As I worked on this, the importance of some things that united Perelman and Olbrechts-Tyteca, Johnson, Walton, Burke, Rescher, Lakatos, Chomsky, Ollman and Bourdieu became more apparent and more important. This further delayed things and led to a restructuring of my response, involving a summary of my points critical of de Gondi's arguments and then a new second section, which, due to the length of all this I've now made into a separate diary. This may be of interest to those not interested in the debate about dialectic. In the second diary I consider how these thinkers are linked by a desire to defend reason and the heritage of Enlightenment thinkers (in their variety, not the monolithic caricature of it, found even on the Left).
As so often happens with my diaries, it just kept on growing, so I've provided a short summary of the main points for those not so interested in the detailed arguments and who might like to move on to the second, more general diary: Dialectical Enlightenment.
Main points
Harsh criticism and the lack of evidence
The main objection was to his "harsh" criticism of dialectic in general and he persists with that, only slightly modified by a concession that there's not a lot of difference between it and rhetoric - so why attack one while uncritically accepting the other? He has still failed to provide support for this general attack - one quotation from Derrida is hardly convincing, especially as Derrida's "deconstruction" is hardly typical of dialectic.
Recent theory
The secondary claim that recent argumentation theorists ignore or dismiss dialectic is not borne out by the facts, he misrepresents the views of Walton and exaggerates the significance of Perelman and Olbrecht's preference for rhetoric. He accepts Pragma-dialectics as a counter-example, and there are other recent theorists who are very much in favour of dialectic, such as N. Rescher and those influenced by him.
Rhetoric
He ignores the obvious problems with rhetoric which, like the closely related dialectic, is just a tool and capable of being used for "intellectual sham" by "wankers", arguably more so.
Definition
He NOW argues that one ought to start by giving a definition relevant to the issue being discussed, despite having failed to do so himself. He doesn't apologize for not having done so and fails to note that I had provided a definition in my reply to his initial comments on my cafe-philo diary. He still doesn't provide a definition which might suggest why he is so critical (nor does he provide a range of examples - as noted above).
Lakatos
De Gondi refers to the book "For and against Method", which has exchanges between Feyerabend and Lakatos. He claims that the relative absence of reference to dialectic in it is, supposedly, further proof of the irrelevance of dialectic. In fact the exchanges are not particularly serious and Lakatos's early, ground-breaking work on mathematics was fruitfully influenced by dialectic and experts on his work, including Moterlini, the editor of the book cited by de Gondi, argue that his later work was also influenced by dialectic.
____________________________
Discussion
I started this discussion with a pretty open mind; I hadn't even used the word "dialectic" in my diary on cafe-philo. I just objected when de Gondi responded to Number 6's comment (which referred to dialectic) with a vehement condemnation of dialectic in general. Clearly his mind was made up and he's been seeking to defend his "harsh" and very general criticism.
When de Gondi further claimed that recent argumentation theorists ignored or dismissed dialectic I was surprised about this, but when I looked at the evidence I did not find his claim to be at all accurate. But, having committed himself to a very negative view of dialectic and to his claim about recent theory, he was clearly unwilling to accept my evidence.
However, I'm sad to say that this leads him to distort the views of these recent theorists to fit his negative attitude. He does modify his attitude somewhat and admits that there isn't a great deal of difference between dialectic and rhetoric (as Aristotle concluded, as noted by Perelman, see below):
the authors can develop a strong heuristic model (héuresis- to invent, explore, discover) in which the contrived separation of the two arts is superfluous.
But if it's only a "contrived" separation why this continued hostility to dialectic and claim that recent theorists dismiss it ?
Then, when referring to Pragma-dialectics, he has to admit:
Certainly this latter case would serve to confute my initial broadsides but not my observations here.
However his "observations here" include a justification of his "harsh" attack, again due to the way some people have used the term:
I may have developed a distaste for "dialectics" as a portmanteau word battered around by the elite, the effete and jolly good old wankers, most often to confound or show off or support a degenerative programme in need of props.
