But if you do have a solid argument that you believe in and that makes sense at the level of logos, then there is nothing wrong with appealing to both the hearts and the heads of your readers.
Pathos can thus serve you well when writing a persuasive essay. This refers to the character of the writer, or the extent to which people are inclined to trust the writer's words and thoughts.
Logos refers to the part of rhetoric that deals with rational persuasion.
This has to do with whether the argument you are making makes sense and hangs together at the level of logic.
Whereas an expository essay is about just telling people the facts of the subject, the persuasive essay is intended to make people A persuasive essay is the main form of writing that you can use to convince other people that your view of an issue is the right one.
Today, there are clearly a lot of different issues about which we all have some very strong feelings.
This means that you can boost your ethos by being a good student, getting good grades, being known as trustworthy, and so on.
But there is no way to insert ethos into the text of the persuasive essay itself, because ethos isn't really about that.
In fact, pathos may well be the most commonly used element of rhetoric, for the simple reason that it is easy to use, especially if you aren't good at logos: you could try to persuade people by just scaring them or angering them, as opposed to making a rational argument that truly convinces them.
Pathos is very common in almost all political news rhetoric today.