Subjective, Intersubjective, Objective

Triangulation is the idea that two or more creatures responding to one another and to a shared stimulus in the environment form a triangle whose points fix the content of their thoughts. Davidson argues that without this interaction there would be no basis for deciding what a creature's responses are about, since a solitary creature's reactions could be assigned many equally good contents. The concept of objectivity, the idea that a belief can be true or false regardless of what one thinks, arises only when one recognizes that another mind can disagree. Triangulation therefore replaces the picture of an isolated mind consulting its own ideas, and it links the three titular kinds of knowledge.

Many philosophers have worried that if the content of our thoughts depends on environmental and social factors we cannot inspect, we should not have special authority about what we think. Davidson argues that this worry misfires. Authority comes from the fact that an interpreter must treat a speaker's sincere avowals as presumptively true in order to interpret them at all, so error is possible but cannot be widespread. His view is discussed alongside the literature on Putnam-style and Burge-style externalism, and critics have asked whether his response explains authority or simply stipulates it. The essays here are central texts for that debate.

Davidson does not try to prove the external world from indubitable premises. He argues instead that the skeptical scenario is incoherent because what our beliefs are about is partly determined by their typical causes, so beliefs formed in normal conditions cannot be massively false. Combined with the interpretive requirement that we share a mostly true outlook with those we understand, this yields an anti-skeptical conclusion from facts about meaning. Critics such as Barry Stroud have pressed whether this transcendental-style argument actually engages the skeptic's challenge or merely assumes the framework the skeptic questions.

The collection extends the program of radical interpretation, developed in Inquiries into Truth and Interpretation, from questions about meaning into epistemology and the philosophy of mind. It also revisits themes from Essays on Actions and Events, especially the anomalism of the mental, the view that mental events are physical yet not captured by strict psychophysical laws. Readers can treat it as showing how his semantic and metaphysical commitments converge on a single account of the mind. Without the earlier volumes, some essays presuppose background that newcomers may find opaque.

Descartes treated knowledge of one's own mind as the secure starting point from which knowledge of other minds and the external world must be built. Davidson rejects this foundational ordering. He holds that the three domains are so intertwined that none can be established first, because thought requires a community of interpreters and a shared environment. This does not abolish first-person authority, but it explains it differently, as a feature of how interpretation works rather than a special inner access. The contrast with Cartesian and empiricist foundationalism is a central organizing theme across the essays.

A frequent misreading takes the claim as social constructivism or as the view that truth is whatever a community agrees upon. Davidson argues for something narrower: that the concept of objective truth requires interaction with other creatures, not that truth is determined by their agreement. Beliefs remain answerable to a shared world, and an entire community can be mistaken about particular matters. The role of others is to make the very idea of error available. Reading the book as a defense of relativism misses the realist commitments that run through the essays.