2. §. Demonstration's Genus is Syllogism: And herein it agrees with the Dialectical. Its Diffe∣rence is fetch'd from the End, which is Science. Now the Word Science is either taken largely to signifie any Cognition or true Assent; or strictly, a firm and infallible one; or lastly, an Assent of Propo∣sitions made known by the Cause or Effect. And that only comes under the Notion of Science, here, which is gotten by the Cause or the Effect; and is proper to this Place, &c.
Ax. 2. Of Demonstration, one is, Why a thing is, and the other, That a thing is.
Ax. 3. That of Why is that which not only proves the thing is or is not; but also renders a Reason, why the thing is or is not.
Ax. 4. The Demonstration That, only proves that the thing either is or is not.
1. §. Now this Division is fetch'd from the End: For, whereas Demonstration is a Syllogism Scientific, it altogether follows, that how many-fold Science is, so many must Demonstration be; But Science, one is Why, and the other That; and therefore so must Demonstration be. See Cap. 13. Book 1. of the Post.
Science and Demonstration, in short, Why, differ from that of that a thing is, in the Ratio and Quality of the Medium, which in that of Why a thing is, is the next Cause; that is, such a Cause as that being put, the Propriety must be put also; and that ta∣ken away, the Propriety also must be taken away, when that of the other is not the Cause, but Effect; at least, not the next, but remote, as will hereafter be made appear, &c.
In the Interim, take we a View of what is necessa∣ry to be known before we enter upon this Head.