Funding information Research Council of Norway for the project MiMS (Microvariation in Multilingual Acquisition & Attrition Situations), Grant/ Award Number: 250857 Abstract This paper discusses the interplay between acquisition and theory construction. It endeavors to show how a more direct and crucially bi-directional relationship between formal linguistic theory and the study of heritage language bilingualism can provide mutual benefit. It will be argued that data from acquisition—not exclusively but indeed especially from heritage language bilingualism—provide windows into the tenability of formal linguistic proposals. As a result, acquisition evidence—both developmental and in ultimate attainment—should be welcomed by all formal theorists, as they can confirm or disconfirm otherwise seemingly unverifiable theoretical arguments. Our claims will be illustrated by three research areas: language change, differences between functional and lexical features, and the interplay between core syntax and other components of the grammar.

中文翻译：

---

传承语言习得：它揭示的内容以及为什么它对正式的语言理论很重要

挪威资助信息研究委员会的MiMS（多语种习得和减员情况中的微变）项目，资助/获奖号：250857摘要本文讨论了习得与理论构建之间的相互作用。它试图说明形式语言理论与传统语言双语研究之间的更直接和至关重要的双向关系如何能够带来互惠互利。可以说，来自获取的数据（不仅是排他性的，而且确实是从遗产语言双语学中获取的）确实为形式语言建议的持久性提供了窗口。结果，所有正式的理论家都应该欢迎获得的证据，包括发展性的和最终的成就，因为他们可以证实或不赞成原本看似不可验证的理论论证。