The history of philosophy, in eight parts by Thomas Stanley.

CHAP. V.

The Elements and Office of Dialectick.

OF Dialectick, the first and chiefest Element according to Plato, is, first, to consider the essence of every thing; next, the accidents thereof. What a thing is, it considers, either from its superiors, by division and definition, or contrariwise by Analysis. Accidents which adhere to substances, are considered, either from those things which are contained by induction, or from those which do contain by Syllogisme.

Hence the parts of Dialectick are these, Division, Definition, Ana∣lysis, Induction, Syllogisme.

Of Divisions, one is a distribution of the Genus into Species, and of the whole into parts; as when we divide the Soule into the rationall part, and the irrationall; and the latter, into the concupiscible and the irascible. Another is of a world into divers significations, when the same may be taken severall waies. A third of accidents, according to their subjects; as when we say of good, some belong to the soul, some to the body, some are externall. The fourth of subjects, according to their accidents; as of men, some are good, some ill, some indifferent. Division of the Genus into its Species, is first to be used, when we examine the essence

of a thing, this cannot be done but by definitions.

Definition is made by Division in this manner, we must take the Genus of the thing to be defined, as that of man, living crea∣ture; that we must divide by the next differences, descending to its species, as rationall, and irrationall, mortall, and immortall. Thus by adding the first difference to the Genus, is made the de∣finition of man.

Of Analysis there are three kinds, one by which we ascend from Sensibles to primary Intelligibles, another whereby we ascend by demonstrates and subdemonstrates, to indemonstrable imme∣diate propositions. The last, which from supposition proceedeth to those principles which are taken without supposition.

The first kind is thus, as if from that Beauty which is in the body, we should proceed to that of the minde, from that to an∣other conversant in the offices of life, thence to that of Lawes, and so at last to the vast ocean of Beauty, that by these steps, as it were, we may arrive at the sight of the supream Beauty.

The second kind of Analysis is thus; We must suppose that which we seek, and consider those which are precedent, demon∣strating them by progression, from inferiours to superiours, untill we arrive at that which is first and generally granted: From which, beginning anew, we return synthetically to that which was sought. As for example, I enquire whether the Soul be im∣mortall, and supposing it to be so, I enquire whether it be al∣waies moved. This being demonstrated, I again enquire, whe∣ther that which is alwaies moved, is moved by its selfe, which being again demonstrated, we examine, whether that which is moved by its selfe, be the principall of motion. Lastly, whether a principall is ingenerate; this, as most certain, is admitted by all. That which is ingenerate, is also incorruptible; whence, as from a thing most certain, we collect this demonstration. If a Principle be ingenerate and incorruptible, that which is moved by its selfe is the principle of motion; but the soul is moved by its selfe, therefore the soul is incorruptible, ingenerate, and im∣mortall.

The third kind of Analysis upon supposition is this; He who enquireth after a thing, first, supposeth that thing, then observes what will follow upon that supposition. If a reason for the sup∣position be required, assuming another supposition, he enquireth, whether that which was first supposed, follow again upon an∣other supposition: This he alwaies observeth; untill he come at last to that principle, which is not taken upon supposition.

Induction is every method by reason, which proceedeth either from like to like, or from Singulars to Universalls: It is of great efficacy to excite naturall notions.