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It is also to this place we reduce the proposals of a difficulty under its various cases, whether it be in speculation or practice: as to shew the reason of sunbeams buruing wood, whether it be done by a convex glass or a concave; or to shew the construction and measuration of triangles, whether you have two angles and a side given, or two sides and an angle, or only three sides. Here it is necessary to distribute or divide a difficulty into all its cases, in order to gain a perfect knowledge of the subject you contemplate.
It might be observed here, that logicians have sometimes given a mark or sigu to distinguish when it is an integral whole, that is divided into its parts or members, or when it is a genus, an universal whole, that is distributed into its species and individuals. The rule they give is this: whensoever the whole idea can be directly and properly affirmed of each part, as a bird is an animal; a fish is an animal; Bucephalus is a horse ; Peter is a man'; then it is a distribution of a genus into its species, or a species into its individuals : but when the whole cannot be thus directly affirmed concerning every part, then it is a division of an integral into its several species or members; as we cannot say the head, the breast, the band, or the foot is an animal; but we say, the head is a part of the animal, and the foot is another part.
This rule may hold true generally in corporeal beings, or perhaps in all substances: but when we say the fear of God is wisdom, and so is human civility : criticism is true learning, and so is philosophy: to execute a murderer is justice, and to save and defend the innocent is justice too: in these cases it is not so easily determined, whether an integral whole be divided into its parts, or an universal into its species: for the fear of God may be called either one part, or one kind of wisdom: criticism is one part, or one kind of learning : and the execution of a murderer may be called a species of justice as well as part of it. Nor in. deed is it a matter of great importance to determine this controversy.
Sect. XI.-Of an orderly Conception of Things. The last rule to direct our conceptions is, that we should rank and place then, in a proper method and just order. This is of necessary use to prevent confu. sion; for as a trader who never places his goods in his shop or warehouse in a regular order, ror keeps the accounts of his buying and selling, paying and re. ceiving, in a just method, is in utmost danger of plunging all his affairs into confusion and ruin; so 8 student who is in the search of truth, or an author or teacher who communicates knowledge to others, will very much obstruct his design, and confound his own mind or the mind of his hearers, unless he ranges his ideas in just order.
If we would therefore become successful learners or teachers, we must got conceive of things in a confused heap, but dispose u.r ideas in some certain method, which may be most easy and useful both for the understanding and memory; and be sure as much as may be to follow the nature of things, for which many rules might be given, viz.
1. Conceive as much as you can of the essentials of any subject, before you consider its accidentals.
2. Survey first the general parts and properties of any subject, before you extend your thoughts to discourse of the particular kind or species of it.
3. Contemplate things first in their own simple na. tures, and afterwards view them in composition with other things; unless it be your present purpose to take a compound being to pieces, in order to find out or to shew the nature of it by searching and discovering of what simples it is composed.
4. Consider the absolute modes or affections of any being as it is in itself, before you proceed to consider it relatively, or to survey the various relations in which it stands to other beings, &c.
Note, These rules chiefly belong to the method of instruction which the learned call synthetic.
But in the regulation of our ideas there is seldom
an absolute necessity that we should place them in this or the other particular method: it is possible in some cases that many methods may be equally good, that is, may equally assist the understanding and the memory: to frame a method exquisitely accurate, according to the strict nature of things, and to maintain this accuracy from the beginning to the end of a treatise, is a most rare and difficult thing, if not impossible. But a larger account of method would be very improper in this place, lest we anticipate what be. longs to the fourth part of logic.
Sect. XII.-The five Rules of Conception exemplified.
may be useful here to give a specimen of the five special rules to direct our conceptions, which have been the subject of tbis long chapter, and represent them practicaily in one view. Suppose the theme of our discourse were the
pas. sions of the mind.
Ist. To gain a clear and distinct idea of passion, we must define both the name and the thing.
