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THE FOURTH PART OF LOGIC.
Of Disposition and Method. It is not merely a clear and distinct idea, a well-formed proposition, or a just argument, that is sufficient to search out and communicate the knowledge of a subject. There must be a variety and series of them disposed in a due manner, in order to attain this end ; and therefore it is the design of the last part of Logic, to teach us the art of method. It is that must secure our thoughts from that confusion, darkness and mistake, which unavoidably attend the meditations and discourses even of the brightest genius who despises the rules of it.
I. We shall bere consider the nature of method, and the several kinds of it.-II. Lay down the general rules of metlod, with a few particulars under them,
CHAP. I.--Of the Nature of Method and the several kinds
of it, namely, Natural and Arbitrary, Synthetic and Analytic.
METHOD, taken in the largest sense implies the “ placing of several things, or performing several operations, in such an order, as is most convenient to attain some end proposed :" and in this sense it is applied to all the works of nature and art, to all the divine affairs of creation and providence; and to the artifices, schemes, contrivances, and practices of mankind, whether in natural, civil, or sacred affairs.
Now this orderly disposition of things includes the ideas of prior, posterior, and simultaneous ; of superior, inferior, and equal; of beginning, end, and middle, &c. which are described more particularly among the general affections of being, in ontology.
But in Logic method is usually taken in a more limited sense, and the nature of it is thus described : “Method is the disposition of a variety of thoughts on any subject, in such order as inay best serve to find out unknown truths, to explain and confirm truths that are known, or to fix them in the memory."
It is distributed into two different kinds, namely, natural and arbitrary.
Natural method is that which observes the order of nature, and proceeds in such a manner, as that the knowledge of the things which follows, depends in a great measure on the things which go before, and this is two-fold, viz. synthetic and analytic, which are sometimes called synthesis and analysis. *
Synthetic method is that which begins with the parts, t and leads onward to the knowledge of the whole; it begins with the most simple principles, and general truths, and proceeds by degrees to that which is drawn from them, or compounded of them; and therefore it is called the method of composition.
Analytic method takes the whole compound as it finds it, whether it be a species or an individual, and leads us into the knowledge, of it, by resolving it into its first principles or parts, its generic nature, and its special properties; and iherefore it is called the method of resolution.
As synthetic method is generally used in teaching the sciences after they are iovented, so analytic is most practised in finding out things unknown. Though it must be confessed, that both methods are sometimes employed to find out truth and to communicate it.
If we know the parts of any subject easier and better than the whole, we consider the parts distinctly, and by putting them together, we come to the knowledge of the whole. So in grammar, we learn first to know letters, we join them to make syllables, out of syllables we compose words, and out of words we make sentences and discourses. So the physician and apothea cary kvows the nature and powers of bis simples, namely, his drugs, his berbs, bis minerals, &c. and putting them together, and considering their several virtues, he finds what will be the nature and powers of the bolus, or any compouud medicine ; this is the synthetic method.
* The word analysis has three or four senses, which it may not be improperto take police of here.
1. It sigoifies the general and particular beads of a discourse, with their motual coopection, both co-ordinate aod subordinate, drawn out by way of abstract into one or more tables, which are frequeatly placed like an index at the begiouiog or end of a book.
2. It signifies the resolving of a discourse into its various subjects and argumedis, as when any writing of the ancient prophets is resolved into the propheti. cal, bisturica!, doctrigai, and practical parts of it; it is said to be analysed in general. When a sentence is distinguished joto the nouns, the verbs, pronoups, adverbs, and otber particles of speech which compose it, then it is said to be analysed grammatically. When the same sedlence is distinguished into subject predicate, proposition, argument, act, object, cause, effect, adjunct, opposite, &c. theo it is analysed logically, and metaphysically. This last is what is chiefly meant in the theological schools, when they speak of analysing a text of scripture.
3. Analysis signifies particularly the science of Algebra, wherein a question being proposed, one or more letters, as x, y, 2, or vowels, as a, e, i, &c. are made use of to sigoify the unknowa number, wbich being intermingled with several koowo ouinbers in the question, is at last, by the rules of art, separated or re. leased from that entanglement, and its particular value is found out by shewe jog its equalion, or equality to some koowa number.
4. It sigoifies analytical method, as here explained in Logic,
+ Note. It is confessed that synthesis often begins with the gepus, and proceeds to the species aod individuals. But the geous or generic nature is then considered oply as a physical or essential part of the species, though it be sometimes celled en universal, or logical whole. Thus syathetic method maintajos its own description still, for it begins witb the pasis, and proceeds to the whole, bich is como, posed of thein.
But if we are better acquainted with the whole than we are with particular parts, then we divide or resolve the whole into its parts, and thereby gain a distinct knowledge of them. So in vulgar life we learn in the gross what plants or minerals are ; and then by chemistry we gain the knowledge of salt, sulphur, spirit, water, earth, which are the principles of them. So we are first acquainted with the whole body of an animal, and then by anatomy or dissection, we come to learn the inward and outward parts of it. This is the analytic method.
According to this most general and obvious idea of synthetic and analytic method, they differ from each other as the way which leads up from a valley to a mountain differs froin itself, considered as it leads down from the mountain to the valley; or as St. Matthew and St. Luke prove Christ to be the Son of Abraham; Luke finds it out by analysis, rising from Christ to his ancestors; Matthew teaches in the synthetic method, beginning from Abraham, and shewing that Christ is found among his posterity. Therefore it is a usual thing in the sciences, when we have by analysis found out a truth, we use the synthetic method to explain and deliver it, and prove it to be true.
