Grice e Cavallo: filosofia naturale, filosofia trans-naturale

  Of Natural Philosophy ;—~its Name ;•—its Objeft —its Axioms ; —and the Rules of Philofophizing . T HE word Philofophy, though ufed by ancient authors in fenfes fomewhat different, does, however, in its moft ufual acceptation, mean the love of general knowledge. It is divided into moral and natural. Moral philofophy treats of the manners, the duties, and the condud of man, confidered as a rational and focial beings but the bufinefs of natural philofophy, is to colled the hiftory of the phenomena which take place amongft natural things, viz. among# the bodies of the Univerfes to inveftigate their caufes and effeds ; and thence to deduce fuch natural laws, as may afterwards be applied to a variety of ufeful purpofes*. Natural * The word philofophy is of Greek origin. Pitagoras, a learned Greek, feems to have been the firfl who called himfelf philofopher j viz. a lover of knowledge, or of wifvol. r. b dom. 2 Of Philosophy in general. Natural things means all bodies ; and the aflemblage or fyftem of them all is called the univerfe. The word phenomenon fignifies an appearance, or, in a more enlarged acceptation, whatever is perceived by our fenfes*. Thus the fall of a ftone, the evaporation of water, the folution of fait in water, a tlafh of lightning, and fo on ; are all phenomena. As all phenomena depend on properties peculiar to different bodies ; for it is a property of a ftone to fall towards the earth, of the water to be cvaporable, of the fait to be foluble in water, &c. therefore v/e fay that the bufinefs of natural philofophy is to examine the properties of the various bodies of the univerfe, to inveftigate their caufes, and thence to infer ufeful deductions. Agreeably dom, from the words piaoj, a lover or friend , and croplxi, of knowledge or wifdom. Moral philofophy is derived from the latin mos , or its plural mores , fignifying manners or behiyiour. It has been likewife called ethics, from the Greek r,ccs, mos, manner, behaviour. Natural philofophy has alfj been called p hylics , phyfology, and experimental phi Ifophy: The ftrft of thofe names is derived from nature, or gv-T.hr., natural ; the fecond is derived from pvair, nature , and >. a dijeourfe ; the laft deno nination, which was introduced not many years ego, is obvioufly derived from the juft method of experiment. ' inveftigation, which has been univerfally adopted ftnee the r P.vul of learnin-"- 'n Europe. * Phenomenon, whofe plural is phenomena, owes its origin to the Greek word pf.-.ai, to appear. and the Rules of Philofophizing. 3 Agreeably to this, the reader will find in the courfe of this work, an account of the principal properties of natural bodies, arranged under diftincft heads, with an explanation of their efFefts, and of the caufes on which they depend, as far as has been afeertained by means of reafoning and experience; he will be informed of the principal hypothefes that have been offered for the explanation of faffs, whofe caufes have not yet been demonflratively proved; he will find a flatement of the laws of nature, or of fuch rules as have been deduced from the concurrence of fimilar facts ; and, laftly, he will be inftrudted in the management of philofophical inflruments, and in the mode of performing the experiments that may be thought neceffary either for the llluftration of what has been already afeertained, or for the farther inveftigation of the properties of natural bodies. We need not fay much with refpect to the end 01 defign of natural philofophy.—Its application and its ufes, or the advantages which mankind may deuve therefrom, will be eafily fuggefted by a very fuperficial examination of whatever takes place about us. The properties of the air we breathe ; the action and power of our limbs ; the light, the found, and other perceptions of our fenfes ; the adcions of the engines that are ufed in hufoandry, navigation, &c. ; the viciffitudes of the feafons, the movements of the celeflial bodies, and io forth ; do all fall under the con fideration of b 2 the 4 Of Philosophy in general ; the philofophcr. Our welfare, our very exiftenee-. depends upon them. A very flight acquaintance with the political ftate of the world, will be fufficient to fhew, that the cultivation of the various branches of natural philofophy has actually placed the Europeans and their colonies above the reft of mankind. Their . difcoveries and improvements in aftronomy, optics, navigation, chemiftry, magnetifm, mineralogy, and in the numerous arts which depend on thofe and other branches of philofophy, have fupplied them with innumerable articles of ufe and luxury, have multiplied their riches, and have extended their powers to a degree even beyond the expectations of our predeceffors. The various properties of matter may be divided into two claffes, viz. the general properties, which belong to all bodies, and the peculiar properties, or thofe which belong to certain bodies only, exclufively of others. In the firft part of this work we fhall examine the general properties of matter. Thofe which belong to certain bodies only, will be treated of in the l'econd. In the third part we fhall examine the properties of fuch fubftances as may be called hypothetical ; their exiftenee having not yet been iatisfadtorily proved. In the fourth we fhall extend our views beyond the limits of our Earth, and fhall examine the number, the movements, and other properties of the celeltial bodies. The and the Rules of Philofophizing. 