Discuss the pros and cons of using internal vs external evidence in morphological theory. As an entrée into the debate, consider for example the following quote from Singh (1982):

"Contemporary linguistics divides linguistic evidence into two types: 'internal' and 'external'. For some, the former alone is relevant. They see the latter as necessarily vitiated by what Roeper (1982) calls 'intervening variables'. For others, the former has a privileged and the latter a secondary, supporting status (cf. Kiparsky 1968, Hyman 1970, Hooper 1976, and Fromkin 1973, amongst others). While no one explicitly rules out 'external' evidence, it is generally suspect and at best treated as icing on the cake. I would, however, like to plead that so-called internal evidence is perhaps no evidence at all [...] Although it is true that intervening variables do vitiate system-external data, we must sort through the mess rather than adopt the strong version of the distortion hypothesis."

In your discussion you can discuss any sort(s) of internal and external evidence that you find particularly interesting or compelling, but given our set of lecture topics in Michaelmas you may find it easier to (i) focus just on diachronic evidence or just on acquisition evidence, or (ii) consider both acquisition and change (as opposed to the many other domains which are potentially relevant such as speech errors, grammaticality judgements, etc., though you are welcome to address these as well/instead if you prefer).

Suggested/optional readings:

Archibald, J. & G. Libben. 2019. Morphological theory and second language acquisition. In: J. Audring & F. Masini (eds). The Oxford Handbook of Morphological Theory. Oxford: OUP, 522-540.

Blom, E. 2019. Morphological theory and first language acquisition. In: J. Audring & F. Masini (eds). The Oxford Handbook of Morphological Theory. Oxford: OUP, 511-521.

Botha, Peter. 1979. External evidence in the validation of mentalistic theories: a Chomskyan paradox. (pdf)

Bybee, Joan. 1988. The diachronic dimension in explanation. In: J. Hawkins (ed.). Explaining Language Universals. Oxford: Blackwell, 350-379. (pdf)

Clark, E. 2001. Morphology in Language Acquisition. In: A. Spencer & A. Zwicky (eds). The Handbook of Morphology. London: Blackwell, 374-389.

Gamache, Jessica and Cristina Schmitt. 2012. Children’s forms as derivational steps: external evidence for a new synthetic compound structure. (pdf)

Hüning, M. (2019). Morphological theory and diachronic change: In: J. Audring & F. Masini (eds). The Oxford Handbook of Morphological Theory. Oxford: OUP, 476-492.

Lignos, C. & C. Yang. 2017. Morphology and Language Acquisition. The Cambridge Handbook of Morphology. Cambridge: CUP, 765-791.

Prunet, Jean-Francois. 2006. External evidence and the Semitic root. Morphology 16:41–67. (pdf)

Singh, Rajendra. 1982. In defense of external evidence. Canadian Journal of Linguistics 33.4:329-343. (pdf)

Singh, Rajendra. 1988. How to Live with External Evidence in Phonology: A Note on the Challenge of Interference. Canadian Journal of Linguistics/Revue Canadienne De Linguistique, 33(4), 423-429. (pdf)

Zwicky, Arnold. 1980. Internal and external evidence in linguistics. (pdf)

Zwicky, Arnold. 1986. In and out in phonology. Ohio State University Working Papers in Linguistics 32:34-45. (pdf)

Advanced readings:

Dressler, Wolfgang, C. Schaner-Wolles & W. Grossmann. 1985. On the acquisition of morphology in normal children and children with Down's syndrome. Studia gramatyczne 7:13-26. (pdf)

Hale, Kenneth. 1973. Deep-surface canonical disparities in relation to analysis and change: an Australian example. (pdf)