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
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
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
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