Isn’t Psychology Just Common Sense?

Years ago, when I was a full-time college professor and even as Director of Training for a graduate program in Clinical Psychology, students approached me with the question: “Isn’t psychology just common sense?” Most often, I would smile, shake my head “no”, and bring up the following ideas.

  • Common sense refers to sets of ideas that are often broad, deceptively unspecific, and when held up to scientific scrutiny, they do not accurately predict outcomes. Here are some examples.
    • “Birds of a feather, flock together, right?” Psychology experiments have determined that to be true. Sometimes.
    • “Opposites attract, correct?” Again, sometimes but not always, suggest data coming from psychology labs.
    • “It’s better to rid yourself of angry feelings by ‘letting it out’ (shouting, beating on pillows, etc.), right?” Again, nope. Psychology experiments show that doing so only makes people angrier!
    • “People don’t confess to a crime they did not commit.” Psychology experiments indicate the opposite, and people often do provide false confessions.
    • “In an emergency, there is more safety in numbers.” Actually, psychology experiments have shown the opposite. You have a greater chance of someone helping you in an emergency with fewer surrounding people.
  • Common sense relies on experience and deductive reasoning, which can be based on false premises, often transferred intergenerationally and across social groups. Psychology relies on the scientific method to: observe a phenomenon; craft hypotheses about it; design controlled studies to collect unbiased, reliable, and valid data; analyze the results and assess statistically the probability that the finding is “true” and not a false positive or false negative; develop a theory based on empirical results to guide future, disciplined explorations of the phenomenon.
  • Common sense draws on an individual’s personal experience (e.g., “It has been my experience that . . . .”), which, because it is limited, can lead to wrong decisions. Psychology makes conclusions most frequently based on scientifically collected data from groups of people.
  • Common sense is atheoretical. Psychology relies on investigators developing testable theories to guide and discipline research.
  • Common sense is dramatically subject to confirmation bias. Psychology studies have demonstrated that if a belief appears widely held – especially by self-anointed ‘experts’ – people unconsciously look for examples that confirm that belief.
  • Common sense implicitly encourages rush to judgment, intolerance of ambiguity, hindsight bias, and confirmation bias. Psychology studies by being well-controlled, driven by theory, with data collected and analyzed statistically encourages critical analysis, appropriate skepticism, sensitivity to interpretive biases, and an emphasis on replication of findings.


Lilienfeld, S. O., Lynn, S. J., Ruscio, J., & Beyerstein, B. L. (2010). 50 great myths of popular psychology: Shattering widespread misconceptions about human behavior. New York: Wiley.