The rules of persuasion were defined over 2,000 years ago, and they are as true now as they were then

To call Aristotle a philosopher is to do him a disservice. In his elegant writings, he established the foundations of many disciplines, from botany to logic to epistemology to ethical reasoning. Sadly, only about a third of his writings survived antiquity, but in one of them Aristotle explains exactly what persuasion is and how it works. For Aristotle, persuasion was a demonstration that something is true. It is important to think about that definition for a moment, since it has many important implications. When he says that persuasion is a demonstration, first and foremost, we see that persuasion is an action — it is something that requires action. Moreover, persuasion requires truth, or the appearance of truth, in order to function. This condition turns out to be a handy thing, since the speaker is not really the one who persuades. Rather it is truth itself that persuades. The communicator’s job is to demonstrate truth. That’s it. Once a listener concludes that truth has been established, persuasion follows automatically, assuming the listener is a rational person, of course.
For Aristotle, there were two kinds of persuasion. Persuasion about knowing (science) and persuasion about belief (opinion), and these were (and still are) very different things. The Rhetoric is a book about the second kind of persuasion, which is also our focus. Now, having defined persuasion as the demonstration that something is true, Aristotle presents the insight that is the foundation of this book. He writes:
Of the modes of persuasion furnished by the spoken word there are three kinds. The first kind depends on the personal character of the speaker; the second on putting the audience into a certain frame of mind; the third on the proof, or apparent proof, provided by the words of the speech itself.
Let’s examine carefully what he says above. Persuasion works in three ways, he claims. The first way is through the character of the speaker. As he notes:
Persuasion is achieved by the speaker's personal character when the speech is so spoken as to make us think him credible. We believe good men more fully and more readily than others: this is true generally whatever the question is, and absolutely true where exact certainty is impossible and opinions are divided. This kind of persuasion, like the others, should be achieved by what the speaker says, not by what people think of his character before he begins to speak. It is not true, as some writers assume in their treatises on rhetoric, that the personal goodness revealed by the speaker contributes nothing to his power of persuasion; on the contrary, his character may almost be called the most effective means of persuasion he possesses.
The last part of the sentence quoted above is the one that is most important to us: character may almost be called the most effective means of persuasion. Nothing Aristotle ever says is said casually. He selects his words carefully. Character, in his opinion, may just be the most powerful persuasive mode known to human beings. This is a remarkable statement to me, especially when I think about how often people tell me that they never speak about themselves when trying to persuade, because they do not think they “should be part of the story.” For Aristotle, not using character to persuade would be like not using a sail in a sailboat. Character, for him, is essential to persuasion.
Continuing, Aristotle adds the following:
Secondly, persuasion may come through the hearers, when the speech stirs their emotions. Our judgements when we are pleased and friendly are not the same as when we are pained and hostile. It is towards producing these effects, as we maintain, that present-day writers on rhetoric direct the whole of their efforts.
Persuasion, he claims, can come when the right emotions are aroused in the listener. Most people, I suspect, would agree with him on this point. Almost everyone has experienced being moved by a tragic speech in a movie or a thundering speaker at a political event. However, most people have not considered exactly why it is that emotion can have such a profound persuasive effect. Moreover, they have typically not considered how emotions are aroused by the skillful communicator and what happens when an unskilled speaker arouses the wrong feelings. Indeed, the use of emotion in persuasion is such a difficult thing that it is exceedingly rare to see it done well. Most speakers either avoid emotions altogether or fail to produce the right ones, often with disastrous consequences.
To character and feeling, Aristotle added a third mode:
Thirdly, persuasion is effected through the speech itself when we have proved a truth or an apparent truth by means of the persuasive arguments suitable to the case in question.
Argument, then, is the third element in Aristotle’s persuasion trilogy. In this term we include things such as proofs, witnesses, facts, and all manner of specific information that, when arrayed correctly and presented effectively, can persuade someone that something is true.
There we have it: character, emotion and argument are the three things that persuade. Aristotle, living when he did, made his claims about human speech, but, as we have come to understand, his claims apply to any form of human communication, including film, poetry, music, art, social media platforms and political commercials. Whenever and wherever human beings persuade, the three techniques that Aristotle discovered are, and must be, in use.