Critics often complain that science is a closed shop, blindly committed to defending established dogmas, and unwilling to entertain ideas -- such as intelligent design, ESP or homeopathy -- that fall outside accepted paradigms. Scientists circle the wagons around accepted theories, say the critics, and dismiss unorthodox ideas out-of-hand.
Are the complaints valid?
Within my lifetime several firmly-held theories have been tossed overboard on the basis of new evidence. When I was in college, the so-called Steady-state universe held sway among the majority of cosmologists. Ten years later the Big Bang had swept the field. Likewise for the rigidity of the Earth's crust. In 1950, the only crustal movements geologists were prepared to admit were (more or less) up and down. Twenty years later the lateral drift of continents was de rigueur. In both cases, new reproducible data overwhelmed resistance.
Reproducibility is the gold standard of science. Believers and doubters alike should be able to make the same observations or perform the same experiments and achieve the same results.
Writing some years ago in Nature, Paul Grant, then a science fellow at the Electric Power Research Institute in California, said of a current controversy: "If you've got an exciting result that may send you to Stockholm, the next thing to do, after you've established publication and patent priority, is to get your worse competitor to reproduce it."
One does not throw out a successful paradigm on the basis of anecdotal evidence or someone's assertion of personal incredulity. Yes, science is conservative, but it is not a closed shop. Let proponents of an unconventional theory come up with consistently reproducible, quantitative evidence and you can be sure that the "establishment" will give even the wildest notion a fair hearing.