prosleptic proposition

logic

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July 13, 2026

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The term "prosleptic proposition" originates from Theophrastus of Eresus, a successor to Aristotle. It refers to a type of proposition that implicitly contains a third, indefinite term in addition to two definite terms. This concept is part of the logic developed by Theophrastus, who explored various figures and syllogisms involving these propositions.1

While "prolepsis" in literature is a figure of speech anticipating future events, in logic, a prosleptic proposition is a specific structure within arguments. Theophrastus's work on prosleptic propositions, along with hypothetical syllogisms, laid groundwork for the logic of propositions, though sustained investigation in this area didn't occur until later.21

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history of logic
Theophrastus of Eresus
Such propositions he called prosleptic propositions, and inferences involving them were termed prosleptic syllogisms. Greek proslepsis can mean “something taken in addition,” and Theophrastus claimed that propositions like these implicitly contain a third, indefinite term, in addition to the two definite terms (“α” and “γ” in the example).
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Such propositions he called prosleptic propositions, and inferences involving them were termed prosleptic syllogisms. Greek proslepsis can mean “something taken in addition,” and Theophrastus claimed that propositions like these implicitly contain a third, indefinite term, in addition to the two definite terms (“α” and “γ” in the example).
Read More