Prosleptic syllogism

A prosleptic syllogism (/prəˈslɛptɪk/; from Greek πρόσληψις proslepsis "taking in addition") is a class of syllogisms that use a prosleptic proposition as one of the premises.

The term originated with Theophrastus.[1]

Figures

Prosleptic syllogisms are classified in three figures, or potential arrangements of the terms according to the figure of the prosleptic proposition used. First figure: "A is universally predicated of everything that is universally predicated of G" Second figure: "Everything predicated universally of A is predicated universally of G" Third figure: "A is universally predicated of everything of which G is universally predicated"

Consequently, a third figure prosleptic syllogism would read "A is universally affirmed of everything of which G is universally affirmed; G is universally affirmed of B; therefore, A is universally affirmed of B." ("All G are A; all B are G; therefore, all B are A" or "Statement A is always true of everything for which statement G is always true; statement G is true of all things B; therefore, statement A is true of all things B.")

Notes

  1. ↑ "History of Logic: Theophrastus of Eresus" in Encyclopædia Britannica Online.

References

  • William & Martha Kneale, Prosleptic Propositions and Arguments, in M. S. Stern, Albert Hourani, Vivian Brown (eds.), Islamic Philosophy and the Classical Tradition, London: Bruno Cassireer, 1972, pp. 189-207.


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