• • Ambiguity (N), ambiguous (Adj) come from the Latin verb ambigere, “to discuss, to be in controversy”: qui ambigunt ‘those engaged in a discussion’ (Cic. Fin. 2,4)” (Gaffiot, Ambigo). To refer to the issue, the point upon which the partners disagree, Cicero uses the expression “illud ipsum de quo ambiguebatur”, “precisely that – about which – [they] dissent” (ibid.). Ambiguitas means “doubt”; the answers given by the Oracles were ambiguous in this sense.
    The word amphiboly is sometimes used in the discussion of the Aristotelian fallacies of ambiguity. It adapts a Greek word [amphibology] composed of amphi “on both sides”; bolos “throwing on all sides”; logos, “word”, and means “having a double meaning, equivocal”. Literally, an amphiboly is an “explosion of meaning”.

The word ambiguity may be used to refer to three fallacies “dependent on language”, homonymy, amphiboly, accent. These fallacies are defined as violations of the rule of syllogism or of dialectical reasoning, which require that language be univocal, S. Dialectic; Fallacies (2): Aristotle foundational list.

Issues of ambiguity arise at the word level (homonymy, accent), at the sentence level (syntactic ambiguity), or at the level of discourse. Such issues combine with the fact that non-ambiguous sentences may have several layers of signification, S. Presupposition; Words as Arguments.

1. Syntactic ambiguity

Sentence ambiguity, discussed by Aristotle from the perspective of a grammar of argumentation, is now seen as a syntactical issue. The famous Chomskyan ambiguous statement “flying planes can be dangerous” can be paraphrased as:

In some circumstances, flying planes is a dangerous activity
Planes are dangerous when they are flying.

These paraphrases are non-equivalent. The no less famous statement “the teacher says the principal is an ass” is syntactically ambiguous, it admits of two syntactic structures whose difference is marked by intonation or punctuation:

“The teacher”, says the principal, “is an ass”
The teacher says: “The principal is an ass”.

Ambiguity is sometimes a de-contextualization artifact, produced for the sake of grammatical or logical theory. In practice, the addition of a sufficient amount of left and right context suffices to clarify the intended meaning, as shown by the re-contextualization of the sentence “we saw her duck” (Wikipedia, Ambiguity), which is four times ambiguous when decontextualized:

we saw her duck swimming in the pool
we saw her duck to pick up something on the floor
we have no knife, so we saw her duck
she is a smart bridge player, we saw her duck

Serious ambiguity occurs when context does not disambiguate the sentence. The reduction of ambiguity to univocity is no less important for the interpretation of texts, sacred and others, than it is for logic, S. Interpretation. In De Doctrina Christiana, St Augustine specifies a rule to be applied when trying to interpret religious texts:

But when proper words make Scripture ambiguous, we must see in the first place that there is nothing wrong in our punctuation or pronunciation. Accordingly, if, when attention is given to the passage, it shall appear to be uncertain in what way it ought to be punctuated or pronounced, let the reader consult the rule of faith which he has gathered from the plainer passages of Scripture, and from the authority of the Church.
Augustine, [397] On Christian Doctrine, in Four Books, (our emphasis)[1]

The interpretive rule in the emphasized passage appeals to the consistency of the field of theological argument. It applies to the interpretation of the first verse of the first chapter of the St John Gospel. The issue is nothing less than the very concept of God. It must be shown that the correct “punctuation”, that is the correct reading of this verse, coincides with the orthodox conception of the Trinity, which affirms the divine identity and equality of the Father, the Son and the Holy Spirit. The reading which attributes a syntax of coordination to the utterance results in denying the identity of the Word, that is the Holy Spirit, with God; so, is must be considered heretical and rejected as such.

Now look at some examples. The heretical [punctuation], “In principio erat verbum, et verbum erat apud Deum, et Deus erat” “(In the beginning was the Word, and the Word was with God, and God was”); so as to make the next sentence run, “Verbum hoc erat in principio apud Deum” (“This word was in the beginning with God”), arises out of unwillingness to confess that the Word was God. But this must be rejected by the rule of faith, which, in reference to the equality of the Trinity, directs us to say: “et Deus erat verbum” (“and the Word was God”); and then to add: “hoc erat in principio apud Deum” (“the same was in the beginning with God”). (Id., Chap. II, 3)

It thus follows that, for Augustin, the orthodox punctuation and construction of the verse is:

In principio erat verbum, et Verbum erat apud Deum, et Deus erat Verbum. (Biblia Sacra…Parisiis, Letouzey et Ané, 1887).

This is a case of argumentative interpretation. The starting point is a sentence taken from the sacred text:

et verbum erat apud Deum et Deus erat
the Word was with God₁ and God₂ was

First reading, God₂ resumes (is co-referential with) God₁. This is a mere case of repetition, a kind of stylistic anaphora.

the Word was with God₁ and [God₁] was.

