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A proposition or theory is '''falsifiable''' if it is hypothetically possible to conduct an experiment that proves it false.<ref>[http://www.encyclopedia.com/doc/1O87-falsifiability.html Definition] A Dictionary of Psychology, Andrew M. Colman, via encyclopedia.com</ref>  A proposal or theory that can never be shown to be false with any hypothetical experiment is not falsifiable.

A proposition or theory is '''falsifiable''' if it is possible to conduct an experiment such that, if the proposition were false, then it can be proven to be false.<ref>[http://www.encyclopedia.com/doc/1O87-falsifiability.html Definition] A Dictionary of Psychology, Andrew M. Colman, via encyclopedia.com</ref>  A proposal or theory that could not possibly be shown to be false, even if it were false, is not falsifiable.

As an incredibly simple example, it is a generally accepted scientific principle that dropped objects fall downward.  (Ignore various issues about imparting initial upward velocity, that is, throwing the object, or unusual frames of reference, like centrifuges.)  But it is possible to visualize what it would look like if one dropped an object and it fell upward.  Therefore, the theory that dropped objects fall downward is falsifiable.

As an incredibly simple example, it is a generally accepted scientific principle that dropped objects fall downward.  (Ignore various issues about imparting initial upward velocity, that is, throwing the object, or unusual frames of reference, like centrifuges.)  But it is possible to visualize what it would look like if one dropped an object and it fell upward.  Therefore, the theory that dropped objects fall downward is falsifiable.