Martin Rees, president of the Royal Society, called for more restraint and regulation in scientific research (Dark materials, June 10). He tells us that "opinion polls reveal public concern that science may be advancing too fast to be properly controlled", and agonises about bio- and cyber-terrorism: "Even a single person will have the capability to cause widespread disruption through error or terror."
Our society has been afflicted with ever more extreme risk aversion since 9/11. Even so, Rees takes pessimism into new territory. His proposed solution is worldwide surveillance and regulation. This is both foolish and wicked. Controls on biological technologies are particularly foolish. The diseases that kill millions are not biowar lab nasties but naturally occurring pathogens such as HIV, Sars and flu. If the US and Europe won't let Sudanese students do PhDs in pathology then Khartoum won't have capable public-health services - which could be bad news for us next time a virus starts making its way down the Nile.
Controls on IT have been another battleground for the past 20 years. Western governments tried to stop semiconductor technology spreading to the far east, to halt the use of cryptography and to block the reporting of computer security vulnerabilities. These efforts failed, and thank goodness for that. However pessimistic the scenarios painted by government experts, the facts of life have turned out to be optimistic. Crumbling barriers to trade and the spread of dependable IT everywhere are lifting millions out of poverty. My wife's cousin - a school headmistress in Tamil Nadu - is more interested in the forthcoming arrival of broadband in her town than in al-Qaida: the earnings of English-speakers are set to double.
Progress happens because people decide that the benefits outweigh the costs. Of course there are losers, and sometimes the losers get violent. But let's keep a sense of perspective. Lord Rees admits: "Even nuclear physics has its upside: its medical uses have saved more people than nuclear weapons actually killed." Although some controls on technology may be sensible, the research lab isn't the place to put them: it's just too difficult to predict which scientific discovery will later lead to good applications or bad ones.
Thankfully, the public are beginning to see through scaremongering. Straight after the July 7 bombings there was a calm, gritty public reaction: "Something like this was bound to happen, but they're not going to stop us." Later, once the lobbyists had figured out their agendas, the fear mounted rapidly, but the public's initial reaction was spot on.
The only real answer to terrorism is to refuse to be terrified. It is a stoical shrug. Scientists cannot start being scared about doing their work on the off-chance that someone discovers a new way to hurt someone. People will inevitably invent new weapons as well as drugs and software - and we will live with that.
The scientist's job is to shine light in the darkness, and if we occasionally burn our fingers on the candle, so be it. Lord Rees can choose the darkness if he wants. I'm not going to.
· Ross Anderson is professor of security engineering at Cambridge University, and chairs the Foundation for Information Policy Research
· If you wish to respond, at greater length than in a letter, to an article in which you have featured either directly or indirectly, email response@theguardian.com or write to Response, The Guardian, 119 Farringdon Road, London EC1R 3ER.
We cannot guarantee to publish all responses, and we reserve the right to edit pieces for both length and content.