Skeptical Physicist Offers Critique of Psi

Dossey Stung by Stenger

By Victor J. Stenger

Larry Dossey has not responded to my essays in a meaningful way. Instead of participating in a professional discussion of the merits of my arguments, he resorts to an ad hominem attack against me and other skeptics. He says, “Religion-and-health researchers would benefit by informing themselves about past psi skirmishes to understand why skeptics are going out of their way to criticize their field.”
He suspects that I am “agitated by studies in intercessory prayer” for the same reason I am “vexed by psi.” Actually, I am not agitated or vexed by either one. I am, however, quite unimpressed, as a matter of science and basic statistics, with the claim that existing studies show positive effects from intercessory prayer, or contain evidence for the existence of psi effects, beyond the results which would occur by chance or other mundane means.
I am a scientist and will go whatever way the data lead me. So far, the data lead me to the conclusion that no effect has been demonstrated. When the data say otherwise, then I will change my mind. Dossey is criticizing me for being honest.
I agree that my arguments against the significance of prayer studies are similar to earlier arguments I have made against the significance of psi. Déjà vu happens. My “well-worn” criticisms of psi research have not changed since my 1990 book Physics and Psychics, because the flaws in psi research remain the same. Those criticisms have stood the test of time. I now see the same flaws in more recent prayer studies. Neither of these types of studies have demonstrated the level of statistical significance nor met other criteria that are normally applied in other fields. I am not suggesting that the standards for studies investigating possible positive health effects from religion, or possible psi effects, be any more stringent than those applied to other fields of scientific inquiry.
On what basis should prayer and psi experiments be held to a lower standard? Either the associated phenomena exist, or they do not. If they do, then their existence will be demonstrated by results of adequate statistical significance arising from well-controlled and well-designed experiments. I have pointed out that the data in the studies at issue do not meet those tests of significance and that the experimental procedures were flawed. A serious scientist concerned with these supposed phenomena would welcome this input and eagerly correct the faults to produce reliable data.
Dossey says that the effect sizes in psi experiments have held up over the years. In fact, they have remained small or fallen off. For 150 years, the claimed effects have been too small to conclude that psi is real. If any other field had such a continuing record of failure, its investigators would have given up years ago and gone on to work that is more fruitful.
Dossey incorrectly asserts that I singled out the Byrd study. In fact, I also presented the results of the prayer study published in Archives of Internal Medicine and referred to several reviews. I did not claim to conduct an exhaustive review of every possible study in such a short essay. Dossey agrees with skeptics that the Byrd study is “imperfect” but presents no example of a specific study, for prayer or psi, that provides the “compelling evidence” he says exists. You would think that the editor of a peer-reviewed journal would know of at least one.
Dossey then proceeds to single out the opinions of statistician Jessica Utts without mentioning the overwhelming majority of statistics experts who disagree with her. I happened to hear Utts give a talk a few years ago where she presented her arguments in favor of psi. I remember very well her making a comparison of the relative significance of psi studies and medical reports that were being used as a basis for recommending an aspirin be taken every day to help ward off heart attacks. She claimed that the significance of psi experiments was greater. As I recall, she asked why people believed the aspirin results and not the psi results. This was completely disingenuous on her part. No violation of any known principle of scientific medicine was implied by the aspirin results. So nothing extraordinary was being claimed.
As I mentioned in one of my essays, medical journals publish proposed treatments that may be of therapeutic value without demanding a high level of significance. I have no strong objection to that aspect of medical practice, but an inevitable result is that not every treatment contained in an article published in a medical journal turns out, over time, to be scientifically justified.
The reality of psi and intercessory prayer are wholly different matters. These would be extraordinary if true and toss out much well-established scientific knowledge. In Dossey’s essay and published books, he would have us believe that experiments have already achieved that objective. Not by a long shot. Plausible alternative explanations that are consistent with existing knowledge have not been ruled out. In many cases, that explanation is a simple statistical artifact. If one sets the rejection level at a p-value of 0.05, one of every 20 experiments will produce an artifactual effect at this level. The other 19 just do not get published.
Dossey quotes the late Charles Honorton as asking science to honestly confront the findings of parapsychology. Science has, and found them wanting. Parapsychologists and those studying the medical efficacy of religious practices need to honestly examine their own motives as well. All scientific investigators must work diligently to avoid selectively choosing only those data that support the conclusions they want to find. And when the verdict is in, honest investigators must accept the truth no matter what that truth may turn out to be, even though it undermines their deeply held beliefs.

Victor J. Stenger is professor emeritus of physics at the University of Hawaii and visiting fellow in philosophy at the University of Colorado. To learn more about professor Stenger and his new book, visit