[MannoFr]

Initially,

Language does not reflect a society's cognitive development, nor the cognitive development of a human being, except in a limited evolutionary sense.

Anyone who has done programming understands that language is merely syntax.

Now, I have said language is merely syntax.

Common language by itself is simply too imprecise. Then,
The evolution of common, crude imprecise language that by modern standards, decades of education serve to rectify.

Language is as much a cultural phenomenon as it is a measure of cognitive development.

However, the structure underlying that language may require enormous amounts of mental ability to grasp.

Now, enhanced language skills might aid one's memory, attention, perception and mental imagery. And now,

Undeniably, a well-developed language will play some role (the degree will vary) in the cognitive development of certain individuals. The above quoted specific statements, in three specific parts, clearly show a gradual shift from a heedless complete denial to a reasonable acceptance of the undeniable fact that a well-developed language undeniably plays an important and decisive role in the cognitive development of society.

Gladly, the discussion so far has successfully yielded one more individual from the state of complete denial to the state of acceptance of the undeniable fact. This is more than sufficient, irrespective of the incorrect demarcation of the degree and the number of individuals involved, as it is equally applicable to all societies.

Given identical spread of human abilities, those 'certain' individuals would translate into a percentage of the population of a society, which should be the same for all societies; and therefore, a society with larger population should produce more number of those 'certain' individuals than a society with a smaller population. Therefore, given identical human abilities, the scenario should result in equal cognitive developmental growth of all societies, which was not, and is not, the case. Why? The answer to this is as follows.

Society, by its very nature, is a dynamic system. And like any dynamic system, whose response depends on its initial conditions, the developmental course of a society is also governed by its initial conditions set by the initial world-view adopted by the society, which essentially depends upon the quality of apprehension and interpretation of the reality around them.

The world-view adopted thus, essentially sets the course of "The way of thinking" and "The way of doing things" of the society, which sets the course of their language and/or languages and thus the course of their Cognitive Process. The Cognitive Process set up thus; sets the path of the society's cognitive journey; which also sets the beginning of the accumulation of the society's Cognitive Endowments.

Since, Cognitive Endowment is an accumulated, intangible wealth of a society; the rate at which such wealth is accumulated would depend on the rate at which new and diverse valid, rational and logical cognition in all conceivable and possible real fields is acquired.

The rest is as explained in my first post, which was also pepeated again recently, about the develomental courses of the four types of societies. Please go back to that post, read it again, considering as it is inserted here as continuation of what has been said above, to grasp the essece of mechanism and dynamics involved in the developmental process of human societies.

Like any dynamic system, an injection of the new input or the component changes or modifies the legacy of its initial conditions and enhances its performance, the shift of language to a richer and well-developed one, is more likely to change the course of Cognitive Process and thus the Cognitive Development of the society.

Therefore, the degree and percentage by which a well-developed language could enhance the Cognitive Process and thus the Cognitive Development of a society would greatly depend on the percentage of people coming out of the held fixed and narrow world-view and adopting a relatively flexible and broader world-view expressible in the new language, which reflects "The way of thinking" and "The way of doing things" of a different, but developed society.