Truth

In Logic, Kant noted that to judge whether a cognition is true, one must compare it with its object, and this requires another cognition of the object, which may be fallible—hence the judgment of truth is not sufficient for truth. Kant took this to show that the correspondence definition is useless as a criterion of truth. By contrast, followers of Kant took it to show that correspondence truth is unknowable or even unthinkable, since it requires comparing a cognition with its uncognized object, which is uncognizable. One can compare a cognition only with other cognitions. Moreover, a cognition cannot copy or resemble an object. This difficulty led many philosophers in the nineteenth century to seek an alternative to the correspondence definition, and they naturally sought to define truth in terms of the criterion of truth.

In "How to Make Our Ideas Clear," the American pragmatist Charles Sanders Peirce (1839–1914) proposed a method of clarifying our everyday conceptions: a conception is to be identified with the conception of the practical effects of its object. For example, "To say that a body is heavy means simply that, in the absence of opposing force, it will fall" (1992b, p. 48). Applying this to truth, to say that a belief is true is to say that it would permanently survive sustained inquiry conducted in a proper way. This is an epistemic definition of truth, since it defines truth in terms of proper inquiry. An epistemic definition runs into circularity if proper inquiry is in turn defined in terms of the aim of true belief. In "The Fixation of Belief," Peirce answered this threat of circularity by characterizing proper inquiry without employing the notion of truth—as inquiry that fixes belief by eliminating doubt.

Like Peirce, William James (1842–1910) applied a pragmatist theory of meaning to true and identified the notion of true belief with that of the consequences for experience of the belief's being true—"truth's cash-value in experiential terms" (p. 200). James differed from Peirce in characterizing a true belief as one that is eventually verifiable, rather than one that would be permanently fixed in sustained inquiry. This allows the possibility that a true belief will be permanently retracted after its eventual verification in sustained inquiry. James was more pragmatist than Peirce in attempting to use his pragmatist theory of true belief to explain the practical, and not merely cognitive, utility of true belief. A true belief is one that would fit my experience in a counterfactual circumstance. Because my true belief that the cowpath leads to a house would fit my experience were I to go down the path, it enables me to select the more useful course of action—going down the path that leads to food, as opposed to one that does not. Moreover, James, unlike Peirce, was guided in his choice of a definition of truth by the aim of finding a definition that explains the practical utility of true belief.

British idealists developed coherence theories of truth in the late nineteenth century. One motivation for these theories was epistemological: knowledge of whether a given judgment is true cannot result from comparing the target judgment with its object, as the correspondence theory requires; it must result from comparing judgments with other judgments. The available criterion here is coherence of the judgments with one another. This motivation for the coherence theory received its most extensive expression in the twentieth century in the American idealist Brand Blanshard (1892–1987) (pp. 225–237, 268). An alternative metaphysical motivation, to be found in the work of Francis Herbert Bradley (1846–1924) and Harold H. Joachim (1868–1938), appeals to the doctrine of internal relations. According to this doctrine, every relation is grounded in the natures of the relata. This is said by Bertrand Russell (1872–1970) to be equivalent to the monistic theory of truth, that judgments are not true one by one, but only abstracted from a concrete known whole (1906–1907, p. 37). From monism, it is supposed to follow that the truth of a judgment consists in its coherence with the whole, rather than in correspondence. Russell objects to the coherence theory on the ground that it does not rule out contrary propositions both being true: "coherence as the definition of truth fails because there is no proof that there can be only one coherent system" (1912, p. 122).