This article reviews the ethics of rhetoric in critical care. Rational appeals in critical care fail to move patients or surrogates to a better course of action. Appeals to their emotions are considered illegitimate because they may preclude autonomous choice. This article discusses whether it is always unethical to change someone's beliefs, whether persuasive communication is inherently harmful and whether it leaves no space for voluntariness. To answer these questions, the article engages with Aristotle's work, Rhetoric. In considering whether there is a place for emotionally charged messages in a patient-provider relationship, the article intends to delineate the nature of this relationship and describe the duties this relationship implies. The article presents examples of persuasive communication used in critical care and discusses whether providers may have a duty to persuade patients. This duty is supported by the fact that doctors often influence patients' and families' choices by framing presented options. Doctors should assume responsibility in recognizing these personal and contextual influences that may influence the medical choices of their patients. They should attempt to modify these contextual factors and biases in a way that would assist patients and families in reaching the desired outcomes. The opening sections surveyed a number of definitions found in relevant literature and outlined some of the concepts included in the proposed definition. This definition helps to distinguish instances of persuasion from cases of manipulation, coercion and deception. Considering the fact that patients and families often make irrational decisions and the fact that doctors inadvertently influence their choices, the article suggested that persuasion can be a positive tool in medical communication. When patients or families clearly do not understand the risks or make decisions that contradict their long-term goals, persuasion can be used as a positive influence.