"Harsh" criticism ought to be more specifically targeted and supported by evidence and reasons.
In his diary de Gondi uses an image, then, in a comment, cites Derrida's commentary on it. But:
a) this is hardly a typical example of dialectic - but it is an example of the kind of "postmodern" discourse criticized by Chomsky (and by Bricmont and Sokal - see separate diary: Dialectical Enlightenment).
b) a single example doesn't justify such a generalized attack.
I have no problem with harsh criticism, I do it myself (e.g. my diary on Zizek), but it ought to be a bit focused and backed up with a range of relevant evidence (I supplied a great deal in the Zizek diary), especially if somebody else has questioned it. The email by Chomsky, which I had already cited, is an example of harsh but reasonably focused and justified criticism. He was talking about the Parisian intellectual elite (mainly philosophers) of a few decades ago. While apologising for not properly supporting his dismissive comments (but somebody asked him for his opinion), he did give examples, explained what he objected to and qualified what he said, e.g. he said he had more time for Foucault. He explained his attitude in a bit of detail in one case - Derrida:

Now Derrida, Lacan, Lyotard, Kristeva, etc. - even Foucault, whom I knew and liked, and who was somewhat different from the rest - write things that I also don't understand, but (1) and (2) don't hold: no one who says they do understand can explain it to me and I haven't a clue as to how to proceed to overcome my failures. That leaves one of two possibilities: (a) some new advance in intellectual life has been made, perhaps some sudden genetic mutation, which has created a form of "theory" that is beyond quantum theory, topology, etc., in depth and profundity; or (b) ... I won't spell it out.
...
Specific comment. Phetland asked who I'm referring to when I speak of "Paris school" and "postmodernist cults": the above is a sample.
He then asks, reasonably, why I am "dismissive" of it. Take, say, Derrida. Let me begin by saying that I dislike making the kind of comments that follow without providing evidence, but I doubt that participants want a close analysis of de Saussure, say, in this forum, and I know that I'm not going to undertake it. I wouldn't say this if I hadn't been explicitly asked for my opinion - and if asked to back it up, I'm going to respond that I don't think it merits the time to do so.
So take Derrida, one of the grand old men. I thought I ought to at least be able to understand his Grammatology, so tried to read it. I could make out some of it, for example, the critical analysis of classical texts that I knew very well and had written about years before. I found the scholarship appalling, based on pathetic misreading; and the argument, such as it was, failed to come close to the kinds of standards I've been familiar with since virtually childhood. Well, maybe I missed something: could be, but suspicions remain, as noted. Again, sorry to make unsupported comments, but I was asked, and therefore am answering.
http://vserver1.cscs.lsa.umich.edu/~crshalizi/chomsky-on-postmodernism.html
Derrida's silly speculation and reliance on real frauds like Freud and Lacan would not be recognized as remotely resembling serious dialectic by Johnson, Ollman, Rescher, etc. Anyway, it is just one example, so it is no support for such a general accusation.
Dialectic and recent theorists
We got distracted from the basic issue, his over-general, "harsh" criticism. The discussion of those who, he claimed, showed that dialectic is merely ignored or dismissed by recent argumentation theorists, is a side-issue to the main point.

Walton and Johnson
However, his attempt to defend this secondary claim is itself mistaken, based, for example, on his misrepresentation of Walton's article. When presented with Walton's own words, which display an obvious respect for Johnson's dialectical approach, he attempts to demean Johnson (after all, if he's for dialectic, he must, according to de Gondi, be a "wanker") and prefers to believe that Walton is being merely polite, if not sarcastic - but supposition is not evidence. He claims that Johnson's arguments are "feeble" but provides no examples to support this. In fact Johnson is an important and widely respected figure in recent argumentation theory:
Johnson has been credited as one of the founding members of the informal logic movement in North America, along with J. Anthony Blair who co-published one of the movement's most influential texts, "Logical Self-Defense," with Johnson.
wikipedia
Cf.:
In 1979, Johnson and Blair founded the Informal Logic Newsletter, which became the journal, Informal Logic, in 1985. In 2004 he co-founded the Network for the Study of Reasoning, a cluster of Canadian experts researching the theory and its applications of reasoning and argument. His articles have appeared in such journals as American Philosophical Quarterly, Synthese, Argumentation, Philosophy and Rhetoric and Informal Logic.
