Dynamic semantics

Dynamic semantics is a framework within formal semantics and logic that conceptualizes the meaning of linguistic expressions, particularly sentences, as their capacity to update or modify an ongoing discourse context or information state, rather than as fixed truth-conditional content in isolation.^[1] This approach addresses limitations of static semantic theories by accounting for contextual dependencies, such as anaphora and presupposition, through dynamic processes that accumulate information across utterances.^[1] The foundational ideas of dynamic semantics emerged in the early 1980s, primarily through two independent but closely related contributions. Hans Kamp introduced Discourse Representation Theory (DRT) in his 1981 paper "A Theory of Truth and Semantic Representation," published in 1984, which models discourse interpretation via mental representations that evolve with each sentence, introducing discourse referents for entities and relations that bind pronouns and resolve anaphoric links.^[1] Concurrently, Irene Heim developed File Change Semantics in her 1982 doctoral dissertation "The Semantics of Definite and Indefinite Noun Phrases," framing semantic interpretation as incremental updates to a "file" of information cards representing the common ground, with indefinites adding new entries and definites requiring familiarity conditions. These theories shifted focus from sentence-level truth to inter-sentential coherence, enabling compositional analyses of complex discourses.^[1] Subsequent developments refined and generalized dynamic semantics. In 1991, Jeroen Groenendijk and Martin Stokhof proposed Dynamic Predicate Logic (DPL), a non-representational, compositional extension of first-order logic where connectives and quantifiers are interpreted dynamically, allowing variables to bind across clause boundaries and handling phenomena like donkey anaphora without intermediate structures.^[2] DPL's emphasis on variable assignments as information states influenced later work on presupposition projection, plurals, and tense.^[2] In recognition of their pioneering contributions, Hans Kamp and Irene Heim were jointly awarded the 2024 Rolf Schock Prize in Logic and Philosophy.^[3] Dynamic approaches have also integrated with type-theoretic frameworks, such as in Reinhard Muskens' 1996 work combining Montague semantics with discourse representation, facilitating broader applications in computational linguistics and cognitive modeling.^[4] Key features of dynamic semantics include its treatment of conjunction as non-commutative (order affects update outcomes), dynamic entailment (where premises update to entail conclusions), and mechanisms for accommodation in presupposition failure.^[4] It excels in explaining discourse-level phenomena, such as conditional perfection and evidentials, by viewing meaning as a transformative process akin to program execution in computational terms.^[2] While primarily applied to natural language, dynamic semantics draws from dynamic epistemic logics in philosophy and has inspired extensions to questions, imperatives, and multimodal discourses.^[4]

Introduction

Definition and Scope

Dynamic semantics is a theoretical approach in natural language semantics that conceptualizes the meaning of a sentence as its potential to update or modify an information state, rather than as a static truth value assigned independently of context.^[5] In this framework, interpretation involves a dynamic process where each utterance incrementally builds upon and alters the shared knowledge or discourse context, treating sentences as functions that transform input contexts into output contexts.^[6] This perspective shifts focus from isolated propositional content to the evolving nature of meaning in ongoing communication.^[7] The scope of dynamic semantics encompasses context-dependent linguistic phenomena, including anaphora, presuppositions, and the maintenance of discourse coherence, where the interpretation of expressions relies on prior utterances.^[8] It stands in contrast to static semantics, such as Montague grammar, which evaluates sentences compositionally for truth conditions relative to a fixed model, without accounting for inter-sentential dependencies.^[9] By modeling meaning as context change, dynamic semantics addresses how discourse accumulates information over sequences of sentences, enabling a unified treatment of both local and global interpretive effects.^[5] A primary motivation for dynamic semantics arises from the limitations of compositional static approaches in handling context-sensitive elements, like pronouns that refer back to antecedents in previous discourse.^[7] For instance, consider the pair: "A woman walks in the park. She sits down." In a static framework, the pronoun "she" would lack a clear referent without external resolution, but dynamic semantics interprets the first sentence as introducing a discourse referent for "a woman," which the second sentence then updates by binding "she" to it, ensuring coherent interpretation across the discourse.^[6] This mechanism highlights how dynamic theories capture the incremental, interactive buildup of meaning in natural language use.^[8]

