Full Idea
Wright says the Fregean arithmetic can be broken down into two steps: first, Hume's Law may be derived from Law V; and then, arithmetic may be derived from Hume's Law without any help from Law V.
Gist of Idea
We derive Hume's Law from Law V, then discard the latter in deriving arithmetic
Source
report of Crispin Wright (Frege's Concept of Numbers as Objects [1983]) by Kit Fine - The Limits of Abstraction I.4
Book Reference
Fine,Kit: 'The Limits of Abstraction' [OUP 2008], p.41
A Reaction
This sounds odd if Law V is false, but presumably Hume's Law ends up as free-standing. It seems doubtful whether the resulting theory would count as logic.