Softcopy notes were given, I just copy paste the key points

Theories 1. Behaviourist Theory
By Skinner (1957), language is learnt. Language is acquired by conditioning and reinforcement. Listening and responding to input is sufficient.

Theories 2: Nativism
Maintains that using a language requires a set of highly abstract, unconscious rules – a universal grammar that is innate and common to all languages. Argues that the cognitive abilities that support language development are highly specific to language.

Evidence for this position is provided by the universal and species-specific nature of language, and by observations of invented sign language among groups of deaf children that imposes grammatical structure onto simple signs. The approach is criticized for focusing almost exclusively on syntax and ignoring the communicative role of language