Historical Background

The origins of dynamic semantics trace back to the 1970s, when linguists began addressing limitations in static truth-conditional approaches, particularly in handling anaphora and discourse structure. Lauri Karttunen's introduction of discourse referents in 1976 provided an early framework for tracking entities introduced in discourse, enabling incremental interpretation beyond isolated sentences.^[10] This work laid groundwork for viewing semantics as a process of updating contextual information, influencing subsequent dynamic models. Meanwhile, Richard Montague's formal semantics in the early 1970s established a compositional, truth-conditional paradigm but struggled with phenomena like pronoun resolution across sentences.^[11] A pivotal milestone came in 1981 with Hans Kamp's Discourse Representation Theory (DRT), which formalized semantics as the construction and update of discourse representation structures to account for anaphora and truth conditions in connected discourse.^[1] Kamp's "A Theory of Truth and Semantic Representation" shifted focus from static denotations to dynamic processes, integrating insights from Karttunen and enabling compositional analysis of discourse. Independently, Irene Heim developed File Change Semantics in her 1982 doctoral dissertation "The Semantics of Definite and Indefinite Noun Phrases," offering a similar framework that models context as a "file" of information states updated by sentences, particularly refining the treatment of definite and indefinite noun phrases.^[12] Heim's approach emphasized familiarity conditions for referents, bridging presupposition and anaphora in a unified dynamic framework. In the 1990s, dynamic semantics advanced through the work of Jeroen Groenendijk, Martin Stokhof, and Frank Veltman, who developed update semantics to formalize context as evolving information states. Groenendijk and Stokhof's 1991 Dynamic Predicate Logic (DPL) recast first-order logic as relations between input and output information states, enhancing handling of quantification and scope in discourse.^[2] Veltman's 1996 update semantics further incorporated defaults and non-monotonic reasoning, drawing influences from logic programming to model epistemic updates and conditionals.^[13] These developments marked a maturation of dynamic approaches, emphasizing incremental interpretation over Montague-style static models and establishing core tools for later linguistic theories.^[14]

Foundational Concepts

Context and Information States

In dynamic semantics, the context is formally represented as an evolving information state, typically modeled as a set of possible worlds, variable assignments, or discourse referents that captures the partial knowledge accumulated during discourse.^[14] This representation allows sentences to update the context incrementally, reflecting how linguistic expressions modify the shared information among interlocutors rather than merely describing static truths.^[15] Information states embody this partial information about the world, serving as the input to semantic interpretation and the output of updates. Assertions add constraints by intersecting the current state with new possibilities, thereby narrowing the set of compatible scenarios, while tests filter states by checking consistency without adding new information. Formally, if C denotes the current context (an information state) and \phi a sentence, the updated context is C[\phi], the result of applying \phi's context change potential to C; alternatively, the notation [[ \phi ]]_{C} denotes the set of output states reachable from C via \phi.^[16] In systems using possible worlds, such as update semantics, an information state \sigma is a subset of worlds W, updated by an atomic assertion p as \sigma = \{ w \in \sigma \mid p holds at w \}.^[13] In assignment-based approaches, states are sets of variable assignments, updated relationally to track discourse referents.^[16] These updates exhibit key properties that ensure systematic information growth. Monotonicity guarantees that if one state \sigma is a subset of another \tau, then \sigma[\phi] \subseteq \tau[\phi], meaning additional prior information does not lead to less information post-update. Compositionality holds dynamically, where the meaning of complex expressions is derived from the composition of their parts' context change potentials, such as sequential application for conjunction.^[16] For example, updating an initial context C (all possible worlds) with "It is raining" yields C' = \{ w \in C \mid raining holds at w \}, eliminating worlds incompatible with rain and thereby refining the interlocutors' shared knowledge. This mechanism briefly accommodates variable bindings, which extend states to link pronouns or descriptions to prior discourse elements.^[16]

