Verification and Falsification

Posted by Ali Reda | Posted in | Posted on 9/07/2014

The classical view of the philosophy of science is that it is the goal of science to come up with a hypothesis, whether by some inductive scheme or by some creative insight, and then seeking to find confirmatory evidence from observational data.

Verificationism asserts that a sentence which does not express either a formally true proposition (a priori) or an empirical hypothesis is devoid of literal significance or meaning. Strong verification is only possible 'if, its truth can be conclusively verified in experience'. Weakly verified 'if it is possible for experience to render it possible'.

But a problem appeared Science prepositions which are not a result of an empirical observation are neither proven empirically or necessarily true. So Ayer reformulated the verification principle in order to avoid this problem. A statement is directly verifiable only when it is an observation statement and in conjunction with one or more observation statements, entails at least one observation statement that is not deducible from these premises alone. A statement is indirectly verifiable, when in conjunction with other premises it entails at least one directly verifiable statement which isn't deducible from the premises alone and these other statements do not include statements that aren't either analytic or directly verifiable, or capable of being independently verified.

One notices a white swan. From this one can conclude:
At least one swan is white.
From this, one may wish to conjecture:
All swans are white.
It is impractical to observe all the swans in the world to verify that they are all white. So a need of another doctrine to verify and prove this statement is needed.

Popper argued that this would require the inference of a general rule from a number of individual cases, which is inadmissible in deductive logic. However, if one finds one single black swan, deductive logic admits the conclusion that the statement that all swans are white is false. Popper maintained that having come up with a hypothesis, one should seek evidence which refutes it. The best hypotheses were bold, and at least superficially, easy to refute because they made many testable claims. A bold hypothesis which survived these tests was well corroborated.

Popper envisioned science as evolving by the successive rejection of falsified theories, rather than falsified statements. Falsified theories are to be replaced by theories that can account for the phenomena that falsified the prior theory with greater explanatory power. For example, Aristotelian mechanics explained observations of everyday situations, but were falsified by Galileo's experiments, Newton's mechanics replaced Galileo's, and so on.

Popper claimed that, if a theory is falsifiable, then it is scientific. Because no number of experiments can ever prove a theory, but a single experiment can contradict one. I can't see UFOs then they can't be falsified, so they aren't scientific. Popper's scheme seemed both simple and straight forward. The crucial test seemed to be logically conclusive. It lead to a clear demarcation between science and non-science.

Popper noticed that the philosophers of the Vienna Circle had mixed two different problems, that of meaning and that of demarcation (to distinguish between science and non-science), and had proposed in verificationism a single solution to both. In opposition to this view, Popper emphasized that there are meaningful theories that are not scientific, and that, accordingly, a criterion of meaningfulness does not coincide with a criterion of demarcation. Thus, Popper urged that verifiability be replaced with falsifiability as the criterion of demarcation. On the other hand, he strictly opposed the view that non-falsifiable statements are meaningless or otherwise inherently bad, and noted that falsificationism does not imply it.

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