Full Idea
Second-order logic is inherently incomplete, so its semantic consequence relation is not effective.
Gist of Idea
If a logic is incomplete, its semantic consequence relation is not effective
Source
Stewart Shapiro (Foundations without Foundationalism [1991], 1.2.1)
Book Reference
Shapiro,Stewart: 'Foundations without Foundationalism' [OUP 1991], p.12