We want our beliefs to be true. But what is truth? In one sense the answer is easy: almost anyone can tell you that “snow is white” is true because snow is white. Philosophers have nonetheless developed several competing theories of what truth consists in, and the differences matter.
The correspondence theory
The oldest and most widely held view is the correspondence theory: a statement is true when it matches, or corresponds to, the way the world actually is. Aristotle gave a classic statement in the Metaphysics, here in W.D. Ross's 1908 translation: “To say of what is that it is not, or of what is not that it is, is false, while to say of what is that it is, and of what is not that it is not, is true.”
The idea has three parts worth separating:
- Truth-bearers. Something must be capable of being true or false: a statement, a belief, or a proposition.
- Truth-makers. Something in the world makes it true: a fact, or state of affairs. The belief that the cat is on the mat is made true by the cat actually being on the mat.
- The relation. Truth is a relation between the two: the belief fits the world.
A crucial consequence follows: truth does not depend on what anyone thinks. The earth was round before anyone believed it, and if everyone came to believe it was flat, it would still be round. This makes truth objective, and it is why we can discover that we were wrong. Belief is our attempt to get things right; truth is the target.
The theory faces real questions. What exactly is a fact? What is the correspondence relation? How do true statements about the past, about mathematics, or about what does not exist (“there are no unicorns”) correspond to anything? Defenders have offered detailed answers, and many philosophers still accept some form of the theory, but these puzzles motivated the alternatives.
The coherence theory
The coherence theory says a belief is true if it fits consistently into a larger system of beliefs, supporting them and supported by them. It appealed to British idealist philosophers such as Harold Joachim and F.H. Bradley, who doubted we could step outside our beliefs to compare them with reality directly. The main objection: a well-crafted novel or an elaborate delusion can be perfectly coherent and still false. Coherence, critics say, is good evidence of truth, not what truth is.
The pragmatist theory
American pragmatists tied truth to inquiry and practice. Charles Sanders Peirce suggested in 1878 that truth is the opinion that would ultimately be agreed on by everyone who investigates, if inquiry went on long enough. William James, in Pragmatism (1907), described true ideas as those we can assimilate, validate and verify, ideas that work in the course of experience. Critics replied that a belief can be useful without being true (a comforting falsehood), and true without being useful.
Deflationary theories
Deflationists argue that truth is not a deep property at all. Frank Ramsey suggested in 1927 that saying “it is true that Caesar was murdered” means no more than “Caesar was murdered.” Later thinkers built on the logician Alfred Tarski's observation that the sentence “snow is white” is true if and only if snow is white. On this view, the word “true” is a handy tool, letting us endorse claims we cannot list (“everything she said was true”), but there is nothing further to explain.
Taking stock
Each theory captures something: correspondence explains objectivity, coherence describes how we test beliefs against each other, pragmatism links truth to inquiry, and deflationism clarifies how the word works. Whatever theory they favor, most philosophers agree that whether a claim is true is not settled by our wishes, and that shared commitment is what makes honest inquiry and the correction of error possible.
Worked example: four theories, one belief
Imagine a sailor lost at sea in 1900. His family, with no news, comes to believe he survived on a distant island. The belief comforts them, fits with everything else they believe about his skill and luck, and shapes their lives for years. In fact, he drowned on the first night.
Correspondence: the belief is false, because it does not match what happened. It was false from the start, even while no one could know it. Most people find this exactly right.
Coherence: the belief coheres well with the family's other beliefs. Defenders reply that coherence must be judged against the widest possible system of beliefs, including all the evidence that would ever be available, which would include evidence of his drowning. Notice that this reply quietly brings the world back in.
Pragmatism: the belief “worked” in the sense of giving comfort. James would answer that he meant working in the long run, through experience and verification, not mere comfort. Still, the case shows why critics worry about tying truth to usefulness.
Deflationism: “It is true that he survived” just means “he survived.” He did not, so it is not true. Deflationism gets the verdict right, but says little about why truth matters to us.
The lesson: whatever theory you hold, it should deliver the verdict that the family's belief was false. A theory that cannot do so has a problem.