Falsifiability

Falsifiability is a criterion for scientific theories, hypotheses, or propositions proffered by Karl Popper in the 1930s. This criterion implies that for any of these to be scientific, they must be refutable or falsifiable, and if they are not, they are merely dogmatic stances. In other words, a scientific theory or idea that cannot be refuted provides nothing of value because any claim or event could or would be consistent with the theory or idea. For an assertion to be falsifiable, there must be empirical evidence that would show the assertion to be false. For example, the assertion “Phonics instruction is the most effective way to teach reading” could be falsified by observing one instance in which phonics instruction did not lead to the ability to read. This criterion has several limitations. There are any number of scientific theories that are true by definition (for example, Newton's laws of motion) or are approximations rather than literally true. Popper's concern was specifically with what he considered scientific rather than whether a theory, idea, or proposition was right or wrong. Indeed, throughout history, science has been wrong, and ideas that may not be scientifically sound may be right but simply beyond the ability of current science to test. The criterion of falsifiability is most often associated with the uses of experimental and quasiexperimental designs in evaluation, and although it has limitations, it can be a useful heuristic to challenge taken-for-granted ideas and the meaning and value of a theory.