4. Dialectics, the first part of Logic, has reasoning for its object, and treats: 1. of Simple Apprehension; 2. of Judgment; 3. of Reasoning. -- Reasoning is a complex operation, whose elements are judgment and simple apprehension. Every reasoning supposes several judgments, and every judgment supposes the apprehension of two ideas. Hence, before considering reasoning in itself, we must treat of judgment and simple apprehension.
ART. I. -- NATURE OF SIMPLE APPREHENSION.
5. Simple Apprehension is that first operation of the intellect by which it seizes or perceives an object without any affirmation or negation concerning it. -- The first act of the mind is a simple view by which it apprehends objects presented to it, without affirming or denying anything of them. The result of this operation is an ideal reproduction of the object perceived; this reproduction is called a mental term, concept, notion, or idea. If the mental term is expressed orally, it is called an oral term or word.
ART. II. -- IDEAS AND ORAL TERMS.
6. An idea is a mere intellectual representation of an object, by which that object is known. -- The human intellect is not necessitated by its nature to know any one determinate object. Now, since it is indifferent in this respect, it must, when it actually knows an object, be determined to know by that object. But this object can determine the intellect to know only by being united to it in some way. The intellect, evidently, cannot go out of itself to effect this union, nor can the object in its physical reality enter the intellect. The union of object and intellect, therefore, must be effected by a species, form, or likeness of the object. It is this medium of union, and therefore of knowledge, that we call an idea.{1} It must be carefully distinguished from the sensible image or phantasm, which is proper to sense only, and is therefore material; whereas the idea is spiritual and proper to intellect, and represents not the sensible qualities of an individual object, but its nature as one of a class of objects.
7. An oral term is a conventional word which expresses an idea. -- Unlike the idea or mental term, which from its very nature represents the object, the oral term has a meaning only in virtue of the usage and agreement of men. It directly expresses the idea, and through this the object itself; but habit leads us usually to unite the idea of the word with the idea of the thing.
ART. III. -- DIVI5ION OF TERMS.
8. Ideas are concrete or abstract, clear or obscure, distinct or confused, complete or incomplete. -- Considered with reference to the manner in which the object is presented to the intellect, an idea is concrete when the object is apprehended in its physical reality with all its belongings; as the idea of a "learned man" or a "marble statue." It is abstract when the object is apprehended apart from its real existence or its physical connections; as the idea of "learning" or of "whiteness."
In respect to the degree of perfection with which the object is apprehended, an idea is clear or obscure according as the object perceived through it can or cannot be distinguished from other objects. The idea we have of a "brother" or "sister," or of "virtue," v.g., is clear.
An idea is distinct or confused according as it does or does not exhibit the marks by which the object is distinguished from other objects; the idea of "virtue," v.g., is distinct when by it we know not only that virtue is an acquired habit, but also that it inclines the will to act rightly.
An idea is complete and adequate or incomplete and inadequate according as all or only some of the constituent elements of the object are known; the idea of "man" as a rational animal is complete.
9. An oral term is significant or insignificant, fixed or vague, univocal or equivocal, analogous by attribution or analogous by proportion. -- An oral term is significant if it means something, as "man;" it is insignificant if it has no meaning, as "tervoc."
An oral term is fixed if it has a settled meaning, as "God;" it is vague if its meaning varies at the will of him who uses it, as "Nature," which sometimes means the visible universe, sometimes the essence of a thing, etc.
An oral term is univocal when it has but one meaning for the several objects to which it is applied, as "man," which signifies the same thing when applied to Peter and to Paul; it is equivocal when its meaning varies for each of several things, as "dog," when applied to a star and an animal. An oral term is analogous, if it signifies several things which are not of the same nature, but have some similitude, as "foot," which is applied to a part of the animal body and to the base of a mountain. A term is analogous by analogy of attribution when it denotes one thing primarily and intrinsically, and applies to others only on account of the relation which they have to the first, either extrinsically, as when "healthy" is predicated of food and of the animal organism; or intrinsically, as when "being" is predicated of God and creatures, of substance and accident. A term is analogous by proportion when it is applied to several things which differ in reality, but which bear a certain proportion to one another; as "principle," which has a proportionate resemblance when applied to source, heart, and point.
10. Mental and oral terms are significant by themselves or with another term, positive or negative, concrete or abstract, real or logical, absolute or connotative, incomplex or complex, transcendental or predicamental, connexed or disparate, predicable or subjective, antecedent or consequent, collective or distributive, singular or universal. -- A term, whether mental or oral, is significant by itself when by itself it has a meaning, and therefore may be the entire subject or attribute of a proposition, as "hero;" it is significant with another when by itself it has no meaning, and therefore cannot alone be subject or attribute of a proposition, as "some."
