Malka Rappaport Hovav
Words are sensitive to syntactic context. Argument realization is the study of the relation between argument-taking words, the syntactic contexts they appear in and the interpretive properties that constrain the relation between them.
Blocking can be defined as the non-occurrence of some linguistic form, whose existence could be expected on general grounds, due to the existence of a rival form. *Oxes, for example, is blocked by oxen, *stealer by thief. Although blocking is closely associated with morphology, in reality the competing “forms” can not only be morphemes or words, but can also be syntactic units. In German, for example, the compound Rotwein ‘red wine’ blocks the phrasal unit *roter Wein (in the relevant sense), just as the phrasal unit rote Rübe ‘beetroot; lit. red beet’ blocks the compound *Rotrübe. In these examples, one crucial factor determining blocking is synonymy; speakers apparently have a deep-rooted presumption against synonyms. Whether homonymy can also lead to a similar avoidance strategy, is still controversial. But even if homonymy blocking exists, it certainly is much less systematic than synonymy blocking.
In all the examples mentioned above, it is a word stored in the mental lexicon that blocks a rival formation. However, besides such cases of lexical blocking, one can observe blocking among productive patterns. Dutch has three suffixes for deriving agent nouns from verbal bases, -er, -der, and -aar. Of these three suffixes, the first one is the default choice, while -der and -aar are chosen in very specific phonological environments: as Geert Booij describes in The Morphology of Dutch (2002), “the suffix -aar occurs after stems ending in a coronal sonorant consonant preceded by schwa, and -der occurs after stems ending in /r/” (p. 122). Contrary to lexical blocking, the effect of this kind of pattern blocking does not depend on words stored in the mental lexicon and their token frequency but on abstract features (in the case at hand, phonological features).
Blocking was first recognized by the Indian grammarian Pāṇini in the 5th or 4th century
Bracketing paradoxes—constructions whose morphosyntactic and morpho-phonological structures appear to be irreconcilably at odds (e.g., unhappier)—are unanimously taken to point to truths about the derivational system that we have not yet grasped. Consider that the prefix un- must be structurally separate in some way from happier both for its own reasons (its [n] surprisingly does not assimilate in Place to a following consonant (e.g., u[n]popular)), and for reasons external to the prefix (the suffix -er must be insensitive to the presence of un-, as the comparative cannot attach to bases of three syllables or longer (e.g., *intelligenter)). But, un- must simultaneously be present in the derivation before -er is merged, so that unhappier can have the proper semantic reading (‘more unhappy’, and not ‘not happier’). Bracketing paradoxes emerged as a problem for generative accounts of both morphosyntax and morphophonology only in the 1970s. With the rise of restrictions on and technology used to describe and represent the behavior of affixes (e.g., the Affix-Ordering Generalization, Lexical Phonology and Morphology, the Prosodic Hierarchy), morphosyntacticians and phonologists were confronted with this type of inconsistent derivation in many unrelated languages.
Andrej L. Malchukov
Morphological case is conventionally defined as a system of marking of a dependent nominal for the type of relationship they bear to their heads. While most linguists would agree with this definition, in practice it is often a matter of controversy whether a certain marker X counts as case in language L, or how many case values language L features. First, the distinction between morphological cases and case particles/adpositions is fuzzy in a cross-linguistic perspective. Second, the distinctions between cases can be obscured by patterns of case syncretism, leading to different analyses of the underlying system. On the functional side, it is important to distinguish between syntactic (structural), semantic, and “pragmatic” cases, yet these distinctions are not clear-cut either, as syntactic cases historically arise from the two latter sources. Moreover, case paradigms of individual languages usually show a conflation between syntactic, semantic, and pragmatic cases (see the phenomenon of “focal ergativity,” where ergative case is used when the A argument is in focus). The composition of case paradigms can be shown to follow a certain typological pattern, which is captured by case hierarchy, as proposed by Greenberg and Blake, among others. Case hierarchy constrains the way how case systems evolve (or are reduced) across languages and derives from relative markedness and, ultimately, from frequencies of individual cases. The (one-dimensional) case hierarchy is, however, incapable of capturing all recurrent polysemies of individual case markers; rather, such polysemies can be represented through a more complex two-dimensional hierarchy (semantic map), which can also be given a diachronic interpretation.
