There is an interesting piece in New Scientist on falsification in science. (Sorry, subscription only.)

Even when scientists accept that a theory has failed some test, they rarely junk it as being false. Popper recognised this too. Krauss points to the classic case of Newton versus Einstein. During the 20th century, Newton’s theory of gravity was repeatedly “falsified” by observations: for example, by predicting only half the observed bending of light by the sun’s gravitational field.

The point that some theories where previously considered unfalsifiable and therefore not scientific was discussed.

The false assumption is made that a so called “falsification” is always valid. If a mistake is found in the falsification, a “disproven” theory becomes an un-disproven theory. Also what is called pseudo scientific by scientists need not always remain so. If a theory is found to make testable predictions, it becomes scientific. The boundary of what is empirically testable and untestable is always changing.

But whatever one regards as the essence of science – black-and-white falsification or subtle shades of grey – in the end it is still empirical observations that decide if a theory gets taken seriously. “At some level, you cannot give up the idea of falsification,” says Krauss. “Rumours of the death of science have been greatly exaggerated.”

AC1

PS Feyerabend was not mentioned if you were wondering.