Sir

The Editorial 'Enough talk already' (Nature 448, 1–2; doi:10.1038/448001b 2007) concludes that governments should respond to the public concern expressed in engagement exercises, and invest in research on the health and environmental risks of nanotechnologies. I agree. I would, however, suggest that this is not enough.

Although we need more scientific research on the risks of nanotechnologies, we also need to encourage broader dialogue on notions of progress, quality of life, human needs and our visions of the future — both with and without nanotechnology.

In the social sciences, the concept of uncertainty has been extended beyond that of risk and a lack of research. First, within complex, open and interacting social and natural systems, there is an inherent and irreducible form of uncertainty that prevents the full range of impacts being delimited. An additional form of uncertainty results from the diverse values, interests and positions held on questions such as what actually constitutes social and environmental health. Finally, given the novel properties used within nanotechnologies, there will also inevitably be novel impacts that we are currently simply ignorant about. This is ignorance about the right questions to ask, rather than ignorance about the answers.

This means that we need a broader dialogue to take place, about the real-life value of potential applications coming from nanotechnology. Otherwise we risk falling into the trap of believing we can base decisions about nanotechnologies on an assessment of their potential impacts alone, disregarding our values in the face of multiple forms of uncertainty.

Public-engagement exercises can begin this kind of dialogue — but not if their purpose is simply building public trust in order to win acceptance of potentially controversial technologies.