Tag Archives: Mencken

Common sense fallacy

by Tim Harding

The American writer H L Mencken once said “There is always a well-known solution to every human problem — neat, plausible, and wrong.” He was referring to ‘common sense’, which can be superficially plausible and sometimes right, but often wrong.

The Common Sense Fallacy (or ‘Appeal to Common Sense’) is somewhat related to the Argument from Popularity and/or  the Argument from Tradition. However, it differs from these fallacies by not necessarily relying on popularity or tradition.

Instead, common sense relies on the vague notion of ‘obviousness’, which means something like ‘what we perceive from personal experience’ or ‘what we should know without having had to learn.’ In other words, common sense is not necessarily supported by evidence or reasoning. As such, beliefs based on common sense are unreliable.  The fallacy lies in giving too much weight to common sense in drawing conclusions, at the expense of evidence and reasoning.

In some ways, scientific methods have been developed to avoid the errors that can result from common sense. For instance, common sense used to tell us that the Earth is flat and that the Sun revolves around the Earth – because that is the way things appear to us without scientific investigation.  Another example of ‘common sense’ is that the world appears to have been designed, so therefore there must have been a designer.

Einstein’s theories of relativity were initially resisted, even by the scientific community, because they defied common sense.  They seemed to belong more in the realm of science fiction than reality, until they were later verified by scientific observations.  Our modern Global Positioning System (GPS) now uses Einstein’s relativity theories.  This initial resistance may have led Einstein to later say that ”Common sense is nothing more than a deposit of prejudices laid down by the mind before you reach eighteen” .

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Filed under Logical fallacies