Psychology is just common sense.

Or, at least some prominent figures think so. Popular radio talk show host Dennis Prager says, “Use your common sense. Whenever you hear the words ‘studies show’ — outside of the natural sciences — and you find that these studies show the opposite of what common sense suggests, be very skeptical. I do not recall ever coming across a valid study that contravened common sense” (Lilienfeld et al., 2010, p.5).

It appears that Prager has not read many scientific studies.

For centuries scientists, science writers and philosophers have encouraged us to trust our common sense (Lilienfeld et al., 2010; Furnham, 1996). Common sense is a phrase that generally implies something everyone knows. One of the definitions of common sense given by Wikipedia is, “good sense and sound judgment in practical matters.”

Common sense psychology is a myth. What appears to be common sense is often common nonsense. Scott Lilienfeld, co-author of 50 Great Myths of Popular Psychology, says we should mistrust common sense when evaluating psychological claims (Lilienfeld et al., 2010).

Some examples of common sense psychology include:

  • Working while in high school will help students build character and value money.
  • Children who read a lot are not very social or physically fit.
  • People with low self esteem are more aggressive.
  • The best way to treat juvenile delinquents is to get tough with them.
  • Most psychopaths are delusional.
  • We know what will make us happy.

However, not a single one of these is true. Scientific evidence refutes each of the common sense claims listed above.

The failure of common sense can be seen in areas other than just psychology. What could be more obvious than the flatness of the earth? Additionally, isn’t it apparent that the earth is stationary? These claims about the earth were seemingly obvious in previous centuries, but we now know them to be false. (Of course, this doesn’t mean common sense is always wrong.)

Yesterday’s common sense is often today’s common nonsense. To illustrate this point consider some of the following notions.

Yesterday’s common sense:

  • Women don’t have the “smarts” required to vote.
  • The best place for people with disabilities is an institution.
  • African Americans can’t be taught how to read.

One hundred and fifty years ago the statements made above were common sense. We now recognize the above-mentioned statements — yesterday’s common sense — as nonsense (Stanovich, 2007).

“[C]ommon sense is the collection of prejudices acquired by the age of 18. It is also a result of some pervasive and extremely stupid logical fallacies that have become embedded in the human brain over generations, for one reason or another,” says Albert Einstein (Shakespeare, 2009)

Indeed, because when empirically tested common sense often fails the test, it becomes common nonsense.