In general, to evaluate an argumentative discourse is to pass upon this discourse a justified positive or negative “value judgment”, S. Value. The assessment activity is one argumentative activity among others, which may be misleading or well founded, regardless of the quality of the discourse it approves or condemns. In order to avoid arbitrariness, the evaluation must specify its method, criteria and reference assessment scale, and remain open to criticism — as is the case for any other argumentation.
1. Dimensions of evaluation
1.1 Assessment scales
Arguments may be evaluated on the basis of different kinds of scales, such as:
An efficiency scale — The best argument is the one that best orients its target towards the thesis it defends, or the action it advocates.
A scale of logical-scientific validity — Good arguments are valid deductions, starting from true premises and conveying their truth to their conclusion according to valid rules and methods.
Invalid arguments are misleading, and effective argumentation may be so; in fact, effective arguments are systematically suspected of being misleading. Conversely, a valid argument may be totally ineffective: for example, “P, so P” is a valid deductive inference but it has no persuasive power. It could be argued that ordinary arguments often simply just camouflage this kind of truism by using two distinct formulations of the same proposition P “P, therefore (paraphrase of P)”. Since trains never leave before the scheduled time, the following account is not a real justification:
Due to the delay, the train will not start on time.
1.2 Binary and gradual evaluation
— Binary evaluation classifies arguments as valid (good, accepted) and invalid (bad, rejected). This evaluation follows the rules and criteria of formal logic. It requires the translation of the argumentation produced in ordinary language into a logical language. The evaluation bears on this logical characterization, taken as expressing the essence of the argumentation, and this logical evaluation is then transferred to the original discourse, S. Connectives.
— Gradual evaluation positions the argument on a gradual scale, as more or less good or bad. In practice, the evaluation criteria depend on the argument scheme considered, and on the availability of a relevant set of critical questions, which can be rather heterogeneous. The argument under consideration is then checked for each condition, and its global evaluation may be only a precarious synthesis of the results of these different operations.
2. The diagnosis of fallacy
The imputation of fallacy is an adversarial procedure condemning, rejecting, or disqualifying a discourse. The accused arguer has the right to defend his or her argument, in view of the principle of “no execution without representation”. Discussions about the fallacious nature of argumentation are, in principle, open-ended and their conclusions are defeasible and adjustable. They are arguments like any others, possibly themselves fallacious. At any rate, meta-argumentative disputes about argument evaluation provide interesting data for argumentative analysis.
Hamblin gives a clear answer to this question: the logician is not the arbiter of the argument or dispute (Hamblin 1970, p. 244-245):
Consider, now, the position of the onlooker and, particularly, that of the logician, who is interested in analyzing and, perhaps, passing judgment on what transpires. If he says “Smith’s premises are true” or “Jones argument is invalid”, he is taking part in the dialogue exactly as if he were a participant in it ; but, unless he is in fact engaged in a second-order dialogue with other onlookers, his formulation says no more than the formulation “I accept Smith’s premises” or “I disapprove of Jones’s argument”. Logicians are, of course, allowed to express their sentiments but there is something repugnant about the idea that Logic is a vehicle for the expression of the logician’s own judgments of acceptance and rejection of statements and arguments. The logician does not stand above and outside practical argumentation or, necessarily, pass judgment on it. He is not a judge or a court of appeal, and there is no such judge or court: he is, at best, a trained advocate. It follows that it is not the logician’s particular job to declare the truth of any statement or the validity of any argument.
While we are using a legal metaphor it might be worthwhile to draw an analogy from legal precedent. If a complaint is made by a member of some civil association such as a club or a public company, that the officials or management have failed to observe some of the association’s rules or some part of its constitution, the courts will, in general, refuse to handle it. In effect the plaintiff will be told: “Take your complaint back to the association itself. You have all the powers you need to call public meetings, move rescission motions, vote the managers out of office. We shall intervene on your behalf only if there is an offence such as a fraud.” The logician’s attitude to actual argument should be something like this.
The diagnosis of fallacious speech operates on a meta-argumentative level, but this second level does not transcend the dialogue under scrutiny, it remains an integral part of the argumentative game. In other words, the judgment “this argument is fallacious” works in the same way as any other ordinary refutation, whether carried by a participant (ordinary use of the word fallacy) or by an analyst, who then behaves as a participant. One must then speak of an ad fallaciam argument.
