Logic — Conclusions
The doctrine of Glenn's Dialectics set out as numbered theses, following the three mental operations, with the syllogistic laws given in his own verse.
Tract: Dialectics · Paul J. Glenn · 1929 · 18 articles in three Books, plus an appendix on the reduction of syllogisms School: Thomist Supports: every other tract. Paired with: Epistemology — Dialectics treats correctness of inference, Criteriology treats truth of content; neither is complete without the other.
What this tract is for
Dialectics is the practical science of correct thinking — not of true thinking, which belongs to Criteriology. Its formal object is correctness or legitimacy of inference; its material object is the three operations of the mind: simple apprehension, judgment, and reasoning. Glenn’s image for the division of labour is the miller, who must master his machinery before he can judge the grain that goes into it.
A cheatsheet fits this tract oddly, and it is worth saying why. Logic is not a set of conclusions but a set of tools. Most of what follows is definition, classification and rule rather than thesis. The theses below are therefore closer to a structured index than to the demonstrated propositions of Ontology or Theodicy — which is the honest shape of the material, not a failure of the format.
The architecture
The three Books follow the three operations of the mind, and each Book runs the same three-step pattern: the operation itself, the operation expressed in language, and the operation put to use.
- Book I — The Idea. The idea itself; the idea expressed (the term); the idea explained (definition and division).
- Book II — The Judgment. The judgment itself; the judgment expressed (the proposition), with its classification and relative properties.
- Book III — Reasoning. Reasoning itself; reasoning expressed (the syllogism, its laws, figures and moods, and imperfect forms); then the fallacies to avoid.
Nothing later is intelligible without the earlier: comprehension and extension (Th. 4) govern definition and division; distribution of terms governs the syllogistic laws; and the whole of Book III presupposes the four propositional forms of Book II.
Book I — The Idea
1. An idea is the mind’s grasp of an essence — of what makes a thing the kind of thing it is — abstracted from the individuating notes in which it is accidentally clothed. → B1 C1 A1 — Description and Definition of the Idea
2. The idea is formed by simple apprehension, involving sensation followed by the intellectual acts of attention, abstraction, comparison, reflection, analysis and synthesis. → B1 C1 A1
3. There are three grades of abstraction, and correspondingly three grades of ideas. (This is the division that grounds the classification of the sciences — physical, mathematical, metaphysical — used throughout the series.) → B1 C1 A1
4. Comprehension and extension stand in inverse ratio. The essential notes of an idea are also called its metaphysical grades. This single relation is the most-used tool in the tract: definition analyses comprehension, logical division analyses extension, and the distribution of terms in the syllogism depends on extension. → B1 C1 A1
5. Ideas classify on five bases: by origin (intuitive, derivative); by perfection (clear or obscure; distinct or vague; complete or incomplete); by comprehension (simple or compound; concrete or abstract); by extension (singular, universal, particular, transcendental); by relations (identical, formally or materially, or different — and among different ideas, associable or opposed, by contrariety, contradiction, relation, or privation). → B1 C1 A2 — Classification of the Idea
6. The Universal is viewed in two aspects, reflex and direct. The Reflex Universal is predicated of its inferiors in five ways — as Genus, Species, Specific Difference, Property or Attribute, and Accident — and these modes of predication are the Predicables or Categoremata. → B1 C1 A3 — The Universal Idea
7. The Direct Universal yields the classification of things as they are in nature: the mind grasps objective reality either as substance or as one of the nine accidents. These ten classifications are the Predicamentals or Categories. (Predicables are modes of predication; Predicamentals are classes of reality. Conflating them is the standard error, and Glenn separates them by placing them in opposite halves of one article.) → B1 C1 A3
8. A term is the sign of an idea — and of the reality the idea represents. Signs divide as formal and instrumental, the latter into natural and arbitrary; terms as oral, gesticular and written. → B1 C2 A1 — Definition and Classification of the Term
9. By exactness of signification, terms are univocal, equivocal, or analogous — analogy dividing into analogy of proportion and analogy of attribution. Further classifications: positive, negative, privative; simple, complex; concrete, abstract; singular, universal, indefinite, particular, collective — singular terms being proper or common. → B1 C2 A1
10. A term’s general meaning must be distinguished from its supposition — its use in a particular instance. Supposition is material (the term standing for itself as a word) or formal, and formal supposition is logical or real; real supposition of collective terms is collective or distributive. → B1 C2 A2 — The Use of the Term
11. Appellation is the application of terms to terms, and is material or formal. → B1 C2 A2
12. Definition is nominal or real. Nominal definition explains only the sense of a term; real definition divides into essential definition and description. Four Rules of Definition govern the practice. → B1 C3 A1 — Definition
13. Logical Division analyses extension, as definition analyses comprehension. It is contrasted with Real Division, physical and metaphysical. Every division has three elements — the totality divided, the principle of division, and the dividing members — and rules must be observed for it to serve its purpose of clarifying ideas. → B1 C3 A2 — Logical Division
Book II — The Judgment
14. Judgment is the mind’s comparison of two ideas and its pronouncement of their agreement or disagreement in comprehension. Agreement enunciated makes the judgment affirmative; disagreement, negative. Three elements enter: the two ideas, their comparison, and the mind’s pronouncement. → B2 C1 — The Judgment Itself
