The most influential pragmatist work in the philosophy of logic.
The lesson:
in any particular case, you can substitute a rule (that tells you you can go from this to that) with an axiom.
But there have got to be some moves you can make without having to explicitly license them by a principle.
I.e. you’ve got to distinguish between 1.) premises from which to reason 2.) principles in accordance with which to reason.
This teaches an un-get-over-able lesson about the necessity for an implicit practical background of making some moves that are just okay. Things that would be put in a logical system, not in the forms of axioms, but in the form of rules.
(This is from one of his Sellars lectures)