Occam’s razor

20.03.2015 |

Episode #7 of the course “Philosophical ideas that everyone should know”

Occam’s razor is named after William of Occam, a 14th-century philosopher. The ‘razor’ signifies removing unneeded assumptions from theory. Also known as parsimony, Occam’s razor is a call to avoid finding more complicated ways to explain events if a simple idea is already present. If more than one explanation is present, Occam’s razor directs you to choose the simplest.

Consider an example. Geometric shapes in fields that are made of flattened wheat, barley, or rye are crop circles. When first observed, there was a lot of speculation in the media about how they were created. Many believed that the circles were alien landing sites or caused by UFOs burning a pattern into a field. But humans created the circles by using ropes and other tools to make the designs.

Here each explanation seems to fit the evidence, but how do we decide which is true? Without knowing more, can we rationally choose one? According the idea of Occam’s razor, we can. This theory only states that we are to select the simplest approach that makes the most sense.

So for the UFO theory, we have to believe that UFOs exist for this theory to be valid. However, there hasn’t been clear evidence of this yet. But for the human-created theory, we have to believe that people are capable of pranks, which is a typical behavior. Therefore, rationally, we can choose the theory that the crop circles are a hoax created by humans because it is the simpler of the two answers. In this case, Occam’s razor works well.

Occam’s razor is sometimes criticized because there can be many explanations for presented evidence. But the idea is not that simple is always right, but that the simple explanation is more likely to be correct. So, it is a good rule of reason to follow when trying to figure out where given evidence may lead.


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