In this commentary, I question Westergaard's argument that third language (L3) data can be used to decide between theories such as Full Transfer Full Access, involving wholesale transfer initially, and Full Transfer Potential, involving property-by-property transfer. I suggest that much L3 data will be amenable to explanation under either theory.…

Westergaard (2021) presents an updated account of the Linguistic Proximity Model and the micro-cue approach to the parser as an acquisition device. The property-by-property view of transfer inherent in this approach contrasts with other influential models that assume that third language (L3) acquisition involves the creation of a full copy of only…

This provocative article raises many important issues that need to be addressed and in so doing will advance the fields of second language (L2) and third language (L3) acquisition in several important ways. Fundamental questions concerning multilingual development persist especially with respect to the role of Universal Grammar in this language…

In her keynote article advocating the Linguistic Proximity Model for third language (L3) acquisition, Westergaard (2021) presents several arguments against 'copying and restructuring' in nonnative language acquisition, mechanisms central to Schwartz and Sprouse's (1996) Full Transfer/Full Access model of second language (L2) acquisition. In this…

This article is a response to commentaries on the article, "Microvariation in Multilingual Situations: The Importance of Property-by-Property Acquisition" (EJ1300541). This response is divided into sections focusing on the following issues: (1) full transfer and the notion of copying; (2) the definition of linguistic proximity; (3) some…

This commentary discusses Westergaard's (2021) keynote article, which presents a comprehensive model of first language (L1), second language (L2), and third language (L3) acquisition. The commentary presents evidence from a previous study of L3 learners that provides support for Westergaard's property-by-property transfer proposal. The commentary…

This article offers commentary that the Multiple Grammar (MG) language acquisition theory proposed by Luiz Amaral and Tom Roeper (A&R) in the present issue lacks elaboration of the psychological mechanisms at work in second language acquisition. Topics discussed include optionality in a speaker's grammar and the rules of verb position in…

Amaral and Roeper (this issue; henceforth A&R) argue that all speakers -- regardless of whether monolingual or bilingual -- have multiple grammars in their mental language representations. They further claim that this simple assumption can explain many things: optionality in second language (L2) language behaviour, multilingualism, language…

In this commentary, the author defends the Multiple Grammars (MG) theory proposed by Luiz Amaral and Tom Roepe (A&R) in the present issue. Topics discussed include second language acquisition, the concept of developmental optionality, and the idea that structural decisions involve the lexical dimension. The author states that A&R's…

This article offers the author's commentary on the Multiple Grammars (MG) language acquisition theory proposed by Luiz Amaral and Tom Roeper in the present issue. Multiple Grammars advances the claim that optionality is a constitutive characteristic of any one grammar, with interlanguage grammars being perhaps the clearest examples of a…

This article offers commentary on the Multiple Grammars (MG) language acquisition theory proposed by Luiz Amaral and Tom Roeper in this issue. It argues that more precise definitions are needed for the terms "rule," "simple," and "productive." Topics discussed include Amaral and Roeper's verb second (V2) rule,…

Amaral & Roeper's Multiple Grammars (MG) proposal offers an appealingly simple way of thinking about the linguistic representations of bilingual speakers. This article presents a commentary on the MG language acquisition theory proposed by Luiz Amaral and Tom Roeper in this issue, focusing on the theory's implications for child…

Optionality is a central phenomenon in second language acquisition (SLA), for which any adequate theory must account. Amaral and Roeper (this issue; henceforth A&R) offer an appealing approach to it, using Roeper's Multiple Grammars Theory, which was created with first language in mind but which extends very naturally to SLA. They include…

The central claim in Amaral and Roeper's (this issue; henceforth A&R) keynote article is that everyone is multilingual, whether they speak one or more languages. In a nutshell, the idea is that each speaker has multiple grammars or "sub-sets of rules (or sub-grammars) that co-exist". Thus, rather than positing complex rules to…

This article offers the author's commentary on the Multiple Grammar (MG) language acquisition theory proposed by Luiz Amaral and Tom Roeper in the present issue and touches on other second language acquisition research. Topics discussed include the concept of second language (L2) optionality, a hypothesis regarding the acquisition of the…