Designing wisdom through the Web: The passion of ranking

by Gloria Origgi
, 30 September 2008

How can people and computers be connected so that—collectively—they act more intelligently than any individuals, groups, or computers? Gloria Origgi claims that Internet is a giant network of ranking and rating systems in which information is valued as long as it has been already filtered by other people. The Information Age is being replaced by a Reputation Age.

Where is the wisdom we have lost in knowledge?

Where is the knowledge we have lost in information?

T.S. Eliot

With the outstanding potential of the Web 2.0. of aggregating socially distributed information to obtain intelligent outcomes, the very idea of collective intelligence has entered a new era [1]. What was not much more than a curiosity in the history of thought, that is, that the aggregation of many unsophisticated judgements may sometimes result in a more sophisticated and precise result than the one produced by a single expert mind, is nowadays a major fact that is revolutionizing our everyday way of thinking and taking decisions and needs to be taken seriously. Google searches, Wikipedia entries, eBay transactions are all based on the simple correlation between the data filtered by the many and the relevance for us of the information we get. Yet, a major concern with these new collectively intelligent systems is that our control over the path of aggregation of information is sometimes poor, and the individual or institutional capacities of intervention on the design of the aggregation process are often very limited. I think we should take the design issue very seriously in order to be aware of the biases of these systems and their potential misuses. And this is a general point about institutional design. No matter how many people are involved in the production of a collective outcome – a decision, an action, a cognitive achievement etc. – the way in which their interactions are designed, what they may know and not know of each other, how they access the collective procedure, what path their actions follows and how it merges with the actions of others, affects the content of the outcome. Of course this is well known by policy makers, constitution writers and all those who participate into design of a democratic system, or any other system of rules that has to take into account the point of view of the many. But the claim may appear less evident – or at least in need of a more articulate justification - when it deals with the design of knowledge and the epistemic practices on the Web. That is because the Web has been mainly seen as a disruptive technology whose immediate effect was to blow up all the existing legitimate procedures of knowledge access, thus “empowering” its users with a new intellectual freedom, the liberty to produce, access and distribute content in a totally unregulated way. Still, methods of tapping into the wisdom of the crowds on the Web are many and much more clearly differentiated that it is usually acknowledged. In his book on the Wisdom of Crowd, James Surowiecki writes about the different designs for capturing collective wisdom. He says: “In the end there is nothing about a futures market that makes it inherently smarter than, say, Google. These are all attempts to tap into the wisdom of the crowd, and that’s the reason they work”. Yet, sometimes the devil is in the details and the way in which the wisdom of crowds is captured makes a huge difference on its outcome and its impact on our cognitive life. The design question that is thus central when dealing with these systems is: How can people and computers be connected so that—collectively—they act more intelligently than any individuals, groups, or computers?

I will try to go through the details of some of the collective wisdom systems that are nowadays used on the Web. I will provide a brief “technical” description of the design that underlies each of them. Then, I will argue that these systems work because of their very special way of articulating (1) individual choices and collectively-filtered preferences on one hand and (2) human actions and computer processes on the other. I will then conclude by some epistemological remarks about the role of ranking in our epistemic practices, arguing that the success of the Web as an epistemic practice is due to its capacity to provide not so much a potentially infinite system of information storage, but a giant network of ranking and rating systems in which information is valued as long as it has been already filtered by other people. My modest epistemological prediction is that the Information Age is being replaced by a Reputation Age in which the reputation of an item – that is how others value and rate the item - is the only way we have to extract information about it. This passion of ranking is a central feature of collective wisdom. James Surowiecki imposes a very illuminating list of conditions on the characterisation of a wise crowd. Not any crowd is a wise crowd. In order to avoid well known phenomena such as group polarization, information cascades, conformism, a group must display certain features that make it a potentially intelligent entity. Suriowiecki proposes four main characteristics: 1. diversity of opinion (each person should have some private information) 2. independence (people’s opinions are not determined by others) 3. decentralization (people are able to draw on local knowledge) 4.aggregation (presence of mechanisms that turn individual judgements in collective decisions). I’m tempted to add a fifth one that is for me crucial especially in order to “speed up” the collective filtering of information: 5. presence of a rating device (each person should be able to produce a rating hierarchy, rely on past ranking systems and make – at least in some circumstances – his or her rating available to other persons).

