In grammar, the comparative is the form of an adjective or adverb which denotes the degree or grade by which a person, thing, or other entity has a property or quality greater or less in extent than that of another, and is used in this context with a subordinating conjunction, such as than,...
s and superlative
Superlative
In grammar, the superlative is the form of an adjective that indicates that the person or thing modified has the quality of the adjective to a degree greater than that of anything it is being compared to in a given context. English superlatives are typically formed with the suffix -est In...
s also may be used:
- Sensu latiore and sensu ampliore are the comparative degrees, meaning "more broadly" or "more relaxedly" speaking. Similarly sensu strictiore means "more strictly" speaking. The comparative degrees may be appropriate when describing changing degrees of restriction of the sense, such as: "Inclusion of newly described species in the genus sensu latiore might well force us to unite the sister genus with..."
- Sensu strictissimo ("in the strictest sense") and sensu latissimo ("in the widest sense") are useful at times.
Latin, its current relevance or convenience
There is no definite limit to how sophisticated a level of Latin may be brought to bear in such terminology; it really dates back to the days when all standard communications in such subjects were written in Latin. That was not so long ago; Latin only really began to fall out of favour for such purposes in the eighteenth century, and gradually at that. The presence of these terms in modern writing is largely the residue of the terminology of old documents.These finer distinctions may well help in expressing intended meanings more flexibly, but they need not always be taken too seriously. An inspection of any collection of references will produce a range of very variable and dubious usages, and often a great deal of unnecessary fuss. In contrast, the glossary attached to the textbook on Biological Nomenclature produced by the Systematics Association expresses a very dismissive attitude to the question; the only relevant entries it presents are:
- sens. str.: see s.s.
- sens. lat.: see s.l.
- sensu amplo: see s.l.
- sl., sens. lat., sensu lato : Latin, in the broad sense; i.e. of a taxon, including all its subordinate taxa and/or other taxa sometimes considered as distinct.
- s.s., sens. str., sensu stricto : Latin, in the strict sense, in the narrow sense, i.e. of a taxon, in the sense of the type of its name ; or in the sense of its circumscription by its original describer ; or in the sense of its nominate subordinate taxon (in the case of a taxon with 2 or more subordinate taxa) ; or with the exclusion of similar taxa sometimes united with it.
As far as they go, those are useful entries, but it all suggests that the Systematics Association is not much concerned with hair-splitting in the use of the Latin terms.
In informal or non-technical English, one might say: "strictly speaking" for Sensu stricto and "broadly speaking" for sensu lato and so on. There is however no need even in formal writing for anyone to use the Latin terms if he prefers the proper use of the vernacular
Vernacular
A vernacular is the native language or native dialect of a specific population, as opposed to a language of wider communication that is not native to the population, such as a national language or lingua franca.- Etymology :The term is not a recent one...
, or is more confident in using the vernacular.
Valid reasons for using the Latin words should have nothing to do with pretentiousness; they include:
- Tradition: Where the terms and their abbreviations have been used formally for generations and appear repeatedly in records and textbooks in fixed contexts, it can be cumbersome and confusing to change unexpectedly to more familiar English or other vernacularVernacularA vernacular is the native language or native dialect of a specific population, as opposed to a language of wider communication that is not native to the population, such as a national language or lingua franca.- Etymology :The term is not a recent one...
. - Precision: Vernacular expressions that most nearly correspond to these terms in meaning, might also be understood in subtly or even crashingly misleading senses, whereas the Latin terms are used according to strict conventions that are not easy to mistake in professional circles familiar with the usages.
- Efficiency: Not only are these terms compact (even in comparison to say, broadly speaking and strictly speaking) but in the proper contexts they lend themselves to understandable abbreviation as s.s. and s.l., better than the most compact vernacular expressions. In much the same way, think of etcEt ceteraEt cetera is a Latin expression that means "and other things", or "and so forth". It is taken directly from the Latin expression which literally means "and the rest " and is a loan-translation of the Greek "καὶ τὰ ἕτερα"...
or &c ; practically everyone knows what those mean, and uses them unthinkingly, even people who do not know that they are abbreviations for et cetera or even et caetera, or that those mean "and the rest" in Latin. Even monoglot laymen would not usually trouble to write "and so on" instead of etc.
Sensu with non-Latin qualifiers; circumscription in biological taxonomy
Another convenient usage is in conjunction with a concept author citation ("sec. Smith", or "sensu Smith"), indicating that the intended meaning is the one defined by that author. (Here the meaning of "sec." is "secundum": "in accordance with".) Such an author citation is different from the (more common) citation of the nomenclatural author citationAuthor citation (botany)
In botanical nomenclature, author citation refers to citing the person who validly published a botanical name, i.e. who first published the name while fulfilling the formal requirements as specified by the International Code of Botanical Nomenclature...
