The question of language deficit is also polarized by the debate over language. Proficiency in a language usually includes being able to speak, read, write, and listen; and to be competent in a standardized version in many domains. Due to education and migration forces (See 21st Century), and language mixing- this level of competence is not often reached. Bilinguals and multilingual speakers do not always have the same level of competence in each language, or have poor ability levels in more than one language. (See also Cognitive and Psychological.)
This appears to be a deficiency view of language, that also requires a ‘corpus’ or static body of language structure. In addition, the claim is that students/speakers draw on different parts of their linguistic repertoire and this is not deficiency. Perhaps it is more clearly a deficit only in school settings or other institutional domains where a comprehensive proficiency by domain is needed, such as writing as well as reading and speaking.
Then, is language hybridity semi-lingualism and language deficit or a reconceptualized natural view of language evolution? One view is that the claim relies on the static views of language as a bounded system. However, an overemphasis on blurring the boundaries and calling it hybridity becomes an easy way to not have to do anything about the loss of languages
“the diagnostic of language deficit…becomes a fuzzy concept with many ingredients of deficiency, but as well useful for an appeal to responsibility to do something against its detrimental consequences ….to explain things away…The modern emancipatory attempts may appear reductive when they clash with postmodern deconstructionism. It can be argued once again that linguistic classifications play a major role in justifying the salaries of linguists rather than helping the poor and needy” (Tochon, 2009)
Semilingualism can cause impoverished inner identities when a polarization because competence, cultural competence or detachment occurs through language. It can polarize communities or families when some are more linguistically competent, or some don’t speak the language at all.
For researchers and language preservationists, particularly with immigrant populations and endangered languages, the question is how to classify language and what to do with it- contribute to preserving a corpus or allowing the language to evolve and mix with a dominant language.
See Language Variations, Oral Languages.