and Topic (the latter equivalent to Dialectic, and including Sophistic) were special names by which he denoted parts or applications of Logic. He used no one term to designate the whole science. Plato used the term Dialectic to denote more than Logic proper includes, while Aristotle used it to denote less, and it is usually regarded as the most ancient synonym for Logic. With whom the designation Logic originated does not appear; but it is ancient, being used by Cicero, and is attributed by Boethius to the early Peripatetics.

§ 2, "A Science is a complement of cognitions, having, in point of form, the character of logical perfection; in point of matter, the character of real truth." The logical perfection of a branch of knowledge is attained by systematically arranging and exhibiting its objectmatter, clearly, distinctly, completely, and in harmonious connection. This implies classification. Again, the object-matter of a science must be real truth, otherwise it cannot be said to be known; what is unreal or false cannot be a constituent of a science.' Hence the definition may be conveniently abbreviated thus: A Science is a perfected system of real truths; or thus: Science is classified knowledge. Few branches of knowledge have reached this ideal perfection; if not the mathematics, none have done so. But since in many departments knowledge has far outgone its crude beginnings, and made great progress towards this ideal, such branches are properly called sciences. "The distinction between science and art is, that science is a body of principles and deductions to explain some object-matter; an art is a body of precepts, with practical skill, for the completion of some work. A science teaches us to know, an art to do; the former declares that something exists, with the laws and causes which belong to its existence; the latter teaches how something must be produced." In science scimus ut sciamus; in art scimus ut producamus. Science discovers laws; art gives rules. Περὶ γένεσιν τέχνη, περὶ τὸ ὃν ἐπιστήμn. This distinction holds good, in reference to the extremes, as to pure speculative sciences and mere manual arts. But science often leads so directly into art, and art, except in its rudest forms, is so dependent on science, that usually they cannot be set clearly apart.

'Hamilton's Logic, p. 335.

* Scientific knowledge (rò inioraolai), except when of axiomatic principles (votiv), requires a conviction of the truth of the given proposition, and a knowledge of its reason or cause.-Aristotle's Anal. Post. i, 2, 1.

4

• Thomson's Outline of the Laws of Thought, § 6.

• Aristotle.

Moreover, there is a body of practical sciences, e. g. Ethics, Economics, etc., that occupy intermediate ground, and yet are never called arts; others again, e. g. Rhetoric, Grammar, etc., are commonly viewed as arts."

Some logicians have viewed Logic as an art, and entitled it The art of thinking (Arnauld '); The art of reasoning (Aldrich); The right use of reason (Watts), etc. Others pronounce it to be both, thus: Ars artium, et scientia scientiarum (Duns Scotus, 13th century);* The art and science of reasoning (Whately); The art of thinking, which means, of correct thinking, and the science of the conditions of correct thinking (Mill). The extreme view of Logic as an art is that it teaches us how to think. This is evidently absurd. A course in Logic is about as needful for making men thinkers as a course in Ethics is to make them virtuous, or a course in Optics to make them see. A modified view is that Logic teaches us how to think correctly, or, negatively, how to avoid fallacy, or that it teaches how to test the validity of given arguments. If such is the scope and object of Logic, it may be set aside as of little or no value, consisting of a system of rules which the initiated never use and the uninitiated never miss. Such views have historically brought Logic into great discredit, just as Chemistry was brought into disrepute by the extravagant pretensions of the alchemists.1o

But Logic is not primarily, nor even secondarily, an art. It is strictly a science; the science teaching how we do think and how we must think if we think correctly. It is the theory of reasoning; or, better, it is the theory of thought. The difference between Logic and an Art of Thinking is similar to that between Anatomy and Surgery. The value of Logic is such as belongs to pure science, which, in this day, needs no demonstration. It is something of profoundest interest to know what are the mental processes in the intellectual act of thinking, and of such matter the liberal mind asks primarily, Is it true? not, Is it useful? Knowledge is power, but we have to do

"See Hamilton's Metaphysics, pp. 81-84.

'L'Art de Penser, 1662, that most admirable work, known commonly as the "Port-Royal Logic."

• See Hamilton's Logic, p. 28.

• Ex. of Hamilton's Phil. vol. ii, p. 149.

1o See Locke's contemptuous opinion of Logic, Essay, bk. iv, ch. xvii. Also Goethe's, in Faust, pt. i, speech of Mephistopheles to "der Schüler." It may be objected that this is merely the mocking gibe of Mephistopheles; but cf. in Wahr. und Dicht. pt. i, bk. iv.

with it here as knowledge, not as power. Where, however, one has mastered the science, there is a practical result in a special cultivation of his reasoning powers; and, moreover, whatever process one clearly understands, it is manifest he can more clearly and efficiently perform."

The Greek Aristotelians, and after these the scholastic Aristotelians, subdivided Logic into what the latter called Logica docens and Logica utens. The former is explained as an abstract theory of thoughtquæ tradit præcepta; the latter as a concrete practice, as an application of these rules to use-quæ utitur præceptis. Hamilton, following Kant, calls the former "General or Abstract Logic," the latter "Special or Concrete Logic." The former only is Logic; the latter, quite properly called "Applied Logic," and treating chiefly of the methods by which particular sciences should be logically developed, is no part whatever of the science of Logic, of Logic proper, and accordingly will be disregarded in the present treatise."

