If you have spent any time in a psychology classroom lately, then you have probably forgotten what the practice of science is all about. Be reminded that science is not interested in, nor is it capable of, advancing proofs. Proofs belong to the ideal systems of mathematics, physics, geometry, logic, and so on. Theories are credible in science not because they are true, but because they are falsifiable. A scientific claim may be judged as strong if easy to refute, but, despite ease, no refutation has been made. The theory of the gravitational constant is strong because it could be easily refuted by dropping an object that reaches a maximum velocity of something other than 9.8m/sec. But in nearly 400 years this hasn’t happened.
Scientific claims may be contrasted with beliefs. Beliefs generally accompany comprehensive world-views—that is, coherent systems of meaning and explanation such as a religion. A small handful of religions have survived thousands of years, and have supplied their communities of believers with structures of meaning helpful for making sense of life, existence, evil, and so on. Following the development of modern science by among others Isaac Newton (who was himself deeply religious), religious beliefs were criticized for their nonfalsifiability—that is, religions were challenged on the grounds that they were not scientific. But believers are not pretending to be scientists, and therefore do not rely on hypothesis testing to defend their beliefs. Religion should not be measured using a scientific yardstick.
Despite a history of measuring all other systems of knowledge with the scientific yardstick, scientists today are having trouble remembering to use it for themselves. Scientists have largely abandoned their Enlightenment-Era rule for evaluating scientific claims, and have instead begun practicing Science—that is, the religious belief in other scientists.
In order to learn about a scientific claim, a student cannot begin or end with the truth of the claim. That would be accepting the claim on faith—that is, believing in it. Accepting without question that the gravitational constant is 9.8m/sec requires a leap of faith, which takes the scientific theory in its least scientific and most irrelevant quality. In order to understand the scientific quality of a theory, one must instead ask “What evidence could be obtained that would refute this claim.”
Remember now that there is no evidence sufficient for a Christian to believe there is no God, because the Christian’s faith is not dependent on the scientific method. Belief is another matter entirely. It would be just as foolish to expect a student of science to accept a scientific claim on the basis of faith.
A science education can only proceed by confronting the falsifiability of scientific claims. But then, as you can imagine, conversations would repeatedly ground out and stall, because the scientific process is complicated and there are always dozens of possible confounds to consider. That’s how it goes with science. Courses move more smoothly when research findings are explained one after the other like rules in Leviticus, even though this ignores the very quality of science in the sciences.
When students learn a scientific discipline by reading about it in a book and accepting what they read as true, they are learning to believe like children in Sunday School. While perfectly acceptable with religious belief, this runs afoul the process of science. Students learn that claims a, b, c, …, z are true because scientists have discovered them. But students seldom get to confront claims a, b, and c in the very qualities that make them scientific. Today there is an almost religious fervor that neuroscience is capable of explaining all human behavior. That is to say, neuroscience provides a worldview useful for understanding and explaining human behavior, and this worldview is accepted on faith.
The academic discipline of psychology has grown from nothing in the 19th century to one of the biggest industries of the 21st. At many universities psychology is the most popular major. Psychology claims to be a science, and has used this scientific credibility to build an enormous medical industry known colloquially as the “mental health industry.” Students can train to become medical social workers, counselors, clinical psychologists, psychiatrists, and so on. You might wonder what they learn while training.
It is a common claim among mental health professionals and scientists that depression is in the brain. Already and only this year (as of August 18) there have been over 1,200 peer-reviewed articles on the topic of depression and the brain. It no longer surprises me when students explain without blinking that “depression is in the brain” or even “psychology is all about the brain.”
To pick on the most popular depression-as-brain-disorder claim, consider with me the monoamine hypothesis, which explains that depression is the consequence of too-little Serotonin in the blood. The claim is a reasonable one, since Serotonin is a neurotransmitter thought to be responsible for that feeling of satisfaction you get after mowing the lawn or acing an exam. But in order to evaluate the scientific credibility of this claim, it is not enough for it to be reasonable. We must ask: “What sort of evidence, if gathered, would refute this claim?” If there is no such evidence that could be supplied, then the claim is unfalsifiable and must therefore be chalked up to belief. It is not unlike the Christian belief that a righteous life will be rewarded with happiness and so on.
Sadly, the opacity of the skull makes it difficult to count Serotonin molecules directly, so psychiatric researchers have devised an indirect way of looking. They have given depression-sufferers selective-Serotonin reuptake inhibitors (SSRIs), which prevent nerve-cells from being stingy with their release of Serotonin. The chemistry involved, which I have to imagine few psychiatric nurses understand beyond what I’ve described, suggests that SSRIs should increase Serotonin-levels in the blood and therefore correct the depression problem.
Knowing all of this, it is time to think like a scientist: what evidence would refute the claim that depression is caused by too-little Serotonin? For example, how long would you wait to see improvements before rejecting the claim? If it doesn’t start working in 30 minutes, should the claim be thrown out? Three hours? If you took an SSRI, would it seem reasonable for it to take three days before correcting the depression problem, or would you have to judge the hypothesis false? If I told you that it takes three weeks, I suspect you would find the monoamine hypothesis a poor one. But, according to psychiatric scientists, three weeks is how long it takes.
Imagine now that your patience and generosity in the face of such results exceed my own, and that you are willing to withhold judgment against the claim based on the three-week window. What percentage of depressed persons would you expect to benefit from SSRIs? What if, for example, I told you that SSRIs improve the symptoms of only about 40% of depression sufferers? This means that if you were to pick a depressed person at random, then they would not benefit from SSRIs. Would this be enough to reject the claim that depression is caused by too-little Serotonin?
(Reflect for a moment at how much time we have spent considering this one psychiatric claim, and how many other claims we could have covered by now were I to simply list them as facts, one after the other, and asked that you believe in them.)
I suspect I have tested your patience as a scientist, but, pray, indulge me one more example. Imagine that you haven’t been scared away by the three-week wait or the meager percentage of people helped by SSRIs. For those 40% of people whom SSRIs do help, how big of a change in depression symptoms would you expect in order to let stand the claim “depression is caused by too-little Serotonin?” What if I told you the majority of the effect SSRIs have on depression symptoms comes not from the chemical action of the drug on Serotonin molecules, but from the placebo effect—that is, the belief patients have that the SSRI drug will help them?
(The role belief plays in the effectiveness of psychiatric treatment is revealing all by itself.)
Of course the hypothetical evidence I have given is not hypothetical, but the state of the art in psychiatric science. The monoamine hypothesis stands as the best hypothesis that depression is in the brain. I wonder: upon what evidence would it be acceptable to refute this claim?