Since the reintroduction of Aristotle to rhetoric in the 60s, there has been a tendency to read him in a post-positivist light. That is, the logical positivists (building on Cartesian thought) insisted on a new way of thinking about thinking—on an absolute binary between “logic” and “emotion.” This was new—prior to that binary, the dominant models involved multiple faculties (including memory and will) and a distinction within the category we call “emotions.” While it was granted that some emotions inhibited reasoning (such as anger and vengeance) theorists of political and ethical deliberation insisted on the importance of sentiments. The logical positivists (and popular culture), however, created a zero-sum relationship between emotion (bad) and reasoning (logic–good). Thus, when we read Aristotle’s comment about the three “modes” of persuasion post-positivist world, we tend to assume that he meant “pathos” in the same way we mean “emotion” and “logos” in the same (sloppy) way we use the word “logic.” And we get ourselves into a mess.
For instance, for many people, “logic” is an evaluative term—a “logical” argument is one that follows rules of logic. Yet, textbooks will describe an “appeal to facts” as a logos (logical) argument. That’s incoherent. Appealing to “facts” (let’s ignore how muckled that word is) isn’t necessarily logical—the “facts” might be irrelevant, they might be incorporated into an argument with an inconsistent major premise, the argument might have too many terms. In rhetoric, we unintentionally equivocate on the term “logical,” using it both to mean any attempt to reason and only logically correct ways of reasoning. (It’s both descriptive and evaluative.)
The second problem with the binary of emotion and reason is that, as is often the case with binaries, we argue for one by showing the other often fails. Since relying entirely on emotion often leads to bad decisions, then it must be bad, and relying on logic must be good. That’s an illogical argument because it has an invalid major premise. Were it valid, then someone who made that argument would also agree that relying on emotion must be good because relying purely on logic sometimes misleads (it’s the same major premise—if x sometimes has a bad outcome, then not-x must be good).
So, even were we to assume that emotion and logic are binaries (they aren’t), then what we would have to conclude is that neither is sufficient for deliberating.
And, in any case, there’s no reason to take a 19th century western notion and try to trap Aristotle into it.
A better way to think about Aristotle’s division is that he is talking about: what the argument of a speech is, who is making the speech, and how they are making it. So, the logos (discourse) in a speech can be summarized in an enthymeme because, he said, that’s how people reason about public affairs. There are better and worse ways of reasoning, and he names a few ways we get misled, but he didn’t hold rhetoric to the same standards he held disputation—that is where he went into details about inference. An appeal to logos, in Aristotle’s terms, isn’t necessarily what we mean by a logical argument.
Aristotle pointed out that who makes the speech has tremendous impact on how persuasive it is (and also how we should judge it)—both the sort of person the rhetor is (young, old, experienced, choleric), and how the person appears in the speech (reasonable, angry). And, finally, how the person makes the speech has a strong impact on the audience, whether it’s highly styled, plain, loud, and so on.
And all of those play together. A vehement speech still has enthymemes, and it’s only credible if we believe the speaker to be angry—if we believe the speaker to be generally angry (or an angry sort of person) that will have a different impact from an angry speech on the part of someone we think of as normally calm. Ethos, pathos, and logos work together, and they don’t map onto our current binary about logic and emotion.