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V/e ufually reckon three fefts of Academics ; though 

 fome make five. I'he ancient Acatlnny was that which was 

 founded by Plato; and confided of thofc followers of this 

 eminent philofopher, wlio tauglit the dodrine of their maf- 

 ter without mixture or corruption. The firfl of th-jfe was 

 Speusippus; he was Aicceeded by Xenocratts. After 

 his death the direftion of the academy devolved upon Po- 

 LEMO, and then upon Cratfs, and terminated with 

 Grantor. After the death of Crates, a new tribe of philo- 

 lophers arofe, who on account of certain innovations in their 

 manner of philofophifing, which in fome meafure receded 

 from the Platonic fyllem, without entirely dcfcrting it, have 

 been diftlnguiflied by the appellation of the Second or Mid- 

 dle Academy. The firll preceptor, who appears in this clafs, 

 and who, in confequence of the innovations which he intro- 

 duced into the Platonic fchool, has been commonly con- 

 fidered as the founder of this Academy, is Arcesilaus. 



In order to conceive jullly concerning the nature and 

 caufes of this revolution, it will be proper to advert to the 

 ftate of opinions in the preceding period. It had been very 

 generally maintained by both the Greek and Barbaric plii- 

 lofophers, that there can be no certain knowledge of things 

 ib variable and fluduating as thofe mater' il objedts which 

 fall under the notice of the fenfes. But they did not ima- 

 gine, that human reafon is wholly incapable of arriving at 

 truth ; ngr was the doftrine of univerfal fcepticifm intro- 

 duced in the infancy of philofophy. In excluding material 

 objefts from the department of fcience, the firll philofophers 

 diicovered an inclination to inquire with modefty concerning 

 the nature of things, to divert themfelves of prejudice, and to 

 fatisfy themfelves with a fober alTent to thofe truths which lay 

 within the reach of the human underftanding. Befides, the 

 Barbaric philofophers, and after them the Greeks, held two 

 kinds of doftrine, the popular for the amufement of the 

 vulgar, and the concealed, which was communicated in the 

 confidence of mere private inftruftion to their profelTed dif- 

 ciples. Such was the (late of philofophy, when Socrates 

 appeared, and exerted him.felf in regulating the conduft of 

 the human mind. In oppofition to the Sophills, who 

 boafted that they knew every thing, he confeffed that he 

 knew nothing ; by which acknowledgment he did not mean 

 to alTeit the univerfal uncertainty of human knowledge, but 

 merely to convince his followers of the futility of thofe fpe- 

 culations, which do not reft upon the firm foundation of ex- 

 perience, and to teach them modefty in their inquiries, and 

 diffidence in their affertions. Among the fefts who fprung 

 out of the fchool of Socrates, the greater number deviated 

 into the mazes of difputation,andrefumed the Sophiftic mode 

 of arguing on either fide of every queilion, that was pro- 

 pofed. Plato inclined to a ftricler method of philofophifing ; 

 and in his public diiputations after the Soeratic manner, 

 whilil he refuted the opinions of others, and left his hearers 

 imdecided concerning his own, he fully explained the prin- 

 ciples of his philofophy to thofe pupils who were indulged 

 with his private and confidential inllruelion. His doftrine 

 was, that no certain knowledge can be obtained concerning 

 the varying forms of natural bodies, and that ideas are the 

 only objerts of fcience. This doftrine was univerfally 

 taught in the Old ylcademy ; but before the time of Arcefi- 

 laus, it was never denied, that ufeful opinions may be de- 

 duced from the fenfes. Cic. Acad. 1. I. c. 8. torn. ii. Ed. 

