Axiom:Leibniz's Law/Historical Note

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Historical Note on Leibniz's Law

Leibniz used this law as the definition of equality.

However, Alfred Tarski notes:

To regard Leibniz's law here as a definition would make sense only if the meaning of the symbol "$=$" seemed to us less evident than that of expressions [such as 'every property $x$ has, $y$ has'].

Hence it can be argued that Leibniz's law should either be adopted as an axiom, or not adopted at all.