In a letter to Scherer, the economist Leon Walras refers to a controversy between Scherer himself and Guéroult:
I take […] your [= Scherer’s] study of December 30 to the point where you […] clearly and plainly address the more general considerations about the divergence between his [Guéroult’s] opinions and yours.
“Perfectibility, you say is a modern idea, one of those that best indicate the distance between the old world and the new world. It bears within itself its own self-evidence, so that its adversaries are only a few sophists or some misanthropes. It has passed into the common law of intelligence. Yet, as M. Guéroult seems sometimes to do, perfectibility should not be confused with the possibility of perfection. This confusion is not merely a matter of words; for those who understand the scope of the questions, it marks the dividing point between two systems, liberalism and socialism. Socialism, reduced to its principle, is nothing other than the belief in the possible perfection of society and the effort to realize this state.”
This is clear and precise. M. Guéroult and you agree up to a point: for both of you, humanity advances and does not retreat; the law of the development and organization of society is a law of progress and not of decadence. Beyond these limits, you separate, you think that society is only perfectible, while M. Guéroult, on his part, thinks that society, sooner or later, will be perfect; you are a liberal, M. Guéroult is a socialist. Perfectibility or perfection, liberalism or socialism, such is the alternative and the question that is raised. (Léon Walras, [“Socialism and liberalism”], )
Schérer argues that Guéroult concludes from the possibility of the perfectible (point upon which they agree) the possibility of the perfect (point upon which they disagree). This is a typical argument built upon derived words. Schérer does not consider this inference to be a sophism (he does not attribute to Guéroult the intention to mislead his readers) not even to be a mistake, a fallacy of “confusion”, simply a criticism. The analysis is not made from an external logical point of view; it comes from a political opponent, making this point as a sub-issue of a greater debate “Liberalism or Socialism?”.
3. For a laissez-faire in argumentation
Ordinary argumentation is carried out in specific fields by speech communities corresponding to what Hamblin calls “civil association[s]”, having their, interests, programs, ways of thinking and rules for deliberation and action. In these fields, the logician does not, as such, have the substantial specialist skills required. This remark is at the heart of “critical liberalism”, advocating a laissez-faire attitude with argumentation.
From such a viewpoint, what becomes of evaluation? Hamblin’s objection is taken into account, and the evaluation of the arguments is entrusted to the “civil association” with which the arguing party, interested in the outcome of the issue, is affiliated. The data to be considered for the evaluation is not limited to the one isolated argument under scrutiny, but consists in a well-defined selection of contradictory discourses developed around the same issue.
As a result, the evaluation process may be empirically documented and criticized on three levels:
— Non-thematized criticism: description of the practices of evaluation in action, such as concessions, objections, refutations and counter-discourses in general.
— Emergence of a specific ordinary critical metalanguage: charges of fallacy, misplaced authority, irrelevance, emotionality, amalgam and impugned motives, etc. (Doury 2000).
— Evaluations carried out by the specialists of the field. This level, which includes scientific expertise, is the ultimate level of evaluation. Scientists routinely evaluate the discourses and fallacies of their colleagues; historians and social scientists evaluate the fallacies of historians (Fisher 1970), and the teachers and pupils evaluate the pupils’ and teachers’ arguments.
All these activities are “[meta-argumentative]”, as opposed to “ground level argumentations” (Finocchiaro, 2013, p. 1). Provided that the intervention is useful and desired, the specialist in argument analysis can intervene at all levels. As Hamblin has explained, his or her function and deontological position are those of a “well-trained advocate”. As such, the specialist can evaluate all the arguments of the world, the posture being that of the participant analyst and evaluator, working under a double constraint of externality / internality well known in ethnomethodology. He or she may meaningfully intervene in court as a jurilogician or a jurilinguist, that is as a counsel, not a substitute for the judge.
Argumentative discourse is in itself evaluative and critical; scholarly evaluation is a process of argumentative expansion and deepening of the issue itself. There is no super-evaluator capable of putting an end to the critical process by providing a final, conclusive evaluation to silence all other participants.
 Quoted after Léon Walras L. (1896). “Socialisme et libéralisme”. In Études d’économie sociale – Théorie de la répartition de la richesse sociale Lausanne: Rouge & Paris: Pichon. P. 4.