What is emergentism and how does it relate to second language acquisition? What is the evidence for it?
Emergentism is the view that SLA occurs "bottom-up," that is, learners use general mechanisms to acquire an L2, as opposed to innate language-specific methods.
From this perspective, the basic idea is that grammatical rules and other formal aspects of language 'emerge' (that is, are constructed and abstracted) from language use and experience, rather than being innate, or learned as abstract structures? (Second Language Learning Theories, by R. Mitchell, F. Myles & E. Marsden, 3 ed., p. 99)
One model, proposed by N.C. Ellis in multiple papers, breaks emergentism down into the "CREED model."
Construction-based: Learners identify abstract constructions, such as "give [someone] [something]," and recycle them. Constructions aren't limited to syntax, either, and can include lexical items, and morphosyntax.
Rational: This expresses the idea that the mind stores representations of the most likely relevant forms in discourse, which are continually updated.
Exemplar-drived: An exemplar is an example of a certain form. (I don't know why they don't call them examples). As you hear more exemplars, you build up a statistical representation of the most common forms of a construction like
Verb + Adverb, which lets you guess at how to use new verbs and adverbs you acquire.
Emergent: The basic idea that structure is determined from what forms a speaker is exposed to rather than relying on underlying (e.g. UG) rules.
Dialectic: Finally, language must appear in context, and interations with interlocutors and conscious learning aid an L2 learner.
Emergentism is closely related to the idea of statistical learning (or "chunking").