Full Idea
Logical positivists did not adopt old-style logicism, but rather logicism spiced with varying doses of If-thenism.
Gist of Idea
Logical positivists adopted an If-thenist version of logicism about numbers
Source
Alan Musgrave (Logicism Revisited [1977], §4)
Book Reference
-: 'British Soc for the Philosophy of Science' [-], p.113
A Reaction
This refers to their account of mathematics as a set of purely logical truths, rather than being either empirical, or a priori synthetic.