Code-switching beyond phases

This study examines the syntactic structure of Urdu–English code-switching (CS) through a lens of Phase Theory, focusing on parametric variation between two languages. Recognizing CS as a vibrate domain of contact language, this analysis assumes that bilingual syntax is governed by the universal computational principles. Employing a <i>mixed-method research</i> design, this study gathers naturalistic data from balanced Urdu–English bilinguals. Findings reveal frequent use of phase heads—<i>That</i> in English and <i>keh</i> in Urdu—as well as light verbs <i>kar</i> and <i>ho</i>, each showing distinct preferences in bilingual context. The Urdu complementizer <i>keh</i> introduces embedded clauses irrespective of clausal mood and notably does not project a specifier position. Moreover, verbal phase heads are categorized into agentive and stative types based on <i>argument structure</i>. These light verbs are selected not by tense phrase (TP), but by the aspect head <i>Asp</i>, which intervenes between the <i>v</i>P and TP. In Urdu–English CS, light verbs are embedded within a layered structure comprising voice, aspect and tense—each computing language-specific features independently. The findings support Phase Theory, affirming that syntactic derivation precedes in discrete, hierarchical phases, validating a universal <i>bilingual architecture</i>.