In this easy view of things, these two kinds of method may be preserved conspicuously, and entirely distinct ; but the subjects of koowle:Ige being infinite, and the ways whereby we arrive at this knowledge being almost infinitely various, it is very difficult, and almost impossible, always to maintain the precise distinction between these two methods.
This will evidently appear in the following observations:
1. Analytic method being used chiefly to find out things unknown, it is not limited or confined merely to begin with some whole subject, and proceed to the knowledge of its parts, but it takes its rise sometimes from any single part or property, or from any thing whatsoever that belongs to a subject which happens to be tirst or most easily known, and thereby enquires into ihe more abstruse and unknown parts, properties, causes, effects, and modes of it, whether absolute or relative: as for instance,
(1.) Anlysis finds out causes by their effects. So in the speculative part of natural philosophy when we observe light, colours, motions, bardness, sofiness, and other properties and powers of bodies, or any of the common or uncommon appearances of things either on earth or in heaven, we search out the causes of them. So by the various creatures we find out the Creator, and learn his wisdom, power and goodness.
It finds ont effects by their causes. So the practical and me chanical part of natural philosophy considers such powers of motion, as the wind, the fire, and the water, &c. and then contrives what uses tbey may be applied to, and what will be their effects in order to make mills and engines of various kinds.
(3.) It finds out the general and special nature of a thing by considering the various attributes of the individuals, and observing what is common and what is proper, what is accidental, and what is essential. So by surveying the colour, the shape, motion, rest, place, solidity, extension of bodies we come to find that the nature of body in general is solid extension; because all other qualities of bodies are changeble, but this belongs to all bodies, and it endures through all changes ; and because this is proper to body alone, and agrees not to any thiog else ; and it is the foundation of all other properties,
(4.) It finds out the remaining properties or parts of a thing, by having some parts or properties given. So the area of a triangle is found by knowing the height and the base. So by having two sides, and an angle of a triangle given we find the remaining side, and angles. So when we know cogitation is the prime attribute of a spirit, we infer its immateriality, and thence its immortality.
(5.) Analysis finds the means necessary to attain a proposed end, by having the end first assignerl. So in moral, political, economical affairs, haviog proposed the government of self, a family, a society, or a nation, in order to their best interest, we consider and search out what are the proper laws, rules and means to effeet it. So in the practices of artificers, and the manufacturers of various kinds, the end being proposed, as, making cloth, houses, ships, &c. we fiod out ways of composing these things for the several uses of human life. But the putting any of these means in execution to attain the end, is synthetic method.
Many other particulars might be represented to shew the various forms of analytic method, whereby truth is found out, and some of them come very near to synthetic, so as hardly to be distinguished.
II. Not only the investigation of truth, but the communication of it also is often practised in such a method, as neither agrees precisely to synthetic or analytic. Some sciences, if you consider the whole of them in general, are treated in synthetic order; so physies, or natural philosophy, begins usually with an account of the general nature and properties of matter or bodies, and by degrees descends to consider the particular species of bodies with their powers and properties ; yet it is very evident, that when philosophers come to particular plants and animals, then by chemistry and analomy they analyse to resolve those bodies into their several constituent parts : On the other band, VOL. VII.
Logic is begun in analytic method ; the whole is divided into its integral parts, according to the four operations of the mind : yet here and there synthetic method is used in the particular branches of it, for it treats of ideas in general first, and then descends to the several species of them ; it teaches us how propositions are made up of ideas and syllogisms of propositions, which is the order of composition.
The ancient scholastic writers have taken a great deal of pains, and engaged in useless disputes about these two methods, and after all have not been able to give such an account of them as to keep them entirely distinct from each other, neither in the theory nor in the practice. Some of the moderns have avoided this confusion in some measure, by confining themselves to describe almost nothing else but the synthetic and analytic methods of Geometricians and Algebraists, whereby they have too much narrowed the nature and rules of method, as though every thing were to be treated in mathematical forms.
Upon the whole, I conclude, that neither of these two methods should be too scrupulously avd superstitiously pursued, either in the invention or in the communication of knowledge. It is enough, if the order of nature be but observed in making the koowledge of things following depend on the knowledge of the things which go before. Oftentimes a mised method will be found most effectual for these purposes ; and indeed a wise and judicious prospeet of our main end and desiga must regulate all method whatsoever.
Here the rules of natural method ought to be proposed, (whether it be analytic, or synthetic, or mixed :) but it is proper first to give some account of arbitrary inethod, lest it be thrust at too great adistance from the first mention of it.
Arbitrary method leaves the order of nature, and accommo dates itself to inany purposes ; such as, to treasure up things, and retain them in memory; to harangue and persuade inankind to any practice in the religious or the civil life ; or to delight, amuse, or entertain the mind.
As for the assistance of the memory, in most things a natural order has an happy influence; for reason itself deducing one shing from another, greatly assists the memory by the natural connexion and mutual dependence of things. But there are varivus other methods which mankind have made use of for this purpose, and indeed there are some subjects that can hardly be reduced to analysis or synthesis.
In reading or writing history, some follow the order of the governors of a nation, and dispose every trapsaction under their poarticular reigns : so the sacred books of Kings and Chronicles are written. Some write io annals or journals, and make a new chapter of every year. Some put all those transactions together