Theoretical linguistics, or general linguistics,
is the branch of linguistics which inquires
into the nature of language itself and seeks
to answer fundamental questions as to what
language is; how it works; how universal grammar
(UG) as a domain-specific mental organ operates,
if it exists at all; what are its unique properties;
how does language relate to other cognitive
processes, etc. Theoretical linguists are
most concerned with constructing models of
linguistic knowledge, and ultimately developing
a linguistic theory.
The fields that are generally considered the
core of theoretical linguistics are phonology,
morphology, syntax, and semantics. Although
phonetics often guides phonology, it is often
excluded from the purview of theoretical linguistics,
along with semantics. Theoretical linguistics
also involves the search for an explanation
of linguistic universals, that is, properties
that all, or many languages have in common.
== Terminology ==
In the first half of the 20th century, the
term "general linguistics" was more common
(cf. Ferdinand de Saussure's famous Course
in General Linguistics), which could be contrasted
with "language-particular linguistics" (which
is more often called descriptive linguistics).
Since the 1960s, the term "theoretical linguistics"
has typically been used in more or less the
same sense as "general linguistics", even
though it also contrasts with applied linguistics,
and even though it is often said that language
description is inherently theoretical. The
usual terminology is thus not entirely clear
and consistent.
== Major fields ==
=== 
Phonetics ===
Phonetics is the study of speech sounds with
concentration on three main points :
Manner of articulation|Articulation: the production
of speech sounds in human speech organs.
Perception : the way human ears respond to
speech signals, how the human brain analyses
them.
Acoustic features : physical characteristics
of speech sounds such as, loudness, amplitude,
frequency etc.According to this definition,
phonetics can also be called linguistic analysis
of human speech at the surface level. That
is one obvious difference from phonology,
which concerns the structure and organisation
of speech sounds in natural languages, and
furthermore has a theoretical and abstract
nature. One example can be made to illustrate
this distinction:
In English, the suffix -s can represent either
/s/, /z/, or can be silent (written Ø) depending
on context.
==== Articulatory phonetics ====
The field of articulatory phonetics is a subfield
of phonetics. In studying articulation, phoneticians
attempt to document how humans produce speech
sounds (vowels and consonants). That is, articulatory
phoneticians are interested in how the different
structures of the vocal tract, called the
articulators (tongue, lips, jaw, palate, teeth
etc.), interact to create the specific sounds.
==== Auditory phonetics ====
Auditory phonetics is a branch of phonetics
concerned with the hearing, acquisition and
comprehension of phonetic sounds of words
of a language. As articulatory phonetics explores
the methods of sound production, auditory
phonetics explores the methods of reception—the
ear to the brain, and those processes.
==== Acoustic phonetics ====
Acoustic phonetics is a subfield of phonetics
which deals with acoustic aspects of speech
sounds. Acoustic phonetics investigates properties
like the mean squared amplitude of a waveform,
its duration, its fundamental frequency, or
other properties of its frequency spectrum,
and the relationship of these properties to
other branches of phonetics (e.g. articulatory
or auditory phonetics), and to abstract linguistic
concepts like phones, phrases, or utterances.
=== Phonology ===
Phonology (sometimes called phonemics or phonematics)
is the study of how sounds are used in languages
to convey meaning. Phonology includes topics
such as stress and intonation.
The basic unit of analysis for phonology is
called phoneme. A phoneme is a group of sounds
which are not distinguished by the language
rules in determining the meaning. In English,
for example, [t] and [tʰ] are different allophones
that represent a single phoneme /t/.
=== Morphology ===
Morphology is the study of the internal structure
of words. For example, in the sentences The
dog runs and The dogs run, the word forms
runs and dogs have an affix -s added, distinguishing
them from the base forms dog and run. Adding
this suffix to a nominal stem gives plural
forms, adding it to verbal stems restricts
the subject to third person singular. Some
morphological theories operate with two distinct
suffixes -s, called allomorphs of the morphemes
Plural and Third person singular, respectively.
Languages differ with respect to their morphological
structure. Along one axis, we may distinguish
analytic languages, with few or no affixes
or other morphological processes from synthetic
languages with many affixes. Along another
axis, we may distinguish agglutinative languages,
where affixes express one grammatical property
each, and are added neatly one after another,
from fusional languages, with non-concatenative
morphological processes (infixation, umlaut,
ablaut, etc.) and/or with less clear-cut affix
boundaries.
=== Syntax ===
Syntax is the study of language structure
and phrasal hierarchies, depicted in parse
tree format. It is concerned with the relationship
between units at the level of words or morphology.
Syntax seeks to exactly delineate all and
only those sentences which make up a given
language, using native speaker intuition.
Syntax seeks to formally describe exactly
how structural relations between elements
(lexical items/words and operators) in a sentence
contribute to its interpretation. Syntax uses
principles of formal logic and Set Theory
to formalize and accurately represent the
hierarchical relationship between elements
in a sentence. Abstract syntax trees are often
used to illustrate the hierarchical structures
that are posited. Thus, in active declarative
sentences in English the subject is followed
by the main verb which in turn is followed
by the object (SVO). This order of elements
is crucial to its correct interpretation and
it is exactly this which syntacticians try
to capture. They argue that there must be
a formal computational component contained
within the language faculty of normal speakers
of a language and seek to describe it.
=== Semantics ===
Semantics is the study of intension, that
is, the intrinsic meanings of words and phrases.
Much of the work in the field of philosophy
of language is concerned with the relation
between meanings and the word, and this concern
cross-cuts formal semantics in several ways.
For example, both philosophers of language
and semanticists make use of propositional,
predicate and modal logics to express their
ideas about word meaning.
== See also ==
Biolinguistics
Cognitive science
Computational linguistics
Critical discourse analysis
Digital infinity
Discourse analysis
Formal language
Generative grammar
Linguistic relativity
Minimalist program
Pragmatics
Psycholinguistics
Universal grammar