The following argued interpretation might be developed from this reading:

(i) Data: (1) B does exist — (2) A is with B.
(ii) Semantic rule:   if A is with B, then A is not B; that is,A and B are two different entities.
(iii) So, conclusion, by instantiation of the rule, The Word is not God.

To sum up, God exists, and He is unique (not Trinitarian). According to Augustine, this first interpretation is heretic.

Second reading, God₂ is co-referential with the Word:

the Word { [ was with God ] and [ was God ] }

Now, the Logos is God. This is the basis of the orthodox concept of the Trinity. The first reading is deemed fallacious, that is to say heretical. The alleged semantic rule (iii) is disposed of in the name of the mysterious nature of the Trinitarian link.

An interpretation is based upon a reading of the text; when necessary, this reading must itself be based upon a grammatical argument, the conclusion of which may or may not be decisive. Disambiguation is the founding operation for the vast and important domain of interpretive argumentation.

2. Word ambiguity: Homonymy, polysemy

Two words are homonymous when they have the same signifier (same spelling (homographs), same pronunciation (homophones) or both of these, yet have entirely different meanings. Homonymous words are listed as different entries in the dictionary:

Mine: “that which belongs to me.” (MW, Mine)
Mine: “a pit or excavation in the earth from which mineral substances are taken” (ibid.).

Polysemous words are semantic particularizations or acceptations of the same signifier within the same grammatical category. In the dictionary, they are listed under the same entry, and correspond to the first subdivision of meaning:

Mine, noun
1 a: a pit or excavation in the earth from which mineral substances are taken. b: an ore deposit.
2: a subterranean passage under an enemy position.
3: an encased explosive that is placed in the ground or in water and set to explode when disturbed.
4: a rich source of supply (id.)

When two different lines of derived words stem from the same root word, this word is in a process of splitting into two homonyms; this is the case of the three series derived from the word argument, S. To Argue, Argument.

2.1 Paralogism and sophism of homonymy

A syllogism is fallacious by homonymy when it articulates not three but four terms, one of the terms being taken in two different senses, S. Paralogism.

In the Euthydemus, Plato provides an example of sophisticated practice using a very special kind of homonymy. Euthydemus the sophist, the eponymous character of this dialogue, asks Clinias “who are the men who learn, the wise or the ignorant?” (Euth., 275d; p. 712). Poor Clinias blushes and answers that “the wise [are] the learners”; and six turns of speech later, he must agree that “it is the ignorant who learns” (Euth., 276a – b; p. 713). The young Clinias is quite stunned, and Euthydemus’ followers “broke into applause and laughter” (ibid.). Such sophisms are not intended to deceive their victims, but to destabilize their naive certainties about the language. By this salutary shock, the public becomes aware of the opacity and the proper form of language, S. Persuasion; Sophism. As Socrates later explains, “the same word is applied to opposite
 sorts of men, to both the man who knows and the man who does not” (id., 278a, p. 715).

Generally, the subject and object of a verb cannot be permuted; the situation where “A loves B” is different from the situation where “B loves A”. As to learn, to be the host of, to rent present this property:

to rent 1. pay someone for the use of (something, typically property, land, or a car). 2. (of an owner) allow someone to use (something) in return for payment.) (MW, Rent)

2.2 Homonymous and polysemous shifts

The plurivocity of words is blamed as a major source of confusion. Scientific language prohibits polysemy as well as homonymy, and calls for the use of univocal, well-defined terms stabilized in their meaning and syntax, in a given scientific field. Homonymy between a scientific term and a current word is harmless. In physics, the use of the word charm to refer to a particle, the charm quark creates no ambiguity.

In a reasoning using natural language, the meaning of terms is constructed and recomposed in the course of discourse, S. Object of discourse. The meaning of a word used by the same speaker may change from one stage of the argument to the following one. This results from a variety of mechanisms, such as the use of homonymous or closely similar words, or the use of a word in its literal and figurative senses in the same discourse. The discussion about the credit to be given to a person may, for example, subtly shift between setting the amount of a loan and trusting that person. In German, it seems that the economic discussion of financial debt remains linked to the discussion of moral fault, the same signifier, Schuld, having these two meanings. (Reverso, Schuld).

Homonymy and Polysemy may be re-adjusted by the operation of distinguo^@.

3. “Accent”: stress and paronomasia

In a language where word stress is linguistically relevant, shifting the stress from one syllable to another may change the meaning of the word, for example in Spanish (my underlining):

Hacía: stress on the second syllable, means “did”.
Hacia: stress on the first syllable, means “to”, preposition.

