Pragmatism gathers eight lectures James delivered in 1906 and 1907. He opens by claiming that every philosophy expresses a temperament, and he sorts thinkers into the tough-minded, who follow facts and the senses, and the tender-minded, who prize principles, unity, and religion. Most people, he observes, want both facts and faith, yet the reigning systems force a choice. He presents pragmatism as a way to satisfy both demands at once.
The central lecture explains what pragmatism means. Using the trivial puzzle of a man circling a tree while a squirrel keeps its belly turned toward him, James shows that the quarrel dissolves once you ask what 'going round' practically means. Generalized, this is the pragmatic method: interpret any idea by tracing its practical consequences, and treat notions that make no difference to experience as meaning the same thing. He credits Charles Peirce with the principle and extends it across philosophy.
James then turns from method to a theory of truth, his most contested claim. Truth is not a stagnant property an idea carries; truth happens to an idea, which becomes true as it is verified, corroborated, and made to agree with reality. Agreement means being led prosperously through experience. True beliefs are those we can assimilate and act on without frustration, and in his briefest formula the true is simply the expedient in the way of our thinking, judged in the long run and on the whole.
Across the middle lectures he applies the method to old metaphysical problems: substance, materialism, design, and free will, asking in each case what the rival views actually promise. He devotes a lecture to the one and the many, which he calls the most central of philosophic problems, and concludes that the world is one in some respects and many in others. Pending the verdict of experience, he sides with pluralism, since absolute monism forbids even considering a world that is still imperfectly unified.
The closing lectures join pragmatism to humanism and religion. Reality, James argues, is not wholly independent of us; human thought always builds out the given world. He ends with meliorism, the view that the world's salvation is neither guaranteed nor impossible but genuinely possible, and that our acts help decide it. Pragmatism, refusing both blank optimism and despair, again positions itself as the mediator that keeps facts and faith together.