toki pona is a language developed over the last decade by Sonja Elen Kisa (a great toki pona name, by the way), a Canadian language professional. It is meant to be a very small language, easy to learn and master. To understand how it is more than that, we need to look at the philosophy and the problems that lie behind its creation.
The central concept underlying toki pona is simplicity ("toki pona" means, among other things, "simple language"). The importance of this concept to Kisa ("jan Sonja" among the users of the language)sprang from three sources: Daoism, mental distress, and the linguistic chicanery of the modern world. Daoism and a language which incorporated some of its teachings were seen as a possible answer to the other two factors.
Daoism is an ancient (-5th century) Chinese philosophy which stressed a return to a simpler style of living and a simpler society, one without distinctions of rank and wealth. And part of the path to this society was (as in all ancient philosophies) the rectification of names, calling a spade a spade and a dictator a murdering. maniac. Once things were called by their proper names, then people would not be confused (and bamboozled) by the tricky slogans. And then most of the mental problems would disappear, since they are caused by the disconnect between what the hype says -- the expectations -- and what actually follows. To be sure, some significant portion of mental distress arises simply from the complexities of the modern world, even without its use to conceal chicanery, so simplifying life -- at least the things that we need to heed -- makes a further contribution to mental health.
Although we cannot, by and large, go back to the primitive, agrarian society of even more ancient China, we can take advantage of some parts of Daoism even today. We can come to use -- in our private observation of the world, definitely, and in society insofar as the language spreads -- a language with a small number of words and express all that is significant in our lives in terms of these few words. Thus we need focus on only a few factors and to treat anything more complex as built up from those factors in an intelligible way, a way that allows us to go back to how they affect our normal life. If we can't do that with some notion (credit swaps, say), then it is not a part of real life and is to be avoided.
For such a language, the choice of those few words is important: too many and complex notions fit in, too few and you cannot say all you want. And this last problem arises, too, if the words chosen do not fill the world adequately. toki pona has about 120 words and, while I do not know how they were selected, jan Sonja claims them to be appropriately small and experience has shown them to be appropriately broad, covering a wide variety of circumstances. Whether the vocabulary needs changes is something that only further experience with the language can tell.
So far, the explanation of the origins of toki pona has made it sound like a very deep study indeed. But, while we can hope that you derive some advantages from learning it well -- in terms of mental health and a more effective bullshitometer, the real reason for learning toki pona is that it is and easy-to-learn, fun language, that has enough of a community (only on the internet, alas) to allow you to develop some (virtual) friendships and acquire some expertise in a new language, always a thrilling experience (if done outside the horrific teaching methods of many schools). So join us as we turn to the basics of toki pona (and, happily, there is not much beyond the basics).
[ Pedantic footnotes.
"Kisa" is the tokiponization of the Acadian French name Richard (does anybody still remember Maurice and Henri, the Rocket and the Pocket Rocket, who led the Habs in the NHL from the 1940s into the '8os?).
There is a lot more to Daoism than what is described above. In particular, it holds that ultimately all words are useless and all distinctions should be lost so that we live entirely in accord with nature, without any artificiality at all.
"on the internet, alas" toki pona is a language for face to face communication, in contexts available to both interlocutors, for much of the conveyance of messages is done by using features of the context. The toki pona seen on the internet is excessively elaborate because the users have to fill in large parts of the context. Thus, internet toki pona tends to have fairly long noun phrases -- a head noun and a long string of modifiers -- where face-to-race toki pona could usually do with only the noun and perhaps a simple modifier, since it only has to pick something out from the limited context, not from the whole world. ]