I think that this last condition is particularly useful to understand the processes of collective intelligence that the Web 2.0. has made possible, although it is not limited to it. Of course, this opens the epistemological question of the epistemic value of these rankings, that it, to what extent their production and use by a group changes the ratio between truths and falsities produced by that group and, individually, how an awareness of rankings should affect a person’s beliefs. After all, rankings introduce a bias in judgement and the epistemic superiority of a biased judgement is in need of justification. Moreover, these rankings are the result of collective human registered activities with artificial devices. The control of the heuristics and techniques that underlie this dynamics of information may be out of sight or incomprehensible for the users who find themselves in the very vulnerable position of relying on external sources of information through a dynamic, machine-based channel of communication whose heuristics and biases are not under their control. For example, that companies used to pay to be included in search engines or gain a “preferred placement” was unknown to 60% of users [2] until the American Federal Trade Corporation wrote in 2002 a public recommendation asking to search engines companies to disclose paid link policies and clearly mark advertisements to avoid users’ confusion.

The epistemic status of these collectively produced rankings thus opens a series of epistemological questions:

1. Why do people trust these rankings and should they?

2. Why should we assume that the collective filtering of preferences produces wiser results on the Web?

3. What are the heuristics and biases of the aggregating systems on the Web that people should be aware of?

These questions include a descriptive as well as a normative perspective on the social epistemology of collective wisdom systems. A socio-epistemological approach to these questions - as the one I endorse - should try to elucidate both perspectives. Although here I will explore more the descriptive side of the question, by showing the design of collective wisdom systems with their respective biases, let me introduce these examples by some general epistemological reflections that suggest also a possible line of answer to the normative issues. In my view, in an information-dense environment, where sources are in constant competition to get attention and the option of the direct verification of the information is simply not available at reasonable costs, evaluation and rankings are epistemic tools and cognitive practices that provide an inevitable shortcut to information. This is especially striking in contemporary informationally-overloaded societies, but I think it is a permanent feature of any extraction of information from a corpus of knowledge. There is no ideal knowledge that we can adjudicate without the access to previous evaluations and adjudications of others. And my modest epistemological prediction is that the higher is the uncertainty on the content of information, the stronger is the weight of the opinions of others in order to establish the quality of this content. This doesn’t make us more gullible. Our epistemic responsibility in dealing with these reputational devices is to be aware of the biases that the design of each of these devices incorporates, either for technical reasons or for sociological or institutional reasons. A detailed presentation of what sort of aggregation of individual choices the Internet makes available should be thus accompanied by an analysis of the possible biases that each of these systems carries in its design.

1. Collective intelligence out of individual choices

People - and other intelligent agents - often think better in groups and sometimes think in ways which would be simply impossible for isolated individuals. The Internet is surely an example of this. That is why the rise of the Internet created from the onset huge expectations about a possible “overcoming” of thought processes at the individual level, towards an emergence of a new – more powerful – form of technologically-mediated intelligence. A plethora of images and metaphors of the Internet as a super-intelligent agent thus invaded the literature on media studies – such as the Internet as an extended mind, a distributed digital consciousness, a higher-order intelligent being, etc…

Yet, the collective processes that make Internet such a powerful cognitive media are precisely an example of “collective intelligence”, that is, a mean of aggregation of individual choices and preferences. What Internet made possible though – and this was indeed spectacular - was a brand new form of aggregation that simply didn’t exist before its invention and diffusion around the world. In this sense, it provided a new tool for aggregating individual behaviours that may serve as a basis for rethinking other forms of institutions whose survival depends on combining in the appropriate way the views of the many.