The words seem homonymous save for the accent (verbal and written), but are in reality two different words. Much like the fallacy of homonymy which shifts the meaning of a single signifier, the fallacy of accent also shifts the meaning of the word via a minimal but crucial supra-segmental change. This process occurs as though the difference between the signifiers is not considered salient enough to discriminate between the variations of meaning.

This is a special case of paronomasia (or annominatio), defined as a:

(Pseudo-) etymological play on the slightness of the phonetic change on the one hand and the interesting range of meaning which is created by means of the change on the other. The range of meaning can in such cases be raised to the level of paradox. (Lausberg [1960], §637)

Generally speaking, paronomasia creates a meaning generating cell, by contrasting or assimilating a word (signifier) W₀ with a minimally different word (signifier) W₁.

In dialogue, the paronomastic resumption of a term used by the opponent operates as a rectification, breaking the orientation of this discourse, S. Orientation Reversal, “this is not a crisis of conscience, this is a crisis of confidence”.

[1] Bk III, Chap. 2, 2. No pag. Quoted after https://www.ccel.org/ccel/augustine/doctrine.txt . (11-08-2017)

Agreements can be considered under four perspectives.

(1) In general, fully developed argumentative interactions are characterized by a preference for disagreement, which distinguishes them from consensual interactions, governed by a preference for agreement (Bilmes 1991), S. Politeness.

(2) The existence of “preliminary agreements” (Perelman, Olbrechts-Tyteca) in regard to both the organization of the discussion and the issues to be discussed, can be considered as a necessary condition for the fruitful conclusion of argumentation. In a dialectical exchange, previous specific agreements are imposed on the participants, as the rules of a game are imposed on the players. In a rhetorical address, the orator seeks a priori areas of agreement with the audience.
In civil life, argumentative encounters (courts, conciliation offices, parliaments, decisional meetings…) follow pre-established standard procedures upon which volens nolens, the participants must agree and comply with, whether they find them fair or not, S. Rules; Conditions of discussion.

(3) The production of an agreement can be regarded as the ideal purpose of argumentative interactions. In combination with (2), this makes argumentation a technique for transforming preliminary agreements into a final consensus. S. To persuade; Persuasion.

(4) The existence of a consensus can be exploited as an argument. In argumentations that justify a proposal by claiming that it is the subject of general consensus agreed on by everyone. The actual opponent to the claim appears therefore as an isolated eccentric individual, excluded from “our community”. His or her opinion is disqualified, and can be dismissed without taking the trouble to refute or even consider his or her arguments, S. Dismissal.

• • Lat. populus, “people”.

The label “populist speech” is both descriptive and evaluative. Such speech is stigmatized and is widely considered to be used to promote negative values, xenophobia and other irrational and brutal phobia; to call for action on the basis of non-controlled emotions and poor analysis as opposed to argued rational conclusions; and to make indiscriminate promises, suggesting that the proposed solutions are the only ones possible, easy to implement, that they will work miracles, and will have no negative consequences.

Populist discourse appeals to immediate satisfaction, and is opposed to the hardship discourse of perseverance and slow improvements: “If you vote for me, you will have to accept sacrifices. But, later, may be…”

“Populist” is the new label for ancient and modern “demagogues”, developing, for the sake of pure short-term electoral benefits, a discourse which they know is untenable.

1. Appealing to the beliefs of a group

The ad populum argument is sometimes defined as an argument derived from premises admitted by the audience, rather than from universal premises. Such an argument would therefore aim to achieve adherence rather than truth (Hamblin 1970, p. 41, Woods and Walton 1992, p. 211).

According to the Socratic criticism of assembly discourse as focusing on social persuasion when addressing the audience about their everyday affairs and worries, to the detriment of transcendental truth, all political speech would be inherently populist, S. Probable. In this sense, all rhetorical or dialectical arguments would be ad populum. The argument ad populum is then no different from the argumentation on the interests, beliefs and passions of the audience, abundantly referred to as ex concessis, ex datis, or ad auditores argument.

2. Appealing to emotion

“We can define the paralogism known as argumentum ad populum as an attempt to win the popular assent to a conclusion by arousing the emotion and enthusiasm of the masses” (Copi 1972, p. 29; quoted in Woods and Walton 1992, p. 213). The ad populum argument is negatively related to hatred and fanaticism, and not always positively to enthusiasm: it is caught in the general condemnation of passions, without taking into account the fact that on the one side, emotions may or may not be justified, and that, on the other side, good and bad arguments may be based on strong emotions, S. Emotion.

This definition corresponds to the designation ad captandum vulgus “playing to the gallery”, in other words, to theatrical oratory, not an exclusive characteristic of politicians. The orator becomes an actor. The criticism of ad populum joins the moral criticism of flattering discourse, and the critique of enthusiasm, conformism and group effects in general, as “bandwagon fallacies” and alignment with the majority crowd (ad numerum), S. Pathos; Emotions; Laughing; Consensus.

