A Proprium (or property) of a genus, species, or individual is any attribute which follows from its comprehension either deductively or causally. If it follows from the comprehension of the genus, the property is called generic; if from that of the species, specific; and if from that of the individual object, individual. Thus, an individual thing may have its individual property, its specific property, or a property following from the species to which the individual belongs, and even a generic property following from the genus to which its species belongs. This last may be included in the specific property. A species may have two properties, one following from its differentia, and the other from its genus. The former is called the specific, and the latter the generic property, of the species; or both together are simply called its property. 'Memory,' for example, may be regarded as a property of man, following either from the genus animal, or from the differentia rational; 'power of judging' is likewise a property of man following from the differentia. The properties of the triangle, as proved in the Elements of Euclid, follow partly from the comprehension of its genus figure, partly from that of triangle, and partly from those of special kinds of triangles.

An Accidens (or accident) of an individual, genus, or species is any attribute which is possessed by it, and which does not follow, from, or form a part of, its comprehension. If an accidens J always belongs to an individual, or if it belongs to all the members of a genus, or species, it is called an inseparable accidens of that individual, genus, or species; as the place or date of birth of a particular person, the hair of man, the blackness of the crow, the whiteness of snow, &c. If, on the other hand, an accidens is sometimes present and sometimes absent in an individual, or if it belongs to a part only of a species or genus, then it is called a separable accidens of that individual, species, or genus; as the walking or sitting of a particular person, the wisdom of man, the solubility in water of salts, the opacity of gases, the learning of man, &c.

When the predicate of a proposition is a proprium, or an

accidens, of the subject, the latter in extension is included in the former, that is, the extension of the accidens or proprium, when taken as a general term, is a greater whole than that of the subject; while, in comprehension, the predicate expresses an attribute not contained in the connotation of the subject, that is, it imparts some new information about it; and the proposition, therefore, belongs to the class of real. In the proposition "Water boils at 100o C., under a pressure of 760 mm.," the attribute expressed by the predicate is not a part of the connotation of the term water.

The five terms-genus, species, differentia, proprium, and accidens―are called predicables, because whatever may be predicated (affirmed) of a subject in a proposition is, in relation to the subject, one or other of the five. A predicable is thus a name of a class of predicates in relation to the subjects. It should be distinguished, on the one hand, from the word 'predicament,' or 'category,' which means a most general class of both subjects and predicates, and, on the other, from the word 'predicate,' which means what is affirmed or denied of a subject. Given a term: whatever be affirmed of it, the predicate, in relation to the subject, is a predicable, that is, it is either a genus, species, differentia, proprium, or accidens; and the subject as well as the predicate must belong to some category or other. Aristotle gave four predicables, viz., genus, definition, proprium, and accidens. Later logicians added 'species' and 'differentia to Aristotle's list, and removed 'definition' from it. Thus there came to be the five predicables we have explained above. Some logicians have made further additions to the list. Professor Fowler, for example, gives 'synonym,' 'definition,' 'designation,' idion (a Greek word signifying a peculiar property), in addition to the five, while others regard them as falling under one or other of the five predicables adopted by them: 'synonym' and 'designation,' for example, would be regarded by some of them as included in accidens, 'definition' as a compound of genus and differentia, and 'idion' as coming under either differentia or property.

Besides the terms explained above, the older logicians use the term summum genus to mean a highest genus or a genus which cannot be a species, being the highest and most general of its kind, and the term infima species to mean a lowest species or a class which cannot be a genus to another, being the lowest of its kind, while the intermediate genera and species are called by them subaltern genera and species. 'Substance,' for example, is regarded by them as a summum genus, 'man' as an infima species, incapable of further subdivision into species, and 'body,' 'living being,' and 'animal' as subaltern genera and species.

The two terms 'genus' and 'species' express the relation of containing and contained. Any class containing another is popularly called a genus in relation to the latter, which is called a species. In the Sciences of Classification, in Botany and Zoology, for example, groups of a particular description are called genera in relation to others of an equally definite nature, which are called species. In order to express the relation of containing and contained, we not only use the two old terms, genus and species, but also many others according to the position of the groups in a system of division or classification. ample, the terms kingdom and sub-kingdom, class and sub-class, order and sub-order, genus and sub-genus, species and subspecies, variety and sub-variety, used in Zoology and Botany, mark as clearly the relation of containing and contained as the two words, genus and species.

