How does mill defend the freedom of speech?

Mill defend the freedom of speech by the following statements:

Mill defends the freedom of speech by stating that any opinion or arguments must be made whether it seems to be right or wrong in a making a decision.Based on the arguments proper discussion has to be made that may lead to a suitable conclusion.These discussions can be made with similar or opposition parties to get into a conclusion.Lack of communication leads to faulty approval of rejected statements and affects the quality of speech involved in decision making process.So even the discussion is done based on the false statement or conspiracy theories that provides knowledge about the freedom of speech.Thus one shall make a proper decision based on this freedom of speech act by interacting with others.