Source: p 108, With Good Reason, An Introduction to Informal Fallacies (6 ed, 2000) by York U. Prof. S. Morris Engel
The fallacy of amphiboly* is the product of poor sentence structure. It results when words are incorrectly or loosely grouped in a sentence, giving rise to a meaning not intended by the author.
[I omit this book's deficient etymology of 'amphiboly'.]
OED redirects amphiboly to amphibole; the latter's Etymology states:
< French amphibole, 1. adj. ‘ambiguous, of a double sense’ (Cotgrave 1611), 2. the mineral;
< Latin amphibol-um ambiguous,
< Greek ἀμϕίβολ-ονthrown or hitting on both sides
, ambiguous,
< ἀμϕί on both sides + βολ-, βαλ- stem of βάλλ-ειν to throw.
What underlying semantic notions connect the notion of thrown or hitting on both sides
(from the Ancient Greek etymon) to the modern definition in Informal Logic?