 Olivet. Two fefts arofe about this time, which threatened 

 the deftruCtion of the Platonic fyllem ; one was founded 

 by Pyrrho, which held the dotlrine of univerfal Icepticlfm, 

 and the other by Zeno, which maintained the certainty ot 

 human knowledge, and taught with great confidence, a 

 dodriae elfeatialTy different ftom that of Plato. In this 



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fituation, Arccfilaus ihonght it ncceflV.ry to fxcrcifo a cats- 

 tious referve with regard to tlie doflrine of his mailer, and 

 to conceal his opinions fi-om tlie vulgar, under the appc.v- 

 ance of doubt and uncertainty. Profelfnig to ilerivc hit 

 dodrine concerning the uncertainty of knowledge from 

 Socrates, Plato, and other philofophers, he manitaincd, 

 that though there is a real certainly in the nature of 

 things, cverj- thing is uncertain to the liuman underAand- 

 ing, and confequently that all confident affertions arc un- 

 reafonable. He ihoiiglit it difgraceful to affent to any pro- 

 poliiion, the truth of which is not fully cftablifhed, and 

 maintained that, in all queftions, oppofitc opinions may be 

 fupported by arguments of cqu:d weight. He dilputcd 

 agalnll the teillmony of the fenfes, and tlic aulhoiity of rea- 

 fon ; acknowledging at the fame time, that tluy ftiniifli 

 probable opinions fulficient for the condud of life. I low- 

 ever, his fecret dtllgn feems to have been to cft.iblifh the 

 dodriue of Plato, that the knowledge derived from fenfiblc 

 objeds is uncertain, and that the only true feieuce is that 

 which is employed upon the immutable objeds of intelli- 

 gence, or ideas. 



After the death of Arcefilaus, the Platonic fchool was 

 fucceffively under the care of I.ACvnES, who is faid to 

 have founded a new fchool, merely becaufc he changed the 

 place of inllrudion, and held it in the garden of AttaJus, 

 within the limits of the Academic grove, and of Evanderand 

 Egefinus. Arcefilaus, however, had oppofed the Stoics 

 and other dogmatical philofophers, with lucli violence, and 

 extended his dodrhic of uncertainty fo far, as to alarm not 

 only the general body of philofophers, who treated him as a 

 common enemy to philofopliy, but even the governors of 

 the ftate, who apprehended that his opinions would diffolvc 

 all the bonds of focial virtue and of religion. His fucceffors, 

 therefore, found it difficult to fupport the credit of the 

 academy; and Carne adf.s, one of the difciplcs of this 

 fchool, relinquifhed, at leaft in words, fome of the more ob- 

 noxious tenets of Arcefilaus. 



From tills period the Platonic fchool alTumed the appel- 

 lation of the Neil) Acndemy, which may be reckoned tiie 

 th'ird in order from its firft eftabhftiment. It was the doc- 

 trine of this Academy, that the fenfes, the underftanding, 

 and the imagination, frequently deceive us, and therefore 

 cannot be infallible judges of truth ; but that, from the 

 impreffions produced on the mind, by means of the fenfes, 

 called by Carneades phantafies, or images, we infer ap- 

 pearances of truth, or probabilities. Thefe images do not 

 always correfpond to the real nature of things, and there is 

 no infallible method of determining when they are true or 

 falfe ; and confequently they afford no certain criterion of 

 truth. But, with refjied to the condud of life and the 

 purfuit of happlnefs, probable appearances are a fufficient 

 guide, becaufe it is unreafonable not to allow fome degree 

 of credit to thofe witneffes who commonly give a true re- 

 port. See Probability. According to the dodriiic of 

 the Nrzv Acmlemy, the judgments ariling from the operation 

 of the mind in cftimating the different degrees of probability, 

 are not fcience, but opinion, which is all the knowledge that 

 the human mind is capable of attaining. Tiie chief point of 

 difference between the Middle and the Neiu Academy, feems 

 to have been, that the latter taught the dodrinc of unca-- 

 talnty in lefs exceptionable terms than the foiTiier. Dr. 

 Waiburton, however, offers fevcral reafons to lluw that 

 both thefe AcademieH were in reality the fame, and that 

 they were as real fceptics, as the fed which was fo deno- 

 minated. See Div. Leg. of Mofes, vol. ii. p. 117, n8, 

 4th ed. Arcefilaus, in his zeal for overturning all other 

 feds, furuiflied his opponents with a prete.vt for charging 

 N z iiiin 



