In general, rhetoric is the art of persuading another person to do something or to have a particular opinion. There are a number of tactics, or rhetorical strategies, that can be used to aid in persuasion. The most famous of these are Aristotle's three types of appeals — logos, ethos and pathos. Mastering techniques for using these strategies can help writers and speakers frame their rhetoric in ways that will be most persuasive to their audiences.
Logos is Greek for "logic." A logical appeal often presents and analyzes objective data, often by means of explaining causes and effects. For example, if a person is writing an article about global climate change, he or she might present information about average worldwide temperatures and shrinking polar ice caps. The writer might then go on to analyze what has caused climate changes and what effects climate change is likely to have.
When using logic as one of the rhetorical strategies, writers and speakers should be careful to avoid logical fallacies. A statement that may appear to be reasonable but actually is not is said to contain a logical fallacy. For instance, some scientists have argued that climate change may have been a factor leading to the extinction of dinosaurs. It would not make sense to say that climate change caused the extinction of dinosaurs though, because it would also cause the extinction of humans. This is a fallacy known as a hasty generalization — saying that since an event had a particular outcome one time that it will always have the same outcome.
The second of Aristotle's rhetorical strategies is ethos, meaning "ethics." In rhetoric, an ethical appeal is most often one that establishes the character or credibility of the person making the argument. This may involve the writer or speaker presenting his or her qualifications, such as a PhD in environmental studies, or explaining why he or she cares about the environment. Another good way to establish credibility with an audience is simply to present an argument in a way that is easily understood and free from factual or grammatical mistakes. Occasionally, ethos can also mean an appeal to the audience's ethical or moral responsibility to take action on an issue.
Pathos is the rhetorical strategy that appeals to the audience's emotions. One highly effective way of doing this is by providing specific examples in addition to generalizations. For instance, telling about how a particular family's fishing business failed due to the climate change would appeal to the hearer's emotions more than a statistic about income lost due to climate change. Narration, pictures and sensory descriptions are specific types of rhetorical strategies that can provide emotional appeals.