. The author citation refers only to the type of the name, the specimen or specimens that one refers to in deciding whether other specimens are members of that species or not. Given that an author (such as Linnaeus, for example) was the first to supply a definite type specimen and to describe it, it is to be hoped that his description would stand the tests of time and criticism, but even it it does not, then whether his description was correct or not, or whether he had correctly identified its biological affinities
Affinity (taxonomy)
Affinity — mainly in life sciences or natural history - resemblance suggesting a common descent, phylogenetic relationship, or type. The term does however have broader application, such as in geology , and similarly in astronomy Affinity (taxonomy) — mainly in life sciences or natural history -...
; as far as practical the name that he had assigned will apply, in preference to any subsequent names or descriptions that anyone proposes. This does not always happen of course; all sorts of errors occur in practice, such as a collector who scoops a netful of small fish and describes them as a new species, whereas it turns out that he had failed to see that there were several (possibly unrelated) species in the net. If it is not clear what he had named, then his name can hardly be taken seriously, either s.s. or s.l.
After a species has been established in this manner, specialist taxonomists
Taxonomy
Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...
may work on the subject and make certain types of changes in the light of new information. In modern practice it is greatly preferred that the collector of the specimens immediately passes them to specialists for naming; it is rarely possible for non-specialists to tell whether their specimens are of new species or not, and not many publications or their referees would accept an amateur description.
In any event, the person who finally classifies and describes a species has the task of taxonomic circumscription
Circumscription (taxonomy)
In taxonomy, circumscription is the definition of the limits of a taxonomic group of organisms. One goal of taxonomy is to achieve a stable circumscription for every taxonomic group. Achieving stability can be simple or difficult....
. Circumscription means in essence that anyone competent in the matter can tell which creatures are included in the species described, and which are excluded. It is in this process of Species description
Species description
A species description or type description is a formal description of a newly discovered species, usually in the form of a scientific paper. Its purpose is to give a clear description of a new species of organism and explain how it differs from species which have been described previously, or are...
that the question of the sense arises, because that is where the worker produces and argues his view of the proper circumscription. Equally, or perhaps even more strongly, the arguments for deciding the questions of higher taxa
Taxonomy
Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...
such as families
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
or orders
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
, requires very difficult circumscription, where changing the sense applied could totally upset an entire scheme of classification, either constructively or disastrously.
Sensu in circumscription
Readers unfamiliar with technical aspects of taxonomyTaxonomy
Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...
might find it helpful first to think of everyday examples of the principles. When we deal with groups and parts of groups (subgroups) of different types of things, we sometimes wish to speak of the whole lot, and sometimes just a small part, but we almost always want to deal with some particular part; if we tell someone to poll the opinions of twenty-one members of the village community, we will not usually be satisfied if the pollster returns with the reactions of two heads of households, three infants, four dogs, five cats, six rats, and a tramcar. That would be taking sensu lato beyond good sense.
Instead we would generally tell someone which sense we had in mind, such as sensu stricto (or strictiore):
- * "...all the heads of households on the north side of the stream," or "...all the children in hospital with mumps", or "...the men the district attorney questioned this morning," or "Zachiariah Quenton Henton of 22b Baker Street".
or sensu lato (or latiore):
- * "... five of the school football team", or "the first few friendly-looking people you find in the street," or "...some of the people in the district."
The important thing is that in each example we circumscribed the people we had in mind; that means that we said which people were wanted and correspondingly, which were to be left out.
Our circumscription could be in terms of very specific criteria
Problem of the criterion
In the field of epistemology, the problem of the criterion is an issue regarding the starting point of knowledge. This is a separate and more fundamental issue than the regress argument found in discussions on justification of knowledge....
:
or the criterion could be very casual, even vague:
However simple, even simple-minded, that may sound, it is supremely important, both in science and in everyday life. Such circumscription amounts to the way we tell things apart in everything we do. If we get that sort of thing wrong, we cannot expect to get anything right in dealing with the world about us.
In biological taxonomy, as you may see in the next section, the same principles are used, but they deal in various ways with circumscribing living things according to any relevant criterion
Problem of the criterion
In the field of epistemology, the problem of the criterion is an issue regarding the starting point of knowledge. This is a separate and more fundamental issue than the regress argument found in discussions on justification of knowledge....
. In modern biology the criterion usually has something to do with which creature descended from which kind of ancestor, and in which ways it changed in the process, and by how much. However, in more general taxonomies
Taxonomy
Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...
, although the principles of circumscription are fundamentally similar, the criteria we use could be largely different. In geology for example, taxonomy differs drastically from biological taxonomy.
