Over the last few years we have seen the Anglican Communion riven apart as bishops and archbishops condemn each other and even refuse to share Communion with each other. Some bishops have been publicly trumpeting their refusal to attend the forthcoming Lambeth Conference because some of the people they are not speaking to will be there. There have been those who compare the situation with quarrelsome children invited to a birthday party.

If we're falling out with each other like this the root question is: by what authority does each faction claim that it is being truer to Christianity than its opponents? The position I shall defend is the one often described as classical Anglican theology, the three-legged stool associated with the sixteenth century Church of England priest Richard Hooker.

Hooker's argument was that authority is to be found not in a single source of information, but in a balance of Scripture, reason and tradition. Each of those three has at times been treated as the supreme authority, infallible and unchallengeable; but when treated like that, each turns out to be inadequate. We need all three, to balance each other. When we use all three in matters of religion we are doing just what we would do in any other field of study.

Firstly, tradition. When the ancient Roman Empire collapsed, educational standards declined and thereafter it became normal to expect that one's own generation knew less than the ancients had known. Tradition became a matter of preserving what the ancients had taught. This continued until the eleventh century when educational standards rose again and people started questioning what tradition taught. These questions generated the medieval faith and reason debate. Which is more likely to be true: the most recent research, or the writings of the ancients?

They resolved that debate by dividing all knowledge into two types. They said knowledge of physical things is gained by observing and measuring them. Traditional authorities like bishops and popes have no right to impose their views about the physical world on scientific researchers. On the other hand they said knowledge of spiritual things is gained by direct revelation from God, as expressed through the Bible and the church's teachings.

To say that tradition was the only source of information in matters of religious belief was to give immense power to church leaders. As the guardians of what God had revealed they could not be contradicted. The church became authoritarian. It also became backward-looking, because all truth was to be inherited from the past. And it became inward-looking, because all truth was to be inherited from the Church's own tradition, not from anywhere else. This was bad news for religious belief. We need tradition to have some authority; but to treat it as the supreme authority, above question, got us stuck in a time warp in a world of our own.

I now turn to Scripture. At the beginning of the Reformation, Catholics and Protestants agreed that the Bible is the most important authority for Christians. Catholics believed many parts of it were difficult to understand so God has also given us the Church, an authority to interpret the Bible for us. The Reformers denied that the Catholic Church had authority to interpret it. So who does have authority to interpret the Bible, and explain the difficult passages? At first there was no alternative Protestant church, and the Reformers argued that nobody had the right to interpret it. The Bible, they said, is to be accepted as it is, the plain, uninterpreted text. This was the doctrine of perspicuity: God, they said, has written the Bible in such a way that it is easy to understand; anybody who can read is able to open it up and understand perfectly the clear teaching of Scripture. To interpret it, they said, would be to treat your own reason as a higher authority than Scripture.

The effect of this doctrine was to convince some Protestants that they understood the Bible perfectly. Within a few years Luther and Zwingli fell out over the words of Jesus at the Last Supper, ‘This is my body'. Today New Testament scholars recognize that there are different ways of interpreting the text; but they believed they were not interpreting it; they were simply accepting its plain teaching. This produced one of the central problems of the Reformation debates, and today's debates echo it. If you and I agree that the Bible is perfectly clear, so we don't interpret it - we just accept it - what happens when we read a text and I think it means one thing but you think it means another? Oh dear. Since I am simply accepting the clear teaching of Scripture, then I can only conclude that you are wilfully rejecting the Bible's authority; and you will reach the same conclusion about me. All over Britain there are monuments to disagreements of this type, in the form of churches built by one faction because they could not tolerate the wilful refusal of the other faction to accept the clear teaching of Scripture.

Of course some biblical texts are perfectly clear; but even then we don't always accept their authority. Gentlemen, Leviticus 19:27 forbids you to cut your beard. I can see for myself that some of you have been disobeying the Bible.

But I won't hold it against you. In practice, nobody obeys all the commands in the Bible. There are just too many. What happens is that we select the ones which seem to us to matter, and we ignore others. We select on the basis of the traditions we have been brought up in, and what seems reasonable. There would be no Christianity without the Bible; but the idea of the Bible as the supreme authority on its own is never really applied, and cannot be. It only survives as rhetoric, the appeal to a favourite text in order to promote one's own agenda.

Tradition, Scripture, and thirdly reason. The Enlightenment, the Age of Reason, was a reaction against the Reformation debates. The early Enlightenment thinkers, led by René Descartes and John Locke, proposed theories of knowledge in which all the disagreements between Catholics and Protestants could be resolved by reason. Reason, they taught, should be a universal court of appeal, whose authority could be recognized by everyone. In order to achieve this aim, they expected reason to produce knowledge with certainty.

