Monitio logica, or, An abstract and translation of Burgersdicius his logick by a gentleman.

CHAP. XXI. Of Precognitions, or Things requisite to be known, before we enter upon De∣monstration.

Ax. 1. IN every Demonstration, 〈 in non-Latin alphabet 〉〈 in non-Latin alphabet 〉, or Why, or Demonstrative Science, three Things are to be considered, viz. Subject, Affection and Cause by which demonstrated, that the Affection is in the Subject, &c.

Ax. 2. Of Subject and Affection is composed the Question: Of Cause with the Affection, First then, Subject Combined, the Premisses or Principles, by which such Question is to be demon∣strated.

Ax. 3. And in these, two things are to be consider∣ed; first Precognitions, and then Conditions, which in such a Demonstration are to be observed.

Ax. 4. Of Precognitions, the one is, whether it be? the other, what that is which is said? or what signi∣fies the Name?

Ax. 5. Of the three Terms, it is to be foreknown what signifies the Name; that is, what the Meaning or Importance of them is. Subject, Cause, also Premisses or Principles, whether they be? And this of the Affection and Conclusion, is to be demonstrated.

1. §. Of the three Terms, what is the Name; be∣cause otherwise we should dispute concerning things unknown.

2. §. Of Subject and Cause, whether they be? For when it is uncertain, whether there is any such

thing as the Cause, the Argumentation is infirm, and begetteth not Science. When Subject, frivolous and inept: For in vain should we prove, for Instance, that the Pigmies are Chol••rick; because of their short Stature, unless it appears, that there are Pigmies, &c. Of Pre∣misses or Principles, also that they are true: For o∣therwise we lay a Foundation of Things that are not known: It remains therefore that of the Affection it should be demonstrated, that it is; and of the whole Con∣clusion, consisting of Subject and Affection, that it be true, or that the Affection is in the Subject, &c.

Ax. 6. Of which Precognitions those that are self∣evident, that is, so, that no body can be ignorant of them, are only made in the mind; those not so, but that they may be unknown, are always express'd in the first Entran∣ces of Sciences.

Ax. 7. And if so soon as produc'd, they are believ'd by the Disciple, they may be properly term'd Suppositions; but if not, and the Disciple be doubtful of them; or e∣ven encline to a contrary Opinion, Postulata, or things to be required or demanded.

1. §. There are some things, says Aristotle, in Sciences, of which no one can be ignorant, and these they call Suppositions, as we said before, or A∣xioms; that is, such as carry such a Native Clarity with 'em, as they are worthy of every body to be credi∣ted; some of which one may: But yet, so soon as proposed by a Master, are believed without Proof; And such as these, are termed Definitions: And some not so immediately; but delivered Precariously, and by way as it were of Agreement; because the Probation of them, if any, belongs to the Metaphysicks. And such as these they call Postulata, or things required, or to be demand∣ed, &c.

And so we come to the Conditions which in eve∣ry Demonstration Why, are to be observed; and First to those of the Question to be demonstrated, and Medium, which is to be used in Demonstration.