Linguistic typology is the typology that classifies languages by their features. Linguistic typology includes morphological, syntactic (sometimes "morphosyntactic"), and phonological typology. Typological classification of languages contrasts with the more familiar genetic classification into families that share an ancestor language (see historical linguistics). A genetic class is a language family, while a typological class is a language type. Research on typology often overlaps with research on linguistic universals.
One set of types is determined by the basic order of subject, verb, and object in sentences:
- Subject Verb Object
- Subject Object Verb
- Verb Subject Object
- Verb Object Subject
- Object Subject Verb
- Object Verb Subject
These are usually abbreviated SVO and so forth, and may be called just "typologies" of the languages to which they apply.
Some languages split verbs into an auxiliary and an infinitive or participle, and put the subject or object between them. For instance, German ("Im Wald habe ich einen Fuchs gesehen" - *"In-the wood have I a fox seen"), Dutch ("Hans vermoedde dat Jan Piet Marie zag leren zwemmen" - *"Hans suspected that Jan Piet Marie saw teach swim") and Welsh ("Mae'r gwirio sillafu wedi'i gwblhau" - *"Is the check spelling after to complete"). In this case, typology is based on the non-analytic tenses (i.e. those sentences in which the verb is not split) or the position of the auxiliary. German is thus SVO/VSO (without "im Wald" the subject would go first) in main clauses and Welsh is VSO (and O would go after the infinitive).
Both German and Dutch are often classified as V2 languages, as the verb invariantly occurs as the second element of a full clause.
Some languages that are inflected are difficult to classify in the SVO typological system, because virtually any ordering of verb, object, and subject is possible and correct. All we can do for such languages is find out which word order is the most frequent. For example, in a non-inflected language, the subject and object of a sentence are determined by word order; in an inflected language, the determination may be made by affixes applied to nouns to designate their grammatical roles. In such a system, fixed word order is not necessary to determine meaning (although highly inflected languages do sometimes develop normative word orders). Inflected languages without a fixed word order include Latin, Polish, and Greek.
Another common classification is according to whether a language is accusative or ergative. In a language with cases, the classification depends on whether the subject of an intransitive verb has the same case as the subject or the object of a transitive verb. If a language has no cases, but is SVO or OVS, then the classification depends on whether the subject of an intransitive verb is on the same side as the subject or the object of the transitive verb.
Many languages show mixed accusative and ergative behaviour (e.g. ergative morphology marking the verb arguments, on top of an accusative syntax). Other languages (called "active languages") have two types of intransitive verbs—some of them ("active verbs") join the subject in the same case as the subject of a transitive verb, and the rest ("stative verbs") join the subject in the same case as the object. Yet other languages behave ergatively only in some contexts (this is called split ergativity, and is usually based on the grammatical person of the arguments or in the tense/aspect of the verb). For example, only some verbs in Georgian behave this way, and, as a rule, only while the tense called aorist is used.
See also: morphosyntactic alignment.