1.1. The Internet and the Web

The salient aspect of this new form of aggregation is a special way of articulating individual choices and collectively-filtered preferences through the technology of the Internet and, especially, of the World Wide Web. In this sense, it is useful to distinguish from the onset between the Internet as a networking phenomenon and the Web as a specific technology made possible by the existence of this new network. The Internet is a network whose beginnings go back to the Sixties, when American scientists at AT&T, Rand and MIT and the Defense Communication Agency started to think of an alternative model of transmitting information through a network. In the classical telephone system, when you call New York from your apartment in Paris, a circuit is open between you and the New York destination – roughly a copper line which physically connects the two destinations. The idea was thus to develop an alternative – “packet-switching” technology, by digitalizing conversations – that is – translating waves into bits, then chopping the result into packets which could flow independently through a network while giving the impression of a real-time connection on the other end. In the early Seventies the first decentralised network, Arpanet, was put in use that was able to transfer a message by spreading its chunks through the network and then reconstructing it at the end. By the mid Seventies, the first important application on the network, the mail, was created. What made this net such a powerful tool was its decentralised way of growing: Internet is a network of networks, which uses pre-existing wires (like telephone networks) to make computers communicate through a number of protocols (things like: IP/TCP) that are not proprietary: each new user can connect to the network by using these protocols. Each invention of an application, a mail system, a system of transfer of video, a digital phone system, can use the same protocols. Internet protocols are “commons” [3], and that was a boost to the growth of the network and the creativity of the applications using it. This is a crucial for the wisdom of the net. Without the political choice to keep these protocols free, the net would not have grown in a decentralised manner and the collaborative knowledge practices that it has realized would not have been possible. The World Wide Web, which is a much more recent invention, maintained the same philosophy of open protocols compatible with the Internet (like HTTP –hypertext transfer protocol or HTML- hypertext markup language). The Web is a service which operates through the Internet, a set of protocols and conventions that allows “pages” (i.e. a particular format of information that makes easy to write and read content) to be easily linked to each other, by the technique of hyperlink. It’s a visualization protocol that makes the display of information very simple. The growth of the Web is not the same thing as the growth of Internet. What made the Web grow so fast is that the creating a hyperlink doesn’t require any technical competence. The Web is an illustration of how an Internet application may flourish thanks to the openness of the protocols. And it is true that impact of IT on collective intelligence are due mostly to the Web.

1.2. The Web, collective memory and meta-memory

What makes the aggregation of individual preferences so special through the Web? For the history of culture, the Web is a major revolution on the storage, dissemination and retrieving of information. The major cultural revolutions in the history of culture have had an impact on the distribution of memory. The Web is one such revolution. Let’s see in what sense. The Web has often been compared to the invention of writing or printing. Both comparisons are valid. Writing, introduced at the end of the 4th millennium BCE in Mesopotamia, is an external memory device that makes possible the reorganization of intellectual life and the structuring of thoughts, neither of which are possible in oral cultures. With the introduction of writing, one part of our cognition “leaves” the brain to be distributed among external supports. The visual representation of a society’s knowledge makes it possible to both reorganize the knowledge in a more useful, more ‘logical’, way by using, for example, lists, tables, or genealogical trees, and to solidify it from one generation to the next. What’s more, the birth of “managerial” casts who oversee cultural memory, such as scribes, astrologists, and librarians, makes possible the organization of meta-memory, that is, the set of processes for accessing and recovering cultural memory.