A term is positive when it signifies some entity, as "light;" it is negative when it denotes the absence of some entity, as "blindness."
A term is concrete when it denotes a thing with its belongings as it really exists, as "Peter;" it is abstract when it denotes a thing viewed apart from the subject to which it belongs, and from which it has no separate existence, as "whiteness."
A term is real when it signifies something having existence outside the intellect, as "God;" it is logical when it signifies a thing which has no existence except what intellect gives it, as "species," "genus."
A term is absolute or substantive when it denotes a thing as existing in itself, whether the thing be really substance, as "man," or accident, as "prudence;" it is connotative or adjective when it denotes something accessory to another, whether the thing be accident, as "good," or substance, as "philosopher."
A term is incomplex when it denotes one thing by a single sign, as "angel;" it is complex when it denotes several realities or consists of several words, as "poet," which denotes the man and his art; "Julius Caesar," which consists of two words; the "Emperor Charlemagne," which is complex in word and in reality, for it embraces two words and two realities.
A term is transcendental when it signifies something applicable to all things, as "being," "something," "one," "true," "good;" it is predicamental when it signifies something which applies only to certain beings, as "brute." Terms are connexed when one includes or excludes the other, as "man and animal," "white and black;" they are disparate when they have no relation of exclusion or subordination, as "white and learned."
A term is predicable when it can be affirmed of another; it is subjective when another can be affirmed of it; thus, in the proposition, "God is just," God is subject and just predicate.
An antecedent term is that which another follows, as "man" in respect to animal; a consequent term is that which follows another, as "animal" in respect to man. If terms are deduced from each other, they are called reciprocal, as "man and rational."
A term is collective when it denotes several things taken conjointly, as "people," "nation;" it is distributive when it denotes several things in such a manner that it may be applied to each in particular, as "man."
A term is singular when it signifies one thing determinately, as "Aristotle;" it is universal when it applies to several things univocally and distributively, as "animal." In treating of universal terms, we may consider: 1. Universal terms in themselves, and the five Species into which they are divided; 2. The division of universal terms into different Supreme Genera, called Categories.
ART. IV. -- UNIVERSALS.
11. Universals are terms which are applied univocally and distributively to many things. -- When the intellect perceives the essence of an object abstracted from the individual characteristics of that object, it may consider the mental term representing the essence as applicable to every being which has the common essence; the term is then called universal, as "man." Its opposite is the singular term, which is applicable to one determinate thing only, as "Socrates." A particular term is a universal affected by the sign of particularity, which limits it to a part of what the term denotes, as "some men."
12. Universal terms have two properties: comprehension and extension, which are in inverse ratio to each other. -- The essence represented by a universal term is made up of one or of many elements; thus, the essence of man consists of "animality and rationality;" the comprehension or intension of a universal term is the sum of the elements which it contains. The essence represented by a universal term is found in a greater or less number of subjects; thus, the essence of man is found in every man; the extension of a universal term is the number of beings to which it applies. The greater the comprehension of a term, the less its extension, and vice versa.
13. There are five modes according to which a universal term may be applied to individuals of like nature; there are, therefore, five classes of universals, viz., genus, species, difference, property, and accident. These universals are also called predicables. -- A universal term expresses either the essence of a thing or something added to the essence, In the former case, it expresses either the whole essence or only a part of it. If it denotes the whole essence, it is a species, and the beings to which it is applied are called individuals, as "man."
If the universal denotes only a part of the essence, it denotes either the part common to other species, or the part by which the essence differs from them: in the first ease it is called genus, and in the second specific difference; thus, "animal" expresses what is common to both man and brute, and "rational" expresses the specific difference which distinguishes man from brute. If the universal denotes what is added to the essence, either this attribute cannot be separated from the essence, but is a necessary attendant of it, so that it is always found in the whole species and in that species only, in which case it is a property; or it can be separated without changing the essence, and then it is an accident; thus, "free will" is a property, "learning" is an accident of man. Genus, species, and difference are divided into highest, intermediates and lowest or proximate, as may be seen in the following diagram.
Substance / \ Corporeal Incorporeal \ Body / \ Organic Inorganic \ Living / \ Sentient Non-sentient \ Animal / \ Rational Irrational \ Man
ART. V. -- PREDICAMENTS OR CATEGORIES.
14. Predicaments or categories are the highest genera in which all real entities are classified; or, they are the highest genera of all things. -- When the intellect examines an object, it seeks what attributes or predicates it can affirm or deny of that object. These predicates all have their place under the predicables. But all the different objects which the intellect can know, have been arranged in logic under certain supreme genera these genera are called predicaments or categories.
