more from Plato

Single Idea 12355

[catalogued under 2. Reason / D. Definition / 5. Genus and Differentia]

Full Idea

'Plane' is the genus of figures in the plane, and 'solid' is the genus of solids. For every figure is either a plane with abc features or a solid with xyz features, so it is the plane and solid which underlie these differentiae.

Gist of Idea

'Plane' is the genus of plane figures, and 'solid' of solids, with differentiae picking out types of corner


Plato (The Republic [c.374 BCE], 1024b01)

Book Reference

Aristotle: 'The Metaphysics', ed/tr. Lawson-Tancred,Hugh [Penguin 1998], p.147

A Reaction

Thus you could hardly define a square by merely mentioning that it is a 'plane figure', and you would need pretty precise differentiae before you could be certain you were only dealing with a square, and not a parallelogram.