In this episode I discuss J.S. Mill's famous thought experiment: "If all mankind were of one opinion, mankind would be no more justified silencing that one person than he, if he had the power, would be justrified in silencing mankind."  We will also take a look at Mill's definition of 'differences of opinion' and his reasons why no opinion should ever be silenced, including the opinion of some people that the Holocaust never happened (holocaust deniers).