... In 2000, he was awarded the Distinguished Research Award by the International Society for the Study of Argumentation.
http://www.uwindsor.ca/crrar/ralph-h-johnson
Here's an article by him defending himself against various criticisms, it's not "feeble" at all, and, note, he's giving the keynote lecture at the beginning of a conference on argumentation:
http://web2.uwindsor.ca/courses/philosophy/johnsoa/keynotetext.htm
De Gondi suggests that I was being misleading in only quoting the first sentence of Walton's closing paragraph, but he is misleading by choosing to omit the fact that in introducing it, I had summarised his conclusion:
Walton, far from condemning dialectic, notes how it became increasingly important in the work of two leading authorities on informal logic and he has some sympathy with this, while arguing that the addition of a study of dialogue provides a better over-all approach.
This does fairly summarise his view, while de Gondi provides only a travesty of it.
Note that just before this conclusion he had said:
"The second point of clarification has to do with the participants in a dialogue, and how they should be defined in dialectical theory. Johnson and Blair (1987a, p. 46) define the dialectical approach as one that identifies an argument as a human practice, an exchange between two or more individuals in which a process of interaction shapes the product. This picture could be broadened to include dialectical argumentation between two computers or between a human user and a computer
....
Thus dialectical argumentation is typically a human practice, but can also involve conversational exchanges between agents that do not actually have to be human beings."
http://www.dougwalton.ca/papers%20in%20pdf/07JBfestIL.pdf
There's no rejection, nor condemnation of dialectic, he's just one of those who argues for a broader approach which includes less formal discussion, but also it could include "dialectical argumentation between two computers or between a human user and a computer". He clearly doesn't reject dialectic as such.
From other papers by him, showing his positive attitude to dialectic within his broader dialogue approach:
This paper has aimed to sketch how traditional dialogue games can be extended to take account of the dialectical nature of argumentation schemes. Most work on argumentation schemes to date, both within argumentation theory, and also in artificial intelligence where such schemes have found a very warm reception, has focused on the representational and inferential aspects. Yet schemes clearly have an inherently dialectical nature, with critical questions forming a crucial component.
http://www.dougwalton.ca/papers%20in%20pdf/07OSSAchris.pdf
For a long time, the old dialectic was thought to be merely an antiquated art that had no place in the science of logic. It was not until recently that a new dialectic insert was put forward (Walton, 1998) with a new classification of types of dialogue and viewed as contexts of argumentation, and meant to be normative models useful for the study of fallacies. Walton departed at some points from the ancient heritage of the old dialectic, developing modern categories of formal dialectics and dialogue games.
http://www.dougwalton.ca/papers%20in%20pdf/Cohesionv4.pdf
The other examples are no more convincing - nor supportive of de Gondi's general attack.
Perelman and Olbrechts-Tyteca
You spend a lot of time on who said what about P & O-T, but what does all this scholarly labour produce ? - a mouse, because:
a) They clearly did not ignore dialectic.
b) As you now admit, dialectic and rhetoric are related and neither is dismissed nor attacked by serious theorists such as these.
What P & OT WERE against was the reduction of reasoning to formal logic (or "demonstration" in Aristotle's terms) and against the retreat from reason into radical skepticism or subjectivism. The former made the defense of values like justice impossible (as Perelman himself had concluded in his early work from a logical positivist approach, later abandoned), the latter reduced it to subjective choice, as in Existentialism.
In between these extremes P & OT found BOTH dialectic and rhetoric. Their choice between these two related approaches to reasoned argument about values and courses of action was of minor importance and Perelman sometimes spoke of dialectic in positive terms which explains why some have spoken of a "rapprochement" with dialectic. Thus, rather than a rejection of dialectic, his rhetoric would involve a development of "dialectical proofs".

