Why We Can't Always Trust Common Sense

Our intuitions about human behavior are often wrong.

Posted Feb 17, 2021

Pixelvario/Shutterstock
Source: Pixelvario/Shutterstock

Key Points: Science helps buffer against flaws in our thinking when it comes to understanding the world, including human behavior. We often mistakenly trust common sense because of hindsight bias, overconfidence and the tendency to perceive order in random events.

Before reading further, click here to test your psychology knowledge. Don't worry; it isn't graded! Now, click here to see the answers. How did you do? Most people miss at least a few.

Why do we think we know so much about psychology? 

Popular psychology lore permeates our culture. We hear soundbites of information from poorly vetted sources across various forms of media every day. Pop psychology is often based on flimsy studies using poorly designed methodology. We then integrate the unsupported knowledge into our fund of information. The psycho-myths spread and become difficult to challenge.

Beyond pop psychology exposure, internal forces are shaping our notions about human behavior. Many people think answers to psychological questions are obvious. Every day on social media, I see commentary asking why we need to do scientific research to understand human behavior that is just "common sense."

In fact, many people believe their intuition—immediate, automatic feeling or thought—is always (or almost always) accurate. And sometimes it is. Often, however, we are wrong.

Flawed thinking often leads us astray

We use heuristics (mental shortcuts) to understand the world around us. Sometimes, these shortcuts are helpful, allowing us to make quick decisions in a fast-moving world. Frequently, the mental shortcuts lead us to make poor decisions.

If I ask you the question, which is further west in the United States, Reno, NV, or San Diego, CA, what would you say? Most people use a heuristic—California is west of Nevada, so San Diego must be west of Reno. Guess what? That is wrong. Reno is west of San Diego. Are you surprised?

Another way to ponder our intuition about the world is to consider adages that guide our everyday thinking. Here are several "common-sense" sayings that many of us have integrated into our thinking.

  1. Birds of a feather flock together.
  2. Opposites attract.
  3. Absence makes the heart grow fonder.
  4. Out of sight, out of mind.
  5. Better safe than sorry.
  6. Nothing ventured, nothing gained.
  7. Two heads are better than one.
  8. Too many cooks spoil the broth.
  9. Actions speak louder than words.
  10. The pen is mightier than the sword

Do you notice anything peculiar about this list? Likely you have heard all or most of these proverbs. You may apply them to situations in your life. For example, when a couple you know lives apart and ends up breaking up, you may say to yourself, "Out of sight, out of mind." Other times, when a couple has a strong relationship despite a long-distance relationship, you may think, "Absence makes the heart grow fonder."

Look carefully; each one of these sayings is contradicted by another statement on the list. How can we hold these assertions as truths when we hold the contradictory proverb as fact as well?

Why we need science and logical thinking

Most of us navigate our daily lives believing we see the world as it is. We are often unaware of the forces that compel us to formulate notions about the world. Our naive realism—the belief that we see the world precisely as it is—creates the foundation for these errors in thinking. We rarely question that our beliefs are inaccurate.

The need for psychological science and the use of logical—rather than intuitive—reasoning to understand human behavior becomes apparent when we recognize our mistaken assumptions about the basics of human behavior.

Most people hear the word science and envision a person in a white lab coat, perhaps looking through a microscope—chemistry, physics, and biology come to mind. Science is merely a systematic approach to evidence—it is a toolbox we use to prevent fooling ourselves about what we observe.

Science is a safeguard against bias. We utilize empirical methods and stringent statistical testing to determine the ideas we should keep and those we should abandon. The scientific method is applied across many disciplines, including the study of human behavior.

Three reasons we trust intuition

While there are various cognitive biases and logical fallacies that contribute to the need for science when studying human behavior, three key ideas can help us understand why we often trust our common sense when we shouldn't.

1. Hindsight Bias

"Anything seems commonplace, once explained." —Sherlock Holmes

The "I-knew-it-all-along" phenomenon plagues many of us. It is easy to see outcomes after the fact and be certain we could have predicted them. This Monday-morning quarterbacking is pervasive. More than 800 research papers have shown that hindsight bias—the tendency, after the fact, to reason we would have predicted an outcome—is a world-wide phenomenon that affects people of all demographic groups.

2. Overconfidence

"We don't like their sound. Groups of guitars are on their way out." —Decca Records turning down a contract with the Beatles in 1962.

Most of us overestimate our own knowledge. Over and over again, research has shown that people's confidence in the judgment of their knowledge is much higher than the accuracy of their knowledge. From the Titanic sinking to the Challenger explosion, overconfidence has proven to be one of the most problematic biases that interfere with accurate understanding and decision-making.

3. Perceiving Order in Random Events

"Chaos was the law of nature; Order was the dream of man." —Henry B. Adams.

Humans are relentlessly eager to perceive order in chaos. Seeing a face on the moon, a religious image on a dirty towel, or the hot hand in basketball are all examples of how we want to apply meaning to our observations in the world.

Have you ever heard of a lucky person winning a huge lottery payout twice? It is such a surprising phenomenon that we are unable to conceive that it is random. As statisticians will tell, however, with large enough samples, just about anything can happen.So, when should we trust our intuition?

Despite the problematic nature of intuitive thinking, sometimes, we need to trust our common sense. In cases where split-second safety is essential, research suggests our intuition is our best bet as snap judgments about the trustworthiness of someone we watched on video tend to be more accurate than chance.

Final Thoughts

Question what you know. Are you making assumptions based on potentially flawed information? When you notice yourself utilizing aphorisms or mental shortcuts regarding explanations for human behavior, consider investigating the evidence rather than accepting your initial hunches. According to research, considering the opposite of what you may be thinking is an efficient way to bypass some of our faulty cognitive mechanisms.

While intuition is a fantastic means to keep us safe, unthinkingly applied to all situations, it can lead to mistaken beliefs and misinformation, which can trigger problematic decision-making.

"Science must begin with myths, and with the criticism of myths." —Karl Popper

The words of Popper, a famed philosopher of science, transcend time. We must critically examine our beliefs to understand human behavior—including our own.