What is truth?

"Do you swear to tell the truth, the whole truth and nothing but the truth?" In a courtroom, everyone answers "I do" without hesitation. But freeze the scene and ask the witness, the judge, yourself: what exactly is this truth you swore to tell? And silence sets in.

The same happens to it as Saint Augustine said of time: if no one asks me, I know; if I am asked to explain, I no longer know. The classical answer is not a loose definition, but a climb in steps, and each step rests only on the one below. There are three: correspondence, coherence and revelation.

First step: truth as correspondence

The most basic step is the one you tread on all day without noticing: a statement is true when it corresponds to reality. "The keys are in the drawer" is true if the keys are there, and you check by opening the drawer. The measure of truth is not in your head; it is in the thing. The Greeks had a word for this, alétheia, unveiling: to lift the veil and let reality appear. Classical philosophy sealed the idea in a formula from Aristotle and Thomas Aquinas, veritas est adaequatio rei et intellectus, the adequation between the thing and the intellect. It is your mind that adjusts to the thing, not the other way around: that is why truth is discovered, not invented.

Second step: the test of coherence

But how do we verify that the mind has reached the thing? Here a finer criterion comes in: a statement is true when it fits, without contradiction, into a coherent whole. In mathematics it seems sovereign, because there is no world out there to point at. Yet there is a crack: a good conspiracy theory is perfectly coherent and may still be entirely false. Coherence is an excellent test of truth, not its definition. It confirms the first step, at the service of correspondence.

The abyss: relativism

When the staircase becomes firm, a voice appears saying it leads nowhere: "there is no truth, everyone has their own." It sounds humble and charges a high price, because it pulls the ground out from under everyone. And it undoes itself from within with one question: and that which you said, is it true? If it is, there is already at least one absolute truth. There are universal truths, two plus two is four in Brazil and in Japan, and the principle of non-contradiction holds for all. Do not confuse opinion with truth: opinion belongs to each; truth is the criterion by which all opinions are measured.

The top: when truth has a face

At the top of the staircase, Christianity adds what reason alone does not deduce: truth is not only a property of correct sentences, it is first of all a person. Before Pilate, who asks "What is truth?", stands the One who had said "I am the way, the truth and the life." And the Gospel of John opens with the reason for everything: "In the beginning was the Logos." The world can be thought because it was thought before it was made; reason finds order in Creation because Creation came from a Reason. This is what Thomas Aquinas called ontological truth: things are true because they correspond to the idea God had of them.

These were not loose theories, but steps of one and the same climb. Truth exists, it is one, it is outside you, and it is reachable, by climbing, step by step.

Continue: What is alétheia · What is relativism · Truth, goodness and beauty
Source class (NousCast Community): The Idea of Truth (F&T 1.7)