Neurologist Robert A. Burton, MD has written a gem of a book: On Being Certain: Believing You Are Right Even When You’re Not. His thesis is that “Certainty and similar states of ‘knowing what we know’ arise out of involuntary brain mechanisms that, like love or anger, function independently of reason.” Your certainty that you are right has nothing to do with how right you are.

Within 24 hours of the Challenger explosion, psychologist Ulric Neisser had 106 students write down how they’d heard about the disaster, where they were, what they were doing at the time, etc. Two and a half years later he asked them the same questions. 25% gave strikingly different accounts, more than half were significantly different, and only 10% had all the details correct. Even after re-reading their original accounts, most of them were confident that their false memories were true. One student commented, “That’s my handwriting, but that’s not what happened.”

Just as we may “know” things that clearly aren’t true, we may think we don’t know when we really do. In the phenomenon of blindsight, patients with a damaged visual cortex have no awareness of vision, but can reliably point to where a light flashes when they think they are just guessing. And there are states of “knowing” that don’t correspond to any specific knowledge: mystical or religious experiences.

A “feeling of knowing” probably had an evolutionary advantage. If we are certain, we can act on that certainty rather than hesitating like Hamlet. Certainty makes us feel good: it rewards learning, and it keeps us from wasting time thinking too much; but it impairs flexibility.

Richard Feynman said,

“I can live with doubt and uncertainty and not knowing. I have approximate answers and possible beliefs and different degrees of certainty about different things… It doesn’t frighten me.”

On the other hand, many people, especially religious fundamentalists, can’t deal with uncertainty. They demand absolute answers and cling to their certainties even in the face of contrary evidence. Why are people so different in their need for certainty? We know there is a gene associated with risk-taking and novelty-seeking. Burton makes an intriguing suggestion: could genetic differences make individuals get different degrees of pleasure out of the feeling of knowing?

There is a “hidden layer” in our brain whose neurons are influenced by genetics, personal experience, hormones, and chemistry. These factors influence all our thought processes without our conscious knowledge. We would like to think that if everyone had the same information they would necessarily reach the same conclusion, but that just isn’t so. There is no such thing as pure reason. “Reason is not disembodied, as the tradition has largely held, but arises from the nature of our brains, bodies, and bodily experiences.”

The autonomous rational mind is a myth. The concepts of the self and free will are innate useful fictions that allow us to function. As Samuel Johnson said, “All theory is against the freedom of the will; all experience is for it.” Modern neurophysiology tells us our decisions are made subconsciously before we are aware of deciding.

Burton discusses how certainty interferes with science. “Integrative medicine” guru Andrew Weil set up tests of osteopathic manipulation for ear infections, and when the experiments showed no effect, he said, “I’m sure there’s an effect there. We couldn’t capture it in the way we set up the experiment.” This kind of thinking is rampant in alternative medicine. Burton thinks that if Dr. Weil recommends osteopathy for an ear infection, he should inform the patient that the recommendation is based on an unconfirmed belief.

Richard Dawkins rejects religion but finds purpose and meaning in science. Burton suggests that purpose and meaning are powerful innate feelings. We feel that our life has purpose and meaning, and we look to science or religion to try to explain that feeling. No amount of rational argument is likely to change us. “Whether an idea originates in a feeling of faith or appears to be the result of pure reason, it arises out of a personal hidden layer that we can neither see nor control.”

Burton thinks irrational beliefs can have adaptive benefits (for instance, the placebo effect) and thinks objectivity and reason should be seen in the larger context of our biological needs and constraints. If science and religion could both accept that all our facts are really provisional, absolutism could be dethroned and a dialog might become possible. What if religious fundamentalists acknowledged even a 0.0000000001% possibility that their beliefs were false? Biology teaches us that absolutism is an untenable stance of ignorance.

I have long thought that absolutism was one of humanity’s greatest problems. There are implications for politics, religion, and every sphere of human activity. The insights from this book can be applied to every human interaction from marital squabbles to terrorism. It may be frightening to recognize the limits of our knowledge. It will be hard for some to give up their cherished certainties, but Burton says he has gained an extraordinary sense of an inner quiet born of acknowledging his limitations.

As a reminder that there is never a 100% guarantee that we are right, Burton suggests we use the words “I believe” instead of “I know.” This is the one place where I disagree with him: I don’t like either word. Belief sounds too much like faith. I don’t like the idea of saying I believe evolution is true. Truth in science, at best, can only mean that the evidence is overwhelming. We can’t “know” absolutely in a metaphysical sense. We provisionally accept evolution because the evidence is so overwhelming that it would be perverse to reject it. We remain open to new evidence.

The author is a neurologist who is also a novelist and a columnist for This well-written book is the result of many years of cogitation by a wise clinician. He supports his arguments with tales of neurology patients, recent research into brain function, and examples of how our senses constantly fool us.

Burton says, “In medicine, we are increasingly developing ethical standards for complex medical decisions that both allow for hope and placebo effect, yet don’t fly in the face of evidence-based medical knowledge.” This subject has come up on this blog before, and it is one we will continue to grapple with.

If there’s anything you think you’re certain of, read this book and you may change your mind.

Posted by Harriet Hall

Harriet Hall, MD also known as The SkepDoc, is a retired family physician who writes about pseudoscience and questionable medical practices. She received her BA and MD from the University of Washington, did her internship in the Air Force (the second female ever to do so),  and was the first female graduate of the Air Force family practice residency at Eglin Air Force Base. During a long career as an Air Force physician, she held various positions from flight surgeon to DBMS (Director of Base Medical Services) and did everything from delivering babies to taking the controls of a B-52. She retired with the rank of Colonel.  In 2008 she published her memoirs, Women Aren't Supposed to Fly.