§ 3. The object-matter of Logic is thought. Thus it is distinguished from other sciences, each of which has its own special objectmatter. Astronomy treats of the stars; geology, of the earth's crust; zoology, of its fauna; botany, of its flora; mathematics, of quantity; theology, of God; philosophy, of principles; psychology, of mind; ethics, of morals, etc.; so Logic treats of thought. Thought denotes only the acts of the understanding, as distinguished from perception, memory, feeling, desire, volition, of whose exercises Logic takes no account. Thought may be simply defined as the cognition of one notion in or under another. Hence in this act we are said to comprehend or understand a thing. E. g., A book lies before me. I may be conscious of the impression the thing makes without cognizing what it is. This is mere perception. But if I cognize what it is, and say, "It is a book," I have brought it under a certain class or concept of things which we call "book." This is thought." Now we think about all conceivable things, but all of these are to Logic perfectly indifferent except one, that is, thought itself. In Logic we think about thought. What thought involves, Logic evolves."

"See Hamilton's Logic, pp. 7, 8; and McCosh's Logic, pt. iii, § 80. 12 Hamilton's Logic, p. 38, and p. 42.

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13 Id. pp. 9, 10.

See Aristotle, De Soph. Elench. ix. Sciences and demonstrations, says he, are possibly infinite, and would require omniscience to treat them. The dialectician has to discover only the principles common to all spheres of thought.

RE

DEFINITION OF LOGIC.

CALIFORNIA

5

§ 4. We observe, then, that Logic does not at all concern itself with what things thought considers. It treats of thought regardless of its content. It is usual to express this by saying that Logic treats of the forms of thought abstractly, i. e. excluding its matter. The form of thought as distinguished from its matter may be exemplified thus: When I think that the book before me is a folio, the matter of this thought is "book;" and "folio," the form of it, is "a judgment." The forms of thought may be represented as empty shells, into which very various matter may enter as the content of thought; or as mere outlines, to which different substances may conform, like as a statue may be formally the same whether of wood, metal, or marble. So the science Morphology treats of the forms of plants and animals, and Crystalology, an abstract geometrical science, treats only of the forms of minerals. The matter and the form have, of course, no separate existence. No object is cogitable except under some form of thought; and no form of thought can have any existence in consciousness unless some object be thought under it. But by analytic abstraction we can consider these apart; we can consider either the object thought, or the manner of thinking it; we can distinguish the matter from the form of thought. Now it is the form of thought, abstracting its matter, that Logic considers. Modern logicians are fond of saying that all matter is extralogical. This might be understood to represent Logic as a science without a content, without matter of its own. But Logic, like every other science, has its own special content. Its object-matter is thought; all other matter is extralogical. Its object-matter is thought discharged of its matter; i. e., it is the form of thought.

Logic, then, is properly an abstract science, one abstracting from cach and all the sciences, and considering only what is common to all; i. e. the formal thought to which all are subjected, and making that its object-matter. Hence Logic is in a similar and equal relation to all sciences, and fundamental to all. Now philosophy is the science of principles, and is therefore the fundamental science in the sense that its object-matter is the primary truths that underlie all knowledge. But philosophy proceeds logically or not at all. Hence Logic is fundamental even to philosophy in the sense that it exhibits the necessary processes of thought which bind philosophy as well as every other science. Moreover, Logic is itself bound to proceed logically, and can become a science only by conforming to those processes which it is its province to explicate and exhibit.

Let it not, however, be supposed that Logic treats of thought only as exercised and displayed in scientific pursuits. It treats of thought universally. Thought as exhibited in all kinds of literature and speech, in common conversation, in silent meditation; all our common every-day thinking, about the most trivial things and at every instant, is formally all of the same nature, proceeds in the same manner, is governed by the same laws, is logical if correct. Consequently, illustrations of the principles of Logic are to be drawn not merely from any of the sciences, but from any kind of knowledge, wherein anything whatever becomes an object of thought. Logic teaches or explains how any human mind rightly thinks at any time about anything.

§ 5. To define Logic as the science of the forms of thought would not be sufficient to set it entirely apart, would not discriminate clearly its character. Psychology is inter alia a science of formal thought, and needs to be distinguished from Logic. Psychology is an empirical science; it is evolved from experience. It is therefore an inductive, natural science, one a posteriori, It systematizes the conscious mental activities, and points out their laws. In dealing with the faculty of thought, it explains the modes in which we think, teaching how we do think, and refers for the test of its doctrine to the reflective consciousness of every individual.

Logic, on the other hand, if taken in its strictest sense, is not at all an empirical, but a speculative or theoretical, science. It accepts from Psychology, or obtains by the analysis of given products of thought, certain primary laws; from these it deduces secondary laws of thought, and thus proceeds to demonstrate the necessary processes of thought, those we must follow in thinking correctly. It is therefore a purely deductive science, one a priori. It teaches not how we do think, as a matter of fact, but how we must think, as a matter of necessity, if the thinking be consequent. It appeals, not to consciousness, but to demonstration, in support of its truthfulness.

Psychology, then, is the natural history of thought; Logic is the theory of thought. Psychology considers thought as an operation; Logic considers it as a product. Psychology treats of conceiving, judging, reasoning; Logic treats of concepts, judgments, reasonings. Psychology treats of thought as it is; Logic of thought as it must be. Psychology teaches how we do think, Logic teaches how we must think. The one treats the forms of thought merely as actual, the other proves them necessary. Like mathematics, Logic is purely de