DISCOURSE OF POLITICAL SCIENCE. THE Sciences which form the subject of our most useful study, and which, next to the cultivation of religion and the practice of virtue, are the source of our purest enjoyments in this world, may be divided into three great classes or branches, according to their several objects. Those objects are-the Relations of Abstract Ideas-the Properties of Matter-the Qualities of Mind. All the subjects of scientific research may be classed under one or other of these three heads; and all the sciences may, accordingly, be ranged under one or other branch of a corresponding threefold division. To the first branch belong the abstract ideas of quantity-that is, of space in its different forms and portions; and of these the science of Geometry treats; the abstract ideas of number, which form the subject of Arithmetic, general or particular, the one called Algebra, the other Common Arithmetic, the comparison and classification of all ideas, generally, whether abstract or not, and whether relating to matter or mind; and this forms the subject of Logic, or the science of reasoning and classification. The first branch deals with mere abstract ideas, and has no necessary reference to actual existences; these form the subjects of the other two, which, accordingly, do not, like the former, rest wholly upon reasoning, but depend upon experience also. The one branch relating to matter, its properties and motions, is termed Physics,* or Natural Philosophy; the other, relating to the nature and affections of the mind, is termed Metaphysics or Psychology,† or Moral or Mental Philosophy. Physical or Natural Philosophy is subdivided into various branches: one, for example, treating of weight and motion, is called Dynamics, or Mechanics and Statics; another, treating of the heavenly bodies, is termed Astronomy; another, of light, is termed Optics; another, of the qualities and composition of substances, called Chemistry; another, of the properties of living bodies, called Anatomy and Physiology; another, of the classification of substances and animals, called Natural History. To all of these accurate observation and experiment may be applied, and to some of them mathematical principles, by which extraordinary progress has been made in extending our knowledge of the laws of nature. Moral or Mental Philosophy consists of two great subdivisions: one treating of the powers, faculties, and affections of the mind-that is, its intellectual as well as its moral or active powers-the faculties of the understanding and those of the will, or our appetites and feelings as well as our intellects-and this branch treats of all spiritual existences, from the Great First Cause, the Creator and Preserver of the universe, to the mind of man and his habits, and down to the faculties and the instincts of the lower animals. This division is sometimes called Psychology, when that phrase is not used for the whole of moral science. The other subdivision treats of our duties towards the Deity and towards our fellow-creatures, and is generally termed Ethics. But perhaps the better and more correct division of the whole of Moral Philosophy is to consider it in two points of view-as it treats of * From the Greek word signifying natural objects or qualities. man in his individual capacity; and man as a member of society. This last branch is termed Political* Science, and forms the subject of the following Dis course. We have already adverted to one important circumstance which distinguishes both the two branches of science which treat of actual existences from those which treat of abstract ideas and their relations. The truths of both Natural and Moral Philosophy differ from those of abstract science in this important particular, that they partly depend on experience and not exclusively on reasoning; they are contingent, and not necessary; the world, moral and material, might have been so constructed as to render untrue all things now known to be true respecting it; whereas the truths of abstract science, arithmetic for example, are independent of all contingencies, and do not result from any experience, and could not possibly have been different from what they are. It is easy to conceive a world in which bodies should attract each other by a wholly different law from that of gravitation; but we cannot form to ourselves the idea of any state of things in which two and two should not be equal to four, nor the three angles of a triangle equal to two right angles. It follows that, in the sciences both of matter and of mind, we must be content with evidence of an inferior kind to that which the mathematical sciences employ; and resting satisfied with as high a degree of probability as we can attain, must draw our practical conclusions with the hesitation which such a liability to error naturally prescribes. The first, or abstract branch, is capable of application to the other two. The precision with which the qualities and the functions of matter are observable, and the ease with which these may be subjected to experiment, enable us to investigate them with great * From the Greek for city or state-the different communities in Greece having originally been cities and their adjoining territories. |