I'm not saying theories are not important. I'm saying they can, and have been at times, disproved.
From Wikipedia:
In a standard application of the psychological principle of confirmation bias, scientific research which supports the existing scientific consensus is usually more favorably received than research which contradicts the existing consensus. In some cases, those who question the current paradigm are at times heavily criticized for their assessments. Research which questions a well supported scientific theory is usually more closely scrutinized in order to assess whether it is well researched and carefully documented. This caution and careful scrutiny is used to ensure that science is protected from a premature divergence away from ideas supported by extensive research and toward new ideas which have yet to stand the testing by extensive research. However, this often results in conflict between the supporters of new ideas and supporters of more dominant ideas, both in cases where the new idea is later accepted and in cases where it is later abandoned. Thomas Kuhn in his 1962 book The Structure of Scientific Revolutions discussed this problem in detail.
Several examples of this are present in the relatively recent history of science. For example:
- the theory of symbiogenesis presented by Lynn Margulis and initially rejected by biologists but now generally accepted.
- the theory of punctuated equilibria proposed by Stephen Jay Gould and Niles Eldredge which is still debated but becoming more accepted in evolutionary theory.
- the theory of prions -proteinaceous infectious particles causing transmissible spongiform encephalopathy diseases- proposed by Stanley B. Prusiner and at first rejected because pathogenicity was believed to depend on nucleic acids now widely accepted due to accumulating evidence.
- the theory of heliobacter pylori as the cause of stomach ulcers. This theory was first postulated in 1982 by Barry Marshall and Robin Warren however it was widely rejected by the medical community believing that no bacterium could survive for long in the acidic environment of the stomach. Marshall demonstrated his findings by drinking a brew of the bacteria and consequently developing ulcers. In 2005, Warren and Marshall were awarded the Nobel Prize in Medicine for their work on H. pylori
Nobody has disputed that, or even hinted that that's wrong. My point, in turn, is that in that respect, theories are no different from laws or facts, which are also found to be wrong from time to time.
Actually continental drift is a fact and plate tectonics is an explanatory theory.
I happen to have taken geology just a few years before plate tectonics was accepted. I can assure you that continental drift was taken quite seriously. Several days of freshman geology was devoted to the supporting evidence, even though there was no known mechanism to make it possible.
Again, you have mistaken the fact that continents move for the theory that explains the movement.
There is a parallel in evolution. Successive replacement of species was widely accepted long before Darwin. What Darwin offered was not the fact of change in species, but an explanatory theory.