15. There are ten predicaments or categories: substance, quantity, relation, quality, action, passion, time, place, posture, habiliment. -- Every being exists either in itself or in another. If it exists in itself, it is called substance; if it exists in another as its subject, it is called accident. Accident is divided into nine genera; for, if we wish to know the accidents of a substance, Pope Leo XIII., for instance, we may put the following questions: 1. How large a man is he? the answer to which gives quantity; 2. Whose father or son is he? which implies relation; 3. What are his qualifications? quality; 4. What does he do? action; 5. What does he suffer? passion; 6. In what age does he live? time; 7. Where is he? place; 8. Is he sitting or standing? posture; 9. How is he clad? habit or habiliment.
16. Comparing with one another the things arranged under the predicaments, we may consider their opposition, priority, simultaneity, motion, and mode of having; these are called post-predicaments. -- Opposition is the repugnance of one thing to another. It may be in four ways: as Contrary, when the two things, falling under a common genus, are mutually incompatible in the same subject, as "heat and cold" under the genus temperature; as Relative, when the repugnance arises from a mutual relation, as "father and son;" as Privative, when the repugnance arises between a thing and its privation, as "sight and blindness;" as Contradictory, when the repugnance is between being and not-being, as "man and not-man."
Priority is that by which one thing precedes another. It is of five kinds: 1. Priority of duration, as "an old man is prior in existence to a youth;" 2. Of consequence, as "man precedes rational;" 3. Of order, as in the study of language "grammar precedes literature;" 4. Of dignity, as "king and subjects;" 5. Of nature, as the "sun and its rays." -- Simultaneity is opposed to priority, hence it is also of five kinds.
Motion is the passage from one state to another. It is of six kinds: 1. Generation, or the passage from non-being to substantial being; 2. Corruption, or the passage from being to non-being; 3. Augmentation, or the passage from a less to a greater quantity; 4. Diminution, which is the opposite of augmentation; 5. Alteration, or the passage from one quality to another; 6. Locomotion, or the passage from one place to another. -- The modes of having are five: 1. Inherence, as "a man has knowledge;" 2. Containing, as "a decanter has wine;" 3. Possession, as "a man has a field;" 4. Relation, as "a father has a son; " 5. Juxtaposition, as "a man has a garment on."
ART. VI. -- PROPERTIES OF TERMS IN A PROPOSITION.
17. Terms have six properties: supposition, appellation, state, amplification, restriction, alienation. -- Supposition is the particular signification of a word in a given proposition, as, "Angel is a word." Angel here signifies merely the word, not the nature of which the word is the sign.
Appellation is the application of one term to another, as "God is good;" here good is applied to God.
State is the acceptation of a term for the time indicated by the verb, as, "Peter sings."
Amplification is the acceptation of a term for a wider time than that indicated by the verb, as, "The dumb speak."
Restriction is the limitation of the signification of a term to a narrower sphere; as, "Eve is the mother of the living." Here the word living is restricted to men.
Alienation is the acceptation of a term in a metaphorical or figurative sense, as "Sun of Justice," used to designate the Saviour. "All nature smiles," is also an instance of the alienation of a term.
18. Supposition is material or formal, real or logical, particular, collective, or distributive. -- The supposition of a term is material when the term signifies itself; as, "Man is a word." It is formal when it denotes an object, as, "Man is rational;" and then it is real, if it expresses an object as it exists in itself independently of any mental consideration; as, "Man is a living being:" or logical, if it denotes an object abstracted from its individual characteristics; as, "Man is a species." Real formal supposition is particular when the term signifies some only of the beings which it can represent; as, "Some men are deceitful." It is collective when it signifies all the beings which it can represent, taken conjointly; as, "The Apostles are twelve;" and distributive when it expresses all and each of the beings which it can represent; as, "Man is mortal."
19. Supposition is subject to the following rules: 1. A term affected by a universal sign has a distributive or collective supposition according to the requirement of the predicate; as, "All the Evangelists are saints," "All the Evangelists are four." 2. A term affected by a particular sign has a particular supposition; as, "Some men are just." 3. When the subject of a proposition is not affected by any sign, it has a universal supposition in necessary matter; as, "Man is rational;" it has a particular supposition in contingent matter; as, "Men are wise." 4. In an affirmative proposition, the supposition of the predicate is always particular; as, "Man is mortal;" in a negative proposition, the supposition of the predicate is universal; as, "Man is not a plant." 5. In every proposition, the supposition of the subject is according to the requirement of the predicate; hence a numerical term requires a collective supposition; as, "The Apostles are twelve;" a necessary term requires a distributive supposition; as, "Animals are sensitive;" a contingent term requires a particular supposition; as, "Men are wise."
