Karl Popper's Falsifiability
Sir Karl Popper's lecture was very thought provoking concerning "where to draw the line." Unlike most people, the validity of the theory was not his concern as much as how that validity is determined. This is an issue that really does not get the attention that it deserves. Popper's claims concerning, "When should a theory be ranked as scientific?" and "Is there a criterion for the scientific character or status of a theory?" seems to be put together in the following summary.
At first Popper seems to just be criticizing the integrity of some sciences and/or scientists who nebulously back their vague and general theories with references to observations that may be inconclusive or scanty which they presumably call "scientific method." He cites Freud and Adler's psychological theories, as well as the socio-economic or historical theory or Karl Marx as theories in which "Whatever happens always confirms it."
The overarching or oversimplification of these theories which seem to many to be a strength, for Popper was actually a weakness. With theories such as these anything could be interpreted into them (or the theory could be interpreted into the evidece). Thus, Popper came to the conclusion that unless a theory can be proven wrong, it cannot be labeled as scientific. He also claimed that risky predictions should be made and be testable. Also, confirming evidence should not count unless it is an attempt to falsify the theory. Now, Popper's concern the problem of the "logic of science" or the "logical problem of induction." Popper sees induction as having the same basic problem as the overgeneralization principle of the psychological, historic theories, ect. He regards no actual rule of induction as even existing. Science and its methods are merely "tests of our conjectures" and "luck". He cites Born and Hume's ideas to form his hypothesis.
The first half of Popper's lecture seems to coincide with Thomas Kuhn's historical account of science. Kuhn speaks of the old astronomical theories held and how they resemble many types of theories today. They "were believed for the same reasons: they provided plausible answers to the questions that seemed important" (Kuhn p.3). Kuhn, however, would agree with Popper that theories must go beyond the content of observation; that it was psychological factors that led the early scientists to group up observations into a systematic formula.
Basically, with every hypothesis, conjecture, observation, etc. I have read about in Kuhn goes to every extreme to avoid any type of test that might refute their claims. The limited observations that they did make could always be interpreted into the theory. What was worse was that those observations that did not fit into the theory were viewed as only "apparent" observations (Kuhn p.39).
Maybe this is another factor involved as to why Copernicus was revolutionary. He did not follow this precedent. Copernicus was not the only one....