Jessica Coon and Clint Parker
The phenomenon of case has been studied widely at both the descriptive and theoretical levels. Typological work on morphological case systems has provided a picture of the variability of case cross-linguistically. In particular, languages may differ with respect to whether or not arguments are marked with overt morphological case, the inventory of cases with which they may be marked, and the alignment of case marking (e.g., nominative-accusative vs. ergative-absolutive). In the theoretical realm, not only has morphological case been argued to play a role in multiple syntactic phenomena, but current generative work also debates the role of abstract case (i.e., Case) in the grammar: abstract case features have been proposed to underlie morphological case, and to license nominals in the derivation.
The phenomenon of case has been argued to play a role in at least three areas of the syntax reviewed here: (a) agreement, (b) A-movement, and (c) A’-movement. Morphological case has been shown to determine a nominal argument’s eligibility to participate in verbal agreement, and recent work has argued that languages vary as to whether movement to subject position is case-sensitive. As for case-sensitive A’-movement, recent literature on ergative extraction restrictions debates whether this phenomenon should be seen as another instance of “case discrimination” or whether the pattern arises from other properties of ergative languages. Finally, other works discussed here have examined agreement and A’-extraction patterns in languages with no visible case morphology. The presence of patterns and typological gaps—both in languages with overt morphological case and in those without it—lends support to the relevance of abstract case in the syntax.
Clitics can be defined as prosodically defective function words. They can belong to a number of syntactic categories, such as articles, pronouns, prepositions, complementizers, negative adverbs, or auxiliaries. They do not generally belong to open classes, like verbs, nouns, or adjectives. Their prosodically defective character is most often manifested by the absence of stress, which in turn correlates with vowel reduction in those languages that have it independently; sometimes the clitic can be just a consonant or a consonant cluster, with no vowel. This same prosodically defective character forces them to attach either to the word that follows them (proclisis) or to the word that precedes them (enclisis); in some cases they even appear inside a word (mesoclisis or endoclisis). The word to which a clitic attaches is called the host. In some languages (like some dialects of Italian or Catalan) enclitics can surface as stressed, but the presence of stress can be argued to be the result of assignment of stress to the host-clitic complex, not to the clitic itself. One consequence of clitics being prosodically defective is that they cannot be the sole element of an utterance, for instance as an answer to some question; they need to always appear with a host.
A useful distinction is that between simple clitics and special clitics. Simple clitics often have a nonclitic variant and appear in the expected syntactic position for nonclitics of their syntactic category. Much more attention has been paid in the literature to special clitics. Special clitics appear in a designated position within the clause or within the noun phrase (or determiner phrase). In several languages certain clitics must appear in second position, within the clause, as in most South Slavic languages, or within the noun phrase, as in Kwakw'ala. The pronominal clitics of Romance languages or Greek must have the verb as a host and appear in a position different from the full noun phrase. A much debated question is whether the position of special clitics is the result of syntactic movement, or whether other factors, morphological or phonological, intervene as well or are the sole motivation for their position. Clitics can also cluster, with some languages allowing only sequences of two clitics, and other languages allowing longer sequences. Here one relevant question is what determines the order of the clitics, with the main avenues of analysis being approaches based on syntactic movement, approaches based on the types of morphosyntactic features each clitic has, and approaches based on templates. An additional issue concerning clitic clusters is the incompatibility between specific clitics when combined and the changes that this incompatibility can provoke in the form of one or more of the clitics. Combinations of identical or nearly identical clitics are often disallowed, and the constraint known as the Person-Case Constraint (PCC) disallows combinations of clitics with a first or second person accusative clitic (a direct object, DO, clitic) and a third person (and sometimes also first or second person) dative clitic (an indirect object, IO, clitic). In all these cases either one of the clitics surfaces with the form of another clitic or one of the clitics does not surface; sometimes there is no possible output. Here again both syntactic and morphological approaches have been proposed.
Jane Chandlee and Jeffrey Heinz
Computational phonology studies the nature of the computations necessary and sufficient for characterizing phonological knowledge. As a field it is informed by the theories of computation and phonology.
The computational nature of phonological knowledge is important because at a fundamental level it is about the psychological nature of memory as it pertains to phonological knowledge. Different types of phonological knowledge can be characterized as computational problems, and the solutions to these problems reveal their computational nature. In contrast to syntactic knowledge, there is clear evidence that phonological knowledge is computationally bounded to the so-called regular classes of sets and relations. These classes have multiple mathematical characterizations in terms of logic, automata, and algebra with significant implications for the nature of memory. In fact, there is evidence that phonological knowledge is bounded by particular subregular classes, with more restrictive logical, automata-theoretic, and algebraic characterizations, and thus by weaker models of memory.
