The principle that the best explanation is the one that requires the fewest unverifiable assumptions. It tells us to use the simplest of several competing theories that describe the same concepts with the same accuracy, i.e., the theory that makes the fewest ad-hoc assumptions.

William of Occam was an English monk and philosopher who lived in the 14th century. The term, "Razor," refers to the fact that the argument is cut down to its simplest form. Occam's razor always comes to the rescue when non-scientists try to explain scientific phenomena with pseudo-science: the scientific explanation is always the simpler.

Here are two examples of Occam's Razor in action:

1976 Viking 1 picture. The contrast was enhanced to show the "face" better.

The higher resolution 2001 Mars Global Surveyor picture.

While grading a test, a teacher notices that two students who are not doing well in class and sit next to each other answered a paragraph long question identically and incorrectly. Two explanations are:
a) the students copied each other,
b) the students made up an answer and somehow both brains came up with the exact same words.
The second explanation could happen, but with an extremely low probability. Given that the teacher knows the students, the most likely explanation is that they cheated.

In 1976, while the Viking 1 spacecraft was in orbit around Mars, it took snapshots of the planet and one of them, in the Cydonia region, looked like a human face (see picture at right). Many people thought that this was evidence for life on Mars. If this were true, many questions would have to be answered:

1. Why does the face look human?
2. Do Martians know what humans look like, or do they look like humans?
3. Do Martians want to send a message to earthlings?
3. How did intelligent life evolve in Mars?
4. How come we haven't detected any evidence of a Martian civilization?

Astronomers working on the Viking photographs had a simpler explanation which involved no assumptions: the "face" was just created by shadows. This explanation was confirmed when the Mars Global Surveyor took better pictures of the Cydonia region in 1998, 2000, and 2001, when the sun was striking at a different angles and no facial features were seen.

Ana Dodgen-Torres

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