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Single Idea 16540

[filed under theme 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

Source

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

Book Ref

-: '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]

The 14 ideas with the same theme [essence as what figures in a successful definition]:

11389 Socrates sought essences, which are the basis of formal logic [Socrates, by Aristotle]
12080 Essence is not all the necessary properties, since these extend beyond the definition [Aristotle, by Witt]
11153 A definition is an account of a what-it-was-to-be-that-thing [Aristotle]
12382 What it is and why it is are the same; screening defines and explains an eclipse [Aristotle]
12285 The definition is peculiar to one thing, not common to many [Aristotle]
16797 Maybe Locke described the real essence of a person [Locke, by Pasnau]
11216 If definitions aim at different ideals, then defining essence is not a unitary activity [Gupta]
11171 Defining a term and giving the essence of an object don't just resemble - they are the same [Fine,K]
11178 The essence or definition of an essence involves either a class of properties or a class of propositions [Fine,K]
16539 A definition of a circle will show what it is, and show its generating principle [Lowe]
16540 Defining an ellipse by conic sections reveals necessities, but not the essence of an ellipse [Lowe]
16548 An essence is what an entity is, revealed by a real definition; this is not an entity in its own right [Lowe]
19291 A canonical defintion specifies the type of thing, and what distinguish this specimen [Hale]
15116 Essences cause necessary features, and definitions describe those necessary features [Koslicki]