Note: For the vast majority of us, the content (and methods) of the biological and physical sciences are a mystery. The temptation of the "critical thinker," therefore, is to think critically in respect to this _Authority_ the grounds of which she/he cannot really grasp. Evolution, the age of the universe, global warming, etc therefore have to be accepted on faith! I am of course quite aware that science in the past _and_ in the present has often been utilized to support the ugliest social programs: e.g., eugenics. But the attempts of non-scientific intellectuals to construct their own critique of science are usually bumbling and incompetent. Non-scientists did eventually 'overthrow' eugenic -- but not by criticizing or even paying any attention to science; they did it by facing the fire-hoses, by rioting in the central cities; by making life uncomfortable for the white majority until it became socially inappropriate to spew forth eugenics. At which point scientists discovered that eugenics was horseshit. Scientists quite properly reject with contempt lay efforts directly to "criticize" sciences -- but like the Supreme Court, they do read the elections returns (or the action in the streets) & clarify their thinking accordingly.
Hence critical thinking almost _always_, when applied to science, is toothless to correct the real defects of science at a given time but very powerful in rejecting valid science. Global-Warming doubters are the most vivid example today of the results of critical thinking.
Carrol