The cogency of circumscription
Notice that although we can generally agree pretty well about which circumscriptions to use for most taxonomies, whether we are looking at say, geological, chemical, philosophical, medical, or legal classification, there is no definitive scheme that is logically and formally compulsory as soon as there is more than one circumscription that could apply (which there practically always is). Nothing stops me from classifying animals as large, medium, or small rather than say, cats, monkeys, and hoofed creatures, but then we would wind up classing domestic cats with pygmy deer and squirrel monkeys, red deer with humans and leopards, and cattle with tigers and gorillas perhaps. That might suit a transport or housing manager, but it would be useless for biologists, and would make no sense to anyone whose interest is in the creatures' habits, physiology, and appearance.Examples in practical taxonomy
Sensu is used in the taxonomy of living creatures to specify which circumscriptionCircumscription (taxonomy)
In taxonomy, circumscription is the definition of the limits of a taxonomic group of organisms. One goal of taxonomy is to achieve a stable circumscription for every taxonomic group. Achieving stability can be simple or difficult....
of a given taxon
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
is meant, where more than one circumscription can be defined.
Examples:
- "The family MalvaceaeMalvaceaeMalvaceae, or the mallow family, is a family of flowering plants containing over 200 genera with close to 2,300 species. Judd & al. Well known members of this family include okra, jute and cacao...
s.s. is cladistically monophyletic."
-
- This means more or less that the members of the entire family of the Malvaceae, (strictly speaking!), which comprises over 1000 species, including the closest relatives of cottonCottonCotton is a soft, fluffy staple fiber that grows in a boll, or protective capsule, around the seeds of cotton plants of the genus Gossypium. The fiber is almost pure cellulose. The botanical purpose of cotton fiber is to aid in seed dispersal....
and hibiscusHibiscusHibiscus is a genus of flowering plants in the mallow family, Malvaceae. It is quite large, containing several hundred species that are native to warm-temperate, subtropical and tropical regions throughout the world...
, all descend from a shared ancestor. That ancestor might have been a single species of plant, or even possibly a single individual plant. Conversely it also means that this does not necessarily apply to any other species of plants that some people might (broadly speaking or s.l.} have included in the family. In short, our circumscription s.s. includes all and only plants that have descended from that particular ancestral stock.
- This means more or less that the members of the entire family of the Malvaceae, (strictly speaking!), which comprises over 1000 species, including the closest relatives of cotton
- "In the broader APGAngiosperm Phylogeny GroupThe Angiosperm Phylogeny Group, or APG, refers to an informal international group of systematic botanists who came together to try to establish a consensus on the taxonomy of flowering plants that would reflect new knowledge about plant relationships discovered through phylogenetic studies., three...
circumscription the family Malvaceae s.l. includes Malvaceae s.s. and also the families Bombacaceae, Sterculiaceae and Tiliaceae."
-
- Here we broaden the circumscription by saying sensu lato; that is what happens whenever we speak more broadly. We have added other groups of plants to the family Malvaceae, including those related to cacao, colaColaCola is a carbonated beverage that was typically flavored by the kola nut as well as vanilla and other flavorings, however, some colas are now flavored artificially. It became popular worldwide after druggist John Pemberton invented Coca-Cola in 1886...
, durianDurianThe durian is the fruit of several tree species belonging to the genus Durio and the Malvaceae family . Widely known and revered in southeast Asia as the "king of fruits", the durian is distinctive for its large size, unique odour, and formidable thorn-covered husk...
, and juteJuteJute is a long, soft, shiny vegetable fibre that can be spun into coarse, strong threads. It is produced from plants in the genus Corchorus, which has been classified in the family Tiliaceae, or more recently in Malvaceae....
. Now it is no longer at all clear that all members of the circumscription descended from that one ancestor. If that is so, we say that Malvaceae s.l. form a polyphyletic group, one that does not share any single ancestor with no other descendants. Then their most recent common ancestor could have lived perhaps tens of millions of years earlier than the common ancestor of the Malvaceae s.s alone.
- Here we broaden the circumscription by saying sensu lato; that is what happens whenever we speak more broadly. We have added other groups of plants to the family Malvaceae, including those related to cacao, cola
- "Banksia subgenus Banksia sensu A. S. George" – This specifies Alex GeorgeAlex GeorgeAlexander Segger George is a Western Australian botanist. He is the authority on the plant genera Banksia and Dryandra...
's particular description of that Banksia.
-
- Here we use a totally different circumscription; "sensu George" simply means that George discussed those Banksias, and that we are now talking about them in that way, — how he saw them. We may or may not like his circumscription, but that is the circumscription we are considering here and now.