Is Common Sense Common?


You just had a shower and your hair is still wet. You are on your way out, when your father suddenly stops you saying: “It is cold outside! If you go out with your hair wet, you will catch a cold”. You hurry back in to dry your hair with a blow dryer, then go on your merry way after a sigh of relief that you just avoided falling sick.

Your father has just given you an advice that would be widely seen as common sense; a widely known piece of information that is commonly perceived as true. However, wet hair is not the cause of a cold, germs are. So, why is it that people perceive certain information as common sense? What exactly is common sense? Can it be improved?

Common sense is defined in Merriam-Webster as “sound and prudent judgment based on a simple perception of the situation or facts,” while Cambridge Dictionary defines it as “the basic level of practical knowledge and judgment that we all need to help us live in a reasonable and safe way”.

Basically, common sense is judgment that is based on things that are common knowledge and established facts, either by the person making the judgment or by society in general. Science has not been able to actually prove the existence of common sense, or explain its development; however, certain observations have been made.

For some time, people wondered if common sense is located in a specific part of the brain. What scientists observed was that patients who underwent prefrontal lobotomies—barbaric surgical procedure that was once performed on the brain of someone who suffered from certain psychiatric conditions— were able to resume their normal lives when they returned to their homes, with one exception that they lacked proper judgment. Scientists thus concluded that this could indicate that the prefrontal region of the brain is to some extent connected to our decision-making process and common-sense response.

Common sense is based on knowledge and experience. If you see a flame you will not try to touch it because you know that this will only lead to a burn. Toddlers, however, do not know that going near a flame would burn them, therefore they cannot act accordingly. You are capable of deducing reasonable judgment from prior knowledge, which is common sense.

Does everyone have common sense? Unfortunately, no; some people seem to lack common sense. What may come as a surprise is that people who have a high IQ level actually tend to lack it; that is according to Bruce Charlton, Editor-in-Chief of the Medical Hypotheses journal.

Charlton believes that a lot of people with very high IQs tend to ignore common sense because they favor reasoning to learned cultural behavior. Some people may see this as a smart thing to do, since sometimes what we believe to be common sense ends up being completely wrong and unfounded. Yet, Charlton believes that this often leads to geniuses coming up with strange responses or behaviors.

Common sense is generally related to universal truths that are learned through social interaction. This also factors into why very smart people lack common sense, because they often favor solitude and therefore forgo key social interaction.

Also, people who usually tend to be overly emotional can also lack common sense because the region of the brain controlling emotions reacts a few milliseconds quicker than the one controlling decision-making. Even though this is such a small difference, it can nevertheless be enough for someone to give an irrational response to something.

People who suffer from Asperger syndrome—an autism spectrum disorder—on the one hand, often have high levels of intelligence. However, they tend to have difficulties in communication, failing to understand social cues, leading people to view them as lacking common sense.

Common sense is not universal as some assumptions go; it varies and changes from one place to another. What some people consider as common sense in one place does not necessarily add up to common sense somewhere else. If you live in an urban area, the first thing you do when you cross a street is look for oncoming cars to avoid accidents; however, if you live in a rural area you would not necessarily behave in the same way since cars would be a rare occurrence.

Just as common-sense changes over place, it changes over time. What was perceived as common sense in the 13th century will not be considered common sense today. Just like certain beliefs were observed as facts then may have been proven wrong and therefore are no longer believed to be common sense.

Common sense is all learned; it is based on information that we acquire from people around us as well as our own personal experience. It can be taught to adults who seem to lack it; however, this would require getting exposed to various “what if” scenarios and have the common-sense response explained to them.

It is common sense that helps us every day; it is, for example, what tells us that drinking too much coffee might deprive us of a good night sleep, not because it is an inherent knowledge that we have, but because we have learned so from past experience.

Voltaire, a French writer, observed that common sense is not “common” in the true sense of the word, since many people seem to fail in applying this faculty to their decisions. Hence, whenever you hear of something that is perceived as common sense, re-examine it to see how much truth it actually holds, and if you are about to decide, make sure you use your common sense.


This article was first published in print in the PSC Newsletter, Summer 2013 issue.

Cover image: Man cutting the branch sitting on. Credits: Frits Ahlefeldt/Museum of Psychology 

About Us

SCIplanet is a bilingual edutainment science magazine published by the Bibliotheca Alexandrina Planetarium Science Center and developed by the Cultural Outreach Publications Unit ...
Continue reading

Contact Us

P.O. Box 138, Chatby 21526, Alexandria, EGYPT
Tel.: +(203) 4839999
Ext.: 1737–1781

Become a member

© 2024 | Bibliotheca Alexandrina