"Universities are islands of repression in a sea of freedom"

So said Dr. Arnold Aberman in an excellent convocation speech in which he cited several recent instances of prominent people, like Ayaan Hirsi Ali and Condoleezza Rice, being prevented from speaking at convocations because of their "controversial" views.  Dr. Aberman went on to cite four examples from science and medicine in which proponents of "controversial" new ideas that ran counter to prevailing "settled science" were ridiculed and shunned but were eventually vindicated and honoured.  Dr. Aberman's conclusions and advice:

... claiming “settled science” is a statement, not an argument. Truth is not discovered by voting. What is “settled science” today may be labelled a mistaken belief tomorrow.

You can’t learn in an echo chamber, welcoming only your ideas. Listen to those who you do not agree with – in fact, I urge, seek them out. 

Oppose their theories with facts, not with censorship.  

Be very suspicious of those who want to cut off debate with “this is against settled science.” Appealing to authority is a sign of weakness, not strength.