Is Psychology a Science?

Is Psychology a Science?

Copyright © 2003-2005, Paul Lutus — Message Page
Updated 08/05/2008Introduction What is science? What Is Psychology? Present-day Human PsychologyPsychology As Religion Conclusion Updates Further Reading Feedback
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Introduction
Since its first appearance in 2003, this article has become required reading in a number of college-level psychology courses. Because the original article was directed toward nonspecialist readers considering psychological treatment, students of psychology should be cautioned that the terms "psychology" and "clinical psychology" are used interchangeably.

The field of human psychology is a powerful force in modern society, and its influence is widespread – in language, law, the social contract, and in our perception of ourselves. Because legal decisions are sometimes made based on psychology, decisions that might cause someone to be incarcerated or freed, decisions that might shape public policy, it is important to establish whether psychology is a science or a simple belief system. We should determine whether psychology can be relied on to objectively support the social and legal policies that are based on it. In modern times, such a serious public burden can only be borne by a field that is based on reason, on science. Which leads to our question: is human psychology steered by science?

What Is Science?

In order to consider whether psychology is a science, we must first define our terms. It is not overarching to say that science is what separates human beings from animals, and, as time goes by and we learn more about our animal neighbors here on Earth, it becomes increasingly clear that science is all that separates humans from animals. We are learning that animals have feelings, passions, and certain rights. What animals do not have is the ability to reason, to rise above feeling.

Science's goal is to create reasonable explanations (theories) to describe reality – theories that rely, not on feelings or passions, but on evidence. Science defines “evidence” in a special way that will seem rather strict to someone only familiar with the legal definition. To science, evidence is gathered and evaluated (and sometimes discarded) according to some rigid rules, rules meant to assure that a scientific theory reflects reality to the best of our ability.

How strict are science's rules of evidence? Well, let's first compare science to law. The legal definition of evidence is (as one example) a set of observations that appear to associate a particular person with a particular event. Typically, legal proceedings begin with an investigation meant to collect evidence, followed by a trial that establishes whether that evidence meets a criterion – “beyond a reasonable doubt” in criminal proceedings, and “according to the preponderance of evidence” in civil proceedings (in the US). This, by the way, is why O. J. Simpson was found innocent in criminal court, but found guilty in a subsequent civil proceeding – using the same evidence, he wasn't guilty “beyond a reasonable doubt,” but he was guilty “according to the preponderance of evidence.”

In an embarrassing and tragic number of cases, innocent people have been placed on death row (and sometimes executed) based on evidence that, notwithstanding the innocence of the convict, met the “beyond a reasonable doubt” standard, when evaluated by a jury of 12 upstanding citizens, people whom we shall charitably assume paid no mind to the color of the defendant's skin. Relatively recently, new ways of gathering evidence – like DNA testing – have proven the innocence of a fortunate few death-row inmates, and others who might have gone unpunished have been arrested.

The point here is that legal evidence is not remotely scientific evidence. Contrary to popular belief, science doesn't use sloppy evidentiary standards like “beyond a reasonable doubt,” and scientific theories never become facts. This is why the oft-heard expression “proven scientific fact” is never appropriate – it only reflects the scientific ignorance of the speaker. Scientific theories are always theories, they never become the final and only explanation for a given phenomenon.

As to the ever-popular expression “scientific law,” this is often an earnest effort by scientists to bridge the gap between the level of certainty required in science and that accepted in ordinary life. In fact and strictly speaking, there are no scientific laws, only theories about which we are very certain, like entropy and gravity, which, if they were to be tersely expressed in everyday language, would read: “Eventually it will break, and when it does, it is going to fall.”

About scientific evidence, philosopher Karl Popper said, “No amount of observations of white swans can allow the inference that all swans are white, but the observation of a single black swan is sufficient to refute that conclusion.” This saying aptly summarizes the difference between scientific evidence and every other kind of evidence, and it dramatizes the difference between science and ordinary human thinking.

This very strict evidentiary standard is essential for science to provide its riches, and it is no problem for people who have been properly educated. But in the lives of people for whom “evidence” means “he said, she said,” certain problems are inevitable.

When properly conducted, scientific investigations never draw conclusions directly from observations. This may sound unnecessarily strict, but it is necessary for science to accomplish what it does.

To demonstrate this, here is a hypothetical conversation between a psychic wannabe (PW) and a scientist (S):

PW: “I successfully predicted 100 coin tosses, therefore I am psychic.”
S: “How many total coin tosses were there?”
PW: “200”.
S: “So you guessed half correctly, and half incorrectly, yes?”
PW: “Yes – isn't that amazing?”
S: “No, not really. It is the outcome predicted by chance.”
(a day goes by ...)
PW: “I correctly guessed eight coin tosses in a row! Now that's proof that I'm psychic!”
S: “How many total coin tosses this time?”
PW: “Umm, 256.”

S: “With that many coin tosses, eight sequential correct guesses has a probability of ½ of coming about by chance. You might be psychic, but there is a much more likely explanation – chance.”
This example highlights a cardinal rule of science: Always consider alternative explanations, never accept anything at face value.

In everyday life, people are regularly taken in by con men who rely on public ignorance of reason and science. Here's an example – you receive a mailing from someone who wants to be your financial advisor. He predicts that the stock market will fall (or rise) during the next month. At the end of the month, his prediction turns out to be correct. Then, for six months straight, he mails you a prediction, and each prediction turns out to be correct. In a quick calculation you realize you would have made several million dollars by following his advice.

Having “proven” his abilities, the financial advisor now wants you to give him control of your portfolio. His is the best performance you have ever seen, he obviously has special skills, what do you do? Well, hopefully you follow the cardinal rule: Always consider alternative explanations.
Here is a very likely alternative explanation – the “financial wizard” is a con man, a hustler. Here is how this well-known con works:

At the beginning of the six-month period, the "wizard" mails a prediction to a list of 16,384 people. He tells half the people the market will rise, the other half that it will fall.
At the end of the first month, he drops half the names from the list (those who got an incorrect prediction) and mails a new prediction to the remaining names.
He repeats this procedure for six months, each month dropping half the names and keeping those that got a correct prediction.

At the end of six months, he has a list of 256 very hot prospects, each of whom has gotten a seemingly miraculous run of correct predictions, each of whom might just sign up for his "services," each of whom is about to be swindled.

These 256 "marks" (the con-man term for someone about to be “serviced”) must either consider alternative explanations, or they stand to lose a lot of money. And very important: for those who decide to accept the con man's services, their decision is perfectly reasonable when based on everyday perceptions. Just like many of the claims of the practitioners of clinical psychology, and to someone unable to think critically, it is perfectly reasonable, and it is wrong.

Apart from being filtered through all possible explanations, scientific theories have another important property – they must make predictions that can be tested and possibly falsified. In fact, and this may surprise you, scientific theories can only be falsified, they can never be proven true once and for all. That is why they are called “theories,” as certain as some of them are – it is always possible they may be replaced by better theories, ones that explain more, or are simpler, or that make more accurate predictions than their forebears.

It's very simple, really. If a theory doesn't make testable predictions, or if the tests are not practical, or if the tests cannot lead to a clear outcome that supports or falsifies the theory, the theory is not scientific. This may come as another surprise, but very little of the theoretical content of human psychology meets this scientific criterion. As to the clinical practice of psychology, even less meets any reasonable definition of “scientific.” http://www.arachnoid.com/psychology/