As in all cases of appeal to the passions, we might suspect substitution of the passions for the logos, hence a lack of relevance (Woods, Walton 1992, p. 215), S. Vicious circle..

3. Argumentative orientation of the word people

The word people can take two opposite argumentative orientations. The individualist, who believes that all virtue resides in the individual, may conclude, by application of the scheme of the opposite, that the crowd is inherently corrupt, and that all argumentation appealing to popular sentiment is therefore fallacious. The people are always the populace.

On the other hand, the adage vox populi vox dei, “the voice of the people, is the voice of God” gives the people a degree of infallibility. The popular corruption argument mirrors the ad superbiam fallacy, that is the accusation of pride (ad superbiam), a sin committed by people who consider themselves to be superior to an inherently corrupt people, S. Dismissal; Collections (2).

Boldly relying on an effect of composition backed by two analogies, Aristotle supports the superiority of the Many over the One:

According to our present practice assemblies meet, sit in judgment, deliberate, and decide, and their judgments all relate to individual cases. Now any member of the assembly, taken separately, is certainly inferior to the wise man. But the state is made up of many individuals. And as a feast to which all the guests contribute is better than a banquet furnished by a single man, so a multitude is a better judge of many things than any individual.

Again, the many are more incorruptible than the few; they are like the greater quantity of water, which is less easily corrupted than a little. The individual is liable to be overcome by anger or by some other passion, and then judgment is necessarily perverted; but it is hardly to be supposed that a great number of people would all get into a passion and go wrong at the same moment. (Aristotle, Politics, III, 15. Jowett, p. 99)

— Maybe “hardly to be supposed”, nonetheless historically well documented.

4. Populum and plebs: The people and the crowd

In republican Rome, the appeal to the people, provocatio ad populum, was a right of appeal (jus provocationis) in criminal trials, a basic human right of the defendant. As a last resort, an accused Roman citizen would be able to bring his case before the populus. The populus is the assembled people, constituted as a political-judicial body, in the comitia centuriata, the solemn assembly of the people, in which full citizens vote and make decisions. In these assemblies, the gods themselves speak via the voice of the people. The populus is therefore very distinct from the vulgus or the plebs as haphazard, unorganized wholes.

This right is linked to Republican institutions: “tradition claims that the provocatio ad populum was created by a law of the consul Publicola the same year the Republic was created” (Ellul [1961], 278). With the Empire, “the provocatio ad Cæsarem evicted the provocatio ad populum” (Foviaux 1986, p. 61), that is to say, that Caesar replaced the People.

• • Lat. incommodum, “inconvenience”.

Bossuet defines the argument ad incommodum as “the argument that brings about an inconvenience” ([1677], p. 131). This is a variant of the refutative use of the pragmatic argument, and can be considered as a kind of appeal to the absurd.

Bossuet illustrates this scheme via an example designed to prove the necessity of absolute political power and absolute religious power. He argues that the negation of these authoritarian postulates would have “pernicious” consequences, respectively “men would devour one another”, which is certainly not a desirable state, and “there would be as many religions as heads”, which is deemed undesirable by Bossuet:

If there were no political authority which one obeys without resistance, men would devour one another. And if there were no ecclesiastical authority to which individuals were obliged to submit their judgment, there would be as many religions as heads. Now, it is false that men should devour one another, and that there be as many religions as heads. Therefore, we must necessarily admit a political authority to which we obey without resistance, and an ecclesiastical authority to which individuals submit their judgment. ([1677], p. 131)

• • Lat. homo, “human being”.

1. Ad hominem as personal attack, ad personam

Today, ad hominem is commonly used to mean ad personam, but classical ad hominem argument is quite distinct from personal attack (or ad personam attack), which seeks to disqualify the person in order to get rid of the arguments.

2. Ad hominem as self-contradiction or inconsistency

The concept of the ad hominem strategy is to be found in Aristotle’s Rhetoric, topic n° 22:

Another line of argument is to refute your opponent’s case by noting any contrast or contradiction of dates, acts or words that it anywhere displays. (1400a15; RR p. 373).

Under that name, the ad hominem argument is defined by Locke as a discussion technique by which the speaker “[presses] a man with consequences drawn from his own principles or concessions. This is already known under the name of argumentum ad hominem”. ([1690], p. 411)

The term “principle” can be taken in the moral or intellectual sense of “first principles”. In both cases, the speaker rearticulates the system of beliefs and values ​​of the opponent, in order to identify a contradiction. Locke rejects this form of argument as fallacious, insofar as it is based on the specific belief structure of a person, without relevance for the discussion of the truth per se of the thesis under debate, “[it does not] follow that another man is in the right way, because he has shown me that I am in the wrong” (ibid.).

