Why Psychology and Statistics Are Not Science

This article was originally posted on RealClearScience.

A few years ago, I caused considerable weeping and gnashing of teeth among psychologists for a piece I wrote explaining why psychology isn’t science. It was predicated upon a lengthier argument, which I co-authored with physicist Tom Hartsfield, on the difference between science and non-science. RCS Editor Ross Pomeroy followed up with his own haymaker, explaining why Sigmund Freud’s ideas — from penis envy to psychoanalysis — were not just whacky but unscientific and wrong.

Many psychologists take exception to our criticism, feeling disrespected by the notion that psychology isn’t science. Perhaps they suffer from the academic equivalent of penis envy? (I keed, I keed.) In all seriousness, being contemptuous is certainly not our intention.

Psychology is very important. We make use of its insights in our daily interactions with other people. Anybody who has taken a management class or read Dale Carnegie’s masterpiece How to Win Friends and Influence People appreciates the power in understanding what makes other people tick. But, of course, psychology isn’t the only field in which we gain important insights on human behavior; indeed, one can learn just as much about human behavior by reading Shakespeare, studying religious texts, or contemplating art. Nobody, however, would consider these academic areas to be a form of science.

Why does this matter? you might be wondering. Isn’t this just a food fight between academics?No, it most certainly is not. This discussion matters because epistemology, the study of knowledge, matters. The question, “How do you know what you claim to know?” is one of the most important questions in both science and philosophy. And in 21st Century America, in which people have their own news sources complete with their own set of (usually unverifiable) facts, we are in need of a very serious discussion on what constitutes genuine knowledge.

The liberal arts, which traditionally includes fields like psychology and economics, offers penetrating insights into human behavior. But, it simply does not measure up to the scientific method, the most powerful pathway to secular knowledge that humanity has ever invented. While psychology uses the scientific method in its experiments, limitations inherent to the field of psychology (such as difficulty in properly defining terms and quantifying data) may forever prevent it from joining the ranks of the hard sciences.

Again, that is not meant as an insult. It is meant only as a reminder that the truth claims made by the liberal arts are not as strong as those made by physics, chemistry, and biology. I would bet my house on the discovery of the Higgs boson, the accuracy of the periodic table, or the efficacy of vaccines. Yet, there is not a single fact in psychology upon which I would be willing to make a similar wager. Even the supposedly time-tested concept known as priming may be wrong.

Another popular misunderstanding is over the status of math and statistics. Math is the language of science. Undeniably, science would not be possible without statistics since it is necessary to discern significant from insignificant results, as well as to help determine cause-and-effect relationships. But, this in itself does not make statistics a science. Science would also not be possible without language, but nobody considers language to be a form of science.

Put simply, mathematicians and statisticians do not perform experiments. As a beautiful example of the power of logic and deduction, mathematical proofs may represent the highest form of knowledge attainable by man. Yet, that does not make it equivalent to science. Instead, proofs help develop tools. And these tools, gifted to us by the sheer brain power of mathematicians, have allowed scientists the ability to perform experiments. Statistics, therefore, should be thought of as the key facilitator of the scientific method.

Of course, though powerful, the scientific method is not infallible. The reproducibility problem in biomedical science attests to that. But a world without the scientific method is one that would never have advanced beyond the primitive technology of the 16th Century. Fully appreciating the Scientific Revolution begins by understanding what science actually is.