Printing, introduced to our culture at the end of the 15th century, redistributes cultural memory, changing the configuration of the “informational pyramid” in the diffusion of knowledge. In what sense is the Web revolution comparable to the invention of writing and printing? In line with these two earlier revolutions, the Web increases the efficiency of recording, recovering, reproducing and distributing cultural memory. Like writing, the Web is an external memory device, although different in that it’s “active” in contrast to the passive nature of writing. Like printing, the Web is a device for redistributing the cultural memory in a population, although importantly different since it crucially modifies the costs and time of distribution. But unlike writing and printing, the Web presents a radical change in the conditions for accessing and recovering cultural memory with the introduction of new devices for managing meta-memory, i.e., the processes for accessing and recovering memory. Culture, to a large extent, consists in the conception, organization and institutionalization of an efficient meta-memory, i.e. a system of rules, practices and representations that allow us to usefully orient ourselves in the collective memory. A good part of our scholastic education consists in internalizing systems of meta-memory, classifications of style, rankings, etc.. chosen by our particular culture. For example, it’s important to know the basics of rhetoric in order to rapidly “classify” a line of verse as belonging to a certain style, and hence to a certain period, so as to be able to thus efficiently locate it from within the corpus of Italian literature. Meta-memory thus doesn’t serve only a cognitive function – to retrieve information from a corpus – but a social and epistemic function to provide an organization for this information in terms of various systems of classifications that embody the value of the “cultural lore” of that corpus. The way we retrieve information is an epistemic activity which allows us to access through the retrieving filters, how the culture authorities on a piece of information have classified and ranked it within that corpus. With the advent of technologies that automate the functions of accessing and recovering memory, such as search engines and knowledge management systems, meta-memory also becomes part of external memory: a cognitive function, central to the cultural organization of human societies, has become automated—another “piece” of cognition thus leaves our brain in order to be materialized through external supports. Returning to the example above, if I have in mind a line of poetic verse, say “Guido, i’vorrei...” but can recall neither the author nor the period, and am unable to classify the style, these days I can simply write the line of verse in the text window of a search engine and look at the results. The highly improbable combination of words in a line of verse makes possible a sufficiently relevant selection of information that yields among the first results the poem from which the line is taken (my search for this line using Google yielded 654 responses, the first ten of which contained the complete text from the poem in Dante’s Rime).

How is this meta-memory designed through the Web technology? What is unique on the Web is that the actions of the users leave a track on the system that is immediately reusable by it, like the trails that snails leave on the ground, which reveal to other snails the path they are following. The combination of the tracks of the different patterns of use may be easily displayed in a rank that informs and influence future preferences and actions of the users. The corpus of knowledge available on the Web – built and maintained by the individual behaviours of the users – is automatically filtered by systems that aggregate these behaviours in a ranking and make it available as filtered information to new, individual users. I will analyse two different classes of meta-memory devices. These systems, although they both provide a selection of information that informs and influences users’ behaviour, are designed in a different way, a difference is worth taking notice of.

2. Collaborative filtering: wisdom out of algorithms

2.1. Knowledge Management Systems

Collaborative filtering is a way of making predictions about the preferences of a users based on the pattern of behaviour of many other users. It is mainly used for commercial purposes in web applications for e-business, although it has been extended to other domains. A well-known example of a system of collaborative filtering which I assume we are all familiar with, is Amazon.com : Amazon.com is a Web application, a knowledge management system which keeps track of users’ interactions with the systems and is designed to display correlations between patterns of activities in a way that informs users about other users’ preferences. The best known feature of this system is the one which associates different items to buy: “Customers who buy X buy also Y”. The originality of these systems is that the matching between X and Y is in a sense bottom-up (although the design of the appropriate thresholds of activities above which this correlation emerges are fixed by the information architecture of the system). The association between James Surowiecki’s book and Ian Ayer’s book Super Crunchers that you can find on the Amazon’s page for The Wisdom of Crowds has been produced automatically by an algorithm that aggregates the preferences of the users and makes the correlation emerge. This is a unique feature of these interactive systems, in which new categories are created by automatically transforming human actions into visible rankings. The collective wisdom of the system is due to a division of cognitive labour between the algorithms which compose and visualize the information, and the users who interact with the system. The classifications and rankings that are thus created aren’t based on previous cultural knowledge of habits and customs of users, but on the emergence of significant patterns of aggregated preferences through the individual interactions with the system. Of course, biases are possible within the system: the weights associated to each item to make it emerge are fixed in such a way that some items have more chances to be recommended that others. But given that the system is alimented by the repeated actions of the users, a too biased recommendation that couples items that users won’t buy together will not be replicated enough times to stabilize within the system.

