Chomsky's theory proposes that the human brain contains a predefined mechanism (UG) that is the basis for the acquisition of all languages. “In analogy, the brain can be thought of as a kind of partially programmed machine ready to be configured”. (Tronolone) So, Chomsky says that a person individual grammar is developed from the interaction between the innate UG and the input from the environment (primary linguistic data): (McGilvary, 2005) Chomsky has stayed “I think, yet the world thinks in me”. This is an evident example of his theory: humans are natural beings and have undergone evolution (UG) common to all humans. One way to approach this concept is posing a hypothetical question: Why does a child learn the language the way it does? If we come back to Plato’s problem: the problem of finding and explanation for how a child acquires language though the child does not receive explicit instruction and the input a child receives is limited, we will be able to identify a limited environmental stimulus referred to a Poverty of stimulus. This means that natural language grammar is unlearnable given the relatively limited data available to children learning a language, and therefore that this knowledge is supplemented with some sort of innate linguistic capacity. And also humans are born with a specific representational adaptation for language that both funds and limits their competence to acquire specific types of natural languages over the course of their cognitive development and linguistic maturation. The Poverty of stimulus arguments attempts to explain how native speakers form a capacity to identify possible and impossible interpretations through ordinary experience. Essentially, stimulus (from the environment necessary to develop an individual’s grammar via UG) is not an entirely adequate way to explain the process UG + input = Grammar.