of various degrees of generality, including individual objects if they need separate record, infima species if such there be, with wider classes, up to the summa genera, or widest notions embraced in the science. In astronomy we deal chiefly with the names of individual objects, and there is as yet but little scope for classification. In such natural sciences as botany or zoology there is seldom or never any need of names for individuals, as an indefinite multitude of individuals generally resemble each other very closely in a great number of properties, so as to constitute what has been called a natural kind. Mr Mill uses this term to denote one of those classes which are distinguished from all others, not by one or a few definite properties, but by an unknown multitude of them; the combination of properties on which the class is grounded being a mere index to an indefinite number of other distinctive attributes." 66 According to Mr Mill's language he seems to include in a nomenclature only the names of supposed species; for he says:-"A nomenclature may be defined, the collection of names of all kinds with which any branch of knowledge is conversant; or more properly, of all the lowest kinds, or infimæ species, those which may be subdivided indeed, but not into kinds, and which generally accord with what in natural history are termed simply species." But the fact is that naturalists have now abandoned the notion that the species is any definite form; many species are divided already into subspecies and varieties, or even varieties of varieties; and according to the principles of Darwin's theory the subdivision might go on indefinitely. It is surely most reasonable to regard the natural kingdoms of vegetables and animals as arranged in an indefinite series of classes and subclasses, and all the names attaching to any such classes belong to the nomenclature. Again, Mr Mill does not include in the nomenclature such general names as denote conceptions artificially formed in the course of induction and investigation. Accordingly, besides a terminology suited for describing with precision the individual facts observed, there is a branch of language containing 66 a name for every common property of any importance or interest, which we detect by comparing those facts: including (as the concretes corresponding to those abstract terms) names for the classes which we artificially construct in virtue of those properties, or as many of them, at least, as we have frequent occasion to predicate any thing of." As examples of this class of names he mentions Circle, Limit, Momentum, Civilization, Delegation, Representation. While the nomenclature contains the names of natural classes, this third branch of language would apparently contain the names of artificial ideas or classes. But I feel great difficulty in giving a clear account of Mr Mill's views on this subject, and, as my object in these Lessons does not allow of the discussion of unsettled questions, I must conclude by referring the reader who desires to continue the subject, to the 4th and 6th chapters of the 4th Book of Mr Mill's System of Logic, which treat of the Requisites of a Philosophical Language. See Dr Whewell's "Aphorisms concerning the Language of Science," at the end of his Philosophy of the Inductive Sciences. Thomson's Outline of the Laws of Thought, contains most interesting remarks on the general nature and use of Language, §§ 17-31. QUESTIONS AND EXERCISES. LESSON I.-Introduction. 1. What are the meanings of a Law of Nature, and a Law of Thought? 2. Explain the distinction between the Form of Thought, and the Matter of Thought. 3. In what sense may Logic be called the Science of Sciences? 4. What is the derivation of the name Logic? 5. How does a Science differ from an Art, and why is Logic more in the form of a Science than an Art? 6. Can we say that Logic is a necessary aid in correct reasoning, when persons who have never studied logic reason correctly? LESSON II.-Three Parts of Logic. 1. Name the parts of which a syllogism is composed. 2. How far is it correct to say that Logic is concerned with language? 3. What are the three acts of mind considered in Logic? Which of them is more especially the subject of the Science? 4. Can you state exactly what is meant by a general notion, idea, or conception? 5. How do the Nominalists, Realists, and Conceptualists differ in their opinions as to the nature of a general notion? 6. What is the supposed fourth part of Logic? LESSON III.-Terms. 1. Define a name or term. 2. What is a categorematic term ? 3. Explain the distinction between a collective and a general term. 4. Distinguish the collective and distributive use of the word all in the following: (1) Non omnis moriar (i.e. I shall not all die). Tennyson. 5. Which of the following are abstract terms? Act, ingratitude, home, hourly, homeliness, introduction, individuality, truth, true, trueness, yellow, yellowness, childhood, book, blue, intention, reason, rationality, reasonableness. 6. Define a negative term, and mention the mark by which you may recognise it. 7. Distinguish a privative from a negative term, and find some instances of privative terms. 8. Describe the logical characters of the following terms, with the precautions given at p. 26. LESSON IV.-Ambiguity of Terms. 1. Define univocal terms, and suggest some terms which are perfectly univocal. 2. What are the other names by which equivocal terms are often called? 3. Distinguish the three kinds of ambiguous terms, and find instances of each. 4. Distinguish the three causes by which the third and most important class of ambiguous terms have been produced. 5. Explain the ambiguity of any of the following terms, referring each to its proper cause, and tracing out as far as possible the derivation of each separate meaning from the original meaning. LESSON V.-Twofold meaning of Terms. 1. Distinguish very carefully the meanings in extension and intension of the terms Quadruped, railway, human being, engine, mountain, Member of Parliament. |