Bindings and Anaphora Resolution

In dynamic semantics, indefinite noun phrases introduce variables that bind to new discourse referents, updating the information state to make these referents available for reference in subsequent discourse. This process contrasts with static semantics, where indefinites function as existential quantifiers with scope limited to their immediate clause, preventing cross-sentential accessibility.^[2] For instance, in the discourse "John has a book. It is interesting," the indefinite "a book" establishes a discourse referent for the variable, which the pronoun "it" can then access through dynamic binding, ensuring coherent anaphora resolution. Anaphora resolution in dynamic semantics relies on pronouns being treated as free variables whose values are determined by the dynamic scope of prior bindings, rather than as unbound elements requiring separate resolution mechanisms.^[2] This approach allows pronouns to link to antecedents introduced earlier in the discourse, as the information state propagates updated assignments forward. Formally, indefinites operate as existential quantifiers whose scope extends dynamically across sentences, introducing pairs of variable-value assignments that persist; anaphoric pronouns then resolve by selecting compatible values from this updated state.^[2] A key challenge addressed by dynamic bindings is the interpretation of donkey sentences, such as "If a farmer owns a donkey, he beats it," where the pronoun "it" must covary with the indefinite "a donkey" embedded under a conditional. In static frameworks, this leads to issues with quantifier scope and unbound pronouns, but dynamic semantics resolves it by quantifying over sequences of assignments, allowing the indefinite to bind the pronoun universally within the conditional's dynamic scope.^[2] This mechanism ensures that the discourse referent for the donkey is available to "it" in a way that captures the intended conditional dependency without requiring intermediate quantifier raising.

Key Frameworks

Discourse Representation Theory

Discourse Representation Theory (DRT), developed by Hans Kamp in 1981, is a foundational framework in dynamic semantics that models the interpretation of natural language discourses through structured representations of information.^[17] It addresses how successive sentences in a discourse contribute to an evolving mental model of the described situation, emphasizing the compositional buildup of meaning across utterances.^[17] At the core of DRT are Discourse Representation Structures (DRSs), which serve as the primary representational units. A DRS is visualized as a "box" containing two components: a universe of discourse referents, typically represented as variables (e.g., x, y) that stand for entities introduced in the discourse, and a set of conditions, which are atomic predicates or equations relating these referents (e.g., \textit{man}(x), x = y).^[17] These structures capture the partial information state resulting from processing the discourse up to a given point, allowing for the representation of unresolved references and dependencies.^[17] The construction of DRSs proceeds incrementally as sentences are interpreted. Indefinite noun phrases, such as "a man," introduce new discourse referents into the main DRS universe and add corresponding conditions, thereby expanding the information state.^[17] Quantifiers like universals ("every") trigger the embedding of subordinate DRSs within the main structure, creating scoped environments where referents in the superior DRS are accessible to the embedded one, thus handling scope interactions dynamically.^[17] This incremental process ensures that each sentence updates the overall DRS in a way that reflects the discourse's evolving context.^[17] Anaphora resolution in DRT relies on the accessibility of discourse referents across DRS embeddings. Pronouns, such as "he," are interpreted by coreferring to an appropriate antecedent referent in the same or an accessible superior DRS, provided no conflicting conditions block the resolution.^[17] This mechanism naturally accounts for phenomena like pronoun binding without requiring static scope rules, as the hierarchical structure of DRSs enforces resolution constraints based on embedding relations.^[17] Formally, the semantics of DRT defines truth conditions for DRSs relative to models through a recursive verification procedure. A DRS is true in a model if there exists an embedding function mapping its discourse referents to model entities such that all conditions are satisfied; for embedded DRSs, this extends by requiring successful embeddings for both the superior and subordinate structures.^[17] This model-theoretic interpretation aligns DRT with classical logic while extending it to discourse dynamics.^[17] A classic example illustrates DRS construction and anaphora: Consider the discourse "A man whistles. He walks." The first sentence introduces a referent x and conditions \textit{man}(x), \textit{whistles}(x) in the main DRS. The second sentence resolves "he" to x (the most accessible antecedent), adding the condition \textit{walks}(x) to the same DRS, yielding a unified structure where x satisfies all predicates.^[17] DRT's key advantage lies in its ability to handle discourse-level phenomena, such as anaphora and tense, compositionally within a single representational framework, providing a unified account of how discourses build coherent interpretations.^[17]

