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and cannot exist independent of each other : the same of length, ibreadth, and thickness ;: and yet we can mentally confine our observations to one of these, neglecting or abftracting from the rest. . Here abstraction takes place where there cannot be a real separation.
o si sono molts' 3798. This power of abstraction is of great utility: A carpenter confidersa log of wood, with regard to hardness, firmness, colour, and texture: a philosopher, neglecta ting these properties," makes the log undergo a chymical analysis; and examines its taste, its smell, and its component principles: the geometrician confines his reasoning to the figure, the length, breadth, and thickness. In general, every artist, abstracting from all other properties, confines his observations to those which have a more immediate connection with his profeffionpodi
39. Hence elearly appears the meaning of an abstračt tern, and abstract idea. 3fJf in viewing an object, we can abstract from fome of its parts or properties, and attach Courselves to othersthere must be the same facility, when we recall this object to the
mind in idea. Bi This leads directly to the definition of an abstract idea, viz. “ A par<tial view of a complex object, limited to
cc one or more of the component parts or El properties; - laying aside or abstracting «c from others. A word that denotes an abstract idea, is called an abstract term. 314:40. The power of abstraction is bestowed upon man, for the purposes solely of rea
foning. It tends greatly to the facility as -well as clearness of any process of reasoning, that, withdrawing from every other circumftance, we can confine our attention to the fingle property we desire to investigate. ***041. Abstract ideas, may, I think, be distinguished into three different kinds, all equally subfervient to the reasoning faculty. Individuals appear to have no end; and did we not possess the faculty of distributing
them into classes, the mind would be lost in an endless variety, and no progress be made in knowledge. It is by the faculty of abstraction that we distribute beings into genera 'and species : finding a number of individuals connected by certain qualities common to all, we give a name to these
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individuals considered as thus connected: which name, by gathering them together into one clafs, ferves in a curt manner to cxpress the whole of these individuals as distinct from others. Thus the word ani. mal ferves to denote every being which hath self-motion; and the words man, borse, lion, &c. answer similar purposes. This is the first and most common sort of abstraction; and it is of the most extensive use, by enabling us to comprehend in our rean soning whole kinds and forts, instead of individuals without end... The next sort of abstract ideas and terms comprehends. number of individual objects considered as connected by some occasional relation, A great number of persons collected together in one place, without any other relation but merely that of contiguity, are deno minated, a crowd ; in forming this term, we abstract from fex, from age, from condition, from drefs, &c. A number of perfons connected by being subjected to the same laws and to the same
government, are termed a nation; and a number of men subjected to the fame mili,
tary command, are termed an army. A
third fort of abstraction is, where a fingle property or part,
be common to many individuals, is selected to be the fubject of our contemplation ; for example, whiteness, heat, beauty, length; roundness, head, arm.
42. Abstract terms are a happy invention : it is by their means chiefly, that the particulars which we make the subject of our reafoning, are brought into close union, and separated from all others however naturally connected. Without the aid of such terms, the mind could never be kept steady to its proper fubject, but would perpetually be in hazard of assuming foreign circumstances or neglecting what are essential. word, a general term denotes in a curt manner certain objects occasionally combined. We can, without the aid of language, compare real objects by intuition, when these objects are present; and, when abfent, we can compare them by means of the ideas we have of them: but when we advance farther, and attempt to make inferences, and draw conclusions, we always employ
even in thinking. It would be as difficult to reason without them, as to perform operations in algebra without signs : for there is scarce any reasoning without some degree of abftraction; and we cannot abstract to purpose without making use of general terms. Hence it follows, that without language man would scarce be a rational being.
43. The fame thing, in different respects, has different names. With respect to certain qualities, it is termed a substance ; with respect to other qualities, a body; and with respect to qualities of all sorts, a subject : it is termed a passive fubje&t with respect to an action exerted upon it; an obje&t with respect to a percipient; a cause with respect to the effect it produces; and an effect with respect to its cause.