The ad hominem argument is of no force and plays no role as an alethic instrument, in the process of establishing truth, S. Collections (3):Modernity and tradition

In regard to this definition, Leibniz notes that:

The argument ad hominem has this effect, that it shows that one or the other assertion is false and that the opponent is deceived whatever way he takes it. ([1765], pp. 576-577)

He thus recognizes the merits of this form of argument in the context of a discussion, as an epistemic instrument, urging a reorganization of a system of knowledge.

Under Locke’s presentation, ad hominem argument bears on explicit propositions as put forward in a knowledge acquisition dialogue and is clearly deductive and propositional.

In general terms, ad hominem argumentation occurs in a dialogue when the speaker builds a discourse, referring not only to propositional beliefs but also to the behavior and actions of his or her opponent, in order to point out some contradiction. This has the effect of embarrassing the opponent and causing him or her to reconsider his or her speech, positions or actions.

Ad hominem argumentation typically results in the feeling of “embarrassment”, considered as a basic emotion by Ekman (1999, p. 55). The production of such an emotion is not an accidental by-product of ad hominem, but is built into it, as revealed by the verb “to press”, that is “to assail, harass; afflict, oppress”. “Embarrassment” is typically a cognitive-emotional feeling, as is the basic argumentative emotion, “doubt”. Nonetheless, ad hominem is not emotional in the same vein as personal abuse can be, S. Personal Attack.

3. Setting up the words against the words

We have a reply ad hominem in the following case:

Proponent: — P. I propose P

Opponent: — Before, you proposed entirely different things.

Issue: — Should the term of the presidential mandate, currently five years, be reduced to four years?

Proponent (former President): — I am for a reduction to four years.

Opponent: — But in an earlier statement, while you were president yourself, you yourself argued that five years were necessary for the proper functioning of our institutions. Please, clarify.

The quoted statement which opposes the present one may be drawned not only from what has been said by the opponent in the past, but also from what has been said by “his or her people”, that is to say, by members of the discursive community sharing the same argumentative orientations: people of the same party, religion, scientific trend, etc., that cannot be easily disavowed.

The ad hominem reply allows the speaker to intervene in a discourse in the third party’s mode, that is, without committing himself to the substance of the debate. He does not explicitly take on the role of an opponent, but speaks simply as a participant in good faith, seeking clarification.

In an accusatory context, the charge of narrative incoherence allows the accused to reject the accusatory narrative, S. Consistency.

Reactions to ad hominem refutation on what has been said before

The target of the ad hominem argument can choose to sacrifice the former position, to reject the contradiction, or to accept it.

(i) Sacrifice the former position:

— Circumstances have changed, we must follow our times.

— I have developed my system

— I have changed, only madmen never change their mind; do you prefer psychorigid people?

(ii) Use a direct rebuttal. The opponent elicits the contradiction: “you say both A and Z, which is inconsistent”; the force of this argument is derived from the quotation mechanism. The proponent did not necessarily say A or Z but something else, A’ or Z’, that the opponent paraphrases, rephrases or reinterprets as A or Z. The contradiction may therefore proceed from a reworking of the speech, S. Straw Man. It follows that the proponent can reply to the letter, and reject the key ad hominem phrase “you yourself admitted” in his or her second turn:

— You make me out to say what I have never said, you distort my words

In other cases, the precise relation between A and Z, that is, the nature and degree of the inconsistency, might be disputable, S. Denying; Opposites.

The ad hominem imputation can be directly dismissed on these two counts.

 (iii) Accept the contradiction. The ad hominem reply seeks an individual free from contradiction. By a classic maneuver in stasis theory, the recipient may choose to assume what he or she has been criticized for, thus making contradiction a system of thought, S. Stasis; Contradiction:

— I fully accept my inconsistencies. I love rain and good weather.

4. Setting up the beliefs of the speaker against their words

In the preceding case, there was direct opposition between a present claim and an earlier assertion. Consider the issue of the withdrawal of troops sent to intervene in Syldavia:

Q:    —Should we withdraw our forces from Syldavia?

S1:    — Yes!

Let us suppose however that S1 has been led to admit A, B, and C; or, at least that S2 speaks as if he sincerely believed that S1 supports these propositions:

S2: — But you said yourself that (A) the Syldavian troops are poorly trained, and (B) that the political unrest in Syldavia is likely to extend to the whole region, there is a real contagion risk. You will agree that such an extension would threaten our own security (C); and no one denies that we must intervene if our security is threatened. So you have to admit that we have to stay in Syldavia.

S1 therefore claims that P; S2 argues ex datis, that is, on the basis of beliefs held by S1 (or attributed to him), and concludes not-P. This is the case considered by Locke. Must S1 admit that he or she has made an error, and that we should not withdraw the troops? Obviously not; S2 simply showed by his objection that one cannot support both {A, B, C} and not-P.

