DISTINGUO

The Latin term distinguo,  is the first-person singular present indicative of the Latin verb distinguere, which means “to separate; to distinguish”. By extension, distinguo can also mean « to make a subtle, hence sophistical distinction. »
Distinguo is a an argumentative technique used to clarify the meaning of a term. In an argumentative situation, distinguo is used to prevent misinterpretation and objection by opponents.
The term  distinguo is also used as a synonym for paradiastole, see orientation reversal.

1. Distinguo as an Analytical Tool

In contemporary usage, to make a distinguo is to make a distinction between the different meanings covered by  a complex or ambiguous notion

(1) The system of ‘territorial development’ is based on the interaction between its two components: the local economic system and the so-called ‘territorial’ system.
The distinguo between these two systems stems from the opposing logics underlying them. The economic system obeys principles that are recognized and explained in economics. The territorial system, for its part, encompasses all human, social, economic and urban functions of a place.
Loinger & J.-C. Nemery, [Recomposition and Development of Territories], 1998.[1]

2. Distinguo as a First Step to Refuting an Argument

A distinguo is an instrument used to reduce ambiguity, it conveys the caveat, “Be careful not to mix everything up!”. A distinguo is justified when based on distinctions that are socially recognized and independently established in a dictionary or an encyclopedia.
For example, it can be used to detect a four-term paralogism , or a shift in the meaning of a term in a reasoning, such as eliminate the confusion created by using the word metal to refer to a chemically simple body and to an alloy.

A distinguo can be used to correct an opponent’s discourse,  for example to reestablish a blurred distinction (Mackenzie 1988). Making a distinguo is saying, “I see some truth and some errors in your speech, and I’m going to clarify the situation.”
Consider the following theological syllogism (after Chenique, 1975, p. 9):

(1) Every man is a sinner.
(2) No sinner will enter heaven.
(3) No man will enter heaven.

The opponent says:

• • I agree with premise (1), “every man is a sinner. »
  • In premise (2), “No sinner shall enter Heaven”, distinguo, I distinguish two different statements:

(2a) “(No sinner) as a sinner shall enter Heaven”, I agree: “No man in a state of sin will enter Heaven.”
(2b) “(No sinner) as a forgiven sinner shall enter Heaven”: I deny this proposition.
The distinguo does not relate to the meaning of the word sinner, but rather to two categories of sinners.

• • Therefore, I reject your conclusion.

The opponent objects that the syllogism is fallacious, because the minor is true in one sense, and false in the other.
This is not a case of a four-terms syllogism that is fallacious by homonymy, see paralogism. Sinner is not ambiguous by homonymy, but because, it can be construed in two different ways in a theological context.

The distinguo is a figure traditionally dismissed as being “scholastic”, and used to draw spurious oppositions. Thomas Diafoirus courts Angélique, who hates him.

Angélique: — But the greatest mark of love is to submit to the will of the one you love.
Thomas Diafoirus: — Distinguo, madam. I concede [concedo] In what does not have to do with possessing her, concedo; but in what does have to do with it, I negate [nego].
Molière, [The Imaginary Invalid], [1673][2]

Thomas Diafoirus is pedantic and brutal. He claims his right to possess Angélique, against her will. Apart from this, however, he is ready to submit to her will. The distinction is equivalent to « I agree except when I disagree.”
A distinguo prevents or rectifies ambiguities, but when it introduces distinctions into a perfectly clear expression, it can itself cause confusion itself.

In these cases, the distinguo may or may not be accepted depending on the value of the distinction made. In the case of the sinner, the distinction might be justified by the parallel case of the criminal. A criminal who has served his sentence cannot be called a criminal without qualification, one cannot say, “He is a criminal, let’s call the police!”. A distinction is clearly necessary.
However, in the case of Angélique, the distinction is arbitrary and ad hoc. It can be countered with a third round of speech such as, « Stop it now! Enough with your scholastic distinguos!« , « Stop quibbling please, you are obnoxious! »

3. Distinguo and Dissociation

According to Perelman, the dissociation technique is, “hardly mentioned by traditional rhetoric, for it is especially important for the analysis of systematic philosophical thought as systematic.” (1977, p. 139). For example Kant believed that natural sciences postulate a universal determinism while morality postulates the liberty of the individual. Thus, the term reality, a confused notion, is  dissociated, into a phenomenal reality, where determinism reigns, and a noumenal reality where individuals can freely choose and act on their decision.
According to Kant (not to Marx) these two types of reality are in a complementary oppositional. relationship.

Rhetorical distinguo nullifies one of the opposed domains, which is not the case of dissociation.

Ancient rhetoric has the concept of distinguo. The distinguo is an operation of clarification carried out on a concept considered as possibly « confusing ». To clarify the concept, the distinguo performs a kind of content analysis to rearrange the semantic and cognitive contents of the word in different subdomains, for example to clearly define the position of the subject of an investigation, as in example (1), (§1 supra)
Such an operation is the basic task of the lexicographer when she decides whether the signifier to be defined has only one meaning, or several related meanings (polysemy), or several unrelated meanings (homonymy). At this point, the operation does not involve any special treatment or evaluation of the relatively independent semantic or cognitive subdomains.
Dissociation goes one steps further by deciding that one of these components is to be evaluated positively, the other negatively and considered negligible for the discussion of the other component.

[1] Loinger G. & Nemery J.-C.. Recomposition et Développement des Territoires, Paris: L’Harmattan, 1998. P. 126.
[2] Molière, Le Malade imaginaire [1673], act II, scene 6. Quoted after Ch. Franks, D. Lettau, http://www.gutenberg.org/files/9070/9070-h/9070-h.htm (11-08-2017)