The scientific method
AN early model of the scientific method was inductivism: repeated observations of associated phenomena lead to general laws. That this attractively simple notion has no logical basis is easily shown by considering the story of the turkey which observed that its feed arrived after the lights came on for 364 consecutive days. Its conclusion that the illumination caused the appearance of food was proven wrong on Christmas eve.
An improvement on inductivism focused on testing predictions. Predictions can be derived from general laws and then put to the test. Positivists argued that by confirming the truth of the predictions (verification), one proves the truth of the theory. Alas, this is logically fallacious because any particular observation is compatible with more than one theory, as illustrated in Box 2.
Box 2. A hypothesis cannot be verified by evidence.
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It follows that verification of a theory is not possible. However, falsification is possible. Finding a viral cause for an infection, for example, falsifies both of the theories in the example in Box 2. The concept of falsification is central to the hypotheticodeductive model of science (Figure 1). This states that scientific knowledge grows through a succession of theories, new theories supplanting older ones which are rejected when their predictions are refuted by experimental evidence, a process which has been called conjecture and refutation.13 A distinguishing feature of science is that its hypotheses permit predictions that can be subjected to falsification through experiment.
This model accepts that there can never be certainty as to the truth of a theory; the best you can say about a theory is …