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Aristotle on identity: close enough!

“…In Logic for Philosophy [17, p. 159], Sider mentions that the conjunction of Aristotle's Law (3.10) and its converse (Leibniz's Principle of the Identity of Indisernibles) 'are sometimes collectively called "Leibniz' Law".' The same holds for Pelletier [5], Gobbo [6] and Mariani [7]. 19 Leibniz held, as one of the first, that all propositions are of the subject-predicate form: saying something (predicate) about something else (subject).…”

“…In Book I, ch. 7 (p. 172), Aristotle points out that besides proper names, reference (Aristotle: indication) by means of contextual definite descriptions is also possible (again our italics): 6 For all these are meant to signify numerical unity. That what I have just said is true may best be seen where one form of appelation is substituted for another.…”

“…In Logic for Philosophy [17, p. 159], Sider mentions that the conjunction of Aristotle’s Law (3.10) and its converse (Leibniz’s Principle of the Identity of Indisernibles) ‘are sometimes collectively called “Leibniz’ Law”.’ The same holds for Pelletier [5], Gobbo [6] and Mariani [7]. 19 All this terminology is however historically erroneous.…”

“…Leibniz’s Substitutivity Salve Veritate Principle (4.2) is about concepts , not about objects , like Aristotle’s Law of Identity (3.10). Admittedly Aristotle did not expound every one of these insights with the generality and clarity as Logic presents them nowadays, let alone that he shared the same background assumptions about predicates and possessed the same concepts as we currently have in Logic (quantifiers, variables, definite descriptions), as the subtle scholarly papers of Miller [10], Barnes [12], Pelletier [5], Gobbo [6] and Mariani [7] bear testimony. True enough.…”

“…3White [2], the index in Barnes [3], the Kneale & Kneale [4], Pelletier [5], Gobbo [6] and Mariani [7] were helpful to find where Aristotle writes about identity.…”