Yesterday’s post (here) argued that we need some explanation for the way speech (in at least its surface appearance) changes over time and yet never degenerates into meaningless babble. Something must be constraining its changes the way natural selection constrains biological changes, but it cannot literally be natural selection because the process is too rapid for random processes to work.
Linguistic evolution is commonly spoken of as a form of cultural evolution, but we define culture so broadly that the notion of its evolution means merely historical rather than biological change. Evolution implies something richer. It is change that preserves something. Biological evolution preserves fitness through adaptation; linguistic evolution preserves meaning, also by adapting to changing circumstances. The three processes I described in natural selection have similar processes in the history of language:
drift: both the sounds and syntax of language are arbitrary, in the sense of being unrelated to the meaning. That’s why cultures can use completely different sounds and grammar to say the same thing. Terrence Deacon’s The Symbolic Species has much to say about the biological constraints that shape sound and syntax, but they offer no guidance as to what keeps these things from becoming meaningless. Chomsky-type rules too propose no built in mechanism for keeping the drift within the bounds of linguistic competence.
conservation: we think of cultural evolution as change. That is particularly natural to residents of an age where last week’s world is so unlike today’s. But language can conserve as well. Indo-Europeans have spoken of time (in terms of the main verb tenses) in pretty much the same way for at least 7,000 years while their neighboring Semitic language speakers have spoken about time in a different way for the same period. There has been constant jostling of the two language families as the Greek-speaking Alexander moved into Semitic-speaking Egypt and Moors pressed up into Spain (to limit myself to two examples). Words moved back and forth across the languages, but the way they spoke of time was conserved.
innovation: people find new ways to talk about things and new things to talk about, providing the language with metaphors and other verbal devices. I once wrote a book about the discovery of the ice age. The main problem in disseminating the idea was that nobody could imagine an ice covered world with huge glaciers moving up and down valleys and over hills, so they dismissed it as nonsense. Believers could persuade people by physically taking them to, say, an ancient moraine and saying, Look there. The observers would look, slap their heads, and believe. But then they would find that others just thought they too had gone crazy. Then, at last, "the necessary poet" appeared. He was an explorer who had spent two winters trapped in northern Greenland near the world's largest glacier. He came back and wrote a hugely successful book about his adventures. Charles Lyell then wrote a book of his own in which he said Europe had once been a giant Greenland. Everybody could understand the metaphor and accept the idea of an ice age. In fact, they had a hard time remembering why they had ever doubted the idea. The struggle to change imaginations shows that the work is not easy, but the success shows it is possible.
Psychology needs an idea for how people can constrain drift, conserve meaning, and even develop new ways of expressing meaning. For non-psychologists the basic explanation seems obvious. People know the meaning of their words and use them according to their understanding. Gestalt psychologists take this kind of thinking seriously, but the American tradition, based on black-box reflexes and automatic computations are at a loss. The basics of understanding language are still a mystery.
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