According to Popper, in science any given hypothesis and resultant experiment must be falsifiable and must not rely on induction as its method of gaining verification. (Stanford Encyclopedia of Philosophy, Karl Popper, 2006 p5) In fact, Popper’s criterion of the scientific status of a theory holds that any hypothesis or theory cannot be conclusively verified as such, but rather needs to be prohibitive of particular events or occurrences and held to account on its measure of corroborative evidence and possible refutation. Falsifiability therefore means the possibility of empirical observations that are incompatible with the theory or hypothesis.
At the root of this reasoning is the notion that all observation and empirical testing is subject to bias and/or error, whether it be human or mechanical and that such observation is selective and theory-laden:
“[Popper] argues that the Baconian/Newtonian insistence on the primacy of ‘pure’ observation, as the initial step in the formation of theories, is completely misguided: all observation is selective and theory laden – there are no pure or theory-free observations.” (Stanford Encyclopedia of Philosophy, Karl Popper, 2006 p5)
The theory therefore depends upon certain corroborative empirical observations, and upon genuine tests and attempts to refute or falsify it. The theory can never be absolutely verified. Added to this, the risk level of the prediction in relation to the theory determines its accountability. Essentially a confirmation should count only if it is the result of a risky prediction. (Popper p26)
Induction is different to falsifiability in that it is a deliberate attempt to observe and draw boundaries around a given occurrence or event and narrow the possibilities for refutation or falsifiability (falsifiability hence being the attempt to refute these boundaries). Induction sets out to be verified and confirmed, rather than held to account on potential on-going and unforeseen contradictions or disproving phenomena (as in the case of falsifiable theories where the more potentially falsifiable the hypothesis, the more empirical data needed, the more rigorous the testing and informative the results). Induction is a selective process that observes an event or occurrence looking for patterns, and eliminates among the number of observed patterns and alternate possibilities until an objective and assumedly unbiased conclusion is arrived at. This is inference based on multiple observations.
Popper associates the inductive method with the unfettered gathering of verification and confirmation. He also identifies logical problems and inconsistencies in this method. Popper asserts that the actual procedure of science is to operate with conjectures (opinion or theory without sufficient evidence or proof) and then to test via repeated observation and experiment. In the case of scientific theories that transcend experience, empirical evidence becomes limited, though according to the principle of empiricism, the acceptance or rejection of scientific statements depends upon observation and experiment. (Popper, p29) Taking this problem and procedure into consideration it is not the explanatory power a theory has that concerns Popper, as he was able to find cases in the lived experience of the world around him in which explanatory theories (scientific or political) could be verified over and over again; in this sense revelatory. It is the testability of a theory that is of concern, rather than the gathering of confirmation. An abundance of confirming instances and verifications was for Popper the root cause of the problem of demarcation.
Popper’s assertion about the scientific method addresses the problem of demarcation; the difference between science and pseudo-science. In essence, Poppers criterion for the scientific status of a theory set up an opposition between falsifiability (refutation and testability) and induction (the gathering of verifying data). Induction is rejected as Popper states:
“Confirming evidence should not count except when it is the result of a genuine test of the theory; and this means that it can be presented as a serious but unsuccessful attempt to falsify the theory.” (Popper, p26)
This serious but unsuccessful attempt to falsify the theory can henceforth become ‘corroborating evidence’ depending on the particular situation. As the theory is still falsifiable this corroborating evidence is essentially different from inductive empirical evidence, as it does not confirm the theory; it does not infer. This state of falsifiability solves the contradiction inherent in induction; that observation will always be incomplete or insufficient in determining the scientific status of a theory. This is of course not to say that such empirical evidence does not, after rigorous testing and attempted refutation strengthen or put in a better standing the theory.
Popper, Karl: “Science: Conjectures and Refutations” http://cla.calpoly.edu/-fotoole/321.1/popper.html accessed 6/1/2008