From TAKING SIDES: Clashing Views in Science and Technology:
Many cause/effect statements are flawed because no
appropriate research or evidence has isolated a single
cause. There may be other hidden factors underlying
the relationship. A good example is this statement:
"Birds fly south in winter because it gets cold in northern
areas." This statement is plausible, and many readers
would accept it because it "makes sense." Data exist
to show a relationship between temperature and bird
population density: population decreases as temperature
- What are other
possible underlying variables here?
- Can you think of experiments desined to eliminate some of the other
However, no experiment has conclusively
established that temperature is a causative factor
of bird migration. Alternative hypotheses may very well
also explain the behavior. Food supplies may become
scarce during low-temperature periods, breeding
instincts may precipitate migration, or the birds may
simply want a change of scenery! If sufficiently controlled
experiments could rule out these alternative
hypotheses, the cause/effect statement could be made.
As it is, a simple correlation (statement of coincidence)
is all that remains.