You can't prove a negative The claim, "you can't prove a
negative" (or "...universal negative") is often used as a
shorthand in discussions to refer to the difficulty of gathering
evidence to "prove" that something does not exist. Proving that
a phenomenon is not real takes a lot more time and effort than
to demonstrate that it is real. This is especially true when the
definition of the phenomenon can be changed at will by its
believers (see God). It is very difficult to prove the general
non-existence of a phenomenon, and this difficulty is used by
believers of many kinds of phenomena to give the appearance of
credibility to their beliefs. Science, hypotheses and statistics
Much scientific practice has developed to address this issue. In
particular, the field of statistics distinguishes between the
so-called experimental hypothesis and the null hypothesis. The
experimental hypothesis is usually the statement that the
scientist would like to investigate the truth of (for example,
that a drug under study is an