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argumentation-schemes

The argumentation-schemes crate provides Walton's argumentation schemes (Walton, Reed & Macagno 2008): a catalogue of presumptive reasoning patterns — argument from expert opinion, ad hominem, argument from consequences, and more — each with named premise slots, a conclusion template, and critical questions that probe its weak points. Scheme instances compile to ASPIC+ premises and defeasible rules, which can then be evaluated via the argumentation crate's Dung semantics. The crate also includes AIF (Argument Interchange Format) serialisation and helpers for wiring schemes directly into StructuredSystem.

Crate: argumentation-schemes (crates.io · rustdoc)

Key types​

SchemeSpec​

The compile-time definition of one argumentation scheme: a unique id, canonical name, premise slots, conclusion template, critical questions, and bibliographic metadata. Instantiate with concrete bindings via SchemeSpec::instantiate(&bindings) or the free function instantiate(scheme, &bindings). → Full docs

SchemeInstance​

The result of instantiating a SchemeSpec with concrete bindings. Holds the resolved premises (as Literal values), the resolved conclusion Literal, and the instantiated critical questions. Pass it to add_scheme_to_system to wire it into an ASPIC+ StructuredSystem. → Full docs

CatalogRegistry​

An in-memory collection of schemes indexed by id, snake_case key, and category. Obtain the full Walton 2008 catalogue via default_catalog() or CatalogRegistry::with_walton_catalog(). Use by_key("argument_from_expert_opinion") for lookup; keys are derived by lowercasing the scheme name and replacing spaces and hyphens with underscores. → Full docs

PremiseSlot​

A named premise slot in a scheme definition. Has a name (used as the binding key), description, and SlotRole (Agent, Proposition, Domain, etc.). → Full docs

ConclusionTemplate​

Template for a scheme's conclusion literal. Slot references use ?slot_name syntax and are resolved at instantiation time. is_negated controls whether the conclusion literal is constructed as a negation (for rebuttal-concluding schemes like ad hominem). → Full docs

CriticalQuestionInstance​

An instantiated critical question — a follow-up challenge a competent reasoner would raise. Holds the question text and the Challenge type (PremiseTruth, ExpertReliability, etc.). → Full docs

Key functions / methods​

FunctionReturnsWhat it does
catalog::default_catalog()CatalogRegistryReturns a registry preloaded with the full Walton 2008 scheme catalogue.
instantiate(scheme, &bindings)Result<SchemeInstance>Free-function instantiation of a scheme with a HashMap<String, String> of bindings. Fails if any required slot is missing.
SchemeSpec::instantiate(&self, &bindings)Result<SchemeInstance>Convenience method delegating to the free function above.
CatalogRegistry::by_key(&self, key)Option<&SchemeSpec>Lookup by snake_case key (e.g., "argument_from_expert_opinion").
CatalogRegistry::by_category(&self, category)Vec<&SchemeSpec>Filter schemes by SchemeCategory (Epistemic, Practical, Causal, etc.).
aspic::add_scheme_to_system(&mut sys, &instance)()Adds the scheme instance's premises and defeasible conclusion rule to a StructuredSystem.
aspic::add_counter_argument(&mut sys, &instance, &target)()Adds a scheme instance as a counter-argument (rebut) attacking target in a StructuredSystem.
aif::instance_to_aif(&instance)AifDocumentSerialises a scheme instance to AIF (Argument Interchange Format).
aif::aif_to_instance(&doc, &registry)Result<SchemeInstance>Deserialises an AIF document back to a scheme instance, looking up the scheme in registry.

Errors​

Error::MissingBinding { scheme, slot }​

A required premise slot had no binding provided at instantiation time.

Error::SchemeNotFound(String)​

A scheme key or id was not found in the registry.

Error::Aspic(String)​

An ASPIC+ structural error when adding a scheme to a StructuredSystem.

See also​