It is the relative crudeness of language that allows its propagation. It seems likely that the everyday use of language will generally tend to be efficient. That said, any process has multiple ways to produce specific effects. A certain amount of effort is associated with each way or configuration. Efficiency refers to the likelihood of achieving rapidly, or reliably, specific effects with the least amount of effort. Language is an efficient process, having evolved a broad range of specific effects with just sufficient effort that linguisticity has propagated to the whole species. The use of language requires muscular effort and synaptic effort. Some people will do it with more or less detail depending on different architectural constraints - such as being a child or an adult - and, possibly, individual priorities - such as being a writer of novels or a sales person.
Let us try a metaphor to illustrate. Many people have, at one time or an other, relied on a Swiss Army knife to help in daily tasks. The portability and number of accessories that composes the knife make it ideal for a variety of typical needs. It is often good enough.
However, for more involved work, or for professional work, the lack of precision that is inherent to the Swiss Army knife limits its performance. Specialized carving, for example, requires several different sharp tools, spoon gouges for example, for the many levels of detail. Since most of us do not require that level of precision, it would be cumbersome to carry several specialized tools. Carving is just one possible specialized task - by extension, it would become impossible to carry all specialized tools for all possible tasks. Though the Swiss Army Knife cannot perform very specialized work, it is sufficient for most of us that do not need to achieve exacting levels of adequacy and thus, the effort of carrying it is appropriate to our needs.
Efficiency is about striving to reach a balance between effort and consequence. Language, like the Swiss Army knife, is portable, adequate, reliable enough and readily available across a population. However, because of its relative performance, language is not immune to misuse or misunderstanding. In turn, some of these faults will generate new uses for old vocabulary.
Lisa Simpson's astute observation, Only kids are that incoherent 1.4 as she approaches and hears a group of ten years old speak, points to a particular way of speaking that generates effects within the ten year old population but not in others. An utterance such as Stuff sucks1.5 or my mom is so gay1.6 would probably not be used by anyone over the age of ten. The vagueness of the first example and the inappropriateness of the second would not fit the requirements of adult speech, partly because, as we get older, the complexities of speech are more accessible and possibly because the requirements of the everyday life of adults demands more specificity. In the first example, the lexical vocabulary is almost entirely stripped of perceptual context. In the second example, children have coopted gay without the complete awareness of its usual use in adult speech. We can imagine that their use of it is somewhat derogatory, as it is often used in adult speech, but the full perceptual context of the word has been lost. In adult speech, a similar erosion of specific effects occurs for all vocables, but, in more subtle ways.
Vocables are entrenched in perceptual cues of a neural kind and uttering them generates specific effects, in hearers, of a similar nature 1.7. But the fact is that, for various reasons, there are a finite number of vocables shared by a population of language users and a significantly smaller number for each individual. While the day to day activities of most people are probably routine, small differences do arise which may require specific vocal interventions. With a limited set of vocables, the strategy is to combine them in such a way that the changes in new contexts can be reflected by the refurbished use of old vocables. This linguistic hooking - connecting to the past - of vocables ensures that our language remains shareable.
Our capacity to discriminate between similar uses does not scale infinitely. Fortunately the everyday requirements of life do not require us to make very fine discriminations. The discriminations we need to make can be made easily by hooking new onto past experiences. This process of generating new, shared, vocables continues inexorably, even through changes so dramatic or numerous to signal a change in language version, as from Early to Middle English.1.8
Why do we not generate new vocables for each new situation? Simply put, it is not efficient. Efficiency can be casually defined as a measure of the difference between energy input and work output, where energy input is always greater than the result. The difference is wasted effort or loss. The more efficient the system, the less the difference. A perfectly efficient system can use its energy input without any loss. For example, a perfectly efficient engine will use its fuel to propel its vehicle forward without generating heat or friction. This ideal degree of efficiency is not possible in this universe because of the second law of thermodynamics [51], so efficiency is something to maximize not to perfect. For most systems maximizing efficiency is not a matter of conscious choice - we find that self-organizing systems that sustain themselves for a prolonged period of time use strategies that maximize resources and longevity. In this sense, humans and their use of language are no different from most self sustaining natural systems.
If we can see it, taste it, smell it, hear or feel it, then it is part of our readily accessible lexical vocabulary. We can imagine that its sensorial richness co-opts many neural resources and also its perceptually bound nature limits the amount and kind of work it can do. Because different people have different perceptual experiences and histories, the use of lexical vocabulary does not scale across a diverse population very well. So, while lexical vocabulary is efficient for certain tasks, its efficiency is not very high across a broad range and requires many neural resources. While generating new vocables to fit each new situation might seem to increase work output, we must remember that language becomes shared on the basis of common past experiences. The shareability of constant novelties is questionable. Also, the sheer amount of neural energy (effort) that would be required to invent an infinite number of vocables is itself infinite.
If lexical vocabulary on one hand does not scale and if on the other hand novelties are too expensive, how do we come to have a shared language such as English that is spoken by millions of people?