In St. John's account of Christ's prayer to his Father after the Last Supper, Our Lord said, “Thy word is truth”. As at the beginning of the Gospel, “word” stands for the Greek word “logos”. To approach the subject of truth I shall begin by talking about logos.

“Logos” is a term applied, not to single words such as are listed in a dictionary, but to coherent pieces of discourse. At the centre of our religious practice there is “logos”. The psalms are “logos”; the Creed is “logos”; Our Lord's pattern prayer is “logos” and he told us to pray like that and not babble, as the Gentiles do. Recently someone left in my study a book maintaining that “battologein” refers rather to praying in sentences: a really spiritual worshipper would instead keep on uttering some chosen “mantra” with incessant, unbroken repetition. This way of taking the Gospel brought to my mind what my old friend Van Quine said: the most explicit writing is not proof against stalwart reading.

The “logos” we get in the Creeds is the sort of “logos” we use to express what we believe or know. Not all “logos” is apt for this. Consider the difference between “Priam's wooden palace” and “Priam had a wooden palace”. We find “logos” in both, but only the second is apt to express belief. To borrow an expression from the German logician Frege, only the second string of words has a content that is “beurteilbar”, judgeable. Judgeable content need not be actually judged: we get the same content when, like Alice, we only say “if …” or when we ask a question that can be answered “yes” or “no”. But it is precisely judgeable content that puts us in the position to assert, truly or falsely.

All too often we hear it said that Christian belief is not belief that so‐and‐so, but belief in or trust in a Person. In one of his writings Chesterton countered this by remarking that in order to trust my mother I must believe that I have a mother and believe that the person with whom I am conversing is indeed my mother. And we read in the Gospel. “These things are written in order that you may believe that Jesus is the Christ, the Son of God”.

Here we must consider further what it is to trust our fellows’ truthfulness. This is not a matter of induction, of expecting an experienced way of things’ happening to continue. If 1 have often heard a man speak and every time he has spoken in a Scottish accent, I expect to hear that accent next time he speaks. But I cannot similarly think, “Hitherto what he says has been true, so 1 may accept the next thing he says to be true”. Trust in truthfulness is more basic than that. A child could not have language unless a lot of the things its elders said were simple truth. It is frivolous to think of lies told to a child as a light matter. For knowledge of its own identity, and place in the world, a child must rely on its elders without being able to check: if its elders lie about this, it is a grievous wrong.

Frege said that truth is the proper object of logic. Some would say that the proper object of logic is not truth, but rather validity, one thing's following from another. But a preference for valid inference would be merely aesthetic if valid inferences did not lead us from true premises to true conclusions. And in saying this I did not need to distinguish different varieties of truths: I could just say “true”.

Consider the figure of speech called asseveration: so‐and‐so as sure as such‐and‐such. For example: “He's guilty, as sure as I’m standing here: they’ll convict him, as sure as eggs is eggs: and then he’ll hang, as sure as God made little apples.” For asseveration to work, the hearer must take the clause following “as sure as” to be unquestionably true: it does not matter that one time the statement is empirical, “I’m standing here”, the second time it is logical, “eggs are eggs”, and the third time it is theological, “God made little apples”.

Whatever the subject matter may be, one truth cannot contradict another. We must knock the doctrine of Two Truths on the head whenever it revives. Given that Divine Revelation is true, any argument from true premises against it must be flawed, logically faulty. The flaw may be missed by a given individual but will in principle be detectable by ordinary human reason; not only by “baptized reason”, whatever that may be. On the other side, we must not betray the faith by obstinately defending bad arguments in its favour; that, as Aquinas would say, only makes for mockery by unbelievers, irrisio infidelium.

Some people prefer to say logic is about consistency, rather than truth or validity. Consistency is indeed a logician's business, simply because it is everyone's business, both in theory and in practice. If somebody's story of his adventures is inconsistent, some part of it must be false; but also, DIY instructions had better be consistent, and if a general gives inconsistent orders he may well lose his battle. Always, what makes inconsistency matter is the way our discourse latches on to the world. When we read a work of fiction, as Frege put it, we content ourselves with thoughts and do not go on to find their truth value: inconsistency doesn’t matter unless it troubles a reader. Ronald Knox discovered that the geographical data in Trollope's Barsetshire novels are inconsistent with one another and with the map Trollope provided: but what does that matter, when thousands have read the novels without noticing?

