Doubt and empirical evidence: the sine qua non of science

“If learning the truth is the scientist’s goal … then he must make himself the enemy of all that he reads.”  (Ibn al-Haytham)

“It will be impossible to believe in whatever is said earlier unless every erroneous statement is criticized and condemned.” (Bhaskaracarya II)

“Nullius in verba” [Take nobody’s word for it].  (Motto of The Royal Society of London)

“nothing should be too obvious; if we wish to be really careful, we should analyse the assumptions, so far taken for granted”.   (Albert Einstein)

“… science is the result of the discovery that it is worthwhile rechecking by new direct experience, and not necessarily trusting the [human] race[‘s] experience from the past.”   (Richard Feynman)

Why have people forgotten to doubt?  Doubt, doubt, reread what you consider the classics of current science…  Are their conclusions based on empirical evidence?  Or do they not always follow from the evidence given?  If evidence is given, that is…

For empirical evidence is all:

“When someone says, ‘Science teaches such and such,’ he is using the word incorrectly.
Science doesn’t teach anything; experience teaches it. One should not say ‘science has shown’, but ‘this experiment, this effect, has shown’.  … It should not be “science has shown’ but ‘this experiment, this effect, has shown.’ And you have as much right as anyone else, upon hearing about the experiments – but be patient and listen to all the evidence – to judge whether a sensible conclusion has been arrived at.”  (Feynman)

Conclusions not based on empirical evidence, or on insufficient evidence, are of the order of belief, not of science.