Peripheral Visions

people’s expertise. How to improvise and cope with only partial knowledge and how to imagine alternatives.
    On the one hand, we overestimate the extent to which cultural patterns are shared and regular. But, on the other hand, we underestimate the possibility of getting along without complete sharing, and the self-organizing properties of human communication. We assume that patterning must come from the past, underestimating the way in which a group of strangers can learn not only to interact in harmony but also to generate new regularities, which come to be treasured. The current debate about how much cultural pluralism any society can tolerate is partly a matter of growing pains but also a symptom of the need to rethink the relationship between identity and adaptation. On the one hand, the demand for multiculturalism is a demand for acknowledgment, a recognition owed to every member of society as a foundation for the sense of self that will allow ongoing learning. But, on the other, multiculturalism fits with the promise of lifelong learning, the promise that individuals will increasingly be able to look at one another with recognition as they continue to grow out of fixed roles.
    Educators, even in universities, are still strangely in thrall to the idea that education precedes participation, even though more and more adults are returning to study or working and studying simultaneously. Education is less and less a preparation for life and more and more a part of it. Except in a few privileged colleges, diversity of age and experience has become the most important resource of the teacher, balanced and supplemented by diversity of ethnic background, so that classrooms can increasingly be orchestrated in ways that allow students to benefit from collaboration and teach one another, mining difference for insight.
    In ecology, diversity may offer resilience to systems, whereas large plantations of single crops are highly vulnerable to pests and diseases. Because of the increasing concern that cultural diversity might prove toxic to society, I was intrigued to learn that diversity could be used to reduce toxicity. Areas of extreme pollution are sometimes seen as emblematic of wider problems in society and in the biosphere, like the famous Love Canal. In the south, there is a five-and-a-half-mile stretch of Chattanooga Creek polluted with a wide range of toxic substances from forty-two hazardous waste dumps. Those who live nearby, who are mainly poor and black, complain of high rates of leukemia and other cancers. Running a mere hundred feet from a school yard, this creek has sediments eight feet thick, containing the insoluble large molecules of polyaromatic hydrocarbons, coal tar derivatives, and pesticides. The usual Superfund tactics for solving such problems are dredging and incineration followed by containment, for although progress has been made in using biological systems, such as pools filled with water hyacinths, to process ordinary sewage, these systems have on the whole been kept deliberately simple so that they would be predictable. It makes engineers nervous to think about more than one organism at a time, for who knows what unexpected patterns might emerge from interactions?
    John Todd of the Center for the Restoration of Waters described to me his experiments with techniques of water purification using biological diversity. He has been interested over the years in human habitations that are ecologically benign and self-maintaining, and subsequently in using biological processes for repair, calling his constructions living machines. What John does is maximize diversity, particularly at the microbial level, where sunlight and photosynthesis can be brought to bear by busy communities of bacteria, but also including the full range of organisms from bacteria to vertebrates. He seeks out organisms that have survived in highly stressed environments and makes sure that his living machines involve recurrent sharp contrasts. Polluted waters are passed through enclosed tanks, then through tanks in greenhouses, and finally through outdoor marshes. The opposite of stagnant ponds, where heavy metals sink and pollutants separate in layers, his processing tanks constantly bring different substances and organisms into contact with one another, a kind of conversation.
    This work is still highly experimental and hard to fund. John claims to have removed more than two-thirds of the different toxins almost entirely and