Connectionism is an important theoretical framework for the study of human cognition and behavior. Also known as Parallel Distributed Processing (PDP) or Artificial Neural Networks (ANN), connectionism advocates that learning, representation, and processing of information in mind are parallel, distributed, and interactive in nature. It argues for the emergence of human cognition as the outcome of large networks of interactive processing units operating simultaneously. Inspired by findings from neural science and artificial intelligence, connectionism is a powerful computational tool, and it has had profound impact on many areas of research, including linguistics. Since the beginning of connectionism, many connectionist models have been developed to account for a wide range of important linguistic phenomena observed in monolingual research, such as speech perception, speech production, semantic representation, and early lexical development in children. Recently, the application of connectionism to bilingual research has also gathered momentum. Connectionist models are often precise in the specification of modeling parameters and flexible in the manipulation of relevant variables in the model to address relevant theoretical questions, therefore they can provide significant advantages in testing mechanisms underlying language processes.
Deponency refers to mismatches between morphological form and syntactic function (or “meaning”), such that a given morphological exponent appears in a syntactic environment that is unexpected from the point of view of its canonical (“normal” or “expected”) function. This phenomenon takes its name from Latin, where certain morphologically “passive” verbs appear in syntactically active contexts (for example, hort-or ‘I encourage’, with the same ending as passive am-or ‘I am loved’), but it occurs in other languages as well. Moreover, the term has been extended to include mismatches in other domains, such as number mismatches in nominal morphology or tense mismatches on verbs (e.g., in the Germanic preterite-presents). Theoretical treatments of deponency vary from seeking a unified (and uniform) account of all observed mismatches to arguing that the wide range of cross-linguistically attested form-function mismatches does not form a natural class and does not require explanatory devices specific to the domain of morphology. It has also been argued that some apparent mismatches are “spurious” and have been misanalyzed.
Nevertheless, it is generally agreed across frameworks that however such “morphological mismatches” are to be analyzed, deponency has potential ramifications for theories of the syntax-morphology interface and (depending on one’s theoretical approach) the structure of the lexicon.
Displacement is a ubiquitous phenomenon in natural languages. Grammarians often speak of displacement in cases where the rules for the canonical word order of a language lead to the expectation of finding a word or phrase in a particular position in the sentence whereas it surfaces instead in a different position and the canonical position remains empty: ‘Which book did you buy?’ is an example of displacement because the noun phrase ‘which book’, which acts as the grammatical object in the question, does not occur in the canonical object position, which in English is after the verb. Instead, it surfaces at the beginning of the sentence and the object position remains empty. Displacement is often used as a diagnostic for constituent structure because it affects only (but not all) constituents. In the clear cases, displaced constituents show properties associated with two distinct linear and hierarchical positions. Typically, one of these two positions c-commands the other and the displaced element is pronounced in the c-commanding position. Displacement also shows strong interactions with the path between the empty canonical position and the position where the element is pronounced: one often encounters morphological changes along this path and evidence for structural placement of the displaced constituent, as well as constraints on displacement induced by the path.
The exact scope of displacement as an analytically unified phenomenon varies from theory to theory. If more then one type of syntactic displacement is recognized, the question of the interaction between movement types arises. Displacement phenomena are extensively studied by syntacticians. Their enduring interest derives from the fact that the complex interactions between displacement and other aspects of syntax offer a powerful probe into the inner workings and architecture of the human syntactic faculty.
Jonathan David Bobaljik
Distributed Morphology (DM) is a framework in theoretical morphology, characterized by two core tenets: (i) that the internal hierarchical structure of words is, in the first instance, syntactic (complex words are derived syntactically), and (ii) that the syntax operates on abstract morphemes, defined in terms of morphosyntactic features, and that the spell-out (realization, exponence) of these abstract morphemes occurs after the syntax. Distributing the functions of the classical morpheme in this way allows for analysis of mismatches between the minimal units of grammatical combination and the minimal units of sound. Much work within the framework is nevertheless guided by seeking to understand restrictions on such mismatches, balancing the need for the detailed description of complex morphological data in individual languages against an attempt to explain broad patterns in terms of restrictions imposed by grammatical principles.
