more from E.J. Lowe

Single Idea 16540

[catalogued under 2. Reason / D. Definition / 6. Definition by Essence]

Full Idea

Defining an ellipse in terms of the oblique intersection of a cone and a plane (rather than in terms of the sum of the distance between the foci) gives us a necessary property, but not the essence, because the terms are extrinsic to its nature.

Gist of Idea

Defining an ellipse by conic sections reveals necessities, but not the essence of an ellipse


E.J. Lowe (What is the Source of Knowledge of Modal Truths? [2013], 6)

Book Reference

-: 'Mind' [-], p.18

A Reaction

[compressed wording] Helpful and illuminating. If you say some figure is what results when one thing intersects another, that doesn't tell you what the result actually is. Geometrical essences may be a bit vague, but they are quite meaningful.

Related Idea

Idea 16539 A definition of a circle will show what it is, and show its generating principle [Lowe]