The arte of logick Plainely taught in the English tongue, according to the best approued authors. Very necessary for all students in any profession, how to defend any argument against all subtill sophisters, and cauelling schismatikes, and how to confute their false syllogismes, and captious arguments. By M. Blundevile.

CHAP. XXII.

Of a sophisticall Syllogisme.

WHat is a Sophisticall or false Syllogisme?

A false Syllogisme is that which is either made of false Propositions, or else of such as seeme probable, and be not in deede, or else of probable premisses not rightly concluding: and of such Syllogismes there be three sortes, the one failing in matter, the other in forme, the third in both.

When is it said to faile in matter?

It faileth in matter, when the Syllogisme hauing true forme, is made of such Propositions as seeme probable, and bee not probable in deede, as thus: no opposites are both true at once, but subcontraries are opposites: Ergo, they are not true. Here though this Maior seemeth probable, because many oppo∣sites, as contraries, and contradictories be neuer both true at once, yet it is not probable in deede: for those opposites which be called subcontrarie and subalternate, may bee both true at once as hath been before.

When is it said to faile in forme?

It faileth in forme, when it is made of probable premisses, not rightly concluding: because they be not orderly disposed according to Moode and Figure, as thus: Some opposites are both true at once, but contradictories are opposites: Ergo, Contradictories are both true at once. Here the premisses be probable, but the Syllogisme halteth in forme, because that of meere particulars no good conclusion can follow.

When is it said to faile both in matter and forme?

It faileth both in matter and forme, when the premisses are neither probable, nor yet doe conclude rightly according to the rules of Logicke, as thus: No opposites are both true at once, but subcontraries are opposites: Ergo, no subcontraries are both true at once. Here first it faileth in matter, because the Maior, (as hath been said before) is not probable in deed. A∣gaine, it faileth in forme, because that contrary to the rules of a

Syllogisme, an vniuersall conclusion is implied, one of the pre∣misses being particular, which should not be.

Is there no other kindes of false Syllogismes?

Yes, there is another kinde of false Syllogisme, called of A∣ristotle, Syllogismus falsigraphus, which proceedeth of the pro∣per principles of some discipline, misconstrued, or not rightly vnderstood, as thus: All lines drawne from one selfe-point to another selfe-point, be equall, a right line and a crooked line be drawne from one selfe-point to another selfe-point: Ergo, a right line and a crooked line be equal, as you see in the figure* 1.1 a. b. in the Margent: Here the Maior being a principle in Ge∣ometrie, is not rightly vnderstood; for the right meaning of the principle is, that the lines should be also drawn in one selfe space, and then they must needes be equall, (that is to say) all of one length: but as touching false Syllogismes, wee shall treate of them hereafter more at large in the Elenches: in the meane time we minde to speake of the other kindes of argu∣ments before mentioned; and first of Induction.

Notes

• * 1.1

  [illustration]