Exercises.

For ex

I. State whether the following propositions are verbal or real, analytical or synthetical, and whether the predicate in relation to the subject is a genus, species, differentia, proprium, or accidens:

1. Oxygen is an elementary gas.

2. Water boils at 100° C., under a pressure of 760 mm.

3. Platinum is a rare metal.

4. Sugar is sweet.

5. The atmospheric air is a mixture of nitrogen and oxygen.

6. Copper conducts heat as well as electricity.

7.

All men have the power of thinking.

8.

All animals are sentient beings.

9. All the flowering plants have fruits.

10. Heat expands bodies.

11. The leaves of plants are green.

12. Spring-water contains many salts in solution. 13. Hydrogen is the lightest substance known.

14. London is the largest city in England.

15. Milton was blind when he composed the "Paradise Lost." II. Give the genus, species, differentia, proprium, and accidens of each of the following terms:

(1) Triangle, (2) Circle, (3) Straight line, (4) Square, (5) Right angle, (6) Element, (7) Force, (8) Material Body, (9) Animal, (10) Chalk, (11) Rock, (12) Virtue, (13) Volition, (14) Knowledge, (15) Pleasure.

§ 11. Miscellaneous Exercises on Propositions.

In describing the logical characters of a proposition, the following method should be followed:

I. What is given is a sentence. Ascertain whether the sentence consists of a single proposition or of a plurality of propositions.

II. In the former case, state whether it is—

i. Categorical, Hypothetical, or Disjunctive.
ii. Affirmative or Negative.

iii. Necessary, Assertory, or Problematic.

iv. Universal, Particular, or Indesignate; Singular and Universal, or Singular and Particular.

V.

Verbal (or Analytical) or Real (or Synthetical).

Both the quality and quantity of a proposition may also be stated at once by saying whether it is A, E, I, or O.

III. In the latter case, state the propositions of which it consists, and treat each of them as detailed above.

IV. Sometimes the quality, quantity, and other characters of a proposition are not quite evident from its form or the manner of its statement. In such cases, verbal changes should be made in order to state it in the logical form, keeping the meaning the same. It is always safe first to ascertain, as in the case of the term, the meaning

of the proposition, or, where this is not practicable, to see, before attempting to describe the logical characters of the proposition, whether the subject be a general term taken distributively or not, whether there be any negative particle attached to the copula or to the predicate, whether there are any signs of universality or negation before the subject, &c.

Examples.

1. "No man is perfect": categorical, negative, assertory, universal, and real.

2. "The three angles of a triangle are together equal to two right angles": categorical, affirmative, assertory in form, but really necessary, universal, and real.

3. "Some elements are not metals": categorical, negative, assertory, particular, and real.

4. "None but material bodies have weight": this proposition really means that "all things having weight are material bodies." In this form it is an A proposition. In the original form, it may be regarded as an E proposition, "no not-material bodies have weight," signifying that having weight is denied of all things other than, or except, material bodies, that none that have weight are other than material bodies, and this last is the same as "all things having weight are material bodies," the proposition we have substituted above for the original one. It should be noted that the proposition does not mean that every material body has weight.

5. "All metals except mercury are solids."-In this proposition 'solids' is affirmed of all metals except mercury, and the proposition may, therefore, be regarded as an A proposition and described as categorical, affirmative, assertory, universal, and real. Or it may be taken as an I proposition, 'some metals are solids,' but in this degraded form, the full meaning of the original proposition is not expressed. Or we might state the names of all the metals except mercury, and form a proposition with them all as the subject and 'solids' as the predicate as before. For example, 'gold, copper, iron, silver, &c., are solids.' Such a proposition would be a combination of the several propositions, having each a certain metal for its subject, and 'is a solid' for its copula and predicate. Thus, 'gold is a solid,' 'copper is a solid,' 'iron is a solid,' and so forth.