2.2. PageRank

Another class of systems that realize meta-memory functions through artificial devices are search engines. As we all know by experience, search engines have been a major transformation of our epistemic practices and a profound cognitive revolution. The most remarkable innovation of these tools is due to the discovery of the structure of the Web at the beginning of this century [4]. The structure of the Web is that of a social network, and contains a lot of information about its users’ preferences and habits. The search engines of second generation, like Google, are able to exploit this structure in order to gain information about how knowledge is distributed throughout the world. Basically, the PageRank algorithm interprets a link from a page A to page B as a vote that page A expresses towards page B. But we’re not in democracy on the Web and votes do not have all the same weight. Votes that come from certain sites – called “hubs”- have much more weight than others, and reflect in a sense hierarchies of reputation that exist outside the Web. Roughly, a link from my homepage to the page of the Harvard University weighs much less than a link to my page from that of Harvard University. The Web is an “aristocratic” network – an expression that is used by the social network theorists – that is, a network in which “rich get richer” and the more links you receive the higher is the probability that you will receive even more. This disparity of weights creates a “reputational landscape” that informs the result of a query. The PageRank algorithm is nourished by the local knowledge and preferences of each individual user and it influences them by displaying a ranking of results that are interpreted as a hierarchy of relevance. Note that this system is NOT a knowledge management system: the PageRank algorithm doesn’t know anything about the particular pattern of activities of each individual: it doesn’t know how many times you and I go to the JSTOR website and doesn’t combine our navigation paths together. A “click” from a page to another is an opaque information for PageRank, whereas a link between two pages contains a lot of information about users’ knowledge that the system is able to extract. Still, the two systems are comparable from the point of view of the design of collective intelligence: neither requires any cooperation between agents in order to create a shared system of ranking. The “collaborative” aspect of the collective filtering is more in the hands of machines than of human agents [5]. The system exploits the information that human agents either unintentionally leave on the website by interacting with it (KM systems) or actively produce by putting a link from one page to another (search-engines): the result is collective, but the motivation is individual.

Biases of search engines have been a major subject of discussions, controversy and collective fears these years. As I’ve mentioned above, the refinement of the second-generation search engines such as Google has allowed at least to explicitly mark paid inclusions and preferred placements, but this needed a political intervention. Also, the “Mathiew effect” of aristocratic networks is notorious, and the risk of these tools is to give prominence to already powerful sites at the expense of others. The awareness of these biases should imply a refinement on the search practices also: for example, the more improbable is the string of keywords, the more relevant is the filtered result. Novices and learners should be instructed with even simple principles that make them less vulnerable to these biases.

3. Reputation systems: wisdom out of status anxiety

The collaborative filtering of information may require sometimes a more active participation to a community than what is needed in the examples above. In his work on Information Politics on the Web the sociologist Richard Rogers classifies web dynamics as “voluntaristic” or “non-voluntaristic” according to the respective role of human and machines in providing information feed-back for the users. Reputation systems are an example of a more “voluntaristic” web application than the ones seen above. A reputation system is a special kind of collaborative filtering algorithm that determines ratings for a collection of agents based on the opinions that these agents hold about each other. A reputation system collects, distributes, and aggregates feedback about participants’ past behaviour.