To begin with the definition of the name: we are not here to understand the word passion in its vulgar and most limited sense, as it siguifies merely anger or fury; por do we take in its raost extensive philosophical sense, for the sustaining the action of an agent; but in the more limited philosophical sense, passions signify the various affections of the mind, such as admiration, love, or hatred; this is the defia nition of the name.
We proceed to the definitiou of the thing. Passion is defined a sensation of some special commotion in animal nature, occasioned by the mind's perception of some object suited to excite that commotion*.
Since this was written, I have published a short treatise of the passions, wherein I have so far varied from this definition as to call them sensible commotions of our whole nature, both soul and body, occasioned by the mind's perception of the obe jects, &c. I made this alteration in the description of the pas. sions in that book, chiefly to include in a more explicit mauner the passions of desire and aversion, which are acts of volition
Here the genus or general nature of passion is a sensation of some special commotion in animal nature; and herein it agrees with hunger, thirst, pain, &c. The essential difference of it is, that this commotion arises from a thought or perception of the mind, and hereby it is distinguished from hunger, thirst, or pain.
adly, We mustconceive of it completely, or survey the several parts that compose it. These are (1.) The mind's perception of some object. (2.) The consequent ruffle or special commotions of the nerves, and blood, and animal spirits. And (3.) The sensation of this inward commotion.
3dly, We must consider it comprehensively in its various properties. The most essential attributes that make up its nature has been already mentioned under the foregoing heads. Some of the most considerable properties that remain are these, viz. that passion belongs to all mankind in greater or lesser degrees: it is not constantly present with us, but upon some certain occasions : it is appointed by our Creator for various useful ends and purposes, viz. to give us vigour in the pursuit of what is good and agreeable to us, or in the avoidance of what is hurtful : it is very proper for our state of trial in this world: it is not ut. terly to be rooted out of our nature, but to be moderated and governed, according to rules of virtue and religion, &c.
4thly, We must take cognizance of the various kinds of it, which is called an extensive conception of it. If the object which the mind perceives be very uncommon, it excites the passion of admiration : if the object appear agreeable, it raises love: if the agreeable object be absent and attainable, it is desirable: if likely to be obtained, it excites hope: if rather than sensations. Yet since some commotions of animal nature attend all the passions, and since there is always a sen. satiou of these commotions, I shall not change the definition I have written here; for this will agree to all the passions, whe. ther they include any act of volition or not; nor indeed is the matter of any great importance. Nov, 17; 1798.
unattaiuable, despair: if it be present and possessed, it is the passion of joy: if lost, it excites sorrow: if the object be disagreeable, it causes in general lia. tred or aversion; if it be absent, and yet we are in danger of it, it raises our fear; if it be present, it is sorrow and sadness, Se.
5thly, All these things, and many more which go to compose a treatise on this subject, must be placed in tlxeir proper order: a slight specimen of which is exhibited in this short acconnt of passion, and which that admirable anthor Descartes has treated of at large; though, for want of sufficient experiments and observations in natural philosophy, there are some few mistakes in his account of animal nature.
SECT. XIII.-- An Illustration of these five Rules by Si
militudes. Thus we have brought the first part of logic to a conclusion: and it may not be improper here to represent its excellencies (so far as we have gone) by general hints of its chief design and use, as well as by a rarious comparison of it to those instruments which mankind have invented for their several conveniences and improvements
The desigo of logic is not to furnish us with the perceiving faculty, but only to direct and assist us in the use of it: it doth pur give us the objects of our ideas, but only casts such a light onthose oljerts which mature furnishes us with, that they may be the more clearly and distinctly known: it doth not add new parts or properties to things, but it discovers the various parts, properties, relat10:s, and dependencies of one thing apon another, anut by ranking all things ander general and special heads, it readers the nature, or any of the properties, puwers, and uses of a thing more easy to be found out, when we seek in what rask of beings it kies, and wherein it agrees witb, and wherein it uif. fers from others.
If any comparisons would illustrate this, it may be thus represented.
When logic assists us to attain a clear and distinct conception of the nature of things by definition, it is