Dialectic and rational persuasion

In an early essay (2006), I suggested that legitimate philosophical argument shall sometimes have some specific sophistic qualities. For example, legitimate pedagogical simplifications, which I dubbed “sophiboles”, or wise exaggerations. The point of that essay was meta-philosophical, to direct attention at the ways in which philosophers, scientists, and sophists are on the same spectrum, despite the fact that they have distinctive aims. Call this the ‘Isocratic thesis’. The motivating case was of Galileo, whose defense of heliocentrism was (rightly) phrased in a bold, realist form for the purposes of popular instruction, though a more conservative probabilistic statement would arguably have been more appropriate at the time. At any rate, the Isocratic thesis was a provocative meta-philosophical statement of purpose. Its central aim is to deflate excessive philosophical pretensions while acknowledging the distinctiveness and productivity of philosophical activity.

I have come to appreciate that the Isocratic thesis concerning philosophy can be distinguished from a more modest thesis about the nature of dialectic. Dialectic, a species of rational argument, is a practice of reducing premises and inferring consequences; Socratic dialogue is the exemplar. But what, exactly, is going on in Socratic exchanges — how does it work, and why do philosophers think it worth doing?

I assume that everyone can agree that the Socratic exchanges have a characteristic rational structure: first, some set of hypotheses are derived from some foundational principles, and then (and only then) consequences are inferred. (Kenny, A New History of Western Philosophy, p.128) In the Phaedrus, Socrates refers to these as processes as generalization and division, and attributed to the dialectician’s toolkit. Call this the “collapse-and-consequence” model of dialectic, and suppose that it is the answer to the how-question. But then there’s still the question of what the philosopher thinks they’re trying to accomplish — what makes their activity productive. An alluring answer would to achieve a greater mutual understanding of some topics and/or decreased confusion, under a guise. Key to this idea is that argument is a conversational effort at reconciliation between two or more divergent perspectives. Hence, the later Hegelian formulation of dialectics as “thesis, antithesis, synthesis”. From these scholarly data-points, one might believe that the aim of dialectic is to be rationally persuasive (under some description), and call that conviction the ‘persuasionist’ interpretation of dialectic.

It is not uncommon to find folks who endorse the persuasionist view today. It is a core element in Trudy Govier’s excellent introductory textbook in critical thinking, A Practical Study of Argument (Seventh Edition): “When we use arguments in the sense of offering reasons for our beliefs, we are responding to controversies by attempting rational persuasion.” (2) Also, it is held in argumentation theory as a pragma-dialectical theory, according to which argument is intended to resolve disputes by diagnosing the appropriateness of the competing standpoint through a model of critical discussion. Resolution, here, can be read as persuasive success or rational cogency.

(I cannot help but also note that Catarina Dutilh Novaes almost endorses something like the persuasionist argument in Dialectica (2015). In that article, she argues that deductive inference as such can be understood as a kind of lopsided debate. “The claim is that, rather than for mono-agent mental processes, (deductive) logic in fact comprises norms for specific situations of dialogical interaction, in particular special forms of debates… It will become apparent that the conception of logic as tightly connected with debating and disputing rather than with thinking has been quite influential throughout the history of logic, even though if it is now mostly forgotten.” (588) Mind you, her account is not as striking as an account of persuasionism, since it applies to a form of inference that has been willfully contorted away from its initial dialogical purpose, in order to provide means for the “built-in Opponent” to get on with their part during the business of disputation. On first blush, I worry that Novaes’s conception is too agonistic, or post-Gricean, to qualify as persuasionist. But I could be wrong about that, and it would be interesting to find out.)

The persuasionist thesis is not the only game in town. It contrasts with the ‘purity thesis’. Purity theorists are sufficiently impressed with the answer to the ‘how-question’ as to think that it tells us everything we need to know about dialectic. The purity theorist holds instead:

  1. Historically, dialectic is defined in terms of pure structure of reasons (the answer to the above-mentioned ‘how question’), without reference to powers of persuasion or any other communicative aims. Hence,
  2. Some kinds of arguments do not seem to involve persuasion at all, e.g., practice arguments, are excluded by the persuasionist. Since persuasionism fails to explain parts of the denotation of the concept of rational argument, it fails as an account.

The purity theorist is wrong on both counts. (1) only makes sense so long as it relies on a provincial and distorted historiography (which Novaes alludes to in the pull-quote in the above parenthetical). Also, (2) is only distinctive so long as it involves eccentric ideas about what counts as an argument in philosophy. In the rest of this post I will only suggest some counter-examples to (1), and will say something about (2) on some other occasion.


