The Jargon -> Pidgin -> Vernacular Progression
Three Stages to a Universal Language:
 Global Vocabulary or “Global Jargon”
 International Auxiliary Language or “International Pidgin”
 Very Slow and Gradual Transformation to a Single World Language or “Universal Vernacularisation”
Let us imagine we are in a foreign land where we do not know the language. What would be the priority - knowing a few words, or knowing the elements of the grammar? Given such a choice we would obviously choose the words, since a theoretical knowledge of grammar without a supply of words is practically useless.
Indeed, researchers have verified that non-linguists in such a situation have tended to rely upon a few common words (a “jargon”) without attempting to organise them grammatically. As might have been expected, this finding parallels the normal process of language development within each individual, in which words precede their grammatical organisation. It might be supposed, then, that inaugurators of IALs would have been motivated to formulate an internationally-acceptable core vocabulary before creating a grammar.
However, we well know that authors of the many IALs listed on the Internet have generally been as much concerned to present a comprehensive grammar as a workable vocabulary.
Why is this? At least three reasons might be suggested:
(1) Because of the huge number of synonyms (for the same concept or object) within the world’s hundreds of languages and many thousands of dialects, the task of formulating an international core vocabulary might well be (or seem) more difficult than creating a grammar, of which there are a limited number of fundamental types.
(2) Potential IALs have to appeal, not only to the public, but also to the originators of public policy. It follows that use of a single IAL at all international conventions, and as the second language of every schoolchild, would never be realised without official endorsement. Thus the IALs are in competition with the great national tongues such as English, and to present a less complete grammar is to risk dismissal on the grounds of cultural inadequacy. In other words, since vocabulary relates more to popular usage than theoretical purview by the powers that be, it tends to be left in abeyance.
(3) A misapprehension that a global IAL is unprecedented in recorded history has led to the notion that the victory will only come from a process of trial and error. Thus there have been numerous IAL attempts, as though the author of each has been seeking the perfect combination of linguistic elements conducive to universal recognition and official approval. (Happily, none of this labour has been wasted, since the best of it will be applied in the future as the IAL develops.)
However, the IAL has indeed had successful precedents or prototypes, albeit on a localised scale. These have been the various pidgins and creoles that have arisen during past centuries. Robert Craig and I provided some background information (see note below) in Chapter 12 of Lango. Since jargons, pidgins and vernaculars have really been stages in the same localised IAL developments, I now refer to the sequence as the jargon -> pidgin -> vernacular progression (JPVP). The essentials of the JPVP might be summarised as follows:
Jargons have arisen where typical non-linguists from very different cultures brought together by the force of circumstance (e.g. whalers, or foreign soldiers and civilians) have found it convenient to attempt to communicate verbally.
Historically, what has emerged in such circumstances has been less a complete language than a lexicon of common words, with grammar provided by sign language and the immediate context. Jargons have usually disappeared along with the forced conditions that gave rise to them.
However, some jargons have subsequently developed into pidgins, which are really international auxiliary languages (if only between two nations) with basic grammar and extra words from various sources. Even though these "surviving" jargons might have been introduced with pidgins in mind, it still remains true that every pidgin has been preceded by a jargon.
History also teaches us that no pidgin has long remained a purely auxiliary language. Either it has died out with the commercial factors that gave rise to it, or the children of traders, seafarers etc. have unconsciously adopted the pidgin as their mother tongue - with all that means for creative development. Another parallel may be found within the cognitive development of the individual, with the JPVP correlating to the cognitive stages first described by Piaget.
Correspondingly it is reasonable to conclude that an IAL should be established by beginning at the “jargon” stage with a global core vocabulary. Also, just as the historic JPVPs each derived from a "superstrate" language - Portuguese, English or French etc., according the language of the traders - with the "substrates" being local indigenous languages, along with extra pidgin words that had proved acceptable elsewhere, it follows that a new "Global JPVP" might derive from an ideal superstrate (on the pattern of Classical Arabic or some such advanced language), with the substrates being all the world's languages, and the "pidgin" element those words which are already internationally current and popular. Here is quite an interesting article on the subject.
This, then, is a proposal to promote an IAL according to the JPVP model: the most successful IAL precedent in terms of pan-societal penetration and follow-through to vernacularisation. For various reasons connected with the sound of existing "international" words, the initial phonology would probably be somewhat biased towards the "West", but happily the same precedent would prescribe an analytic "Chinese-type" grammar - thereby restoring an equitable balance.
(Following Prof. Salikoko Mufwene's contention that creoles arose through the historic "plantation / homestead" situation, and that pidgins, a species pertaining more to the "trading" scenario, neither became "creolised" nor turned into "creoles", I have changed the terminology of the progression from "contact language -> pidgin -> creole" to "jargon -> pidgin -> vernacular". This is a mere verbal modification that does not affect the argument. Although a moot point I suspect that, technically speaking, Prof. Mufwene is probably correct. In any case this alteration allows "contact language" to be replaced by the better term "jargon", coined by Prof. Peter Mühlhäusler.)