The horned man paradox is an argument that purports to show that one has horns. Its premise is that one still has whatever one has not lost. Since one has not lost horns, it concludes that one has horns (Diogenes Laertius 1925, Book VII, §187). The premise is false without the qualification that the object was previously possessed. Not having lost something does not imply ever having had it.
The horned man is one of the seven paradoxes
of Eubulides listed by Diogenes Laertius (1925, Book II, §108).
Diogenes Laertius. Book II, §108 in Lives of Eminent Philosophers, Vol. 1 (Trans. R. D. Hicks). Cambridge, MA: Harvard
University Press, 1925. https://topostext.org/work/221#2.108.Diogenes
Laertius. Book VII, §187 in Lives of Eminent Philosophers, Vol. 2
(Trans. R. D. Hicks). Cambridge, MA: Harvard University Press, 1925. https://topostext.org/work/221#7.187.
