Definition of "falsifiability"

The degree of their testability is of significance for the selection of theories. In this chapter, I shall compare the various degrees of testability or falsifiability of theories through comparing the classes of their potential falsifiers.

1959, Karl Raimund Popper, The Logic of Scientific Discovery

A proposition is scientific if and only if it is falsifiable. This is the criterion or principle of falsifiability. Falsifiability must be distinguished from falsity, of course.

1985, Alexander Rosenberg, The Structure of Biological Science

The need for some such criterion is one reason why falsifiability of theories holds special importance in this book. If theories yield statements in the empirical world that stand to be confirmed or undermined by actual empirical reports, we have the basis for one overarching standard.

1989, James B. Rule, Theories of Civil Violence