A fundamental difference in theoretical models of morphology and, particularly, of the syntax–morphology interface is that between endoskeletal and exoskeletal approaches. In the former, more traditional, endoskeletal approaches, open-class lexical items like cat or sing are held to be inherently endowed with a series of formal features that determine the properties of the linguistic expressions in which they appear. In the latter, more recent, exoskeletal approaches, it is rather the morphosyntactic configurations, independently produced by the combination of abstract functional elements, that determine those properties. Lexical items, in this latter approach, are part of the structure but, crucially, do not determine it.
Conceptually, although a correlation is usually made between endoskeletalism and lexicalism/projectionism, on the one hand, and between exoskeletalism and (neo)constructionism, on the other, things are actually more complicated, and some frameworks exist that seem to challenge those correlations, in particular when the difference between word and morpheme is taken into account.
Empirically, the difference between these two approaches to morphology and the morphology-syntax interface comes to light when one examines how each one treats a diversity of word-related phenomena: morphosyntactic category and category shift in derivational processes, inflectional class, nominal properties like mass or count, and verbal properties like agentivity and (a)telicity.
In the Principles and Parameters framework of Generative Grammar, the various positions occupied by the verb have been identified as functional heads hosting inflectional material (affixes or features), which may or may not attract the verb. This gave rise to a hypothesis, the Rich Agreement Hypothesis (RAH), according to which the verb has to move to the relevant functional head when the corresponding inflectional paradigm counts as “rich.”
The RAH is motivated by synchronic and diachronic variation among closely related languages (mostly of the Germanic family) suggesting a correspondence between verb movement and rich agreement. Research into this correspondence was initially marred by the absence of a fundamental definition of “richness” and by the observation of counterexamples, both synchronically (dialects not conforming to the pattern) and diachronically (a significant time gap between the erosion of verbal inflection and the disappearance of verb movement). Also, the research was based on a limited group of related languages and dialects. This led to the conclusion that there was at best a weak correlation between verb movement and richness of morphology.
Recently, the RAH has been revived in its strong form, proposing a fundamental definition of richness and testing the RAH against a typologically more diverse sample of the languages of the world. While this represents significant progress, several problems remain, with certain (current and past) varieties of North Germanic not conforming to the expected pattern, and the typological survey yielding mixed or unclear results. A further problem is that other Germanic languages (Dutch, German, Frisian) vary as to the richness of their morphology, but show identical verb placement patterns.
This state of affairs, especially in light of recent minimalist proposals relocating both inflectional morphology and verb movement outside syntax proper (to a component in the model of grammar interfacing between narrow syntax and phonetic realization), suggests that we need a more fundamental understanding of the relation between morphology and syntax before any relation between head movement and morphological strength can be reliably ascertained.
David R. Mortensen
Hmong-Mien (also known as Miao-Yao) is a bipartite family of minority languages spoken primarily in China and mainland Southeast Asia. The two branches, called Hmongic and Mienic by most Western linguists and Miao and Yao by Chinese linguists, are both compact groups (phylogenetically if not geographically). Although they are uncontroversially distinct from one another, they bear a strong mutual affinity. But while their internal relationships are reasonably well established, there is no unanimity regarding their wider genetic affiliations, with many Chinese scholars insisting on Hmong-Mien membership in the Sino-Tibetan superfamily, some Western scholars suggesting a relationship to Austronesian and/or Tai-Kradai, and still others suggesting a relationship to Mon-Khmer. A plurality view appears to be that Hmong-Mien bears no special relationship to any surviving language family.
Hmong-Mien languages are typical—in many respects—of the non-Sino-Tibetan languages of Southern China and mainland Southeast Asia. However, they possess a number of properties that make them stand out. Many neighboring languages are tonal, but Hmong-Mien languages are, on average, more so (in terms of the number of tones). While some other languages in the area have small-to-medium consonant inventories, Hmong-Mien languages (and especially Hmongic languages) often have very large consonant inventories with rare classes of sounds like uvulars and voiceless sonorants. Furthermore, while many of their neighbors are morphologically isolating, few language groups display as little affixation as Hmong-Mien languages. They are largely head-initial, but they deviate from this generalization in their genitive-noun constructions and their relative clauses (which vary in position and structure, sometimes even within the same language).
