This paper deals with the conditions under which singular definites, on the one hand, and universally quantified DPs, on the other hand, receive interpretations according to which the sets denoted by the NP-complements of the respective determiner vary with the situations quantified over by a Q-adverb. I show that in both cases such interpretations depend on the availability of situation predicates that are compatible with the presuppositions associated with the respective determiner, as co-variation in both cases comes about via the binding of a covert situation variable that is contained within the NP-complement of the respective determiner. Secondly, I offer an account for the observation that the availability of a co-varying interpretation is more constrained in the case of universally quantified DPs than in the case of singular definites, as far as word order is concerned. This is shown to follow from the fact that co-varying definites in contrast to universally quantified DPs are inherently focus-marked.

This thesis is concerned with the description and analysis of two semantically different types of definite articles in German. While the existence of distinct article paradigms in various Germanic dialects and other languages has been acknowledged in the descriptive literature for quite some time, the theoretical implications of their existence have not been explored extensively. I argue that each of the articles corresponds to one of the two predominant theoretical approaches to analyzing definite descriptions: the `weak' article encodes uniqueness. The `strong' article is anaphoric in nature. In the course of spelling out detailed analyses for the two articles, various more general issues relevant to current semantic theory are addressed, in particular with respect to the analysis of donkey sentences and domain restriction. Chapter 2 describes the contrast between the weak and the strong article in light of the descriptive literature and characterizes their uses in terms of Hawkins's (1978) classification. Special attention is paid to two types of bridging uses, which shed further light on the contrast and play an important in the analysis developed in the following chapters. Chapter 3 introduces a situation semantics and argues for a specific version thereof. First, I propose that situation arguments in noun phrases are represented syntactically as situation pronouns at the level of the DP (rather than within the NP). Secondly, I argue that domain restriction (which is crucial for uniqueness analyses) can best be captured in a situation semantics, as this is both more economical and empirically more adequate than an analysis in terms of contextually supplied C-variables. Chapter 4 provides a uniqueness analysis of weak-article definites. The interpretation of a weak-article definite crucially depends on the interpretation of its situation pronoun, which can stand for the topic situation or a contextually supplied situation, or be quantificationally bound. I make a specific proposal for how topic situations (roughly, the situations that we are talking about) can be derived from questions and relate this to a more general perspective on discourse structure based on the notion of Question Under Discussion (QUD) (Roberts 1996, Buring 2003). I also show that it requires a presuppositional view of definites. A detailed, situation-semantic analysis of covarying interpretations of weak-article definites in donkey sentences is spelled out as well, which provides some new insights with regards to transparent interpretations of the restrictors of donkey sentences. Chapter 5 deals with so-called larger situation uses (Hawkins 1978), which call for a special, systematic way of determining the situation in which the definite is interpreted. I argue that a situation semantic version of an independently motivated type-shifter for relational nouns (shifting relations (he; he; stii) to properties (he; hstii)) brings about the desired situational effect. This type-shifter also applies to cases of part-whole bridging and provides a deeper understanding thereof. Another independently motivated mechanism, namely that of Matching functions, gives rise to similar effects, but in contrast to the type-shifter, it depends heavily on contextual support and cannot account for the general availability of larger situation uses that is independent of the context. The anaphoric nature of the strong article is described and analyzed in detail in chapter 6. In addition to simple discourse anaphoric uses, I discuss covarying interpretations and relational anaphora (the type of bridging expressed by the strong article). Cases where uniqueness does not hold (e.g., in so-called bishop sentences) provide crucial evidence for the need to encode the anaphoric link between strongarticle definites and their antecedents formally. The resulting dynamic analysis of strong-article definites encodes the anaphoric dependency via a separate anaphoric element that is incorporated into a uniqueness meaning. Finally, remaining challenges for the analysis are discussed, in particular the existence of strong-article definites without an antecedent and a puzzling contrast between the articles with respect to relative clauses. The final chapter discusses some loose ends that suggest directions for future work and sums up the main conclusions.

This dissertation proposes a uniqueness-based theory of definiteness that accounts for the semantics and the pragmatics of German (non-) contracted forms of a preposition and the definite determiner (e.g. ‘zum / zu dem’, ‘am / an dem’), but the analysis also carries over to definite descriptions in general. I propose that the definite determiner is ambiguous between a referential and a quantificational reading. Crucially, referential DDs exploit information provided in the surrounding linguistic context, while the interpretation of quantificational DDs heavily relies on extra-linguistic world knowledge that can be represented by an implicit free individual variable and an implicit free relation variable. Non-contracted forms are always interpreted referentially, whereas contracted forms receive quantificational interpretations. This proposal has a wide range of applications: It deals with anaphoric and demonstrative DDs, as well as with typical ‘uniqueness uses’ (such as ‘the moon’ or ‘the sun’), covarying DDs involving explicit and implicit antecedents, bridging definites, and, last but not least, so-called Weak Definites.