The best known and probably simplest reputation system of large impact on the Web is the system of auction sales at www.eBay.com. eBay allows commercial interactions among more than 125 millions of people around the world. People are buyers and sellers. Buyers place a bid on an item. If their bid is successful, they make the commercial transaction, then both (buyers and sellers) leave a feedback about the quality of that transaction. The different feedbacks are then aggregated by the system in a very simple feedback profile, where positive feedbacks and negative feedbacks plus some comments are displayed to the users. The reputation of the agent is thus a useful information in order to decide to pursue the transaction. Reputation has in this case a real, measurable, commercial value: in a market with a fragmented offer and very low information available on each offer, reputation becomes a crucial information in order to trust the seller. Sellers on eBay know very well the value of their good reputation in such a special business environment (no physical encounters, no chance to see and touch the item, vagueness about the normative framework of the transaction – if for example it is realized through two different countries, etc.), so there is a number of transactions at a very low cost whose objective is just to gain one more positive evaluation. The system creates a collective result forcing cooperation, that is, asking users to leave an evaluation at the end of the transaction and sanctioning them if they don’t comply. Without this active participation of the users, the system will be useless. Still, it is a special form of collaborative behaviour that doesn’t require any commitment to cooperation as a value. Non-cooperative users are sanctioned to different degrees: they can be negatively evaluated not only if the transaction isn’t good, but also if they do not participate into the evaluation process. Breaking the rules of e-bay may lead to the exclusion from the community. The design of wisdom thus comprises an active participation from the users for fear to be ostracized by the community (which would be seen as a loss of business opportunities). Biases are clearly possible here also. People invest in cheap transactions whose only aim is to gain reputational points. This is a bias one should be aware of and easily check: if a seller offers too many cheap items, he too concerned with his public image to be considered reliable.

Some reputational features are used also by non-commercial systems such as www.flickr.com. Flickr is a collaborative platform to share photos. For each picture, you can visualise how many users have added it among their favourite pictures and who they are.

Reputation systems differ from other systems of measurement of reputation that use citation analysis, like for example the Science Citation Index. These systems are in a sense reputation-based, given that they use scientometric techniques to measure the impact of a publication in terms of the number of citations in other publications. But they don’t require any active participation of the agents in order to obtain the measure of reputation.

4. Collaborative, open systems: wisdom out of cooperation

The collaborative filtering on the Web may be even more voluntaristic and human-based than the previous examples, while still necessitating a Web support to realize an intelligent outcome. Two are the most discussed cases of collaborative systems that owe their success to active human cooperation in filtering and revising the information made available: the Open Source communities of software development, like Linux, and the collective open content projects such as Wikipedia. In both cases, the filtering process is completely human-made: code or content is made available to a community which can filter it by correcting, editing of erasing it according to personal or shared standards of quality. I would say that these are communities of amateurs instead of experts, that is, people who love what they do and decide to share their knowledge for the sake of the community. Collective wisdom is thus created by individual human efforts that are aggregated in a common enterprise in which some norms of cooperation are shared.

I won’t discuss biases on Wikipedia: it is such a large topic that it could be the subject of another paper. Let me just mention that Larry Sanger, one of its founders, is promoting an alternative project, www.citizendum.org which endorses a policy of accreditation of its authors. Self-promotion, ideology, targeted attacks on reputation may of course act as biases in the selection of entries. But the fear of Wikipedia as a dangerous place of tendentious information has been disconfirmed by facts: thanks to its large size, Wikipedia is hugely differentiated in its topics and views, and it has been shown that its reliability is no less than that of the Encyclopaedia Britannica [6].

