Described by the philosopher A.J. Ayer as a work of 'great originality and power', this book revolutionized contemporary thinking on science and knowledge. Ideas such asnbsp;the now legendary doctrine of 'falsificationism' electrified the scientific community, influencing even working scientists, as well as post-war philosophy. This astonishing work ranks alongside The Open Society and Its Enemies as one of Popper's most enduring books and contains insights and arguments that demand to be read to this day.
Popper responds in this volume in two ways:
(1) The above research program of Logical Positivism is based on a radical misunderstanding of the nature of possible human knowledge. All human knowledge of general laws (aka causation) rests upon postulating hypotheses and testing these hypotheses. The most humans can ever know, is thus, negative propositions such as "Not all X are Y" . No matter how many X one observes, one is never justified in claiming that "All X are Y." There is, in short, no "logic of induction," that allows us to "build up" general laws from particular observations. .
(2) While there is not clearly some "demarcation principle" between science and non-science, if there were, that principle would be falsification, not verification. This is in contradiction to the Vienna Circle's attempt to divide all propositions into "empirical" and "metaphysical" on the basis of whether the proposition can be "reduced to" a string of observations.
Finally, Popper examines the status of probability statements, when certain statements are not possible, and offers a theory of probabilistic truths that mirrors his previous arguments.
Contrary to one of the other reviews here, this book is not a difficult read. It is written in short clear sentences. It does, however, require attention so that one follows the argument. Some grounding in the history of science would also be helpful.