more from Augustus De Morgan

Single Idea 13501

[catalogued under 5. Theory of Logic / E. Structures of Logic / 6. Relations in Logic]

Full Idea

There was a prejudice against relations (in favour of properties) but De Morgan and others that impeccable inferences turn on relations and elude Aristotle's syllogistic. Thus: All horses are animals. Hence, all heads of horses are heads of animals.

Gist of Idea

De Morgan found inferences involving relations, which eluded Aristotle's syllogistic


report of Augustus De Morgan (On the Syllogism IV [1859]) by William D. Hart - The Evolution of Logic 4

Book Reference

Hart,W.D.: 'The Evolution of Logic' [CUP 2010], p.94

A Reaction

This is actually an early example of modern analytic philosophy in action. You start with the inferences, and then work back to the ontology and the definition of concepts. But in pinning down such concepts, do we miss their full meaning?