The coherence theory of truth gained a strong following in the nineteenth century, partly due to the influence of Kant and Hegel, and especially in the thought of the British philosophers influenced by them, known as the British Idealists. One of its implications is that beliefs do not belong to whole systems in the way that pebbles lie on a beach, dis- connected from each other and independent of their neighbours. Rather, they belong organically to whole systems or theories of the world in the way that a hand belongs to an arm or an arm to a body: the interlocking system has the character of a living body, an organic whole in which each part gains its value precisely by its being a part of the whole. This idea, called the holism of belief systems, diverts attention from the single sentence expressing a single truth, to whole theories or systems of belief. As an illustration, think of learning elementary arithmetic. You do not learn, one at a time, that thirteen is greater than eleven, or that twenty-six is an even number. You learn a whole system and a whole set of interconnected implications and applications, and then, as Wittgenstein put it, “light dawns gradually over the whole.”
In nineteenth-century hands the coherence theory had a semi-religious flavour: ideal coherence, it was thought, could belong only to the thoughts of an infinite mind, a mind capable of encompassing an infinity of interlocking beliefs, something like God’s mind, which the idealists christened the Absolute. Anything like it could arrive only at the endpoint of the progress of the Human Spirit, but like the endpoint of the rainbow that could never be reached by mere mortals.
These thoughts might reintroduce a kind of pessimism or skepticism. Coherence is the best we can achieve, but our coherence might not be that of the gods. Again the idea arises that we might be faltering along on the wrong track, disconnected from the real world. The thought is that however much we may be at home with it, the empirical world of common sense and science is but the appearance of a hidden reality of a different nature. In Kant’s jargon the ordinary world of chairs and tables, cars and buses, is “empirically real” – it is what our senses tell us is real – but “transcendentally ideal” – the product of the way our minds structure a reality of which we can form no idea, since in forming any such idea we would be back deploying the structuring powers of the mind. This Kantian doctrine gave a satisfactorily pious, religion-friendly tinge to philosophy in the Victorian age (“now we see through a glass darkly . . .”). There is a standard objection to the coherence theory of truth, canonized as the “Bishop Stubbs objection” because of an example used by Bertrand Russell in his Philosophical Essays of 1910. The Oxford coherence theorist H. H. Joachim had urged that real truth belonged not to individual beliefs but only to the interlocking, godlike “whole truth” that we shall never obtain. Individual beliefs were only ever partially true, and error consisted in misplaced certainty, when we take what is partially true to be wholly true. Russell urged that if this were so, then “Bishop Stubbs wore ecclesiastical gaiters,” held with total confidence, would be deemed erroneous, whereas “Bishop Stubbs died on the gallows,” held as a hypothesis with only modest confidence, might be part of an interlocking coherent story about the man’s life, and would therefore count as true. A little history, however, tells us that it is true that the eminent and respectable Bishop of Oxford, William Stubbs, wore ecclesiastical gaiters (they did in his day) and entirely false that he died on the gallows (he died in 1901 at the age of seventy-five, in his bed).
Although Russell’s amusing objection may have some force against some of the wilder statements of the coherence theory of truth, it is hard to see it as effective against more cautious ways of framing the view, perhaps most obviously because Russell’s thought of Bishop Stubbs dying on the gallows cannot enter into a properly coherent system of beliefs. It would be doing so only as the result of fancy. But firstly, although on occasion we may become convinced of things for which there is remarkably little evidence, we do not allow ourselves to believe anything and everything that is the result of fancy. If you tell me you have just dreamed something up, you give me no reason at all to believe it. And secondly, a principle allowing one to believe anything and everything that is just the result of fancy would rapidly lead to hopeless incoherence. One can fancy all kinds of things true: not only that Bishop Stubbs died on the gallows but also that he died from a surfeit of bananas, drowned at sea, and so on forever. Any of these could equally belong to a coherent fiction, so the coherence theory needs some control, some principle for determining the right coherent system.
So a coherence theorist is within his rights to specify a much more demanding nature of coherence. The image to be avoided is that of a belief system “spinning friction- less in the void”, as the philosopher John McDowell put it. This can only be avoided if we can ensure that a properly coherent system of beliefs contains quite serious controls.