Full Idea
Pragmatism insists that statements and beliefs are inertly and statically true only by courtesy: they practically pass for true; but you cannot define what you mean by calling them true without referring to their functional possibilities.
Gist of Idea
You can only define a statement that something is 'true' by referring to its functional possibilities
Source
William James (The Meaning of the Word "Truth" [1907], p.2)
Book Reference
Peirce,James,Dewey etc: 'Pragmatism - The Classic Writings', ed/tr. Thayer,H.S. [Hackett 1982], p.250
A Reaction
I think this clarifies an objection to pragmatism, because all functional definitions (e.g. of the mind, or of moral behaviour) are preceded by the question of WHY this thing is able to function in this way. What special quality makes this possible?