5. Recommender systems: wisdom out of connoisseurship

Another class of systems is based on recommendations of connoisseurs in a particular domain. An example of wisdom created out of expert recommendations is the Music Genoma Project at www.pandora.com a sort of Web-based radio that works by aggregating thousands of descriptions and classifications of pieces of music produced by connoisseurs and matches these descriptions with the “tastes” of listeners (as they describe them). Then it broadcasts a selection of music pieces that correspond to what the listeners like to hear. Another example of recommender system is www.CiteUlike.org, a free online service to share the academic papers you are reading with other people in your scientific community, find out who is reading the same papers as you, organize a library of some of the papers you are reading by tagging them in a particular way. Preferences are here voluntary shared. Some recommender systems collect information from users by actively asking them to rate a number of items, or to express a preference between two items, or to create a list of items that they like. The system then compares the data to similar data collected from other users and displays the recommendation. It is basically a collaborative filtering technique with a more active component: people are asked to express their preferences, instead of just inferring their preferences from their behaviour, which makes a huge difference: it is well known in psychology that we are not so good in introspection and sometimes we consciously express preferences that are incoherent with our behaviour: If asked, I may express a preference for classical music, while if I keep a record of how many times I do listen to classical music compared other genres of music in a week, I realize that my preferences are quite different).

Conclusions

This long list of examples of Web tools for producing collective wisdom illustrates how fine-grained can be the choice of the design for aggregating individual choices and preferences. The differences in design that I have underlined end up in deep differences in the kind of collective communities that are generated by the IT. Sometimes the community is absent, as in the case of the Google users, who cannot be defined as a “community” in any interesting normative sense, sometimes the community is normatively demanding, as in the case of eBay, in which participation in the filtering process is needed for the survival of the community. If the new collective production of knowledge that the Web – and in particular the Web 2.0 and 3.0 – makes possible should serve as a laboratory for designing “better” collective procedures for the production of knowledge or of wise decisions, these differences should be taken into account.

But let me come back in the end with a more epistemological claim about what kind of knowledge is produced by these new tools. As I said at the beginning, these tools work insofar as they provide access to rankings of information, labelling procedures and evaluations. Even Wikipedia, which doesn’t display any explicit rating device, works on the following principle: if an entry has survived on the site – that is, it has not been erased by other wikipedians – it is worth reading it. This can be a too weak evaluative tool, and, as I said, discussion goes on these days on the opportunity to introduce more structured filtering devices on Wikipedia , but it is my opinion that the survival or even egalitarian projects like Wikipedia depends on their capacity to incorporate a ranking: the label Wikipedia in itself works already as a reputational cue that orients the choices of the users. Without the reputation of the label, the success of the project would be much more limited.

As I said at the beginning, the Web is not only a powerful reservoir of all sort of labelled and unlabelled information, but it is also a powerful reputational tool that introduces ranks, rating systems, weights and biases in the landscape of knowledge. Even in this information-dense world, knowledge without evaluation would be a sad desert landscape in which people would be stunned in front of an enormous and mute mass of information, as Bouvard et Pécuchet, the two heroes of Flaubert’s famous novel, who decided to retire and to go through every known discipline without, in the end, being able to learn anything. An efficient knowledge system will inevitably grow by generating a variety of evaluative tools: that is how culture grows, how traditions are created. A cultural tradition is to begin with a labelling system of insiders and outsiders, of who stays on and who is lost in the magma of the past. The good news is that in the Web era this inevitable evaluation is made through new, collective tools that challenge the received views and develop and improve an innovative and democratic way of selection of knowledge. But there’s no escape from the creation of a “canonical”—even if tentative and rapidly evolving—corpus of knowledge.

[1] A version of this article has been presented at a workshop on Collective Wisdom held at Collège de France in May 2008. I’d like to thank Scott Page and Dan Sperber for their useful comments.

[2] Princeton Survey Research Associates, “A Matter of Trust: What Users Want from Websites”, Princeton, January 2002. The case is reported in R. Rogers (2004) Information Politics on the Web, MIT Press.

[3] Cf. on this point, L. Lessig (2001) The Fututre of Ideas, Vintage, New York.

[4] Kleinberg, J. (2001) “The Structure of the Web”, Science.

[5] Knowledge management systems like Amazon.com have some collaborative filtering features that need cooperation, like writing a review of a book or ranking a book with the five stars ranking system, but these aren’t essential to the functioning of the collaborative filtering process.

[6] Cf. “Internet Encyclopaedias go head to head” Nature, 438, 15 December 2005.