The Scientific Method: Personal Experience Versus Scientific Reasoning

FROM THE LECTURE SERIES: Sci-Phi: Science Fiction as Philosophy

By David K. Johnson, Ph.D., King’s College

Generally speaking, scientists do not give more credence to their own personal experience than they do to scientific reasoning. Science so successfully describes and predicts the world because it recognizes, and is designed to guard against, the myriad of ways personal experience can lead us astray.

Side profile of a woman showing memory loss.
Personal experience is unreliable because the brain and memory have now been shown to be unreliable witnesses. (Image: pathdoc/ Shutterstock)

The Delusion of Memory

Take memory, for example. Our brains are not video cameras. They store the basics but then forget the details. When you recall an event, your brain confabulates new details. When you recall the event again, you’re actually recalling the last time you recalled it. And you can mistake those confabulated details with what actually happened. The more you do this, the more inaccurate the memory becomes.

This is why, when you go back to watch a sci-fi movie you haven’t seen in years, you’ll often remember the plot having gone one way, when in fact it went another. Studies have even shown that flashbulb memories—the memories you have of where you were when traumatic events like 9/11 happened—even those aren’t reliable.

This is a transcript from the video series Sci-Phi: Science Fiction as Philosophy. Watch it now, Wondrium.

The Unreliability of Perception

Our sight is also not as reliable as we assume. Indeed, we don’t see the world as it is; our brain constructs a world for us to see based on its interpretation of the data it receives. Because that interpretation is informed by our assumptions, we often see things that aren’t there and don’t see things that are.

Pareidolia can make us see faces in inanimate objects, the autokinetic effect can make things seem to be moving when they aren’t. We hallucinate; optical illusions fool us. That’s why the moon looks larger over the horizon—it’s an optical illusion. Even our perception of ourselves can be wrong. That’s why anorexics often see themselves as fat.

Indeed, what we see with our eyes is now known to be so unreliable, and our memories of what we’ve seen are so easily manipulated, that eyewitness testimony is becoming useless in the courtroom.

Mistakes in intuitive reasoning also mislead us. Confirmation bias and availability error can make us ignore evidence; proportionality bias and subjective validation can make us misevaluate it. Fallacious reasoning can make us think that taking a medication made us better, when in fact we were already on the mend. The upshot is this: The fact that something seems real doesn’t necessarily mean that it is.

Learn more about human free will.

The Advantage of Science

The photo shows an allergen test being conducted.
Science is based on specific procedure, to avoid the pitfalls of subjective experience. (Image: Shutterstock)

To discover the way the world is, science requires us to follow specific procedures to guard against the many ways we lead ourselves astray.

If you want to know if a medication really works, for example, you have to perform a repeatable, double blinded, placebo-controlled trial. And history has shown this works.

Science has a proven track record of exposing the truth. This is how it’s enabled us to advance technologically, feed billions, and reach the Moon. Of course, some past scientific theories have been overturned, but even they weren’t entirely wrong. Science usually advances by improving on past theories.

Take Copernicus’s heliocentric theory, for example, which placed our sun at the center of the universe. It was more accurate than geo-centrism, which placed our planet at the center of the universe. But it wasn’t as accurate as the theory we have now; our Sun is just one of billions of stars in just one of billions of galaxies. Indeed, the universe probably doesn’t even have a center. And even this theory is probably incomplete, but that doesn’t mean that it’s entirely wrong.

The Conflict of Science and Perception

Because science is more reliable than personal experience, it seems that we should trust the former over the latter. Let’s call this the conflict rule: When there is a conflict between personal experience and the conclusion of cogent scientific reasoning, reject the former and embrace the latter.

Sometimes violating the conflict rule can seem to be rational. For example, Willem de Vlamingh first saw a black swan, in Australia, in 1697. All previously observed swans were white. Consequently, “all swans are white,” was the prevailing scientific view. Willem wasn’t doing anything irrational when, after seeing a black swan, he concluded, “some swans are black”. If we could never rationally violate the conflict rule, scientific knowledge could never advance.

But this is not the kind of personal experience the conflict rule is talking about. Indeed, Willem didn’t have a personal experience; he made an observation—a testable, verifiable, observation. Since Willem and his team were able to verify and confirm that the birds were black, and swans, that the consensus view was overturned. So, personal experience doesn’t advance scientific knowledge; verified observation does.

Learn more abut the nature of science.

The Personal over the Scientific?

In the film Contact, the protagonist Ellie, a scientist, meets an alien. But, when she is asked to provide proof, she can present no evidence except her own experience to prove that this happened. Presented with the idea that she may have hallucinated the experience, Ellie agrees that this is the better, simpler explanation.

But, she says, she can’t doubt her experience. “I can’t prove it,” Ellie says.
“I can’t even explain it. But everything that I know as a human being, everything that I am, tells me that it was real.” But shouldn’t Ellie have doubted her experience in favor of what she admitted was the better, more scientific, explanation—that she hallucinated the whole thing?

Now, some might argue that Ellie can believe what she wants, and even do so rationally, even scientifically, because there is no way to prove, with observation and experiment, one theory over the other.

Ellie can’t prove her alien contact hypothesis, and no one can prove the hallucination hypothesis. But the hallucination hypothesis is simpler, is more conservative (since, given the size of the universe, it aligns with how likely alien contact really is) and explains more things in the movie. So, given what Ellie knows, it doesn’t seem that she is justified in believing that she contacted aliens.

Common Questions about Personal Experience Versus Scientific Reasoning

Q: What have studies shown about the reliability of flashbulb memory?

Studies have even shown that flashbulb memories—the memories you have of where you were when a major historical event happened—aren’t really reliable.

Q: What could you call the conflict rule in science versus personal experience?

Because science is more reliable than personal experience, it seems that we should trust the former over the latter. This could be called the conflict rule: When there is a conflict between personal experience and the conclusion of cogent scientific reasoning, reject the former and embrace the latter.

Q: When can experience overturn established scientific thought?

The conflict rule can be rationally violated and scientific thought can be changed only by verified observation of an experience, not by unverifiable personal experience.

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