The most compelling chapter elegantly traces how, despite numerous studies confirming a lack of association between vaccinations and autism, anguished parents of children with the disorder continue to insist the two are linked. There’s no doubt that the concerns of a parent with an autistic child are valid and wrenching, Specter says. But there’s also no doubt, statistically speaking, that parents who choose not to vaccinate their children put their children (and potentially their neighbors’ children) at greater risk of contracting diseases.

As diseases like measles and polio regain ground among the unvaccinated in the United Kingdom and northern Nigeria, respectively, and as many of us in the United States debate whether to inoculate our children against H1N1, the debate over vaccinations continues to be as relevant as ever.

Specter sees denialists everywhere, not only in the antivaccine movement. “Attacks on progress have become routine,’’ he writes. Denialism proposes an odd synthesis, arguing that parents who reject vaccinations, people who promote alternative medicine, politically correct doctors who refuse to investigate race as a diagnostic tool, and activists who oppose genetically modified crops are linked in a conspiracy against science.

“Either you believe evidence that can be tested, verified, and repeated will lead to a better understanding of reality,’’ Specter writes, “or you don’t.’’ It’s hard to argue with that. I was surprised, though, that he includes only a paragraph on creationists, who have to be the prototypical denialists. Nor does he spend more than a few sentences on the confused souls who refuse to believe that humans have affected the global climate. Perhaps he feels that territory already is well covered.

My misgivings aside, “Denialism’’ is a firestorm of a book, a broadside against anyone who would wish to hold back science out of fear. “Denialism is a virus,’’ Specter writes, “and viruses are contagious.’’ Specter argues that in every case tangible benefits outweigh theoretical harms, even in fields like synthetic biology, which has the potential both to deliver breathtaking answers for the world’s fuel requirements and to reduce the planet, in Prince Charles’s words, to “grey goo.’’

“We are either going to embrace new technologies, along with their limitations and threats,’’ Specter says, “or slink into an era of magical thinking.’’ What if we could generate genome-based, truly personalized medicine? What if we could eradicate malaria altogether? What if we could engineer a “super bee’’ that would be more resistant to the honeybee’s most lethal assailants?

Specter’s most important point is his most irresistible one. The only thing scarier than new technologies is refusing to have a healthy, informed, and civil discussion about them.

Anthony Doerr is the author of “The Shell Collector,’’ “About Grace,’’ and “Four Seasons in Rome.’’