Falsifiability is a deductive standard of evaluation of scientific theories and hypotheses that was introduced by the philosopher of science Karl Popper in his book The Logic of Scientific Discovery (1934). He proposed it as the cornerstone solution to both the problem of induction and the problem of demarcation. A theory or hypothesis is falsifiable (or refutable) if it can be logically contradicted by an empirical test using existing technologies. Popper insisted that, as a logical criterion, falsifiability is distinct from the related concept "capacity to be proven wrong" discussed in Lakatos' falsificationism. Even being a logical criterion, its purpose is to make the theory predictive and testable, and thus useful in practice. Popper opposed falsifiability to the intuitively similar concept of verifiability that was then current in logical positivism. His argument goes that the only way to verify a claim such as "All swans are white" would be if one could theoretically observe all swans, which is not possible. Instead, falsifiability searches for the anomalous instance, such that observing a single...