Book: Reason, Truth and History

Overview
Hilary Putnam offers a systematic reassessment of the nature of truth, the relation between language and the world, and the epistemic standards that make knowledge possible. He rejects a naive "mirror" or correspondence picture where language simply pictures a pre-given, determinate reality, and he also opposes the slide into full-blown relativism. The account he develops aims to preserve objectivity while acknowledging that truth and reference are constrained by human conceptual resources and empirical success.

Internal realism and the demise of metaphysical realism
Putnam formulates "internal realism" as a middle position between metaphysical realism and relativism. Metaphysical realism, on his account, posits a uniquely determinate totality of facts that language must mirror; Putnam argues that model-theoretic results and semantic indeterminacy make such a God's-eye correspondence untenable. Rather than denying an external world, internal realism maintains that claims about what exists and how terms pick out things are intelligible only within conceptual schemes that are subject to revision, rational evaluation, and empirical constraints.

Truth as idealized rational acceptability
Central to Putnam's reconstruction is a pragmatic-inflected conception of truth: truth is what would be accepted under ideal epistemic conditions, the end point of a rational inquiry given the best available methods and evidence. This notion seeks to preserve objectivity without invoking a metaphysically privileged realm of facts. Truth is not merely a matter of social or historical preference, since the standards of acceptability are constrained by rational norms, empirical tests, and intersubjective correction.

Model-theoretic argument and conceptual relativity
Putnam draws heavily on semantic and model-theoretic considerations to show that languages and theories do not uniquely determine a single mapping onto reality. Different but equally coherent models can satisfy the same formal descriptions, yielding an indeterminacy of reference that undermines the idea of a determinate correspondence. From this follows "conceptual relativity": what counts as a natural division or basic ontology depends on how one carves up the conceptual scheme, yet this relativity does not equal arbitrariness because pragmatic and scientific constraints narrow permissible conceptual moves.

Naturalism, skepticism, and the normative
Putnam defends a version of naturalism that treats philosophy as continuous with empirical inquiry while insisting that normative terms like "rationality," "justification," and "truth" retain distinct roles. Skeptical worries about our access to reality are defused not by claiming infallible access but by insisting that successful scientific practice and rational criticism provide reliable constraints. The account rejects reductive eliminativism and preserves normative standards that guide theory choice and conceptual revision within the broader naturalistic enterprise.

Legacy and influence
Putnam's synthesis reshaped debates about truth, meaning, and realism by offering an alternative that kept philosophical rigor while addressing empirical lessons from logic and linguistics. The move toward internal realism influenced later discussions about semantic externalism, pluralism about truth, and the pragmatic underpinnings of epistemic concepts. While Putnam himself later revised aspects of his view, the book remains a rich stimulus for thinking about how language, mind, and world are interlinked without collapsing into either metaphysical absolutism or sheer relativism.