One critical fact about the philosophy of William James is that it is a good deal more subtle than many newcomers to philosophy expect it to be.
The crude use of the word "pragmatism" to mean "unprincipled" or "opportunistic" has contributed to the false impression that there isn't a lot of intellectual/philosophical substance to it. Also, the fact that much of what James wrote on the subject was written with a wider audience in mind than his fellow academics, has had the unfortunate side effect of giving it a reputation in some quarters as the philosophy for those without the patience, or perhaps the intellectual heft, to read real philosophy.
Barzun, in A Stroll with William James, devoted his own considerable gifts to clearing up such misconceptions.
I won't retread that ground here but will move to a related problem: we associate pragmatism as much with Dewey as with James, and through Dewey it has come to have a close connection with "progressive education," which is itself in a rather bad odor in many quarters. One common reaction to this bad odor on the part of Jamesians (and I am guilty of this myself) is to say, "oh, what Dewey was doing was entirely different. You can't blame James for that." But Barzun doesn't do that.
Any two minds of the rank of James or of Dewey will have differences, each will have idiosyncracies at any rate and, from the point of view of the other, each will commit out-and-out errors. Still: James saluted at least the earlier phases of Dewey's thought, the ones James lived long enough to know about.
Barzun does observe that James "had no reason to imagine that schools would turn into places where death by violence, the drug habit, rape, and teenage pregnancy would count as educational problems." But what is more notable, from Barzun's point of view (given Barzun's long career as a teacher): Dewey isn't to blame for 'Deweyite' education either.
Barzun writes in Stroll that Dewey's ideas were "exploited by ignorant and irresponsible people—veritable Smerdiakovs—and impressed upon children, parents, and teachers alike. Anything less ‘pragmatic’ than the ineffectiveness of public schooling would be hard to imagine.”
[For those not as casually erudite as Barzun, it might be well to observe that Smerdiakov is a character in Dostoyevsky's great novel, The Brothers Karamazov, the bastard son of Fyodor Karamazov.]
What Barzun fnds most valuable in James is not pragmatism, at any reading, but radical empiricism, a thoroughgoing opposition to any sharp cut between Mind and Thing, or Knowing Intellect and World Known. When we say with Descartes "I think," we are really saying that there is some chunk of experience that has an "I-quality" to it. Further, if we are Jamesians we will want to subject that part of experience to further examination, to understand that I-quality, and we will resist any temptation to make of it a metaphysical principle (a temptation to which poor Descartes famously succumbed.)
You might say, further, that for Barzun James was the expression in psychology and philosophy of High Romanticism at its best. James was rather late to play this role, but ... no matter. This is history, and it doesn't follow rigid time lines. James looked back toward and conceptually reflected, romanticism. As, in his still more belated way, did Barzun, that always-cheerful pessimist.