Falsifiability

So true
Funny how it seems
Always in time
But never in line for dreams
--Spandau Ballet

Falsifiability is the logical possibility that an assertion can be proven false by a particular observation or experiment. Falsifiability does not mean that a statement is false. It means that if the statement was false, that its falseness can be demonstrated.

For example, claiming that 'no two people are the same' (perhaps regarding a certain trait or behavior) is not falsifiable because it doesn't seem possible to prove wrong. Regardless of how many people are compared and found to be different, one might have to keep comparing all people forever in order to detect a false case.

On the other hand, claiming that 'all people are the same' is falsifiable because presenting one case of differences proves the statement wrong.

Karl Popper (1959, 1963) argued that falsifiability is an important concept in science. Although not sufficient, falsifiability is a necessary criterion for scientific ideas. However, he suggested that unfalsifiable statements such as meta-physical and religious propositions are not without relevance and may lead to testable theories down the road.

Popper also viewed that falsifiable theories that have withstood long periods of testing may be seen as corroborated by experience but not necessarily confirmed. Corroboration through experience does not guarantee that a theory is true. Thomans Kuhn's (1962) work is consistent with this view.

Popper held that falsifiability is a special case of the general notion of criticizability. Criticizability is the openness of an assertion to criticism--i.e., to the logical possibility of specifying what would show the assertion to be mistaken.

The idea is that without openness to criticism, it is difficult to approach truth.

References

Kuhn, T.S. (1962). The structure of scientific revolutions. Chicago: University of Chicago Press.

Popper, K. (1959). The logic of scientific discovery. New York: Basic Books.

Popper, K. (1963). Conjectures and refutations. London: Routledge.