Given the enormous prestige of science, the temptation to call a discipline 'scientific' is understandable; astrology, creationism, Marxism and even psychoanalysis are examples. But how do we distinguish genuine science from pseudo-science? After having defined 'knowledge' I aim to answer this question by proposing some criteria, which should help to draw a line. Traditionally, it was thought that scientific knowledge consists in generalising from the observation of some cases ('some swans') to all cases ('all swans'). This method is called induction. We use inductive reasoning abundantly in our daily lives. Unfortunately, it sometimes fails and it does not do a proper job of distinguishing science from pseudo-science. A better way is the rigorous testing of hypotheses. This method is called testability (or falsifiability). When this method is employed in case studies, astrology and Freudian psychoanalysis do not pass the test. As long as a theory is testable (by experiments, observations) it is scientific, even if it fails the tests.

Literature:

If you do not want to read Karl Popper's classic book The Logic of Scientific Discovery (1959), you may want to look at Popper's Unended Quest (1976). I discuss this material (and case studies) in my book Copernicus, Darwin and Freud: Revolutions in the History and Philosophy of Science (2009). Almost all Introductions to Philosophy of Science will discuss this topic (see suggested books in Episode 6).