The oversized brain of the hunter-gatherer never stops categorizing whatever it encounters, from the moment it is born. In infancy, everything is a surprise and whole new taxonomies get created and destroyed daily. As adults, we are expected to be independent and survive on our own in new situations; it is a common thing that a short time after reaching biological sexual maturity, many humans become suddenly convinced that they know everything they need to know about the world.
These categorizing systems, internal taxonomies if you will, are kind of sorting trees that grow inside the skull. New data enters the main trunk, and through consecutive decisions is routed towards smaller and smaller branches, until there are now more branches. At least, this is conceptually how we think intelligence would work, if it was artificially engineered by us.
The growing networks of trees in our heads are revealed through language. Human natural languages need to be sophisticated, to efficiently transmit the complex multi-level nuances of our internal classification engines. Languages are alive, and any human born today will be immersed in the living linguistic environment of their homes. Through language, both the differences and the similarities of our internal world-models can be exposed.
Words can be set in stone, but language changes constantly. Not just new words are invented; As time passes, old words and phrases take new meanings and connotations, while old meanings are lost or systematically misunderstood.
It is comfortable to think that some inborn building blocks of language are built into the brain at birth; that there is some rudimentary “natural language” common to all humans, that we then learn to fluently translate into the real languages we use. All forests in the world cannot be simplified into just one “true” tree, without losing most of the information. This applies also to the jungle that we call human language: there is no true language able to express everything we use language for.
This actually means more than just spoken language, something that most of us learned before the beginning of our earliest memories. Some exceptional people do not learn language this way, but are still able to “high-function” in society as adults. Even when thinking is mostly visual-sensory, there seems to exist and internal model of the world, with categories and simplifications and associations. Influencing (educating, commanding, negotiating) another mind is just harder without a shared island of language.
As adults, we would like to think that our internal models are fairly correct and consistent. And they are usually good enough for the challenges of normal daily life. That is why it is so surprising to find out that there can be polarizing disagreements on some subjects between otherwise agreeing persons. After all, logic is all about consistency, isn’t it? Perhaps if we lived in a world without surprises, internal consistency of model would suffice. But this is not the case. Sometimes it is necessary to learn to live with paradoxes, or even accept the existence of dialetheia.
Our categories are not naturally exclusive either, they are fuzzy, adaptive and biased in many ways. We humans often desire that our internal categories be clean-cut and exact, and this obsession takes us farther than other animals. By refining categories with ever smaller subcategories, rules of thumb with exceptions, the desire for cleanness leads, paradoxically, to increased complexity.
The internal trees are living things, and adapting on many levels. Languages also evolve, but more slowly. Some computer engineers of the past century (but not Marvin Minsky) may have naively thought that human thought could be replicated by writing a program using logical calculus, and simply run it on a very fast computing machine. Only recently have we started to tentatively adapt our formal models of thought, with fuzzy logic, paraconstistent logic, bayesian inference, to name only a few.