1. Philosophy is the science of things through their highest or ultimate causes, so far as it may be attained by the light of reason. -- Whatever exists may be known in two ways: the first is by a spontaneous, common knowledge of things, such as every man may acquire; the second is by a reflex knowledge, peculiar to minds desiring to account for things and to know them in their principles and ultimate causes: this latter is philosophic knowledge. But the principles of things are partly confined to special sciences, and partly underlie all human knowledge; the former constitute the philosophy of this or that science; the latter alone are the object of philosophy properly so called. These principles or ultimate causes are investigated by the light of reason; and so philosophy is divided off from Sacred Theology, which rests on divinely revealed principles.
2. The excellence and utility of philosophy are manifest, whether it be considered in itself, or in its relations with the other sciences. -- Since philosophy treats of things in their highest causes, it is in itself the noblest object that can engage the mind of man; it teaches him the knowledge of truth and enables him to attain his greatest natural perfection. Relatively to the other sciences, it is evident that since philosophy lays down their first principles, it is their foundation, and exercises the most direct influence over their development, as experience besides has shown.
3. Philosophy may be divided into real, rational, and moral philosophy. -- Every science may be divided into as many parts as there are different aspects under which the object of which it treats may be viewed. But the object of philosophy in general is being, which may be considered under three aspects: as real and possessing attributes independent of our cognition; as ideal and having attributes which result from our mental action; or as moral when regarded as the term{1} of voluntary action. Philosophy, then, may treat of the ultimate principles of things either in the order of reality, or of cognition, or of morality; its divisions are, therefore, called physical, logical, and ethical; or, if we use the Latin equivalents, natural or real, rational, and moral. The ontological order, or order of existence would require us to begin with real philosophy or metaphysics; we must, however, first study rational philosophy, because it points out the laws of the human mind in acquiring knowledge, and trains it to discern the true from the false, thus furnishing the means to study real being more easily and securely.
ITS DIVISION.
Rational Philosophy is divided into Logic, Ideology, and Criteriology. -- AS rational philosophy considers entities in respect to the knowledge which we have of them, it ought (1) to investigate the laws which govern the intellect, the instrument by which we know; (2) to treat of ideas, the means by which we know; (3) to determine the value of the knowledge acquired by the intellect. Hence rational philosophy is divided into three principal parts: 1. Logic, or the science of the laws of thought; 2. Ideology, or the science of ideas; 3. Criteriology, or the science of the criteria of certitude.
DEFINITION OF LOGIC. -- ITS UTILITY. -- ITS DIVISION.
1. Logic is the science of the laws which the intellect must obey in order to acquire readily and surely the knowledge of truth. -- The human mind in its search after truth is subject to laws imposed on it by its very nature. The ascertainment of these laws constitutes Logic. Logic is a science rather than an art, because it considers the laws of the mind in their intrinsic principles and general applications, and is not confined to an enumeration of practical rules.{2}
2. Logic is of great utility for advancing in the cognition of truth, for guarding against error, and acquiring proficiency in any science whatever. -- As Logic habituates the intellect to classify and co-ordinate knowledge, it gives us great facility for progressing still further in the acquisition of truth; moreover, by familiarizing the mind with the nature and structure, as also the artifices, of reasoning, it enables us easily to discern the vices of a sophism and the false appearances by which error seeks to seduce the mind. Finally, it is evident that, as the sciences can advance only by means of reasoning, nothing is more conducive to their progress and easy acquisition than Logic, which is, in fact, the science of reasoning itself.
3. Logic is divided into three princpal parts: the first investigates the nature and laws of reasoning; the second expounds the general conditions of science; the third determines the general rules of method. -- The object of logic is reasoning; but in reasoning three things may be considered: the nature of reasoning, the end of reasoning, which is science, and, lastly, the process or method followed to reach this end more easily. Logic, therefore, is divided into three parts, corresponding to the three aspects under which reasoning may be considered.
{1} "Term in general is a boundary or limit. In Logic, it denotes the subject and predicate of a judgment; the major, minor, and middle of a syllogism. In Metaphysics, it denotes the limit of a cause, more particularly of an efficient cause. In Ethics, the final cause is the term, because the limit of desire." -- HARPER, Metaphysics of the School, vol. i., p. 589. {2} Considered as "an enumeration of practical rules" for the detection and refutation of error, logic is an art. Hence, while logic is chiefly and primarily a science, it is dependently and secondarily an art. -- Aristotle defines art as "science employed in production."