A philosopher's view of science . In this book Popper presents two contradictory theses: (a) science can be based on deductive logic only, and there is no need for induction; (b) science cannot have a logical basis.     Because deduction yields sure knowledge if it is based on sure knowledge and induction always produces only hypothetical knowledge, as Bertrand Russell clearly stated, Popper begins by trying to show that the use of deduction instead of induction can provide a solid logical basis for science. He talks about replacing "inductivism" by "deductivism." In reality, he explains the use of deduction in the testing of a theory: consequences are deduced from the theory and are compared with known facts, which is something known by many. Induction, on the other hand, is used in creating hypotheses in both experimental and theoretical investigations and is again used in generalizing the results of tests (a) to all other possible tests in experimental investigation, and (b) also to some phenomena that cannot be used to test the theory created using the hypothesis, or hypotheses, that are produced inductively. When Popper claims that inductivism can be replaced by deductivism, he is unaware of the fact that induction is used at the beginning of both experimental and theoretical investigations to create hypotheses and again at the end of the investigation to generalize the test results.     But in the rest of the book, Popper concentrates on the generalization of test results, which is done through induction and is what he overlooked to begin with, as explained above. Consequently, Popper proves rightly that scientific knowledge cannot be produced using deductive logic, which is the opposite of what he tried to prove earlier.     The truth is that new knowledge is not a product of logic but is learned from the world about singular phenomena and is generalized through induction. Induction does not yield logically sure knowledge, but evolution created the human brain/mind so that it knows that it has to trust induction. Thus, everyone avoids hitting his or her head against hard objects by learning from past experience through induction. Someone who does not trust such inductive knowledge is punished severely. Similarly, when a scientist or an engineer does not use an accepted theory anywhere in his or her work, he or she is likely to be punished by failure and its consequences of many kinds.    Popper's views should serve to waken up those who seek the comfort of producing all knowledge through deduction only, but in fact, they shed doubt mostly on theories, because a theory is not deduced from anywhere, unlike empirical knowledge is, about some singular phenomena. A theory is constructed and tested by using induction or deduction, as necessary, at various stages of the total process on the basis of empirical knowledge. Popper's views are those of a philosopher who is not familiar with the mission and methods of science and thinks that science is about discovering something that can be called the absolute truth. Read also my evaluation of Kuhn's views.    Another erroneous idea of Popper is that theories can be falsified but cannot be verified. It is true that if a new theory is falsified by a few or even a single test, there is usually no more wish to keep testing it. But when an accepted theory is falsified by one phenomenon, it is not discarded as invalid. Its use continues where it gives good results. It is also true that a theory cannot be verified in an absolute sense, but this is true also about empirical knowledge. The generality of any knowledge is a consequence of induction which is forced upon the mind by the results of evolution, as mentioned. The verification of a theory, or any knowledge, means that it can be used where it gives useful results. Unfortunately, the impossibility of the logical or experimental validation of knowledge in a general way is seen as a weakness of only theories by those who ignore what a theory is and how it is constructed, tested, and used.
Output: NEG