Case marking on nouns serves different purposes, which sometimes overlap. It can help to distinguish between two grammatical functions (e.g., the subject and the object in a transitive clause) or it can encode semantic or pragmatic properties of the noun. In general case cannot be modeled as a strict one-to-one mapping from morpho-syntactic form to meaning or vice versa. There does not seem to be a fixed meaning associated with any particular type of case. The relation between form and meaning can differ among various contexts, due to constraints of varying nature and strength. Cases can be restricted or extended to certain meaning components. The aim of this special issue is to elucidate the semantic and pragmatic aspects of case in natural language. Case is one of the key grammatical concepts in syntax and morphology under various perspectives, as recently documented in the Handbook of Case (Malchukov & Spencer 2009), which provides a comprehensive overview of the various aspects of case. The main interest of case theories is the interaction of morphological encoding, syntactic structure and semantic function of case in its various meanings as well as the cross-linguistic distribution of case patterns (see Blake 2002, Butt 2006). The present special issue focuses on semantic aspects of case variation, in particular differential object marking (DOM) and differential subject marking (DSM). Cases for subjects and objects are generally assumed to be structural cases, i.e. the case assignment is primarily determined by the syntactic structure. In such a perspective, the alternation between two case markers (or between the absence of presence of a case marker) for one and the same syntactic function is hard to explain. Patterns of differential case marking are often accounted for in terms of semantic and discourse-pragmatic conditions such as definiteness, specificity, animacy, topicality, and discourse prominence (Hopper & Thompson 1980, Aissen 1999, 2003, de Swart 2007, de Hoop and de Swart 2008, von Heusinger 2008, Barðdal & Chelliah 2009). The present collection of articles focuses on the particular semantic conditions that determine or influence case variation.

The present collection is opened by a theoretical account on different systems of DOM and DSM. In their contribution Case and referential properties, Udo Klein and Peter de Swart develop an architecture of referential properties determining the conditions of differential object marking in particular languages. They provide ample data from languages with multidimensional DOM systems and show that languages have different preferences in their feature systems controlling DOM and DSM. They model this behavior by a sign-based declarative model. Hanjung Lee examines in her contribution Gradients in Korean Case Ellipsis: An Experimental Investigation the object case ellipsis in Korean. Previous studies have suggested that case markers in Korean cannot be dropped when the object is contrastively focused. Lee uses evidence from an elicitation experiment and a rating experiment to show that Korean case ellipsis is not sensitive to the difference between contrastive and non-contrastive focus. The pattern of case ellipsis in Korean can rather be explained in terms of two competing constraints, IDENTIFY and ECONOMY, such that the former accounts for case marking on highly prominent arguments, while the latter accounts for case ellipsis of arguments high in accessibility. The same two competing constraints are used by Andrej Malchukov and Helen de Hoop in their paper Tense, aspect, and mood based differential case marking to account for patterns of differential case marking triggered by the grammatical features of tense, aspect, and mood. They argue that the interaction between the hearer’s (faithfulness) constraint IDENTIFY and the speaker’s (markedness) constraint ECONOMY can explain tense, aspect, and mood based differential case marking. Another instantiation of differential subject marking is investigated by Klaus von Heusinger, Udo Klein and Dolgor Guntsetseg in their paper The case of accusative embedded subjects in Mongolian. Mongolian is an SOV language that realizes embedded clauses by nominalized verbs. Subject of embedded clauses are assigned genitive, instrumental, subject and accusative case markers. The contribution investigates the condition for an alternation between subject or null-marking on the one hand and accusative marking on the other. The authors show that accusative marked embedded subjects are constituents of the embedded sentence and not raised to the main clause. Their analysis is an interesting extension of possible case variation: Mongolian has one morphological marker for direct objects and embedded subjects.

The next two papers focus on the interplay between the lexical semantics of verbs and case variation. Jóhanna Barðdal in her paper The rise of dative substitution in the history of Icelandic provides a usage-based constructional analysis of the change from accusative to dative subjects in Icelandic. She shows in her comparative study of Old Norse-Icelandic and Modern Icelandic texts that the underlying semantic structure of the class of verbs has changed. The semantic constraints for dative subject verbs are weakened such that more verbs in Modern Icelandic qualify for this construction. It was not until after this change in the semantic structure of the dative subject construction that the construction became semantically coherent enough to start systematically attracting items from the low type frequency accusative subject construction. Beatrice Primus discusses the semantic constraints on impersonal passives in several languages in her contribution Animacy and telicity: Semantic constraints on impersonal passives. She provides corpus data that support the view that the situation denoted by the personal passive is a homogenous event. A second observation is that the demoted agent is often restricted to human or animate agents. In her account, she combines both properties and develops an account in terms of proto-agentivity and shows that the event-structural telicity restriction is a consequence of its demoted referential properties, animacy is an effect of its proto-agent properties.

The final contribution On structural case in Finnish and Korean of Arto Antilla and Jong Bok Kim comes back to one of our original issues, namely the strength of different parameters controlling structural case variation. The authors start out with three hypotheses on the initial functions of case, namely to identify arguments, to distinguish arguments, and to refer to prominence relations among arguments. They implement the three hypotheses in Optimality Theory, which allows them to correctly handle the basic case patterns of Finnish and Korean, but also to account for hitherto not explained variation, in particular multiple nominatives. The authors finally derive a rich set of implicational universals to show what other patterns are predicted or excluded by their theory.

Acknowledgements

The majority of the contributions to this special issue were originally presented at the international conference on Case Variation in Stuttgart, June 2008 organized by Klaus von Heusinger, Udo Klein, Helen de Hoop and Peter de Swart. The contribution of Judith Aissen Case and ‘antipassive’ in Mayan and of Elisabeth Stark What is marked by differential object marking in Romance could not be included in this volume due to other obligations of the authors. The conference has been funded by the project C2 “Case and referential context” of the SFB 732 “Incremental specification in context”. The first author likes to acknowledge additional support from the Fritz Thyssen-Stiftung and the VolkswagenStiftung for their support (opus magnum). The second author gratefully acknowledges the Netherlands Organisation for Scientific Research (NWO) for financial support. As guest editors of this special issue we would also like to sincerely thank the reviewers of the individual submissions for their stimulating and critical comments.

References
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Aissen, J., 2003. Differential object marking: iconicity vs. economy. Natural Language and Linguistic Theory 21, 435-483.

Barðdal, J., Chelliah, S. (Eds.), 2009. The role of semantic, pragmatic, and discourse Factors in the development of case. Benjamins, Amsterdam.

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von Heusinger, K., 2008. Verbal semantics and the diachronic development of differential object marking in Spanish. Probus 20, 1-33.

de Hoop, H., de Swart, P. (Eds.), 2008. Differential subject marking. Springer, Dordrecht.

Hopper, P., Thompson, S., 1980. Transitivity in grammar and discourse. Language, 56, 251-299.

Malchukov, A., Spencer, A. (Eds.), 2009. The Oxford Handbook of Case. Oxford University Press, Oxford.

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de Swart, P., 2007. Cross-linguistic variation in differential object marking. Ph.D. dissertation Radboud University Nijmegen. LOT, Utrecht.