If you are not perplexed, you should be. As the web becomes ever more widespread, infiltrating our lives and shaping what we think is possible, we are increasingly unnerved about what we might have unleashed. Will it promote democratic collaboration and creativity? Or will the web be a malign influence, rendering us collectively stupid by our reliance on what Google and Wikipedia tell us being true, or, worse, promoting bigotry, thoughtlessness, criminality and terror?

Over the next two or three decades, people will start to play quite different roles, seeing themselves increasingly as participants and contributors, as well as workers and consumers.

Participation will, however, mean quite different things in different settings. More companies and brands, politicians and celebrities will try to incorporate their consumers as fans and followers, recruiting celebrants. They will participate, but more in the way a congregation does in a church service. Fundamentalists and terrorists are using the web in a different way, to connect widely distributed followers, disciples and adherents of a faith: the people involved in these networks are not just followers but also activists and initiators. Hacker communities, different again, bring together self-governing, democratic communities of digital craft workers.

But it would be naive to imagine that a new way of organising ourselves will necessarily be exclusively positive. There will be downsides, possibly very significant ones. Critics are already warning us to worry about a whole slew of possible disadvantages: the erosion of professional authority and knowledge; the loss of individuality in a morass of social networking; the eradication of spaces for reflection as a result of our being constantly connected; and the degradation of friendship when relationships are mediated by technology.

Strengths often breed matching weaknesses: the web's power comes from the way that it allows people to share, and that may also be its greatest flaw. There are no central gatekeepers to control access to the internet. It is a platform that virtually anyone can join, on which they can find other people, connect with them and start to share ideas.

A network originally designed to allow an elite of technically savvy US academics and researchers to share files has blossomed to embrace hundreds of millions of people, each with their own reason to want to join in myriad activities. And, unlike television, the internet has allowed people to adapt the technology as they use it, so generating yet more applications.

The internet's remarkable culture of openness will be the source of our greatest challenges and risks. For sharing can also spread diseases, infections and viruses. Ideas and identities once stolen can be spirited away and spread across thousands of computers.

Open networks make us vulnerable. In May 2007, the internet infrastructure of Estonia, one of the most connected societies in Europe, ground to a halt as its public and commercial organisations were hit by an attack from more than one million computers co-ordinated from Russia.

In their different ways, all the web's critics converge on a single worry: it makes the world more unreliable, threatening and out of control. Whatever the limitations of top-down, industrial-era institutions, at least the world they created was relatively orderly and people knew where they stood.

Editors, academics, doctors, scientists and professionals were the gatekeepers of knowledge; they could be trusted to tell us what was fact and what not. Instead of generating more knowledge, the web often seems to sow more doubt and uncertainty, spreading speculation and gossip. Now the means to spread terror are available to anyone with a camcorder, and deadly biological weapons could probably be made using ingredients bought on eBay with information gleaned from Wikipedia. You do not have to believe in conspiracy theories to worry. By 2050, tools for genetic engineering could be available to hapless amateurs releasing dangerous mutations from greenhouses equipped with gene sequencers.

Most of our worries about the world that is opening up to us come back to the fact we have little option but to share with people we do not know and cannot necessarily trust. Our growing connections to other people also leave us exposed to them. We are unavoidably implicated in and compromised by far-off events: in the summer of 2007 panicked British savers queued in their thousands to withdraw their money after a downturn in part of the distant US mortgage market. Keeping things stable when so many people can be connected to so much so easily takes ever more effort, whether in the form of financial market regulation or of the millions of interconnected decisions that we will need to make to tackle climate change.

Studies of forests show that, as they grow, they become more diverse, with plants and animals increasingly occupying specialised niches, to make the most of all the available nutrients. Yet, after a while, forests can become so densely connected that they become increasingly vulnerable to an external shock, such as fire, which can spread very fast.

The world being created by the web is rather like a fast-growing forest - increasingly dense, diverse and connected. When the web really is ubiquitous, will it become more like a forest that is so densely interconnected that a small fire can quickly sweep through vast areas of woodland?

Much will depend on whether the we-think culture can rise to the challenges that are facing us. We are compelled to share our ideas; that is how they come to life. And when we share ideas they multiply and grow, forming a powerfully reinforcing circle. You are not defined simply by what you own. You are also what you share.

© Charles Leadbeater 2008. We-Think, by Charles Leadbeater, to be published on March 3 by Profile Books, £12.99.

Your flexible phone

One glimpse of the future is M-Pesa, a micro-finance pilot in Kenya that uses mobile phones to connect borrowers and lenders. Only 1.3 per cent of Kenyans have internet access and there are only 300,000 landline telephones in the country, mainly in government offices.

Only 10 per cent of people, mainly in towns, have bank accounts. Yet mobile phone networks cover 70 per cent of the country and by 2007 some 6.5 million people had mobile phones, up from just 1 million in 2000.

In 2004 Vodafone's Kenyan affiliate, Safaricom, and the UK Government's Department for International Development each invested about £900,000 in M-Pesa (pesa means money in Swahili), which allows someone to use his or her mobile phone like a credit card or bank account.

An M-Pesa member can go to a mobile-phone airtime provider, usually a local shop, and upload some credit from his or her telephone service providers. They can use the credit themselves or transfer it to another user directly, without going through the bank. Kenya has few banks but lots of airtime dealers.

Overnight, M-Pesa created a low-cost banking infrastructure that can be used from dawn till midnight, ideal for a highly distributed and poor population who transfer small sums: in the pilot phase of the project, the average transfer between users was $2.27.

In February 2007, Vodafone announced a joint venture with Citibank to take the M-Pesa model worldwide, targeting transfers from the world's 190million migrant workers back to their families, transfers worth in total about £135 billion a year.

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