Jamie Hale

Jamie Hale

Monday, August 9, 2010

Common Sense Doesn't Matter

by Jamie Hale

“Albert Einstein said common 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. These malfunctioning thoughts--several of which you've had already today--are a major cause of everything that's wrong with the world” (Shakespeare, 2009).

Webster’s New World Dictionary (2003) defines common sense as: “good sense or practical judgement.” This is probably the most commonly accepted definition of the word.

Wikipedia says:

“Common sense, based on a strict construction of the term, consists of what people in common would agree on: that which they "sense" as their common natural understanding.

Some people (such as the authors of Merriam-Webster Online) use the phrase to refer to beliefs or propositions that — in their opinion — most people would consider prudent and of sound judgment, without reliance on esoteric knowledge or study or research, but based upon what they see as knowledge held by people "in common".

The most common meaning to the phrase is good sense and sound judgement in practical matters.”

A better definition of Common Sense is: commonly held belief, regardless of it’s truth value.

It doesn’t matter which definition you prefer to use when discussing Common Sense, referring to Common Sense as reason for a particular claim is fallacious, it makes an argument invalid. Yesterday’s Common Sense is often today’s Common Nonsense. Once upon a time it was common sense that the World was flat. History is replete with examples of Common Sense failure.

The list below was contributed by Frank Lovell, Kentucky Assocation of Science Educators and Skeptics Member.

Common Sense Counterfactuals

“The sun orbits Earth once a day. FALSE -- Earth rotates under the (relative to Earth, essentially) stationary sun once a day, and orbits the stationary sun once a year.

Velocities are simply additive (1mph+1mph=2mph, and 100,000mps+100,000mps=200,000mps). FALSE -- special relativity.

Time is absolute. FALSE -- Special Relativity.

Space is absolute. FALSE -- special relativity (what IS absolute is "space-time").

Earth's continents do not move. FALSE -- plate tectonics.

Everything that happens is rigorously mechanically determined. FALSE -- quantum mechanics.”

From Lilienfeld et al. (2010, p.6):

“…French writer Voltaire (1764) pointed out, ‘Common sense is not so common.’ Indeed, one of our primary goals in this book is to encourage you to mistrust your common sense when evaluating psychological claims. As a general rule, you should consult research evidence, not your intuitions, when deciding whether a scientific claim is correct.

As several science writers, including Lewis Wolpert (1992) and Alan Cromer (1993), have observed, science is uncommon sense. In other words, science requires us to put aside our common sense when evaluating evidence (Flagel & Gendreau, 2008; Gendreau et al., 2002).”

When engaging in argument avoid using the Common Sense fallacy, it gives and impression that you have no evidence to support your claim. It may perusade some people , but it will fail when arguing with someone who has a firm understanding of logic.


Lilienfeld, S. et al. (2010). 50 Great Myths of Popular Psychology. Wiley-Blackwell.

Shakespeare, G. (2009). 5 Ways “Common Sense” lies to you Everyday. http://www.cracked.com/article_17142_5-ways-common-sense-lies-to-you-everyday.html. (Accessed August 8, 2010).

Webster’s New World Dictionary. (2004). Wiley Publishing Inc.

Wikipeida. Common sense. http://en.wikipedia.org/wiki/Common_sense. (Accessed August 8, 2010).

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