For present purposes, my point of departure is the medieval conception of dialectic. For scholars in the Middles Ages, dialectic was conceived of as a method of disputation. “As the art of discussion– disciplina bene disputandi–dialectic deals with substances”. (Paul Vignaux, Philosophy in the Middle Ages, p. 21) At the time, dialectic was regarded with suspicion, in contrast with the scholastic method, whose point is to make credulous (usually theological) inferences based on the authority of scripture. The method of disputation sure sounds like it has all the airs of an attempt to engage in mutual, rational persuasion (under a description).

Is the medieval conception of dialectic viable in light of other contrasts? I think so, because it follows naturally from the Platonic canon, in its discussion of the contrast between dialectic and rhetoric. Two books are pertinent here, Gorgias and Phaedrus. In Gorgias, the distinction is made in the following way: while rhetoric is directed at persuasion for its own sake (or for the sake of money), depends on the science of human character, is fickle and fleeting. Meanwhile the Socratic method, hence dialectic, is better at persuasion because it is built to last, trading as it does on insight and methodological rigor. Persuasion has a potential role in both forms. The purist’s alternative is to say that dialectic is about pure structure — the collapse and consequence model while rhetoric is about mere persuasion. But this flattens out the nuances of what is said in the above-mentioned passages which most directly bear on the question.

The purity theorist would probably reply by invoking the Phaedrus, where Socrates seems to describe dialectical methods in terms of their potential to allow personal growth and self-education. Hence, the serious pursuit of the dialectician is to “find a congenial soul, and then with knowledge engrafts and sows words which are able to help themselves and him who planted them, and are not unfruitful, but have in them seeds which may bear fruit in other natures, nurtured in other ways — making the seed everlasting and the possessors happy to the utmost extent of human happiness.” (89) We might struggle to make sense of the fruit-seed metaphor in connection with the idea of persuasion. This does not sound much like persuasion, since it lacks a sense of directed acquisition of judgments. But this is a one-sided observation. The persuasionist thinks that argument can occur in contexts of mutual persuasion, which involves an assumption of reciprocal effort with convergent ends. The fruits found by the student may very well differ from the seeds planted by the teacher, but do we think Socrates would have us say that the teacher is released from prizing the fruit once it has grown? One or more parties are expected to recognize the attractiveness of the “winning” argument, if one is found.

In fact, I shall suggest that the persuasionist’s point is entirely resonant in Phaedrus.  Socrates concludes the dialogue with the following remarks. He begins with a fairly clear, though elliptical, reference to the dialectician’s method, and concludes that it is the most effective means of teaching or persuading. “Until a man knows the truth of the several particulars of which he is writing or speaking, and is able to define them until they can be no longer divided… he will be unable to handle arguments according to rules of art, and far as their nature allows them to be subjected to art, either for the purposes of teaching or persuading…” (Phaedrus, 90, emphasis mine) And we have already seen from the Gorgias that he is not inclined to find many resources to distinguish between education and persuasion. The dialectician’s work has clear import to the art of persuasion, if there is one.

It can be objected, at this point, that the collapse-and-consequence model does not say anything at all about the aim of mutual persuasion. Indeed, to be sure, is fairly well established in the canon that dialectic, unlike rhetoric, is not about persuasion of a positive first-order intellectual programme. Instead, I would like to say that dialectic is about clearing the intellectual ground and inferring what follows — its point is to persuade us that some passages of thought are rational, not to compel belief in a particular proposition. So the ‘persuasionist’ label is in a way misleading, since one can try to persuade someone of something without engaging in dialectic. But this is not to say that persuasionism is incorrect; it is only to deny naive persuasionism. Instead, we should say that dialectic — a project of reducing premises and inferring consequences — is a second-order attempt at persuasion. It is not an attempt to convince people about the true and the false, but about the rationality and irrationality of passages of thought and speech through characteristic means.

So, if the villainous brainwasher from Netflix’s Jessica Jones, Killgrave, were to say to me, “Socrates is a mortal”, I would likely be persuaded of the claim’s truth, but it would not be an argument. Meanwhile, if someone gives me the Socratic mortality syllogism, I will be persuaded of the rationality of the conclusion given the premises. And if the same or similar results were given in the collapse and consequence model, it would be dialectic. The point of rational argument is to direct a change in view, allowing an alternative perspective to observe the inferential train as a rational passage of thought or talk. It does not require that they agree with the conclusion or premises.

So I do not quite see the historical appeal of the purity thesis. I am sure there must be a more compelling case, and I have seen some people try to defend it. But I suspect, for the moment, that the problem here is somewhat ironic: namely, that the teachers of classics sometimes resort to sophiboles outside of the classroom. It is a fact that, during the teaching of a freshmen level course, dialectics and rhetoric are simplified for pedagogical purposes. In that context, I can imagine a harried instructor drawing a strong line between them, with ‘persuasion’ on the rhetoric side, ‘pure reason’ on the dialectic side. It is, at best, a wise exaggeration — though I confess I am not convinced of its wisdom.

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