Reactions to the ad hominem refutation on reconstructed beliefs

S1 can re-adjust and rearticulate all the key components of S2‘s discourse. He can argue that A, B, C are abusive reformulations of his beliefs, or that the full analysis of the Syldavian situation is much more complex than these three assertions.

If S1 accepts such a reconstruction of his speech and beliefs, then he or she must reform one or more of these propositions, rejecting for example the idea that the troubles in Syldavia can extend to the whole region. S1 is expected only to correct, clarify or explain more thoroughly why this system of beliefs {A, B, C} cannot be expanded into non-P. This is precisely the point the argument ad hominem is getting at. In this function, ad hominem replies are a powerful educational tool.

5. Setting up the prescriptions and practices of the speaker against their words

A contradiction can also be raised between, on the one hand, what I require from others, what I prescribe or forbid them, and, on the other hand, what I’m doing myself, the kind of example I set. There is some paradox in asking others not to smoke, while I smoke myself. In our culture, acts are considered “to speak louder than words”, and injunctions are systematically flouted if the speaker does not comply with them himself:

Doctor, heal thyself!

He’s not a good marriage counselor, he’s always arguing with his wife!

You claim to teach argumentation and you are unable to argue yourself!

You advocate for the rights of women and at home you never do the dishes.

Note that, in the last two arguments, the conjunction and coordinates two anti-oriented statements, and not, as is more commonly the case, two co-oriented statements, S. Orientation.

The ad hominem game can be played in several moves:

Question: Should hunting be prohibited?
S1:    — yes, hunters kill animals for pleasure!
S2:   — but you eat meat, don’t you?

L2‘s argumentation can be reconstructed as “We must prohibit, suppress hunting. Hunters kill for pleasure. That’s awful!”. The opponent constructs an ad hominem argument:

You say killing animals for pleasure is wrong. But you eat meat, which presupposes that animals are killed for you. You condemn the hunters and you support the butchers. There is a contradiction here.

In his follow up, S1 can retort that there is a decisive difference. The hunter kills for pleasure, the butcher by necessity; and S2 can refute this refutation by arguing that there is no need to eat meat, whereas it is quite necessary to have fun.

This last form of ad hominem corresponds to what Bossuet calls an a repugnantibus argument: “Your conduct does not suit your speech” ([1677], p.140).

The expression “circumstantial ad hominem” refers to cases in which the speaker the notices a contradiction between his or her opponent’s speech and his or her personal circumstances, material welfare, lifestyle or personal position. S. Circumstances.

Defense against such an accusation — The preacher of virtue, to whom one points out that his or her practices do not support his or her counsels, finds support in the Lockian analysis of ad hominem, declared inherently fallacious:

My personal circumstances have no bearing on the truth or moral validity of my preaching.

Such a person may add that he or she has a divided personality:

It is true, I am a sinner, but it is from the depths of darkness that one feels best the necessity of light

This is natural, the cobbler’s children go barefoot.

Nonetheless, this form of argumentation is feared by preachers, who are expected to preach preach not only by exempla but also by example.

The real impact of ad hominem argument is not on the truth of what is said, but on the right to say what is said. The next reply may be “What you say is probably true and right, but I do not want to hear it from you”, or “That’s true, but it’s not for you to say”.

6. Setting up facts against words

S. Irony

7. Argumentation upon the beliefs of the partner

Whereas ad hominem argument goes after possible inconsistencies in the discourse of the opponent, arguments built upon the beliefs of the opponent or of the audience are  a positive form of exploitation of the partner’s belief system, considered as a coherent whole, S. Ex datis; Ex concessis

Some argument schemes are designated by Latin labels, S. A/ab —; Ad —; Ex —. This entry lists the labels using the Latin preposition ad. In classical Latin, the preposition ad is constructed with the accusative and introduces a goal complement; the phrase “argument ad hominem” reads “argument addressing the person”.
According to Hamblin, the oldest scheme in this grouping is ad hominem, which appears in the Latin translations of Aristotle; this naming method was popularized by Locke ([1690]) and by Bentham ([1824]), and most of these terms seem to be nineteenth or twentieth century creations (Hamblin 1970, p. 41; p. 161-162).

1. A list of “ad + N” arguments

2. Characteristics of the “ad + N” family

2.1 A productive pattern

There are many more “ad +N” arguments than there are “a / ab + N” arguments. Only the “ad +N” construction is still productive; the pattern is popular and mocked (ad bananum argument).

2.2 Origin of the labels

Some of these names have been defined and used by Locke and Bentham, S. Collections (III).

Locke has defined the arguments:

ad hominem                      ad judicium
ad ignorantiam                   ad verecundiam

Bentham has defined the arguments:

2.3 Semantic subsets of “ad + N” arguments

These arguments refer to very different strategies. Nonetheless, some groupings can be proposed according to their semantic content.