Update Semantics

Update semantics is a procedural framework within dynamic semantics, developed by Jeroen Groenendijk, Martin Stokhof, and Frank Veltman, in which the meaning of a sentence is understood as a context change potential—a function that transforms an input information state (context) into an updated output state.^[18] This approach shifts focus from static truth conditions to how utterances incrementally modify the shared information in discourse.^[18] The basic update rule treats atomic sentences as tests on the current information state: an atomic proposition p updates a state s by eliminating possibilities in s where p fails to hold, resulting in s = \{ w \in s \mid p is true at w \}.^[13] Complex sentences compose these updates either sequentially or in parallel; for instance, negation \neg \phi updates by excluding the possibilities eliminated by \phi, yielding s[\neg \phi] = s \setminus s[\phi].^[13] At its core, update semantics employs intersective updates, where an assertion intersects the current state with the propositional content of the sentence, thereby refining the set of possible worlds or indexed possibilities to those compatible with the new information.^[18] This mechanism ensures monotonic refinement of the context, assuming no presupposition failure.^[18] Compositionality in update semantics defines logical connectives dynamically: conjunction \phi \land \psi performs sequential update, first applying \phi to the input state and then \psi to the result, formalized as

s[\phi \land \psi] = s[\phi][\psi].

^[18] Disjunction \phi \lor \psi takes the union of possibilities updated by \phi and those updated by \psi after excluding \phi, expressed as s[\phi \lor \psi] = s[\phi] \cup s[\neg \phi][\psi], allowing non-monotonic effects in certain cases.^[18] A representative example is the definite description in "The king of France is bald," which updates an information state by filtering to possibilities where there is exactly one salient referent satisfying "king of France" and that referent is bald; states lacking such a unique referent yield an undefined or empty update, accommodating presuppositional behavior.^[18]

Advanced Topics

Handling Presuppositions

In dynamic semantics, presuppositions are background assumptions triggered by specific linguistic expressions, such as definite descriptions (e.g., "the king of France") or factive verbs (e.g., "regret"), which must be satisfied by the context for the sentence to be appropriately uttered.^[19] These assumptions differ from assertions in that they project through embeddings like negation or questions, remaining as requirements on the global context.^[20] Dynamic semantics treats presuppositions as preconditions on context change potentials (CCPs), where a sentence's update to an information state is only defined if the presuppositions hold in that state; otherwise, the resulting context is undefined.^[20] This approach, formalized in Heim's satisfaction theory, extends file change semantics by requiring local satisfaction: for embedded sentences, presuppositions must be entailed by a temporary context derived from the embedding operator.^[20] Failure to satisfy these preconditions halts the update, modeling the infelicity of presupposition failure.^[21] A key mechanism for handling presuppositions is accommodation, whereby if a presupposition is not satisfied by the current context, it is added to the context to make the update possible, often without explicit assertion.^[21] This process can be global (adding to the entire common ground) or local (within a specific embedding), depending on the trigger and operator.^[20] In contrast to static theories, dynamic approaches distinguish filtering—where a presupposition of a conjunct is entailed by the preceding context and thus filtered out—from strengthening, where the presupposition is incorporated into the assertion of the sentence to ensure satisfaction.^[20] For instance, in "If John has a son, his son is bald," the presupposition of "his son" (that John has a son) is filtered by the antecedent, avoiding global commitment.^[20] Consider the sentence "John regrets smoking," where the factive verb "regrets" presupposes that John smokes. In a dynamic framework, the update succeeds only if the input context entails this presupposition; if not, accommodation adds "John smokes" to the context before applying the assertion that John has a negative attitude toward it.^[21] This ensures the sentence's felicity while distinguishing the presupposed content from the at-issue update. The projection problem addresses how presuppositions "project" from embedded positions to become global requirements, as in "John does not regret smoking," which still presupposes that John smokes despite the negation.^[20] Dynamic semantics resolves this through context inheritance: operators like negation create a local context that inherits the global presuppositions, requiring satisfaction in both local and global states without filtering the trigger's presupposition.^[20] This compositional mechanism predicts projection patterns for connectives and embeddings, unifying presupposition handling with general discourse updates.^[20]

