In defending freedom of speech and ideas from suppression and censorship, subject to the Harm Principle, Mill laid down four arguments to show that such suppression was contrary to the good of ‘the human race, posterity as well as the existing generation’, both to those who are suppressed and more acutely the suppresser. The arguments are as follows; firstly the idea might be true. To assume otherwise is to assume infallibility. Secondly, though the idea might be wrong, it may contain some truth missing from the orthodox view and thus by being openly discussed and refuted the true element may be isolated and incorporated into the larger truth. Thirdly, even if the established truth is the whole truth, it must be criticised and challenged or it will become a received opinion, held without rational argument. Finally, Mill argues, if orthodox opinion goes unchallenged it stands in danger of losing its power and becoming something professed, but not deeply believed. These arguments will be explained in more detail in turn.