Full Idea
A logic can be seen as the ideal of what may be called 'relative justification', the process of coming to know some propositions on the basis of others.
Gist of Idea
Logic is the ideal for learning new propositions on the basis of others
Source
Stewart Shapiro (Foundations without Foundationalism [1991], 2.3.1)
Book Reference
Shapiro,Stewart: 'Foundations without Foundationalism' [OUP 1991], p.36
A Reaction
This seems to be the modern idea of logic, as opposed to identification of a set of 'logical truths' from which eternal necessities (such as mathematics) can be derived. 'Know' implies that they are true - which conclusions may not be.
Related Idea
Idea 13235 Logic studies consequence; logical truths are consequences of everything, or nothing [Beall/Restall]