Modals and Conditionals

In dynamic semantics, modal operators such as necessity (□φ) and possibility (◇φ) are analyzed through test semantics, which differs from the intersective updates used for declarative assertions. The necessity operator □φ functions as a test on the current information state s, succeeding only if φ holds in every world compatible with s; formally, this is captured as s[□φ] = s whenever s[φ] = s, and undefined (or leading to the absurd state) otherwise.^[22] This filtering mechanism ensures that □φ verifies epistemic necessity without altering the underlying possibilities, thereby preserving the context for further discourse updates. Such tests reflect how modals express commitments relative to accessible worlds, emphasizing compatibility rather than outright assertion.^[23] However, pure test semantics faces challenges in handling modal subordination, where subsequent utterances build on the possibilities introduced by modals (e.g., "A wolf might come in. It will eat you if it does"), leading to extensions in dynamic epistemic logic or alternative approaches using selection functions.^[14] The possibility operator ◇φ is similarly treated as a test: s[◇φ] = s if s[φ] ≠ ∅ (i.e., φ is compatible with s), and undefined otherwise.^[22] This tests for epistemic possibility without expanding the state, though extensions address subordination by allowing hypothetical branches.^[23] Unlike standard assertions that narrow the state via intersection (s[φ] = s ∩ ||φ||), modals like ◇φ verify compatibility, accommodating modal subordination where later utterances build on the introduced possibilities in advanced frameworks.^[23] Conditionals, such as "if φ then ψ," extend this dynamic approach by combining testing and updating: the antecedent φ is first tested (filtering to states where φ is compatible), followed by an update with the consequent ψ in the resulting hypothetical context. Formally, s["if φ then ψ"] = s[φ][ψ], where [φ] acts as a test ensuring s[φ] ≠ ∅ before applying the intersective update [ψ].^[23] This semantics captures the conditional's role in restricting outcomes selectively, as in the example "If it rains, we stay home": the update tests for rain-compatible states in the current context and then restricts those to worlds where staying home holds, without committing to rain occurring outright.^[22] Alternative formulations employ selection functions to pick a φ-world from s and evaluate ψ relative to it, yielding s["if φ then ψ"] = {w ∈ s | f(w, φ) ∈ ||ψ||}, where f is a contextual selector, which integrates hypothetical reasoning while avoiding global intersections.^[23] These treatments highlight key differences from intersective semantics: modals and conditionals do not merely narrow the information state but test compatibility or branch into selected subcontexts, facilitating complex interactions like embedded discourse and non-monotonic updates.^[22] For instance, a conditional can project possibilities outward, allowing "If John comes, he might bring Mary" to introduce a new modal scope without collapsing antecedent and consequent worlds. This selective dynamics ensures that modals and conditionals support incremental information growth, central to natural language interpretation.^[23]