(i) Arguments bound to affects, emotions, often via positive interest (rewards) or negative results (threats):

(ii) Arguments involving a subjective system of beliefs, not universal, questionable:

Categories (i) and (ii) list arguments often considered as misleading, insofar as they express the subjectivity of the speaker. In other words, they are related to the ethotic and pathemic components

(iii) Arguments dealing with the substance of the issue (contrasting with the subjective series (i) and (ii))

ad iudicium                      ad rem

1. The fallacy of accident

The fallacy of accident is the first on Aristotle’s list of fallacies independent of discourse, S. Fallacies (II): Aristotle’s foundational list.
The idea is that a valid syllogistic inference develops in the same category domain, for example, the class of animals:

Socrates is a man, man is a mammal, so Socrates is a mammal,

whereas the following fallacious inference develops from an accident:

Socrates is white, white is a color, so Socrates is a color.

The word accident is taken in its philosophical meaning, which contrasts accident with essence. A being is characterized by a set of essential features that determine its place in a scientific classification: its generic features express its genus and its specific difference indicates its species. Unlike “— is a mammal”, which is constantly true of all dogs, the truth of the accidental predicate “— is tired” is circumstantial, it may be true of a dog at a given time but become false as soon as the dog’s condition changes.

The fallacy of accident occurs when an accidental characteristic of a being is mistaken for an essential one. In a definition, the corresponding defect consists in defining a being by a feature which belongs to it only accidentally.
So for example, “— wanders off in the middle of the road” is a relevant definite description, allowing unambiguous reference to a dog, but not a defining feature of « dog”.

All the same, “— is a good time for having a nap” is not a defining feature of “afternoon”, S. Two-term Reasoning.

2. The ad accidens counter-argument

The charge of committing the fallacy of accident is possible only if the accuser can refer to a solid and stabilized categorization, corresponding to a set of essentialist definition, S. Definition (1). In ordinary speech,  the accusation of committing a fallacy of accident is just a counter-argument, which opens a stasis of definition and can itself be defeated.

The ethical value of a profession is evaluated on the basis of an examination of the moral worth of its values and practices. In a classical democratic regime, a politician can be honest or dishonest without ever ceasing to be a politician. Dishonesty is not a necessary condition for becoming a politician; it is an accidental feature; “he is an honest politician” is not an oxymoron, “he is a dishonest politician” is not tautologically true. For those sharing this vision of things and people, characterizing political activity as an intrinsically dishonest activity, is committing the fallacy of accident. The person blamed for committing the fallacy might retort that the argument is not based on any transcendental organization of things, but on an inductive generalization, from “a number of politicians we all know very well”; or on the actual structural condition of our political system.

The argument from the opposite, (or a contrario) argument plays with the essential vs. accidental character of the differences between two categories of beings, “boys can go out at night, so girls should not go out, well, you know, girls are different from boys”. It is refuted by demoting the difference from essential to accidental. The same strategy applies to the distinctions between the defining features of a fact, and its circumstantial, contextual characteristics.

Dissociated from the strict Aristotelian ontology, the “essence vs. accident” opposition corresponds to the distinction between central traits and peripheral traits, and, in everyday life, to the distinction between the important and the incidental.

Ultimately, in the absence of backing by an accepted ontology, the so-called fallacy of accident functions as a refutation arguing from the incidental nature of an element, and finally corresponds to a strategy of minimization of the disputed character.

Lat. abductio, “action of taking”, by an outwardly directed movement (see infra, meaning 2).

1. Abduction as inference from facts to hypothesis

The concept of abduction was introduced in modern philosophy by the philosopher Charles Sanders Peirce. According to Peirce, there are two kinds of inferences: deductive inference and abductive inference or abduction. Abduction starts from the observation of a fact “contrary to what we should expect” Peirce ([1958], § 202), that is to say, a fact that does not fit into an available explanatory system. Abduction is a kind of inference by which one proposes a hypothesis accounting for this fact.
This hypothesis is not the product of the application of a “discovery algorithm”, but the fruit of a creative process, “abduction is, after all, nothing but guessing” (Peirce [1958], § 219).

Abduction is not an issue in logic, but rather a scientific method (id., Chap. 6). Scientific work consists in proposing, on the basis of facts, plausible hypotheses “suggested” by these facts. Abduction is the first step in this process.
The practice of abduction is not guided by logical rules but by general principles, such as the principle of exclusion of so-called metaphysical hypotheses, that is to say, hypotheses which would have no experimental consequences, or the principle according to which every fact has an explanation: an abducted hypothesis is interesting “if it seems to make the world reasonable” (id., §202).

Unlike abduction, which starts from facts in search of theory, the Peircian deduction starts from a theory in search of facts; that is, it seeks to identify the crucial experimental consequences of a hypothesis.