M. Teresa Espinal and Jaume Mateu
Idioms, conceived as fixed multi-word expressions that conceptually encode non-compositional meaning, are linguistic units that raise a number of questions relevant in the study of language and mind (e.g., whether they are stored in the lexicon or in memory, whether they have internal or external syntax similar to other expressions of the language, whether their conventional use is parallel to their non-compositional meaning, whether they are processed in similar ways to regular compositional expressions of the language, etc.). Idioms show some similarities and differences with other sorts of formulaic expressions, the main types of idioms that have been characterized in the linguistic literature, and the dimensions on which idiomaticity lies. Syntactically, idioms manifest a set of syntactic properties, as well as a number of constraints that account for their internal and external structure. Semantically, idioms present an interesting behavior with respect to a set of semantic properties that account for their meaning (i.e., conventionality, compositionality, and transparency, as well as aspectuality, referentiality, thematic roles, etc.). The study of idioms has been approached from lexicographic and computational, as well as from psycholinguistic and neurolinguistic perspectives.
Inflection is the systematic relation between words’ morphosyntactic content and their morphological form; as such, the phenomenon of inflection raises fundamental questions about the nature of morphology itself and about its interfaces. Within the domain of morphology proper, it is essential to establish how (or whether) inflection differs from other kinds of morphology and to identify the ways in which morphosyntactic content can be encoded morphologically. A number of different approaches to modeling inflectional morphology have been proposed; these tend to cluster into two main groups, those that are morpheme-based and those that are lexeme-based. Morpheme-based theories tend to treat inflectional morphology as fundamentally concatenative; they tend to represent an inflected word’s morphosyntactic content as a compositional summing of its morphemes’ content; they tend to attribute an inflected word’s internal structure to syntactic principles; and they tend to minimize the theoretical significance of inflectional paradigms. Lexeme-based theories, by contrast, tend to accord concatenative and nonconcatenative morphology essentially equal status as marks of inflection; they tend to represent an inflected word’s morphosyntactic content as a property set intrinsically associated with that word’s paradigm cell; they tend to assume that an inflected word’s internal morphology is neither accessible to nor defined by syntactic principles; and they tend to treat inflection as the morphological realization of a paradigm’s cells. Four important issues for approaches of either sort are the nature of nonconcatenative morphology, the incidence of extended exponence, the underdetermination of a word’s morphosyntactic content by its inflectional form, and the nature of word forms’ internal structure. The structure of a word’s inventory of inflected forms—its paradigm—is the locus of considerable cross-linguistic variation. In particular, the canonical relation of content to form in an inflectional paradigm is subject to a wide array of deviations, including inflection-class distinctions, morphomic properties, defectiveness, deponency, metaconjugation, and syncretism; these deviations pose important challenges for understanding the interfaces of inflectional morphology, and a theory’s resolution of these challenges depends squarely on whether that theory is morpheme-based or lexeme-based.
Phenomena involving the displacement of syntactic units are widespread in human languages. The term displacement refers here to a dependency relation whereby a given syntactic constituent is interpreted simultaneously in two different positions. Only one position is pronounced, in general the hierarchically higher one in the syntactic structure. Consider a wh-question like (1) in English:
(1) Whom did you give the book to <whom>
The phrase containing the interrogative wh-word is located at the beginning of the clause, and this guarantees that the clause is interpreted as a question about this phrase; at the same time, whom is interpreted as part of the argument structure of the verb give (the copy, in <> brackets). In current terms, inspired by minimalist developments in generative syntax, the phrase whom is first merged as (one of) the complement(s) of give (External Merge) and then re-merged (Internal Merge, i.e., movement) in the appropriate position in the left periphery of the clause. This peripheral area of the clause hosts operator-type constituents, among which interrogative ones (yielding the relevant interpretation: for which x, you gave a book to x, for sentence 1). Scope-discourse phenomena—such as, e.g., the raising of a question as in (1), the focalization of one constituent as in TO JOHN I gave the book (not to Mary)—have the effect that an argument of the verb is fronted in the left periphery of the clause rather than filling its clause internal complement position, whence the term displacement. Displacement can be to a position relatively close to the one of first merge (the copy), or else it can be to a position farther away. In the latter case, the relevant dependency becomes more long-distance than in (1), as in (2)a and even more so (2)b:
a Whom did Mary expect [that you would give the book to<whom >]
b Whom do you think [that Mary expected [that you would give the book to <whom >]]
50 years or so of investigation on locality in formal generative syntax have shown that, despite its potentially very distant realization, syntactic displacement is in fact a local process. The audible position in which a moved constituent is pronounced and the position of its copy inside the clause can be far from each other. However, the long-distance dependency is split into steps through iterated applications of short movements, so that any dependency holding between two occurrences of the same constituent is in fact very local. Furthermore, there are syntactic domains that resist movement out of them, traditionally referred to as islands. Locality is a core concept of syntactic computations. Syntactic locality requires that syntactic computations apply within small domains (cyclic domains), possibly in the mentioned iterated way (successive cyclicity), currently rethought of in terms of Phase theory. Furthermore, in the Relativized Minimality tradition, syntactic locality requires that, given X . . . Z . . . Y, the dependency between the relevant constituent in its target position X and its first merge position Y should not be interrupted by any constituent Z which is similar to X in relevant formal features and thus intervenes, blocking the relation between X and Y. Intervention locality has also been shown to allow for an explicit characterization of aspects of children’s linguistic development in their capacity to compute complex object dependencies (also relevant in different impaired populations).
