Ethos is all about building trust. It can be defined as how well you convince your audience that you are qualified to speak on the subject. It may seem obvious that if someone is listening to a talk about design, they’re more likely to believe a professional designer than a professional cook, but there are many ways to create credibility.

The most obvious one is to use credentials, either yours or by being introduced by a prominent authority in the field who can vouch for your expertise. 

The terms empathy, sympathy and pathetic are all derived from the word pathos, which means “suffering” or “experience” in Greek. It consists in appealing to your audience’s emotions—to make them feel what you want them to feel by triggering specific emotional reactions. Great storytellers are usually skilled masters of this mode of persuasion.

Finally, you obviously need for your message to make sense—or at least to seem logical. Unfortunately, it is possible to use the three modes of persuasion to convince an audience of something wrong.

Logos is the way you present your arguments in a logical order, which must feel so straightforward and rational that no other alternative can be conceived by your audience.

• Establish ethos. You need to build your reputation by developing deep expertise in the topics you want to address.
• Develop pathos. Pathos is all about your ability to tell stories.
• Convey logos. With logos, your goal should be to make your message logical and understandable.