"The issues are ethical. They [the public] don't need to be terribly informed. They can debate a cloned sheep," he says, referring to last month's announcement of Dolly, cloned from an adult sheep, in the world's media.
"Genetically engineering a cloned sheep to me is not ethically neutral," he maintains. As for the scientists who made the breakthrough: "They'd better worry about the consequences. I am glad we live in a time when science raises ethical questions. It argues directly with the 'fact' that science is ethically neutral. And if you think only biology does it, then you're crazy. All of science does."
During the First World War, it was the chemists who drew fire. The German scientist Fritz Haber put bread into people's mouths when he discovered a way to convert nitrogen from the atmosphere into ammonia for fertilisers. But he also oversaw the use of chlorine gas to kill enemy troops.
The next war turned the spotlight on the physicists who developed the atomic bomb. Now it is the biologists' turn.
Hoffmann believes that "the public is more sensitised to environmental questions and questions of reproductive technology and genetic engineering". Sensitised maybe, but still ill-informed, the experts would counter. Still, Hoffmann upholds the public's right to argue, and exhibits a refreshing humility about science's role in the community. His latest book, The Same and Not the Same, embraces the wider world rather than pitching science against it. "My general outlook is that science is firmly embedded in culture," he says. "I really believe there is something that our colleagues in the arts and humanities have learned, and that we can learn from them."
Hoffmann was born in what is now part of Ukraine. At the age of four, he was sent with his family to a Nazi labour camp. His father was executed for trying to escape. Roald and his mother were smuggled out after two years and spent a further year hiding in a school attic until they were liberated by Soviet forces. After the war, they emigrated to the US.
It was in the Sixties that Hoffmann did his most important work, collaborating with Robert Woodward and using ideas from quantum theory to determine whether certain reactions in organic chemistry would go or not. The Woodward- Hoffmann "rules" became indispensable to synthetic chemists, and won Hoffmann the Nobel prize in 1981.
Since then he has written a number of books that set science, and his own science of chemistry in particular, into a broad cultural context. The Same and Not the Same takes chirality - the existence of left-handed and right-handed versions of what are otherwise the same molecules - as its motif, a metaphor for identity conflict in humans, from Haber, giver and taker of life, to ourselves in our reluctant embrace of technology. "That a reasonable human being can be ambivalent about chemicals, seeing in them both harm and benefit, is not a sign of irrationality but of humanity," he writes. "Utility and danger are two poles of a duality .... The tension of asking the question ['Can it help me?'/'Can it hurt me?'] and struggling with the answer links the material and spiritual worlds."
It's all a long way from some British popularisers who seem as keen to mock our readiness to follow what is not scientific, as to increase our understanding. Peter Atkins attacks religion; Lewis Wolpert has a problem with "arty-babble"; Richard Dawkins even takes offence at The X Files.
"I do stand in some contrast with them," admits Hoffmann, whose next book he describes as "a non-confrontational look" at science and religion. "I think scientists are tilting at the wrong windmills here. These are human things which aren't going to go away. Human beings are very nicely of two minds: they accept the rational definitions, but they also believe in other things in some aspects of their life, and they switch between the two."
As for the two-cultures problem: "The synthesis of molecules puts chemistry very close to the arts," Hoffmann writes. Perhaps it is true that, as Rutherford remarked, somebody else would have discovered the electron soon enough had JJ Thomson not discovered it, 100 years ago this month. But competing groups of chemists have achieved the synthesis of new substances such as immunosuppressants, important in transplant surgery, by essentially creative means that take very different paths.
By insisting on a distinction between science and technology, Wolpert also takes scientists "out of the loop" once their discoveries are put to use. For Hoffmann, discovery and application are closely related. If scientists are prepared to take the credit for success, then they must also share the blame for mistakes such as thalidomide or Bhopal.
In his Consumer's Good Chemical Guide, John Emsley is scornful of those who seek out the "natural" in favour of the "chemical," when there may be no essential difference between the two. Hoffmann understands their search. He explains why we prefer the natural in clothing: it gives us a precious feeling of individualism, knowing that no two garments are absolutely identical.
When the actress Meryl Streep protested about apples treated with the growth-regulating chemical Alar, many American scientists pooh-poohed her concern. Not Hoffmann. He, too, was shocked to learn about the practice - and still more so to find that he knew nothing about it. The episode prompted him to observe that we have slipped, apparently without realising it, from washing produce to rid it of bugs and dirt, to washing it to cleanse it of chemical residues.
Today, we see the same battle lines being drawn in the debate over genetically altered soya and corn. Consumers, for the most part ignorant but concerned, mistrust the way they see things going. Scientists, knowledgeable but insensitive, blithely assure us that all is well. So it may be. But people will continue to worry. Hoffmann believes scientists should learn to accept this. Our psychological reasons for preferring the "natural" may be as strong in their own way as any rational justification for artificial alternatives.
To take an extreme example, chemists often argue that "chemical" warfare is no more repulsive than other forms. It's simply a poor choice between one element or another, they reason. Death by chlorine is no worse than death by a lead bullet. But Hoffmann agrees with ethicists that chemical warfare is worse, "Something in the psyche, something deep that associates life with breath, is perturbed," he writes, citing Wilfred Owen's poem, "Dulce et Decorum Est", to underline the point.
'The Same and Not the Same' is published this month in paperback by Columbia University Press