Laura A. Michaelis
Meanings are assembled in various ways in a construction-based grammar, and this array can be represented as a continuum of idiomaticity, a gradient of lexical fixity. Constructional meanings are the meanings to be discovered at every point along the idiomaticity continuum. At the leftmost, or ‘fixed,’ extreme of this continuum are frozen idioms, like the salt of the earth and in the know. The set of frozen idioms includes those with idiosyncratic syntactic properties, like the fixed expression by and large (an exceptional pattern of coordination in which a preposition and adjective are conjoined). Other frozen idioms, like the unexceptionable modified noun red herring, feature syntax found elsewhere. At the rightmost, or ‘open’ end of this continuum are fully productive patterns, including the rule that licenses the string Kim blinked, known as the Subject-Predicate construction. Between these two poles are (a) lexically fixed idiomatic expressions, verb-headed and otherwise, with regular inflection, such as chew/chews/chewed the fat; (b) flexible expressions with invariant lexical fillers, including phrasal idioms like spill the beans and the Correlative Conditional, such as the more, the merrier; and (c) specialized syntactic patterns without lexical fillers, like the Conjunctive Conditional (e.g., One more remark like that and you’re out of here). Construction Grammar represents this range of expressions in a uniform way: whether phrasal or lexical, all are modeled as feature structures that specify phonological and morphological structure, meaning, use conditions, and relevant syntactic information (including syntactic category and combinatoric potential).
Computational models of human sentence comprehension help researchers reason about how grammar might actually be used in the understanding process. Taking a cognitivist approach, this article relates computational psycholinguistics to neighboring fields (such as linguistics), surveys important precedents, and catalogs open problems.
Olaf Koeneman and Hedde Zeijlstra
Many, and according to some estimates most, of the world’s languages allow the subject of the sentence to be unexpressed, a phenomenon known as ‘pro(noun) drop’. In a language like Italian, Gianni parla ‘Gianni speaks’ and Parla ‘(S)he speaks’ are both grammatical sentences. This is in contrast to a language like English, in which not expressing the subject leads to an ungrammatical sentence: *Speaks. The difference between being and not being able to leave the subject unexpressed (or, to put it differently, to have a ‘null subject’) has been related to the richness of the verbal paradigm of a language. Whereas Italian has six different agreement endings in the present tense, English only marks the third-person singular differently (with an -s affix, as in John speak-s). Although this correlation with rich agreement is pervasive, it does not successfully capture all the cross-linguistic variation that is attested. Languages like Japanese and Chinese, for instance, allow unexpressed arguments (including subjects) in the absence of any agreement. For these languages, it has been observed that their pronominal paradigms tend to have transparent, agglutinative nominal morphology, expressing case or number features. Trickier perhaps are languages that allow pro drop under certain conditions only. Some languages, such as Finnish or colloquial variants of German, allow it in certain but not all person/number contexts. Other languages, such as Icelandic, allow the subject to be unexpressed only if it is an expletive, the counterpart of English it (cf. It is raining) or there (There is a man in the garden). For these so-called partial pro drop languages, it is still unclear if one can relate their more restricted absence of overt subjects to other observable properties that they possess.