A falsifiable theory is one that makes a specific prediction about what results are supposed to occur under a set of experimental conditions, so that the theory might be falsified by performing the experiment and comparing predicted to actual results. A theory or explanation that cannot be falsified falls outside the domain of science. For example, Freudian psychoanalysis, which does not make specific experimental predictions, is able to revise its theory to match any observations, in order to avoid rejecting the theory altogether. By this reckoning, Freudianism is a pseudoscience, a theory that purports to be scientific but is in fact immune to falsification. In contrast, for example, Einstein’s theory of relativity made predictions (like the bending of starlight around the sun) that were novel and specific, and provided opportunities to disprove the theory by direct experimental observation.
[The folly of scientism]