Increasingly, scientific studies have recognized the power of positive expectations in the treatment of people who are suffering from various illnesses. The so-called “placebo” effect is so powerful that studies generally try to control for it: fake pills, fake injections, or sometimes even fake surgeries will be given to one group while another group is offered the “real” treatment. If the real drug or surgery is no better than the fake drug/surgery, then the treatment is considered a failure. What has not been recognized until relatively recently is how the power of positive expectations should be considered as a form of treatment in itself.

Recently, Harvard University has established a Program in Placebo Studies and the Therapeutic Encounter in order to study this very issue. For many scientists, the power of the placebo has been a scandal and an embarrassment, and the idea of offering a “fake” treatment to a patient seems to go against every ethical and professional principle. But the attitude of Ted Kaptchuk, head of the Harvard program, is that if something works, it’s worth studying, no matter how crazy and irrational it seems.

In fact, “crazy” and “irrational” seem to be apt words to describe the results of research on placebos. Researchers have found differences in the effectiveness of placebos based merely on appearance — large pills are more effective than small pills; two pills are better than one pill; “brand name” pills are more effective than generics; capsules are better than pills; and injections are the most effective of all! Even the color of pills affects the outcome. One study found that the most famous anti-anxiety medication in the world, Valium, has no measurable effect on a person’s anxiety unless the person knows he or she is taking it (see “The Power of Nothing” in the Dec. 12 2011 New Yorker). The placebo is probably the oldest and simplest form of “faith healing” there is.

There are scientists who are critical of many of these placebo studies; they believe the power of placebos has been greatly exaggerated. Several studies have concluded that the placebo effect is small or insignificant, especially when objective measures of patient improvement are used instead of subjective self-reports.

However, it should be noted that the placebo effect is not simply a matter of patient feelings that are impossible to measure accurately — there is actually scientific evidence that the human brain manufactures chemicals in response to positive expectations. In the 1970s, it was discovered that people who reported a reduction in pain in response to a placebo were actually producing greater amounts of endorphins, a substance in the brain chemically similar to morphine and heroin that reduces pain and is capable of producing feelings of euphoria (as in the “runner’s high“). Increasingly, studies of the placebo effect have relied on brain scans to actually track changes in the brain in response to a patient receiving a placebo, so measurement of effects is not merely a matter of relying on what a person says. One recent study found that patients suffering from Parkinson’s disease responded better to an “expensive” placebo than a “cheaper” placebo. Patients were given injections containing nothing but saline water, but the arm of patients that was told the saline solution cost $1500 per dose experienced significantly better improvements in motor function than patients that were given a “cheaper” placebo! This happens because the placebo effect boosts the brain’s production of dopamine, which counteracts the effects of Parkinson’s disease. Brain scans have confirmed greater dopamine activation in the brains of those given placebos.

Other studies have confirmed the close relation between the health of the human mind and the health of the body. Excessive stress weakens the immune system, creating an opening for illness. People who regularly practice meditation, on the other hand, can strengthen their immune system and as result, catch colds and the flu less often. The health effects of mediation do not depend on the religion of those practicing it — Buddhist, Christian, Sikh. The mere act of meditation is what it important.

Why has modern medicine been so slow and reluctant to acknowledge the power of positive expectations and spirituality in improving human health? I think it’s because modern science has been based on certain metaphysical assumptions about nature which have been very valuable in advancing knowledge historically, but are ultimately limited and flawed. These assumptions are: (1) Anything that exists solely in the human mind is not real; (2) Knowledge must be based on what exists objectively, that is, what exists outside the mind; and (3) everything in nature is based on material causation — impersonal objects colliding with or forming bonds with other impersonal objects. In many respects, these metaphysical assumptions were valuable in overcoming centuries of wrong beliefs and superstitions. Scientists learned to observe nature in a disinterested fashion, discover how nature actually was and not how we wanted it to be. Old myths about gods and personal spirits shaping nature became obsolete, to be replaced by theories of material causation, which led to technological advances that brought the human race enormous benefits.

The problem with these metaphysical assumptions, however, is that they draw too sharp a separation between the human mind and what exists outside the mind. The human mind is part of reality, embedded in reality. Scientists rely on concepts created by the human mind to understand reality, and multiple, contradictory concepts and theories may be needed to understand reality.  (See here and here). And the human mind can modify reality – it is not just a passive spectator. The mind affects the body directly because it is directly connected to the body. But the mind can also affect reality by directing the limbs to perform certain tasks — construct a house, create a computer, or build a spaceship.

So if the human mind can shape the reality of the body through positive expectations, can positive expectations bring additional benefits, beyond health? According to the American philosopher William James in his essay “The Will to Believe,” a leap of faith could be justified in certain restricted circumstances: when a momentous decision must be made, there is a large element of uncertainty, and there are not enough resources and time to reduce the uncertainty. (See this post.) In James’ view, in some cases, we must take the risk of supposing something is true, lest we lose the opportunity of gaining something beneficial. In short, “Faith in a fact can help create that fact.”

Scientific research on how expectations affect human performance tends to support James’ claim. Performance in sports is often influenced by athletes’ expectations of “good luck.” People who are optimistic and visualize their ideal goals are more likely to actually attain their goals than people who don’t. One recent study found that human performance in a color discrimination task is better when the subjects are provided a lamp that has a label touting environmental friendliness. Telling people about stereotypes before crucial tests affects how well people perform on tests — Asians who are told about how good Asians are at math perform better on math tests; women who are sent the message that women are not as smart perform less well on tests. When golfers are told that winning golf is a matter of intelligence, white golfers improve their performance; when golfers are told that golf is a matter of natural athleticism, blacks do better.

Now, I am not about to tell you that faith is good in all circumstances and that you should always have faith. Applied across the board, faith can hurt you or even kill you. Relying solely on faith is not likely to cure cancer or other serious illnesses. Worshipers in some Pentecostal churches who handle poisonous snakes sometimes die from snake bites. And terrorists who think they will be rewarded in the afterlife for killing innocent people are truly deluded.

So what is the proper scope for faith? When should it be used and when should it not be used? Here are three rules:

First, faith must be restricted to the zone of uncertainty that always exists when evaluating facts. One can have faith in things that are unknown or not fully known, but one should not have faith in things that are contrary to facts that have been well-established by empirical research. One cannot simply say that one’s faith forbids belief in the scientific findings on evolution and the big bang, or that faith requires that one’s holy text is infallible in all matters of history, morals, and science.

Second, the benefits of faith cannot be used as evidence for belief in certain facts. A person who finds relief from Parkinson’s disease by imagining the healing powers of Christ’s love cannot argue that this proves that Jesus was truly the son of God, that Jesus could perform miracles, was crucified, and rose from the dead. These are factual claims that may or may not be historically accurate. Likewise with the golden plates of Joseph Smith that were allegedly the basis for the Book of Mormon or the ascent of the prophet Muhammad to heaven — faith does not prove any of these alleged facts. If there was evidence that one particular religious belief tended to heal people much better than other religious beliefs, then one might devote effort to examining if the facts of that religion were true. But there does not seem to be a difference among faiths — just about any faith, even the simplest faith in a mere sugar pill, seems to work.

Finally, faith should not run unnecessary risks. Faith is a supplement to reason, research, and science, not an alternative. Science, including medical science, works. If you get sick, you should go to a doctor first, then rely on faith. As the prophet Muhammad said, “Tie your camel first, then put your trust in Allah.”