Falsifiability

Are all swans white? The classical view of the philosophy of science is that it is the goal of science to "prove" such hypotheses or induce them from observational data. This seems hardly possible, since it would require us to infer a general rule from a number of individual cases, which is logically inadmissible. However, if we find one single black swan, logic allows us to conclude that the statement that all swans are white is false. Falsificationism thus strives for questioning, for falsification, of hypotheses instead of proving them.

http://en.wikipedia.org/wiki/Falsifiability

Falsifiability or refutability is the logical possibility that an assertion can be shown false by an observation or a physical experiment. That something is "falsifiable" does not mean it is false; rather, that if it is false, then this can be shown by observation or experiment. The term "testability" is related but more specific; it means that an assertion can be falsified through experimentation alone.

Falsifiability is an important concept in science and the philosophy of science. The concept was made popular by Karl Popper, who, in his philosophical analysis of the scientific method, concluded that a hypothesis, proposition, or theory is "scientific" only if it is falsifiable.