When inconsistency does matter, it may easily lie hid: it is then brought out by argument – and so we get back to validity, and therefore to truth. A set of statements must be consistent if they are all true, but may be consistent when some are false: so people sometimes fancy that the lesser task of investigating consistency should be undertaken before attempting directly to establish truth. This shows ignorance of what logical investigation has achieved and may be expected to achieve. Consistency proofs that prescind from truth are often extremely difficult. It is thus an error to suppose that before enquiry into the actual attributes of God it is a theologian's task to investigate whether ascription of such and such attributes is consistent, “coherent”. Richard Swinburne gave us a whole volume on “the coherence of theism” before getting to the question whether there is a God to whom the attributes attach. This project was perversely planned: and anyhow ill executed for lack of good tests of consistency. Swinburne often appealed to imagination, which as Leibnitz pointed out is indice trompeur; there is something specially grotesque in his presentation of an imaginary process by which oneself might become omnipresent in a series of developments.

Let us then turn back from consistency to truth. What is truth? A first picture of truth and falsehood is given by a signpost on a road. “London”, let us say, is named on the sign: if the sign is pointing the right way, then by following it you are approaching London, and you are getting farther from London if it is pointing the wrong way. There are many destinations: is true assertion then likewise directed to many goals? To the question that arises here there have been many answers: considering them, one might get lost in a labyrinth. In my own writing I have explored some paths and tried to show they are blind alleys. Here I will not do the like; I mean to present you with one answer, inspired by St. Anselm's De Veritate.

As we saw regarding asseveration, very often one true statement works just as well as another. Nothing in logic requires us to recognise different brands of truth. And much speaks in favour of following St. Anselm and saying that truth is something unitary, the Truth. We shall then regard truth as one unique thing, the goal of our thought and speech: all true judgement points towards that one goal, all error and falsehood point away from it. But so far the unique role of truth is not clearly different from the role of a mathematical object, like a number,

Mathematical objects fall outside the realm of happenings: as Aquinas put it, proof in mathematics makes no appeal to either efficient or final causality. Of a mathematical statement one may ask “How do you know that”? but not “What made that to be so?” or “What is the good of that?” No number affects our fate for good or ill: and nobody thinks we can do anything to numbers. In geometry there is a dramatic language about cutting and dropping and projecting, but this is merely a spur to a jaded pupil's attention. If we thought of truth as like a mathematical object, how might we think of the relation between God and truth? Consider what Plato says in some dialogues. He would have us think of an eternal structure of Ideas or Forms which is simply there; a demiurge (the word is Greek for artisan) makes models of the Ideas in the world of matter and change, and the copies he makes are necessarily imperfect. A curve drawn on paper is a very defective copy of a curve mathematically defined. The planetary orbits are approximately elliptical: for Plato, had he known this, we may be sure that these divergences from mathematical perfection would call for no such explanation as Newton sought and found, but would simply illustrate the way things in our world fall short of the Forms. In fact Plato, in The Republic, did deprecate the attempts of contemporary astronomers to determine accurately the length of the month and the year; in this realm accuracy is not to be sought.

Christianity rejects the Platonic mythology. God is not a workman working to a pattern, nor confronted by Truth as something to which his thoughts should conform. Rather, God constitutes all truth: in necessary matter by his nature, in contingent matter by his effective or permissive will. It is by God's will that all true thinking and saying comes about. If a man circulated a huge number of pictures he had made of himself, it would be insufferable self‐conceit; but God is the most important thing there is, and we do him no honour if we ascribe to him a sort of modesty whereby he would choose something else (say the greatest happiness of mankind) as goal of his activity.

God simply is Truth, and the vision of that Truth is what each of us is made for. We are oriented towards that, as acorns are towards growing into oaks. If a particular acorn never grows into an oak it may have been blasted by external circumstances, but each of us has a real hope of glory, which we can never lose by adverse circumstances, but only by vice and folly. Some have said this hope is attractive only to intellectuals: no, this is for every one of us, for Worren the poor weaver as much as for Doctors of the Church. It was that poor weaver, reviving after having been half hanged, who hurried back for the hangman to finish his task, and said to the astonished Sheriff “If you had only seen that which I have just now seen, you would be as much in haste to die as I now am!”

And I end with words I borrow from Thomas Hobbes: “What Felicity God hath promised to them that devoutly honour him, a man shall no sooner know than enjoy”.