Document Type : Research Paper
Author
PhD in General Linguistics / University of Tehran
Abstract
This article aims to defend the Parallel Morphology Hypothesis as the theoretical foundation of the Optimal Distributed Morphology (ODM) framework. Unlike the standard rule-based model of Distributed Morphology (DM), which assumes a rigid, feed-forward derivational architecture comprising sequential morphosyntactic modules, the parallel hypothesis posits that all post-syntactic operations occur simultaneously within a constraint-based evaluative system. Building upon insights from Trommer (2001a, 2001b) and Foley (2017), the article argues that adherence to the Derivational Architecture Principle (DAP) in classical DM leads to a form of circular reasoning when analyzing irregular inflectional forms. Specifically, decisions regarding operations such as feature bundle fusion or fission often presuppose knowledge of which Vocabulary Items will be inserted. A knowledge that, in a strictly sequential model, should not yet be accessible.
Using representative data from languages such as English and Basque, the article demonstrates that attempts to resolve this paradox within a strictly modular, rule-based DM architecture require extensive stipulations and ad hoc rules. These additions not only undermine theoretical elegance but also compromise the model’s psychological and computational plausibility. In contrast, adopting a constraint-based approach grounded in Optimality Theory (OT), as formalized in the ODM framework, allows for a more economical and predictive analysis. Here, the derivational output is determined through the competition of candidate structures evaluated by violable constraints, rather than deterministic rule application.
A constraint-based analysis of irregular plural formation (e.g., mice vs. mouses) is provided, incorporating three key constraints: *UNDERSPEC, *STRUCT, and CRSP-D. These constraints regulate under-specification, structural economy, and faithfulness to input feature bundles, respectively. Through a formal ranking procedure (Recursive Constraint Demotion), the paper shows how ODM naturally accounts for both regular and irregular morphology without recourse to excessive derivational opacity or lexical idiosyncrasies.
The article concludes that the Parallel Morphology Hypothesis not only offers a more descriptively adequate account of inflectional irregularities but also aligns more closely with broader cognitive and psycholinguistic principles of linguistic architecture.
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