Occam's Razor (or Ockham's Razor) is the philosophical principle
which states: entities should not be multiplied beyond
necessity. In layman's terms this means "Out of several equally
good explanations, pick the simplest one." In this definition,
the word "simplest" means "the explanation that contains the
fewest assumptions." Similarly, "equally good" refers to the
ability of the explanation to account for the observation and
not to the veracity of the explanation. Assume a child contracts
a nasty disease which leaves her in terrible pain. She is taken
to the doctor and is given medicine. Meanwhile, the parents pray
to God for her safe recovery. A few days later she is perfectly
healthy again and the parents, in their happiness, proclaim "God
saved our child!" A better explanation for the child's recovery,
however, would be that the medicine the doctors gave her did its
job. When one compares the two explanations ("God did it" and
"The medicine worked") it is clear that the second requires
fewer assumptions.