soning, are subject to certain laws; Concepts, Judgments, Syllogisms, exhibit certain forms. But the laws of thought are not always competent to determine its form, as has been already shown in the case of all the products of mixed thinking. In a synthetical judgment, for example, the laws of thought can determine only its possible truth, which equally implies its possible falsehood; thus leaving it altogether undecided whether the form of the judgment should be affirmative or negative, universal or particular. The form in all these cases is determined by that universal tendency of the human mind, which has been noticed in a former chapter, the tendency to regard physical phenomena as indicating the existence of a substance or a cause similar to that of which we are directly conscious in our own mental states and operations. It is thus that, when experience presents certain phenomena in juxtaposition, the mind is invariably led to regard them as attributes of one and the same substance; and this constitutes the form of all mixed concepts and judgments. And in like manner, when one phenomenon is the invariable consequent of another, the mind is irresistibly led to regard them as respectively cause and effect; and this constitutes the form in all cases of mixed inference. The same tendencies which thus cooperate with the presentations of experience in the acts of mixed thinking, coöperate in like manner with the laws of thought in acts of pure thinking. In the former case, the attributes are given as empirically related as intuitions; in the latter, they are given as logically related as thoughts; and in both they are regarded as mutually related to some unknown substance or cause. But that these tendencies, however universal or irresistible, cannot properly be regarded as laws of thought or of intuition, is manifest from the fact, that they furnish no criterion for determining the

legitimacy or illegitimacy of any product. Thoughts, whether empirically true or false, whether logically sound or unsound, in this respect present precisely the same features. An assertion, false in point of fact, or self-contradictory in point of thought, contains, as regards the supposed relation of attributes to a common substance, precisely the same form as one logically and empirically valid. The Principles of Substance and Causality are thus rather negative conditions than positive laws of thought. They have a psychological relation to thought as it actually exists, explaining and accounting for the fact of its invariably assuming a certain form; but they have no logical relation to thought as it ought to be, and furnish no criterion of its validity in any special instance.

Logical or pure thinking is not, therefore, called formal, because its product exhibits a form; for the coëxistence of matter and form is common to all thought, and to all spurious imitations of thought. But the justification of the terms formal and material, as applied to pure and mixed processes of thinking, is to be found in the circumstance, that in the former the act of thought is based on the form only of the preliminary data, without reference to the particular matter; while, on the other hand, matter is necessarily taken into account in every process of mixed thinking. To an act of logical conception, for example, it is not necessary to examine in any case the special character of the attributes, as having been actually combined in experience; but only that they should be compatible with the possible existence of an object in space or time. In an act of logical judgment, one of the given concepts being always comprehended in the other, it is indifferent of what special attributes either is composed, provided they possess sufficient clearness and dis

tinctness to enable the mind to discern the relation between them. In an act of logical reasoning, the validity of the conclusion depends solely on the quantity and quality of the given premises, without any reference to the particular terms of which they are composed. In all, so long as the formal relation of the data remains the same, the matter may be changed as we please, without affecting the logical value of the thought. In mixed thinking, on the other hand, the matter is of principal importance. To determine that this or that object of conception actually exists, that this or that judgment is in accordance with experience, that this or that inference is sufficiently probable to furnish a reasonable motive to action, we require to be guided by a knowledge of the nature and circumstances of the particular object in question. And it is for this reason that all examples of logical thinking are better expressed by means of arbitrary symbols than of significant terms; not that it is in any case possible to think without some matter or other, but because it is wholly indifferent what matter we may at the time be thinking about; and, therefore, by employing an unmeaning sign, indifferently representative of any object of thought, we are enabled to clear the process from any accidental admixture of material knowledge, and to exhibit the form alone in its proper relation to the laws of thought.

In accordance with the view here given of Form and Formal Processes, it will be proper to modify slightly some of the definitions of Logic given by those philosophers whose views have been principally followed in the present work. Logic, to omit less accurate views of its nature, has been defined as the Science of the bare Form

of Thought, or as the Science of the Formal Laws of Thought; definitions which, though substantially approaching far nearer to the truth than any antagonist view, still leave something to desire in point of verbal accuracy. The term formal strictly belongs rather to the process of pure thinking than to the laws by which it is regulated, or to the science which takes cognizance of them; and Logic is not the science of the Forms of Thought in general, but only of such as are subservient to other processes of formal thinking. Other forms, such as modality, fall without the province of Logic, and within that of Psychology; to which latter science, indeed, all the forms and laws of thought belong in their relation to the constitution of the thinking subject. To Logic, on the other hand, belong the same forms and laws in relation to those acts and products of pure thinking which are suggested by the one and governed by the other. If, therefore, slightly altering the language of the above definitions, we define Logic as the Science of the Laws and Products of Pure or Formal Thinking, we shall express with tolerable accuracy its character and province, according to the views advocated in the preceding pages.

1 Kant, Logik, Einleitung I.; Hoffbauer, Logik, § 17.

2 Sir W. Hamilton, Discussions, p. 119.

3 This coincides nearly with the definition given by Sir W. Hamilton (Reid's Works, p. 698), The science of the laws of thought as thought.

CHAPTER VIII.

ON POSITIVE AND NEGATIVE THOUGHT.

LOGIC has been described by Kant as the science of the necessary laws of the understanding and of the reason. Psychologically, the propriety of this division of the mental faculties has been called in question by eminent critics.1 And in a logical point of view it is untenable, if, as I have endeavored to show, judgment and reasoning, in so far as they are logical processes, are both governed by the same. laws, and must be referred to the same faculty. In the present chapter, however, it is proposed to examine another expression of the same definition, and to inquire in what sense the Laws of Thought can properly be called necessary. Kant employed this term to distinguish the laws of thought in general from those of thought as employed upon any definite class of objects; it being optional with every man, and therefore contingent, whether he shall exercise his understanding on one class of objects rather than another. This distinction I have preferred to express in other words, by separating pure or formal from mixed or material thinking; but the Kantian phraseology may serve to introduce a subject, the right understanding of which is of considerable importance in Logic: the differ

1 Among others, by Sir William Hamilton (Discussions, p. 17), and by M. Cousin (Leçons sur la philosophie de Kant, L. vi.).

2 Kant, Logik, Einleitung I.