The Promise of Reason p 64
Of course once they had opted for rhetoric they tended to play up the supposed superiority of rhetoric, and played down the more negative side of its history. But they so refined their idea of rhetoric that it became close to that of dialectic, as Aristotle concluded - cited by Perelman:

Perelman and Olbrechts-Tyteca preferred the term "rhetoric" to "dialectic", but, as I said, it was the period of the Cold War and "dialectic" was associated not just with Hegel, but with dialectical materialism and thus with communism. While they say that a more important reason for their choice was to do with audience, the way they refine this idea brings their version of rhetoric close to dialectic (like Aristotle), and some find this aspect of their approach unconvincing:
The Universal Audience is simultaneously one of the most rewarding and the most problematic concepts introduced by The New Rhetoric. On the one hand, it appears to salvage universal standards of reason (or reasonableness) without recourse to metaphysics. On the other, those standards appear to rely on "an absolute timeless validity, independent of human or historical contingencies"--that is, on metaphysics, which makes it vulnerable to attack and dismissal. It is frequently critized and frequently shored up, almost entirely because it is not, as advertised, universal. It is a product of an individual rhetor, projecting his personal (though, in part at least, socially accrued) standards of reasonableness and objectivity into an ideal construct.
http://arts.uwaterloo.ca/~raha/cv/Harris-CognitiveDimensionsOfUA.pdf
Rhetoric ? Really ?

De Gondi supports those who adopt a rhetorical approach, apparently he has no problems with rhetoric in general. Is it supposed to be innately superior to dialectic ? To ask the question is to reveal the absurdity of the idea; it is just a tool, like dialectic, and can also be used for "intellectual sham" and by "wankers". Arguably rhetoric is even more likely to be used in these ways:

Mobilizing one's base and arousing people's passions are natural parts of democratic politics. Aristotle recognized that rhetoric at its best appeals concomitantly to our passions as well as to our character and our reason. The problem with extremist rhetoric is that it mobilizes the base by spurning reason and playing exclusively to the antagonistic passions of disrespect and degradation of argumentative adversaries. Extremist rhetoric insidiously undermines the democratic promise of mobilizing citizens on the basis of some reasonable understanding of their interest and the public interest.
http://www.upenn.edu/president/meet-president/extremist-rhetoric
A classic example of analysis of such rhetoric is Kenneth Burke's "The Rhetoric of Hitler's Battle" (Mein Kampf). Yes, I know that in a dialectical discussion such as this one shouldn't use Hitler, but I'm not accusing de Gondi of being like Hitler; it's just that Burke's essay is too relevant to this discussion to ignore. Moreover, while he is a specialist in rhetoric, I discover that Burke was also a strong advocate of dialectic !

http://www.telegraph.co.uk/news/worldnews/europe/germany/5978047/German-Jews-back-historians-push-to
-publish-new-edition-of-Adolf-Hitlers-Mein-Kampf.html
"In hindsight, it is no hyperbolic praise to call his book review, "The Rhetoric of Hitler's `Battle'," a visionary and prophetic document whose profound examination proved to be only too true! His rigorous examination of Hitler's "acts and attitudes of persuasion" cuts to the core of fascist propaganda.
http://uregina.ca/~rheaults/rhetor/2004/schmidt.pdf
Significantly K. Burke, who was very left-wing and an authority on rhetoric, opted FOR dialectic, but this was at the beginning of WWII. Like P & O-T, Burke was motivated to defend reason and its application to politics. Unlike them he emphasized the dangers of such extreme forms of rhetoric as that found in Hitler's "Mein Kampf", so his appeal to reason was in terms of dialectic, but fundamentally he and P & O-T were involved in a common project, the application of reason to political argument.