Much more than a form of deduction or induction, argumentation should be seen as a form of abduction: because the light is on, “I abduct”, I make the hypothesis, that there is someone in the room; but this hypothesis still needs to be checked, S. Probable, Plausible, True.

Woods redefines abductions as “responses to ignorance-problems. An agent has an ignorance-problem in relation to an epistemic target that cannot be hit by the cognitive resources presently at his command, or within easy and timely reach of it” (Woods, 2009; Gabbay & Woods, 2005). The study of argument as an abductive process has proved especially fruitful in the fields of medicine, science and law (Walton 2004).

2. Abduction as reduction of uncertainty

In its Peircian sense, abduction is a kind of inference by which one arrives at a hypothesis accounting for this fact. Aristotle defines abduction as a kind of dialectical syllogism (Aristotle, PA, II, 25), whose major premise is true, the minor just probable, and, consequently, the conclusion also probable. The conclusion alone, without the minor, is more improbable than the minor. The minor therefore strengthens the relative acceptability of the conclusion. This situation recalls the Ciceronian definition of argumentation, S. Argumentation (I).

For example, if the question is: “can virtue be taught?” we can reason as follows:

A true premise: it is clear that science can be taught.
A doubtful premise: virtue is a science.
Conclusion: virtue can be taught.

Though uncertain, the veracity of the second premise is still less in doubt than the conclusion “virtue can be taught”. This second premise may therefore serve as an argument for the conclusion. We find this montage in speeches such as:

Citizenship can be taught.
Citizenship is essentially a set of social knowledge and practices.
Knowledge is being taught and all practical skills can be improved by teaching. So, citizenship can be taught.

Argument functions “for want of better”. Reduction of uncertainty serves to modify relevantly the epistemic status of a belief. This is a logic not of elimination but of reduction of doubt and uncertainty, S. Default reasoning.

Lat. exemplum, “example”.

In law, the label ab exemplo refers to an argument that interprets the law according to:

1. A previous case, S. Precedent.
2. A traditional interpretation, “the doctrine generally accepted” (Tarello, quoted in Perelman 1979, p. 59).

The argument ab exemplo is therefore distinct from the argument from example.

Some argument schemes are designated by Latin labels, S. Ab —; Ad —; Ex —. This entry lists the labels using the Latin preposition a / ab.

The same Latin preposition has two forms, a or ab: in general, a is used before a noun beginning with a consonant (a contrario argument), and ab before a noun beginning with a vowel (ab auctoritate argument).

1. The construction

In classical Latin, the a / ab preposition means “separation; away from” and governs the ablative case. Grammatically, ab / a introduces only a circumstantial clause of a verb, indicating the origin. This means that the Latin construction “argumentum ab + N” is to be interpreted as elliptical for “argumentum [ducetur, “drawn”] ab [“from”] N”. Latin texts regularly use expressions of this type, Cicero for example, wrote in the Topics:

cum autem a genere ducetur argumentum (my emphasis) (IX, 39; p. 411);

that is “when, however, an argument is drawn from genus”. Genere is the ablative case of the noun genus; the construction is “argumentum [ducetur] a genere”, “argument [provided by, taken] [from] the genus”. Similarly, the rhetoric Ad Herennius suggests that, in order to amplify the charge, the orator has to look first for an argument drawn from authority:

primus locus ab auctoritate sumitur (my emphasis) (Ad Her., II, 48; p. 147);

that is “the first commonplace [primus locus] is taken [sumitur] from [ab] authority [auctoritate]”. Auctoritate is the ablative case of auctoritas, “authority”. Locus means literally “place”, and is taken here metaphorically as “inferential commonplace” or “argument scheme”, S. Topos, Topic Commonplace.

2. List of the “ab (a) + N” arguments

The set of “ab / a + N” arguments belongs to the original stock of Latin argument labels; its core is drawn from the Ciceronian typology, passed on to the Middle Ages by Boethius, up to modern times S. Collections (2).

In stark contrast to the list of “ad + N” arguments (S. Ad — Arguments), the following list contains no label referring to feelings or subjective beliefs.

Table
First column: Latin name of the argument
Second column:

• Meaning of the word(s) (based on Gaffiot).
• (When necessary a word-for-word translation)
• Reference for the corresponding entry

The a / ab arguments constitute the original stock of arguments whose core is taken from Cicero’s typology, S. Collection (2). From Aristotle to Boethius

As opposed to the ad  arguments, we notice that these labels never refer to emotions or subjective beliefs.

The ad  arguments are clearly arguments and not fallacies. In other words, when using the label “ad + N” argument we take the perspective of the proponent, who produces and puts forward the argument, not from the perspective of the opponent whom the argument will impact and who will reject it.