20. Appellation is material or formal. -- Appellation is material when the predicate is applied to the matter of the subject, without regard to the form which denominates the subject; as, "The physician sings." It is formal when the predicate is applied to the form of the subject, i.e., to the quality or form which denominates the subject; as, "The physician cures."{2}
21. Appellation is subject to the following rules: 1. When the subject is a concrete term, the appellation is material; as, "Man is a living being." 2. When the subject is qualified, the predicate is affirmed of the subject only, and the appellation is material; as, "St. Thomas of Aquin was a disciple of Albertus Magnus." 3. When the predicate is qualified, the predicate with its qualifier is affirmed of the subject, and the appellation is formal; as, "Thomas of Aquin was a saintly disciple of Albertus Magnus."
ART VII. -- MEANS TO INSURE PROPRIETY OF TERMS. -- DEFINITION.
22. Terms, to be perfect, must be clear and distinct. To obtain this result, we have recourse to definition and division. -- The aim of these two processes being to clear up what is obscure or confused, it is evident that they should not be employed upon what is already sufficiently clear and distinct.
23. Definition is a brief explanation of the meaning of a term or the nature of a thing. -- Whence it follows that there are two kinds of definition, nominal and real; the first explains the meaning of the word, the second explains the nature of the thing signified by the word. It should be observed: 1. That the nominal definition ought to precede the real, when the nature of a thing is in question and the meaning of the word expressing it is not understood; 2. That the nominal definition, in reasoning, must never be considered tantamount to the real definition; 3. That the real definition only is scientific.
24. There are three kinds of nominal definition: 1. According to etymology; 2. According to usage; 3. According to the meaning which the person using it wishes to attach to it. -- A real definition is either causal or essential. -- A nominal definition may be given according to etymology; as, "Intelligence (from the Latin intellegere, to read within) signifies intimate knowledge." We may also define a term according to usage; as, "By the word God, all understand the Infinite Being." Finally, we may attach to a term whatever meaning we choose. In this case, however, care should be taken: 1. Not to be so arbitrary in our choice as to become unintelligible to others; 2. Not to use the word in a different sense during the discourse.
A causal definition explains a thing by means of the principle which produces or generates it; as, "A sphere is a solid generated by the revolution of a semicircle about its diameter." An essential definition explains a thing by giving its essence; as, "Man is a rational animal." This is the most perfect kind of definition. A thing is sometimes explained by describing it; such a description is called a descriptive or oratorical definition.
25. Definition should contain the proximate genus and specific difference. -- By definition the thing defined should be distinguished from every other thing, and should be known in its characteristics. But without the proximate genus the characteristics of the thing are not known; and without the specific difference the species to which the thing belongs is not known. In this definition, "Man is a rational animal," animal determines the proximate genus, and rational the specific difference. This rule includes that laid down by modern logicians, viz., Definition must apply to the whole of the thing defined and to nothing else.
Three rules are ordinarily given for a definition: 1. The definition should be clearer than the thing defined; 2. It should be convertible with the thing defined; 3. The thing defined should not enter into the definition.
ART. VII. -- DIVISION.
26. Division is the distribution of a whole into its parts. Division is actual{3} or potential. -- As division is the separation of a whole into its parts, there are as many kinds of division as there are different kinds of whole. But a whole may be actual or potential; hence division may be actual or potentiai: actual when the whole is divided into parts which it really has; as, "Man is composed of body and soul;" potential or logical when the whole is divided into parts which it has in virtue of its extension; as, "Substance is corporeal or incorporeal."
27. Division should be adequate, it should be made through the more universal members, and the members should exclude one another. -- 1. The division should be complete, and hence equal to the whole thing divided; thus, we should not divide triangles into isosceles and equilateral. 2. It should proceed from the more general parts to those which are less general; thus, the division of living things into plants, animals, and men would be defective; they should first be divided into sentient and non-sentient. 3. The dividing members should in some way exclude one another; that is, one should not contain another, much less all, so as to be equal to the whole divided; thus man should not be divided into soul, body, and arms. To these three rules may be added a fourth: The division should be brief, that is, the members should be few in number.
{1} When viewed as the product of the joint action of object and intellect, it is called a concept, and the action producing it is called conception.
{2} In the first example the predicate sings must be applied, not to the form or quality of physician, but to the subject man, which the form denominates. In the second example, cures naturally belongs to the physician as such, and therefore is applied to the form. Form, in general, is any determination whatever by which a subject is affected.
{3} An actual whole is either physical or metaphysical; physical when composed of really distinct parts, as body and soul in man; metaphysical when composed of parts that are only logically distinct, as animality and rationality in man.