The document discusses theories of language acquisition, including the innateness theory and three other theories. The innateness theory proposes that language ability is innate in humans and emerges according to a critical period. The imitation theory suggests that children learn language through imitation. However, this theory cannot account for inaccuracies in children's speech or their ability to understand new sentences. The reinforcement theory claims children are reinforced for using correct forms, but corrections often focus on meaning, not grammar. The active construction theory posits that children invent their own grammar rules based on the speech they hear.