Burke's poem "Dialectician's Hymn." Read at the end of The Philosophy of Literary Form, it is a poetic encomium to the power of language. Within its original context, however, both historically and within the trajectory of Burke's work, its emphasis on the power of the dialectic as a response to dictatorship is clearer. The poem was first published in the University Review in December 1939, within months of both the declaration of war in Europe (September 1939) and of Burke's analysis of Adolph Hitler's threat to parliamentary debate, "The Rhetoric of Hitler's `Battle' [`Mein Kampf'] " (published in the Southern Review, summer 1939). In context, the dialectic - the competing diversity of voices whose combined perspectives can best achieve union - can be read not only as a generalized good for Burke but as an argument for Burke's methodology to overcome the human communication failure of World War II.
http://newark.osu.edu/facultystaff/personal/eweiser/Documents/Burke%20and%20War.pdf
Other recent theorists who are pro-dialectic
Rather than de Gondi's examples, I could have focused on others who are serious academics (not "wankers" indulging in "intellectual sham"). I did refer to and briefly quote from Bertell Ollman, quite an eminent scholar, de Gondi passed over him without comment, I assume because he is clearly a major example against his generalisation.
But I could also have referred to the positive views of dialectic of some important theorists, e.g. N. Rescher and the people influenced by his approach to dialectics:
When Nicholas Rescher published his book, Dialectics, A Controversy Oriented Approach to the Theory of Knowledge, in 1977, he gave an important boost to the rigorous study of argumentation, especially to its dialectical features. Professor Freeman has availed himself of Rescher's important insights before today, notably in his own book, Dialectics and the Macrostructure of Argument (1991). Ralph Johnson's book, Manifest Rationality (2000) doesn't have the word `dialectics' in the title at all but, nevertheless, it is very concerned with dialectical theory. The fourth member of this dramatis personae is Trudy Govier. It is Govier's remarks in her book, The Philosophy of Argument (1999), about Johnson's views which have prompted Freeman to bring Rescher's thought back to our attention.
web2.uwindsor.ca/faculty/arts/.../edited_hansen_on_freeman.doc
Rescher - more recently:
Nicholas Rescher, Philosophical Dialectics: An Essay on Metaphilosophy, State University of New York Press, 2006,
So, there we have it: an overview (simultaneously analytic and synthetic) of some significant characteristics of philosophical inquiry, with various of Rescher's own distinctive philosophical themes on display -- the pragmatic evaluation of a process of dialectical systematizing, adverting to fallibility, coherence, holism, and conceptual limitations. This is a slim book with an extensive vision.
...
All philosophers can learn from Rescher's vast body of work, the grand sweep of his philosophical experience and vision -- characteristics that also animate this book. For anyone who wishes to think philosophically about philosophy as a whole, Rescher's book is a useful and engaging place to begin. There is metaphilosophical wisdom in it."
http://ndpr.nd.edu/news/25075-philosophical-dialectics-an-essay-on-metaphilosophy/
Definitions - a bit late in the game!
De Gondi NOW says:
"There are as many varieties [of dialectic] as there are recipes for borsch. The term simply can't be used without being defined beforehand".
Then why didn't he do so before using the term to attack it?!
Why does he make no acknowledgment that, in my first mild objection, I gave a general definition of dialectic ? He says: "one need only establish a definition pertinent to the discussion at hand" - but he still fails to present one pertinent to the justification of his harsh attack. He extracts, from the bits he quoted from P & O-T, something he claimed is about "Socratic dialectic". But they say their point is to do with the Stoics and Medieval philosophers' approach to dialectic and their mistaken tendency to reduce dialectic to logic:
It is easy to see how dialectic, just like argumentation directed to the universal audience, could come to be identified with logic. This was the view held by the Stoics and the medieval thinkers. We think of it as merely an illusion, or a method, which admittedly has played an important role in the development of absolutist philosophy, striving by every means to go from adherence to truth.
P & O-T
The "illusion" refers to this misidentification by the Stoics, etc., and "method" refers to method based on this misidentification. This is no support for a general attack on dialectic - despite all the quotation from P & O-T.
