Synthesized answer
The "pragmatic difference" true ideas make in our lives is that they are ideas we can assimilate, validate, corroborate, and verify [1]. False ideas are those we cannot [1]. This difference is the practical difference it makes to us to have true ideas [1].
The meaning of a concept lies in the concrete difference to someone which its being true will make [3]. If an idea can make no practical difference whether it is true or false, then it has no real meaning [3]. All that the pragmatic method implies is that truths should have practical consequences, which can be mental as well as physical [3]. The truth of an idea lies in the concrete workings that intervene between the idea as a starting point in someone's mind and some particular reality as an end point [2]. These workings constitute the idea's reference to that reality and its adaptation thereto, and together they constitute the idea's "truth" for its possessor [2].
Synthesized from the book passages below. Chat with the book on Feynman for follow-up.
From the book
experiences [may] be different from those which would obtain if the belief were false? How will the truth be realized? What, in short, is the truth's cash-value in experiential terms?" The moment pragmatism asks this question, it sees the answer: TRUE IDEAS ARE THOSE THAT WE CAN ASSIMILATE, VALIDATE, CORROBORATE, AND VERIFY. FALSE IDEAS ARE THOSE THAT WE CANNOT. That is the practical difference it makes to us to have true ideas; that therefore is the meaning of truth, for it is all that truth is known as. 'The truth of an idea is not a stagnant property inherent in it. Truth HAPPENS…
by a vision quite as particular and direct as was the taste of the beer. If he does so, he calls THAT idea, also, true. His idea has, in each case, brought him into closer touch with a reality felt at the moment to verify just that idea. Each reality verifies and validates its own idea exclusively; and in each case the verification consists in the satisfactorily-ending consequences, mental or physical, which the idea was able to set up. These 'workings' differ in every single instance, they never transcend experience, they consist of particulars, mental or sensible, and they admit of…
ous meaning of a concept, says Mr. Peirce, lies in the concrete difference to some one which its being true will make. Strive to bring all debated conceptions to that' pragmatic' test, and you will escape vain wrangling: if it can make no practical difference which of two statements be true, then they are really one statement in two verbal forms; if it can make no practical difference whether a given statement be true or false, then the statement has no real meaning. In neither case is there anything fit to quarrel about: we may save our breath, and pass to more important things. All…
ut him into touch with something that fulfils its intent, or it has not. This something is the MAN'S OBJECT, primarily. Since the only realities we can talk about are such OBJECTS-BELIEVED-IN, the pragmatist, whenever he says 'reality,' means in the first instance what may count for the man himself as a reality, what he believes at the moment to be such. Sometimes the reality is a concrete sensible presence. The idea, for example, may be that a certain door opens into a room where a glass of beer may be bought. If opening the door leads to the actual sight and taste of the beer, the…
to get to the railroad station, don't I implicitly introduce you to the WHAT, to the being and nature of that edifice? It is quite true that the abstract WORD 'how' hasn't the same meaning as the abstract WORD 'what,' but in this universe of concrete facts you cannot keep hows and whats asunder. The reasons why I find it satisfactory to believe that any idea is true, the HOW of my arriving at that belief, may be among the very reasons why the idea IS true in reality. If not, I summon the anti-pragmatist to explain the impossibility articulately. His trouble seems to me mainly to arise…