You judge truth in communication by the accuracy of the communication. Inaccurate communication prevents successful interpretation, creates the opportunity for future falsehoods and devalues your credibility as a communicator. Plato defined the first purpose of communication as truth, accusing the sophists of his day of attempting to sell lies as truth and confuse their audiences. Truth in communication is most important when others will add to your message with their own ideas, building a foundation upon your ideas. Falsehoods devalue the overall message.
John Stuart Mill, in his 1859 work "On Liberty," developed his defense of free speech. He borrowed from Plato's idea of the marketplace of ideas: the concept that ideas are like a marketplace, allowing you to listen to many of them and select the ones you believe are true. Mill expanded on this, suggesting that communication provides a means for expanding the marketplace and giving you the necessary means to evaluate all ideas. Mill believed that free communication was vital to establishing freedom, both legal freedom and intellectual freedom. Mill even supported the necessity for competing ideas, as he believed that the competition of ideas kept both sides from becoming dead dogma.
Interpretation is an essential component of communication, occurring when you interpret your thoughts into words and when you interpret other people's words into your thoughts. Hans-Georg Gadamer, in his 1960 book "Truth and Method," developed his vision of Hermeneutics: the philosophy of interpretation. Gadamer believed that true interpretation was impossible, because you could never fully step into another person's existence, but that some interpretation is possible. He defined the method of interpretation as understanding the culture of the speaker, the way the speaker uses language and the position of the speaker.
Aristotle developed the most comprehensive study of rhetoric, its purposes and its methods. He established that one of the purposes of communication is to persuade others to understand your point of view. For Aristotle, when you work to persuade others, it is your responsibility to ensure that the points upon which you are persuading them are true. Aristotle divided the methods of interpretation into specific appeals. They were logos, the appeal to logic; pathos, the appeal to emotion; and ethos, the appeal to the ethics of the speaker.