The well-read "artisan"
I'm not impressed by this (mock ?) humility: I'm just an "artisan" (maybe there's a chip on the shoulder showing, especially with the side-swipes at "elites" and "theoreticians" who should turn to "everyday activity"). As Chomsky says, there's nothing in the humanities which can't be understood by an intelligent 15 year old prepared to do the reading (if it can't be understood - it's probably just deliberately obscure junk - see Chomsky, quoted above). The "artisan" de Gondi just happens to have on his bookshelves "The New Rhetoric" and the book about Feyerabend and Lakatos. He's obviously done some reading, it's just unfortunate that in this case he's done it in a rather prejudiced manner, finding excuses to ridicule anybody who adopts a dialectical approach of whatever variety.
Lakatos - another hole in de Gondi's foot

De Gondi refers to "For and against Method", which is about Lakatos's exchanges with Feyerabend, and he suggests that the relative absence of reference to dialectic is, supposedly, evidence of the irrelevance of dialectic. However this book is not really a good place to look for the considered views of these two theoreticians, as Ian Hacking points out:
There is no new philosophy here, and little news about the opinions, or even the development of ideas, of either author. It is symptomatic that the editor begins the book with an imaginary dialogue of his own composition, in which the protagonists are named `Lakatos' and `Feyerabend'. It is very well done, succinctly setting out Lakatos's For and Feyerabend's Against. The letters themselves do not add much, but they do convey some of the flavour of those days. The correspondence is conducted mostly between Berkeley, where Feyerabend is manning his lonely outpost, and the LSE, where Lakatos has moved centre stage. Readers who like gossip will not be disappointed. The staid may be appalled by the ribald tone of this little bit of Mitteleuropa am Aldwych.
http://www.lrb.co.uk/v22/n02/ian-hacking/mitteleuropa-am-aldwych
So it's not surprising that in this collection of mainly "ribald" "gossip" there is no serious discussion of dialectic. Had de Gondi searched beyond the gossip he would have had an unwelcome surprise. In fact Lakatos was very influenced by dialectic in his early, ground-breaking work on mathematics, and several people who've studied his work argue that he retained a somewhat dialectical approach in his later work (despite crediting Popper with having helped him free himself - somewhat - from the influence of Hegel):
Ian Hacking:
I would say that his philosophy of science is merely suggestive. He proposed what he called a methodology of scientific research programmes, which was intended to explain the idea of rationality. It was a fascinating if often exasperating theory of scientific dialectic, a theory not exactly of science in action, but a reconstruction of what the action would have looked like, had some sort of Hegelian Absolute Reasoner been running the show.
http://www.lrb.co.uk/v22/n02/ian-hacking/mitteleuropa-am-aldwych
Cf. Moterlini, the editor of the book cited by de Gondi:
In fact, some of Lakatos's most fruitful contributions - such as his dialectical conception of mathematical heuristic, the idea of rational reconstruction and, more generally, the emphasis on the role of criticism in the progress of knowledge - come directly from a peculiar philosophical conflation of Hegelian and Popperian ideas.
http://www2.lse.ac.uk/CPNSS/pdf/DP_withCoverPages/DP56/DP56F-01-C.pdf
So, yet another supposed example of the irrelevance of dialectic turns out to be evidence of its continuing importance.
Dialectical development
My own internal dialectical development while doing this led to what is now a separate but related diary, going beyond the debate on dialectic to what unites Burke, Pereleman and Olbrechts-Tyteca, Johnson, Walton, Rescher, Chomsky, Lakatos, Ollman, Bourdieu, etc.: the defense of reason and the heritage of the Enlightenment thinkers.
I would hope that de Gondi would agree with this support for the wider project of P & O-T AND K. Burke and his dialectical approach, and the related work of people like Chomsky and Bourdieu. I also hope that he will now giving us more examples of what he finds so objectionable, which I suspect might include the other people Chomsky criticizes, as well as Derrida. But I'm sure the real objections have little to do with such people's supposed dialectical approach and more to do with their pretentiousness, dependence on discredited authorities like Freud, and attempts to impress by reference to often poorly understood ideas from the sciences (see second diary: Dialectical Enlightenment).