Maarten Maartensz:    Philosophical Dictionary | Filosofisch Woordenboek                      

 C - Criterion - of Falsifiability


Criterion of Falsifiability: Rule propounded by Karl Popper to the effect that the distinction between scientific and non-scientific theories is that the scientific ones can be falsified by their logical consequences.

The criterion of falsifiability that was most strongly propounded by Popper has two foundations: That there must be given some clear criterion to distinguish scientific statements from non-scientific statements, such as metaphysical or theological statements, and that the criterion of verifiability, that was proposed by the neo-positivists, was mistaken as a criterion.

One may well be somewhat skeptical about the first claim, for even if there is a fundamental distinction between science and non-science it is not necessary that this corresponds to some clear and simple criterion that is applicable to all statements and that then unmistakenly selects just those statements that are properly scientific.

And one may also hold that there is no simple criterion that makes such a distiinction for all the sciences, and that this is not necessary either, for what characterizes a science is usually clear enough, even if it does not reduce to one single characteristic criterion that distinguishes all statements of any science from any statements that are not scientific: Empirical investigation of aspects of the real world, by methods that are objective and capable of being employed by anybody qualified, directed by empirical findings and logical argumentations, and done in an objective, honest and controllable way.

It seemed to the neo-positivists that it is quite important to distinguish science from non-science, and especially from metaphysics and theology, and it seemed to them that they had found a simple criterion to make the distinction: A statement is scientific, the neo-positivists claimed, if and only if the statement is verifiable, and then by an appropriate scientific method, included observation and measurement.

There are quite a few possible rational objections to this, and one important one was strongly argued by Popper: The problem for a scientific theory that gets verified by some of its logical consequences, is that it does not get proved true by such confirmations, and to believe that it does is to assume the fallacy of affirming the consequent.

This involves that if A implies B and B is found to be true, it is not a logically valid conclusion that then A is true, and indeed to argue this way ("A implies B. B is true. Therefore A must be true.") that is a fallacy in deductive logic: If all cats are mammals, and this is a mammal, it doesn't deductively follow that this is a cat.

Popper argued that in contrast to verifiability, the criterion that a theory must be falsifiable is a good way to distinguish science from non-science. His main logical reason was that if A implies B and B is false, then it follows deductively that A is false.


See also:


Popper, Russell

 Original: Mar 24, 2006                                                Last edited: 12 December 2011.   Top