Concluding our series on the uses of critical theory, anthropologist Marilyn Strathern explores where illumination ends and information overload begins

In his novel The Island of the Day Before, the philosopher Umberto Eco has his anti-hero Ferrante sail between islands inhabited by people who live by theory. On one island people are forever on their knees gazing into ponds for they believe that someone who is not seen cannot exist. On another the inhabitants exist only by being the subject of narration - they talk incessantly to keep one another alive, striving to make each story unique in order to be able to tell one another apart. They have mistaken theories for life. But there is a truth behind their actions that a social anthropologist might appreciate.

People everywhere "theorise" their lives through abstract schema which explain both their world and their part in it. Cosmologies, models and ideologies are all abstractions akin to theory. But they are enacted through diverse means. People who model their universe on the house may literally build edifices of cosmological significance - to enter is to enter into a certain existential state. Or those who imagine that groups depend on one another for reproduction may move spouses around, according to rules of who can marry whom, like human pieces on a chess board. Abstraction is a crucially reductive enterprise. What marks out "theory" from these kinds of lived schema is the manner of abstraction.

So one person's lived practice may be material for another's theory. An anthropologist writes about the workings of a marriage system while people go off and get married. The abstract reduction of a world, people's total context of being, to a schema of "rules" can also serve as a reflection on that world's workings (while living out the rules becomes a test of their aptness). But the anthropologist is likely to have been schooled to think of abstraction as a mental activity rendered through debate with words, above all through writing. Not surprising, then, that the revelation that writing is itself a practice with social effects should have swept so vigorously through anthropology as it did about a dozen years ago, producing an interest in narrative that still reaps dividends. However, that has not been the only island on the anthropologist's course.

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Critical theory has been absorbed in various ways into anthropology. One of its liveliest proponents is critical anthropology, which draws not only on literary theory but also on Marxism and post-structuralist philosophy. Critical anthropology heightens consciousness about the anthropologist's practices of reflection as being part of, rather than separate from, the world. Largely European-inspired, "critical anthropology" sometimes takes pains to distinguish itself from its American-inspired counterpart - "cultural critique". At other times the two join together against postmodernism in defence of ethnographic enquiry. Imagining theories talking to one another in this way produces diverse and mixed genealogies.

Yet this can all start sounding too abstract, a criticism often brought against "theory" as such. It is the kind of analysis that makes people anti-theoretical and say we ought to get on with the voyage and stop being diverted by excesses of self-consciousness. This view is both right and wrong. Theory is as crucial to both description and explanation in social anthropology as it is elsewhere in the human sciences. It turns information into knowledge. But the relational and thus distancing effect of abstraction has to compete with anthropology as a field science. This is not simply because of the fascination of other people's theories, nor because of the realness of the "real world", an ideological position if ever there was one, but because fieldwork practice already deals with relationality and distance. Anthropologists as "participant observers" are already reflecting on the world in wondering how to relate to people to whom they do not belong.

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Nevertheless, as a protest against new excesses the protest against "theory" is justified. Technologies of information-dissemination are promoting scholasticism: narrowing down rather than opening up what is to count as theory. There is a fresh spin to the technocracy that was an original impetus for critical theory in pre-war Europe. Writing has been "enhanced" by ease of communication flow that creates a new public virtue - ease of access. A technical feat is mistaken for an intellectual one. Hence those blockbuster publications in which almost any discipline may find its practitioners caught up in yet another reconfiguration of the relationship between different streams of enquiry. The narrowness is that the claim may be all that is there. As a result, the citation of numerous intellectual antecedents may no longer be doing the (selective reductionist) work of theory. The citations only indicate the promise of technology: short cuts to information accessible in abundance. Yet scholars still need to do the original work of tracing relationships in order to translate information into knowledge.

Overabundance of information undermines the practice of knowledge. More information does not necessarily mean more public transparency; it may lead to less understanding, not to speak of less trust. As for volume of paper and emails: each day includes the task of how to absorb the excess of "ideas". For in abundance they no longer work as ideas, only as signs of ideas. In contemplating philosophy Simon Critchley (É«ºÐÖ±²¥S, February 6) referred to the demise of theoretical giants. In their place is a kind of gigantism: an island of people who go around making sure that they have incorporated everyone else's genealogies into their own in case anything vital is left out.

What is vitally left out is the relationship between the abstraction (the genealogy) to what it was abstracted from (works and lives). Perhaps anthropologists can look for fresh inspiration in the inventiveness of the peoples they encounter. For everyone has to work out for themselves how to reduce and delete information in order to make knowledge anew.

Marilyn Strathern is William Wyse professor of anthropology, University of Cambridge.

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