5 The fifth, or laft part, will contain feveral detached articles, fuch as the defeription of feveral additional experiments, machines, &c. which cannot conveniently be inferted in the preceding divilions. The axioms of philofophy, or the axioms which have been deduced from common and conftant experience, are fo evident and fo generally known> that it will be fufficient to mention a few of them only. I. Nothing has no property; hence, JI. No fubftance, or nothing, can be produced from nothing. III. Matter cannot be annihilated, or reduced to nothing. Some perfons may perhaps not readily admit, the propriety of this axiom ; feeing that a great many things appear to be utterly deftroyed by the action of fire ; alfo that water may be caufed to difappear by means of evaporation, and fo forth. But it mud be obferved, that in thofe cafes the lubftances are not annihilated ; but they are only difperfed, or removed from one place to another, or they are divided into particles fo minute as to elude our fenfes. Thus when a piece of wood is placed upon the fire, the greateft part of it difappears, and a few afhes only remain, the weight and bulk of which does not amount to the hundredth part ot that of the original piece of wood. Now in this cafe the piece of wood is divided into b 3 its 6 O/Philosophy in general ; its component fubdances, which the atdion of the fire drives different ways : the fluid part, for inftance, becomes fleam, the light coaly part either adheres to the chimney or is difperfed through the air, &c. And if, after the combuftion, the fcattered materials were collecded together, (which may in great meafure be done), the fum of their weights would equal the weight of the original piece of wood. IV. Every effect has, or is produced by, a caufe, and is proportionate to it. It may in general be obferved with refpedt to. thofe axioms, that we only mean to affert what has been conflantly (hewn, and confirmed by experience, and is not cont rad idled either by reafon, or by any experiment. But we do not mean to affert that they are as evident as the axioms of geometry; nor do we in the lead prefume to preferibe limits to the agency of the Almighty Creator of every thing, wvhofe power and whofe ends are too far re- moved from the reach of our underBandings. Having dated the principal axioms of philolophy, it is in the next place neceffary to mention the rules of philofophizing, which have been formed after mature confideration, for the purpofe of preventing errors as much as poffible, and in order to lead the dudent of nature along the fhorted and fifed way, to the attainment of true and ufeful knowledge.—Thofe rules are not more than four; viz. I. We and the Rules of Philofophizing. 7 I. We are to admit no more caufes of natural things, than fuch as are both true and fufHcient to e:g in the appearances. II. Therefore to the fame natural effects we muft, as far as poffible, affign the fame caufes. III. Such qualities of bodies as are not capable of increafe or decreafe, and which are found to belong to all bodies within the reach of our experiments, are to be efteemed the univerfal qualities ol all bodies whatfoever. IV. In experimental philofophy we are to look upon propofitions colledted by general induction from phenomena, as accurately or very nearly true, notwithftanding any contrary hypothefes that may be imagined, till fuch time as other phenomena occur, by which they either may be corrected, or may be fhewn to be liable to exceptions With refpeft to the degree of evidence which ought to be expected in natural philofophy, it is neceifary to remark, that phyficai matters cannot in general be capable of luch abfolute certainty as the branches of mathematics.—The propofitions of the latter fcience are clearly deduced from a fet of axioms fo very fimple and evident, as to convey perfect convi&ion to the mind ; nor can any of them be denied without a manifeft: abfurdity. But in natural philofophy we can only fay, that becaufe lome particular effects have been conflantly produced under certain circumftances ; therefore they will moft likely continue to bV produced as long E 4 as 8 Of Philosoph Y in general $ as the lame circumftances exifl ; and likewife that they do, in all probability, depend upon thofe circumftances. And this is what vve mean by laias of nature \ as will be more particularly defined in the next chapter. We may, indeed, affume various phyfical princi[>ies, and by reafoning upon them, we may ftndtly demontliate the deduction of certain confequences. But as the demonftration goes no farther than to prove that luch confequences muft neceflarily follow the principles which have been afl'urned, the conlequences themfelves can have no greater degree of certainty than the principles are pofieftedof; fo that they are true, or falfe, or probable, according as the principles upon which they depend are true, or faife, or probable. It has been found, for inftance, that a magnet, when left at liberty, does always direct itfelf to certain parrs of the world ; upon which property the mariner’s compafs has been conftructed ; and it has been likewife obferved, that this directive property of a natural or artificial magnet, is not obftructed by the interpofition or proximity of gold, or filver, or glaft, or, in fhort, of any other fubftance, as far as has been tried, excepting iron and ferrugineous bodies. Now afluming this obfervation as a principle, it naturally follows, that, iron excepted, the box of the mariner’s compafs may be made of any fubftance that may be moft agreeable to the. workman, or that may beft anivver other purpofes. Yet it muft be confefted. and the Rules of Philofophizing. 9 confe fifed, that this proportion is by no means fo certain as a geometrical one ; and (luctly lpeaking it may only be laid to be highly probable ; for though all the bodies that have been tried with this view, iron excepted, have been found not to afifefl the directive property of the magnet or magnetic needle , yet we are not certain that a body, or fome combination of bodies, may not. hereafter be difcovered, which may obftrudt that property. Nqtwithftanding this obfervation, I am far from meaning to encourage fcepticilm ; my only objedt being to fhew that juft and proper degree of conviction which ought to be annexed tophyfical knowledge ; fo that the ftudent of this fcience may become neither a blind believer, nor a uielels fceDtic*. Befides a ftriCt adherence to the abovementioned rules, whoever withes to make any proficiency in the ftudy of nature, (liould make himfelf acquainted with the various branches of mathematics , at leaft with the elements of geometry, arithmetic, trigonometry, and the principal properties of the conic * Scepticifm or fkepticifm is the do&rine of the fceptics, an ancient let of philofopbers, whofe peculiar tenet was, that all things are uncertain and incomprehenlible ; and that the mind is never to afient to any thing, but to remain in an absolute date of hefitation and. indifference. — The word fceptic is derived from the Greek anc7flM®~y which fignifies confederate, and inquiftive. 10 A General Idea of Matter , conic fedions ; for fincc almoft every phyfical effed depends upon motion, magnitude, and figure, it is impofiible to calculate velocities, powers, weights, times, &c, without a competent degree of mathematical knowledge ; which fcience may in truth be called the language of nature.