It is a fact that farmers in the Third World, unable to secure a decent living from coffee, are turning to cocaine in search of a crop that can yield a decent income.

It is a fact that farmers in the Third World, unable to secure a decent living from coffee, are turning to cocaine in search of a crop that can yield a decent income.

Vitelio and Maria Menza have farmed coffee in Pescador, Colombia, for years but have yet to complete their house. When coffee prices fell drastically in the 1990s, they found themselves in serious trouble. To pay for the care of their crop and tide themselves over until harvest, they had borrowed money, a debt they could not pay off when the prices fell.

The only way to survive was to diversify - to grow yucca and beans for food, for example, and seek work on neighbouring farms to pay their debts.

For others, the only escape was to grow coca illegally, and the violence that the industry attracts affected the whole region. Similarly, banana-farmers in the Caribbean are turning to cannabis. Others, less fortunate but subject to the same economic realities, are turning up in urban shanty-towns in search of work, despite the insecurity, division of families and poor conditions they endure.

Whether a product has been produced in exploitative or environmentally damaging conditions, indeed whether it has been bought on socially sustainable terms, cannot be factored into the price. There is therefore a need for us to move beyond the faceless commoditisation of products to a system that can recognise other, more complex values. This is increasingly what consumers want.

Already we are seeing, in the US, the growing impact of single-origin coffees; these rarely incorporate the kind of issues I am discussing, but give us a direction that at least can do so, given a fair wind.

Consumers, increasingly sophisticated and cynical as a result of the excessive environmental claims of the 1980s and the breakdown of trust in the food industry as a result of BSE and other disasters, will support such schemes only if they trust that they do make a difference.

As a society we can - and increasingly do - choose how we want to run our lives, and if consumers want socially and environmentally sound products; if they want to support small farmers against big, "efficient" but socially unsustainable competitors, they will do so. And the market had better respond.

Not so long ago, chimney-sweeps that did not use children would have been regarded as inefficient, but society has changed the rules, and economists have had to catch up by revising their models. Economics is a useful tool to inform our decisions, but when it does not reflect society's values, it is a lousy master.

Civil society organisations (non-governmental organisations, unions and the business community) have developed several ways of co-operating to maximise the social benefits of commercial activity and to minimise its social costs. In the international sphere, such work has been slower to develop and subject to more controversy perhaps than in addressing local issues.

Today, however, we have two well-defined strands of activity which complement each other in many ways, and each of which needs to be taken seriously by a much wider range of companies than at present.

Codes of conduct, if properly implemented, may well enable companies to ensure that no gross exploitation takes place within their supply chains. Linkages with the local economies, and the establishment of monitoring systems, will hopefully also begin to influence other sectors of business in the developing countries.

The challenge we face is the recognition that, while fair trade is, to the consumer market, a niche, appealing to a growing - but still small - proportion of consumers, there are in some product areas literally millions of marginalised producers. Fair trade needs to grow beyond its current niche, and it needs business support to do so.