The newborn child is born with a capacity to assign meaning to his world according to what sort of socialization he undergoes. But there is a delicate balance in how much plasticity in his worldview that must remain in him if he is to live normally. After late adolescence, this cultural plasticity tends to diminish rapidly. Before that time, it is easier for him to learn a new language, assign new meaning to concepts, and undergo a "schizophrenic shift" in what his experiences mean to him. If there is too much plasticity, he ends up unable to make sense of his world the way the rest of society does—his meaning and webs of significance are constantly shifting so that he ends up either schizophrenic or eccentric. If there is too little plasticity, he will be unable, either in late adolescence or beyond, to break out of his rigid, socialized patterns of association, significance, and conceptual frameworks.

Schizophrenic pathology could be seen as a radical plasticity in worldview. The schizophrenic is capable of creating a new "worldview" or belief system through which he interprets and perceives his experiences yearly or even more often—at least as often as he creates new psychotic delusions. The evolutionary advantages to some degree of plasticity in worldview are obvious—individuals with plasticity in worldview allow cultures to adapt to changing environments, especially if those changes are rapid, without being caught in a rigid way of looking at things, a rigid conceptual framework, that cannot be altered to altered circumstances. On the other hand, too many individuals with too much conceptual plasticity may lead to an unstable culture, whose members can never be made "traditional" enough to keep the culture from disintegration.

Nature’s way of dealing with this seems to have been, on the one hand, creating different individuals with differing plasticity in worldview. But this, in terms of genetic makeup, would remain mostly potential, depending upon what environmental conditions made it actual. Our own culture requires more plasticity than a hunter-gatherer society—we do, after all, now call people who are just twelve years younger than me—I am Generation X—a different generation, "the millennial generation" is what I believe they are calling them now. We have such a changing culture that each generation has a new worldview, and so we end up with large generation gaps, the worldview of the new generation, its own conceptual framework, radically different from that of their fathers. So perhaps early education tends to "impress" upon the mind and brain just within what parameters a shift in webs of significance is allowed.

Nature’s other way of dealing with this balance between plasticity and rigidity may have been to make our brains, after late adolescence, less and less able to make a shift in webs of significance. After the age of around twelve we lose the plasticity of childhood—before that age it is much easier to learn a foreign language. And again after that, at around age 25 (these are not absolutes), the brain becomes still less able to learn a foreign language. Then, plasticity continues to diminish, until a fifty-year-old will have a very difficult time learning a new language, unless he has learned others in the past, and his brain has been taught that new meanings and concepts in his worldview are a good thing. The capability to learn a foreign language is a good gauge of conceptual plasticity. This is because of the new grammatical patterns the mind must learn to think in, the new way that a different language boxes off its world into concepts, and simply the assignment of new meanings of words that may not have literal translations, one word in the foreign language standing for several concepts in the native, or one word in the native broken up into several words (with differing concepts) in the foreign language. This may be why schizophrenia, or "plasticity overdrive", develops in late adolescence, just when the brain is getting set in its ways and is leaving the radical plasticity of childhood. It may also shed light on why schizophrenics tend to get better after age thirty.

But schizophrenia is more than mere plasticity in worldview. "Plasticity" would imply the ability to assign new meanings to concepts and experiences that one is taught from the outside. Schizophrenia, on the other hand, is the inability to know what experiences "mean" in a cultural context. It is the inability to take in from the culture the meanings of the world of daily experience, in a way that is stable, so that the mind does not creatively and automatically assign new meanings to experiences, based purely on its own subjectivity. It is the plasticity that Einstein had when he, without being taught from the outside, came up with a new way, from his own creativity, to look at the concepts of space and time.

Such "creative plasticity" in which the new meaning is issued from the mind’s own subjective imagination, rather than being a mere capability to learn new meaning from others, has its own evolutionary advantage as well. When, due to a change in the environment, a culture has to change its worldview, the new concepts and meaning have to start with someone; not everyone can merely be taught them from the outside. And while this type of plasticity requires the plasticity to accept new ways of looking at things, in addition it requires the mind’s ability to automatically generate those beliefs and meanings in everyday experience all on its own.

In any case, the pathology of schizophrenia is only one extreme in a delicate balance nature has given us between plasticity and rigidity, and the related poles of spontaneous creativity that issues from one’s own mind, to mental traditionalism in which the individual adds nothing to his conceptual worldview from himself. The actual disease of schizophrenia may or may not be manifest in an individual, but the genes that predispose one for the illness can themselves be evolutionarily advantageous.