Ockhams razor or Occams razor

From  Encyclopaedia Britannica
http://www.britannica.com/EBchecked/topic/424706/Ockhams-razor
Ockham’s razor, also spelled Occam’s razor, also called law of economy or law of parsimony,  principle stated by William of Ockham (1285–1347/49), a Scholastic, that Pluralitas non est ponenda sine necessitate, “Plurality should not be posited without necessity.” The principle gives precedence to simplicity; of two competing theories, the simpler explanation of an entity is to be preferred. The principle is also expressed as “Entities are not to be multiplied beyond necessity.”

This is very important to us because doctors use it on us all the time.
Misdiagnosis of balance problems as drunkeness,
carpal tunnel instead of stroke.
cognition problems blamed on stroke,
memory problems blamed on stroke