Jacques Maritain somewhere makes a distinction that I find helpful between a ‘problem’ and a ‘mystery’. A problem admits of a solution – ‘can you prove Fermat’s last theorem?’ ‘is there intelligent life elsewhere in the universe?’ ‘does the Higgs boson exist, and if so, at what mass?’ – even if we don’t currently know the solution, it makes sense to look for a final answer which will lay the question to rest. A mystery, by contrast, can never be solved, only clarified; ‘what is beauty?’ might be a mystery: there is in principle no final answer, only a series of explorations (proportion; harmony; the sublime; …) which help us to think more clearly about the issue.
I propose (with no claim to originality) that the interesting questions in theology are all mysteries: we shouldn’t expect answers, so much as hints and definitions that serve to clarify our thoughts about the question. The same is true of most of the interesting questions in the humanities, I suspect: there are (as in theology) some historical questions that are in principle problems (‘Is the homeric corpus the product of a single author?’ ‘Did Hilary and Athanasius ever meet?’) – even if we have to conclude that the historical data will never be available to give a compelling answer, the questions remain problems: in principle they admit of final solution, even if we can never find it. But, ‘what is so special about Shakespeare’s plays?’ is a question that we might be justified in concluding we will never have a complete answer to; there will always be more to be said. (Incidentally, this is not straightforwardly an arts/sciences distinction; I know enough particle physics to regard the question ‘what is an electron?’ (or indeed a Higgs boson) as a mystery: we can model its behaviour mathematically with some accuracy, but it behaves sometimes as a particle, sometimes as a wave, most often as a dispersed probability function (whatever that might be) – its essence appears unknowable, even if its effects can be known.)
Can we ever make advances when we turn to mysteries? The answer is yes – otherwise the humanities would not be worth studying – but the advances are of a different kind. If I can’t hope to discover the whole truth about what makes Shakespeare’s writing so powerful, I can discover aspects of it – and benefit from them (even really trivially, any writer or, particularly, public speaker can improve enormously by studying his use of blank verse). If I can never define beauty exhaustively, I can always understand it a bit better, and give insights it what makes a thing beautiful (I remember the first time I read Ruskin, noticing a comment about parallel lines in the composition of a painting; a couple of days later, I was looking at one of my favourite landscapes, and suddenly saw how that hillside, and that hedgerow, and that roofline, and several other lines in the picture all ran in parallel. This is far from the only thing that makes the picture beautiful, but I understood something more then of why it gripped me.)
Theology often advances by proposing and accepting negative limits to its mysteries: here are some things that must not be said, some lines that cannot be crossed without embracing error. (I was marking essays on Chalcedon this week, which is the classic example: the hypostatic union happened ‘without confusion, without change,without division, without separation’: a series of exclusion clauses that announce that, whatever accounts of the incarnation might be proposed, they must lie on the right side of these lines.) This sort of negative elucidation demands the highest intellectual precision to be done well; the medieval doctors – St Thomas Aquinas; John Duns Scotus; … – are the great models, careful distinctions and subtle arguments deployed to discover with precision the limits of human knowledge.
At the same time, as theologians, we often propose models (here is my account of divine sovereignty, providence, and human freedom; there is yours of God’s triune life; …). At our best, I think we know that our models are just that: models, provisional and partial illustrations that might help us better comprehend this or that mystery. Theology becomes pathological when – as happens far too often in my own, Evangelical, tradition – we mistake the mysteries for problems, and think that our task is to solve them, to give answers that are complete and correct, to bring final resolution to the questions. And theology becomes irrelevant when, as happens far too often in mainstream academic theology today, an awareness of the lack of final answers becomes an excuse to stint on the hard work of careful logic, and to substitute empty rhetorical flourish.
The theologian must be humble, knowing that it will take her hardest intellectual efforts to do know more than bring a little clarity to a question. And she must be cheerful, knowing that, in the good providence of God, bringing a little clarity is itself a work worth doing.