terms, to fignify what from its nature must be limited.

3. Taking that for the caufe of a thing which is only an occafion, or concomitant.

4. Begging the question. This is done, when the thing to be proved, or fomething equivalent, is affumed in the premises.

5. Miftaking the queftion. When the conclufion of the fyllogifm is not the thing that ought to be proved, but fomething elfe that is mistaken for it.

6. When that which is not a confequence is mistaken for a confequence; as if, because all Africans are black, it were taken for granted that all blacks are Africans.

7. The last fallacy lies in propofitions that are complex, and imply two affirmations, whereof one may be true, and the other falfe; fo that whether you grant the propofition, or deny it you are entangled; as when it is affirmed, that fuch a man has left off playing the fool. If it be granted, it implies, that he did play the fool formerly. If it be denied, it implies, or feems to imply, that he plays the fool ftill.

In this enumeration, we ought, in justice to Ariftotle, to expect only the fallacies incident to categorical fyllogifms. And I do not find, that the logicians have made any additions to it when taken in this view; although they have given fome other fallacies that are incident to fyllogifms of the hypothetical kind, particularly the fallacy of an incomplete enumeration in disjunctive fyllogifms and dilemmas.

The different fpecies of fophifms above mentioned are not fo precifely defined by Ariftotle, or by fubfequent logicians, but that they allow of great latitude in the application; and it is often dubious under what particular fpecies a fophifti

cal

cal fyllogifm ought to be claffed. We even find the fame example brought under one fpecies by one author, and under another fpecies by another. Nay, what is more ftrange, Ariftotle himself employs a long chapter in proving by a particular induction, that all the feven may be brought under that which we have called mistaking the question, and which is commonly called ignoratio elenchi. And indeed the proof of this is eafy, without that laborious detail which Ariftotle ufes for the purpose: for if you lop off from the conclufion of a fophiftical fyllogifm ali that is not fupported by the premifes, the conclufion, in that cafe, will always be found different from that which ought to have been proved; and fo it falls under the ignoratio elenchi.

It was probably Ariftotle's aim, to reduce all the poffible variety of fophifms, as he had attempted to do of juft fyllogifms, to certain definite fpecies: but he feems to be fenfible that he had fallen fhort in this laft attempt. When a genus is properly divided into its fpecies, the fpecies fhould not only, when taken together, exhauft the whole genus; but every fpecies fhould have its own precinct fo accurately defined, that one fhall not encroach upon another. And when an individual can be faid to belong to two or three different fpecies, the divifion is imperfect; yet this is the cafe of Ariftotle's divifion of the fophifms, by his own acknowledgement. It ought not therefore to be taken for a divifion ftri&ly logical. It may rather be compared to the feveral fpecies or forms of action invented in law for the redrefs of wrongs. For every wrong there is a remedy in law by one action or another: but fometimes a man may take his choice among feveral different actions. So every fophiftical fyllogifm may, by a little art, be brought under one

or

or other of the fpecies mentioned by Aristotle, and very often you may take your choice of two or three.

Befides the enumeration of the various kinds of fophifms, there are many other things in this treatise concerning the art of managing a fyllogiftical difpute with an antagonist. And indeed, if the paflion for this kind of litigation, which reigned for fo many ages, fhould ever again lift up its head, we may predict, that the Organon of Aristotle will then become a fashionable study : for it contains fuch admirable materials and documents for this art, that it may be faid to have brought it to a fcience.

The conclufion of this treatife ought not to be overlooked: it manifeftly relates, not to the prefent treatise only, but alfo to the whole analytics and topics of the author. I fhall therefore give the substance of it.

cr

"Of those who may be called inventers, fome have made important additions to things long "before begun, and carried on through a course "of ages; others have given a small beginning to "things which, in fucceeding times, will be brought "to greater perfection. The beginning of a thing, though fmall, is the chief part of it, and requires the greatest degree of invention; for it "is eafy to make additions to inventions once "begun. Now with regard to the dialectical art, "there was not fomething done, and fomething "remaining to be done. There was abfolutely "nothing done: for thofe who profeffed the art "of difputation, had only a fet of orations com"pofed, and of arguments, and of captious quef"tions, which might fuit many occafions. These "their scholars foon learned, and fitted to the "occafion. This was not to teach you the art, "but to furnish you with the materials produc

"ed

"ed by the art: as if a man profeffing to teach you the art of making fhoes, fhould bring you a parcel of fhoes of various fizes and fhapes, "from which you may provide those who want. "This may have its ufe; but it is not to teach "the art of making fhoes. And indeed, with re"gard to rhetorical declamation, there are many cr precepts handed down from ancient times; but "with regard to the conftruction of fyllogifms,

"not one.

"We have therefore employed much time and "labour upon this fubject; and if our fyftem ap66 pear to you not to be in the number of those "things, which, being before carried a certain "length, were left to be perfected; we hope for your favourable acceptance of what is done, and your indulgence in what is left imperfect."

CHA P. VI.

Reflections on the Utility of Logic, and the Means of its improvement.

SECT. 1. Of the Utility of Logic.

MEN rarely leave one extreme without run

ning into the contrary. It is no wonder, therefore, that the exceffive admiration of Aristotle, which continued for fo many ages, fhould end in an undue contempt; and that the high esteem of logic as the grand engine of science, should at laft make way for too unfavourable an opinion, which feems now prevalent, of its being unwor

thy

thy of a place in a liberal education. Those who think according to the fashion, as the greatest part of men do, will be as prone to go into this extreme, as their grandfathers were to go into the contrary.

Laying afide prejudice, whether fashionable or unfashionable, let us confider whether logic is, or may be made, fubfervient to any good purpose. Its profeffed end is, to teach men to think, to judge, and to reason, with precifion and accuracy. man will fay that this is a matter of no importance; the only thing therefore that admits of doubt, is, whether it can be taught.

No

To refolve this doubt, it may be observed, that our rational faculty is the gift of God, given to men in very different measure. Some have a large portion, fome a lefs; and where there is a remarkable defect of the natural power, it cannot be fupplied by any culture. But this natural power, even where it is the ftrongeft, may lie dead for the want of the means of improvement: a favage may have been born with as good faculties as a Bacon or a Newton: but his talent was buried, being never put to ufe; while theirs was cultivated to the best advantage.

It may likewise be obferved, that the chief mean of improving our rational power, is the vigorous exercise of it, in various ways and in different fubjects, by which the habit is acquired of exercifing it properly. Without fuch exercise, and good fenfe over and above, a man who has studied logic all his life, may after all be only a petulant wrangler, without true judgement or fkili of reafoning in any fcience.

I take this to be Locke's meaning, when in his Thoughts on Education he fays, "If you would "have your fon to reafon well, let him read Chil"lingworth." The ftate of things is much altered fince Locke wrote. Logic has been much improved,