15. A proposition is a judgment expressed in terms. Its elements are subject, predicate and copula — subject and predicate being the material element, the copula the formal element. The copula is always the present indicative of to be, and propositions using other verbs and tenses reduce to that form. → B2 C2 A1 — Definition of the Proposition
16. In quantity and quality, propositions take four forms: A universal affirmative, E universal negative, I particular affirmative, O particular negative. → B2 C2 A2 — Classification of the Proposition
17. In an affirmative proposition the predicate is undistributed; in a negative proposition it is distributed. This is the rule the whole syllogistic apparatus rests on — the fourth Law of Terms and every figure-law depend on it. → B2 C2 A2
18. In structure, propositions are simple or compound. Compound propositions are modal (necessary, contingent, possible, impossible); categorical — either obviously compounded (copulative, adversative, relative, causal) or not obviously compounded (exclusive, exceptive, comparative, reduplicative); hypothetical (connective, conjunctive, disjunctive); complex; and multiple. → B2 C2 A2
19. Opposition, Equipollence and Conversion are properties of propositions and processes of immediate inference. They let the dialectician see the faulty and illogical character of statements unwarrantedly made in virtue of other statements. Opposition covers contradiction, contrariety, subcontrariety and subalternation. → B2 C2 A3 — Relative Properties of Propositions
Book III — Reasoning
20. Reasoning is mediate inference: when two ideas are too obscure to compare directly, the mind uses a third, middle idea already known to stand in relation to both, and works out the judgment indirectly. It may be defined by its ideas or by its judgments — inferring a conclusion explicitly from two premisses in which it was implicitly contained. → B3 C1 — Reasoning Itself
21. There are two methods of reasoning: induction and deduction. → B3 C1
22. The syllogism is the most perfect form of argumentation — argumentation being the expression in speech of the reasoning process. → B3 C2 A1 — The Syllogism and its Kinds
23. Correctness and truth are distinct, and Dialectics aims only at correctness. A syllogism is correct when the conclusion follows necessarily from the premisses, whatever their truth. Glenn nevertheless supplies basic principles for judging the truth of correct syllogisms. → B3 C2 A1
24. Syllogisms divide as categorical and hypothetical. → B3 C2 A1
25. Eight general laws govern the categorical syllogism, in two groups. Glenn gives them in verse, and they are worth having in his words:
Laws of Terms Three terms there must be, neither more nor less, No wider in Conclusion than in Premiss; Conclusion never dares the Middle mention; The Middle, once or twice, has full Extension.
Laws of Propositions Affirmatives can never breed negation; Two negatives end ever in frustration; Conclusion follows e’er the weaker part; Particulars no argument can start.
Glenn calls these Laws of Thought and insists no single law be accepted on faith — the student is to master the reason for each. → B3 C2 A2 — Laws of the Syllogism
26. Separate laws govern the hypothetical syllogism. → B3 C2 A2
27. The Figure of a syllogism is fixed by the position of the middle term in the premisses, and each figure carries its own derived laws — derivations from the eight general laws. → B3 C2 A3 — Figures and Moods of the Syllogism
28. The valid Moods are sifted out of the sixty-four possible arrangements of the premisses with respect to quality and quantity, and each figure is assigned the moods that may validly occur in it. The Fourth Figure is negligible. → B3 C2 A3
29. Five imperfect syllogisms are to be constructed and criticised: the Enthymeme, the Epichirema, the Polysyllogism, the Sorites, and the Dilemma — together with argument from analogy and from hypothesis. → B3 C2 A4 — Imperfect Syllogisms
30. Five fallacies are treated in order: Equivocation (four terms disguised as three, offending against the First Law); Composition and Division; Evading the Point; Begging the Question; and False Cause — post hoc, ergo propter hoc, illustrated by the pagans, and Gibbon, attributing the fall of the Roman Empire to the rise of Christianity. Glenn names four further self-explanatory fallacies: False Analogy, Defective Induction, Incomplete Enumeration, False Assumption. → B3 C3 — Fallacies to Avoid
31. Equivocation and Evading the Point are the two most common and most powerful enemies of correct thinking. Glenn singles them out in the chapter summary. His practical guidance on equivocation is unusually pointed for a manual: never use vague terminology, and never allow an opponent to get away with a vague argument — make him define his terms. He gives a list of the offending words of his day: democracy, brotherhood, humanitarianism, materialism, optimism, pessimism, prosperity, progress, education, dogmatism, higher planes, contacts, values, higher life, broader vision. → B3 C3
32. To reduce a syllogism is to restate it in the First Figure, whose four moods are Barbara, Celarent, Darii and Ferio. The classical mnemonic names encode the method: the initial letter indicates which First-Figure mood the reduction targets, and internal consonants specify how to perform it. → Appendix — On the Reduction of Syllogisms
Key terms
— Dialectics · logic as the science of correct thinking
— comprehension / extension · the notes an idea contains / the things it applies to
— Predicables · the five modes of predication
— Predicamentals (Categories) · the ten classes of real being
— supposition · the meaning a term bears in a given use
— appellation · the application of terms to terms
— distribution · a term taken in its full extension
— A, E, I, O · the four propositional forms
— Figure / Mood · the position of the middle term / the arrangement by quantity and quality
— reduction · restatement of a syllogism in the First Figure
Reading it properly
B3 C2 A2 (the laws) is the article the tract exists for, and the verse is worth memorising — everything in the figures, moods and fallacies articles is an application of it. Before that, B2 C2 A2 for the distribution rule in Th. 17, without which the fourth Law of Terms cannot be understood.
The one article that repays reading for its own sake rather than as reference is B3 C3 on fallacies: Glenn is writing about the public argument of 1929, and his list of vague words that let bad arguments pass has aged into something closer to social commentary than logic.