  Aristotle notes that even if the opponent fails to speak, she must still act, and if she acts in a certain way, that shows that she thinks that things in the world are one way rather than another, and that some courses of action are better than others. That is why people do not walk into wells or over precipices, and it shows that people think it better not to walk into a well or over a precipice than to do so. Their actions show that they have beliefs that conform to PNC.