So what is reason? If you want it to produce certainty, as Descartes and Locke did, then you restrict it to two processes: deduction, as in logic and mathematics, and empirical observation, as in the sciences. Early Enlightenment thinkers tried to prove the truth of the Christian faith on the basis of these two, logic and observation.

They failed. Later generations rightly observed that if that's what reason is, reason cannot prove the truth of the Christian faith. Or even the existence of God. Perhaps all religion is a big mistake.

But it doesn't stop there. If you want reason to produce certainty, then science would have to do without hypotheses, and the result would be that we hardly know anything. All science has to presuppose two things it cannot prove: that the world is ordered, and that the human mind is capable of understanding it. We have to take these on trust. They are acts of faith: as Augustine put it, ‘I believe in order to understand'.

Worse still, even when we observe and measure things very carefully, sometimes we make mistakes. If you want certainty, philosophers point out these days, all you can be certain of is the contents of your own mind. If you think you're sitting in church listening to me, you may be dreaming; or it may just be the effect of the illegal substance you took last night. We know what our own minds are thinking, but the rest we take on trust.

To summarize so far. In the history of European Christianity, tradition, the Bible and reason have all taken their turn at being exalted to the rank of the supreme authority, capable of producing knowledge with certainty, on its own. As supreme authority, all three have proved a complete disaster. But all three are still needed. This is what the Anglican priest Richard Hooker argued towards the end of the sixteenth century. His arguments have been developed by his followers: William Chillingworth, Jeremy Taylor, the Cambridge Platonists, the Latitudinarians, Joseph Butler and, in the nineteenth century, the contributors to the publications Essays and Reviews and Lux Mundi . I'm doing all this name-dropping to emphasize that it's a rich Anglican heritage. All those people affirmed reason as essential to complement Scripture and tradition, but it was a wider and humbler reason than the Enlightenment philosophers proposed.

The difference was that whereas the Enlightenment philosophers wanted certainty and therefore used a narrow account of reason, restricted to logical deduction and scientific observation, Hooker and his successors did not expect reason to produce certainty and therefore felt free to use a wider account of it. They understood reason to include deduction and empirical observation, but also other processes and information which God puts in the human mind, like for example instinct and intuition. Within that mix they also affirmed an important place for both tradition and Scripture. We do not get certainty either from Scripture or from tradition or from reason, and that's why we need them all.

So what do they do for us?

The Bible. To take an analogy, if you're a Marxist you value the writings of Marx but you don't necessarily agree with everything he said. If you're a Blairite you think Blair had the right approach, but you may think he sometimes made mistakes. In each case you identify with your hero not because he was always right, but because his overall approach was fruitful; it generated new ideas which others developed further. So also with Christians and the Bible. It's the roots of our faith. We don't have to agree with everything it says, but when we learn about why those ancient Jews wrote what they did, we perceive insights which are still valuable today.

So also with tradition. Because of the medieval debate about faith and reason, early modern scientists believed they had no use at all for tradition. They wouldn't need to know what their predecessors had discovered because every generation would work everything out from first principles. It never worked. In practice, in order to learn any science you are taught a tradition. It often happens that new research contradicts what the tradition had previously taught, but we don't conclude that all science is therefore rubbish. Isaac Newton established principles of physics and his successors for a long time believed they were the complete truth; but Einstein showed that they were only true within certain conditions. Even though Newton was wrong, without Newton there would have been no Einstein. This is how traditions develop. We value the past, we use it, and as we use it we make changes. So also, I believe, God calls every generation to value the Christian tradition we have inherited so much that we build on it and hand it on to the next generation as a living thing.

Finally, reason. Without reason there is no society. We need it to communicate with each other, to understand the world around us and to resolve our disagreements. However, reason cannot provide information on its own, and doesn't provide certainty. So religious faith has to trust that God has given us enough powers of reason to relate to God and grow in faith, but has not given us so much that we have nothing left to learn.

All through life we are faced with decisions. When we feel afraid, we long for a simple rule book, or a list of principles where we can work out what to do and follow instructions. If life was always like this it would be secure but very boring.

The life God has given us is richer and more diverse. God gives us not a rule book but resources: a living tradition, the insights of the scriptures and a diverse set of mental capacities. Doing right, and discovering the truth, are not just a matter of looking up the answers in an infallible authority. Faced with a new decision, we are well advised to consult the authorities, but we may come up with a new answer, and we may be right to do so.

I believe the Church today should do the same. The past is full of wisdom, but it's also full of errors. When faced with the questions of today, it's up to us to use our reason, and the insights of our tradition, and our reading of the Bible, to discern what to do today, without expecting infallible answers. God entrusts us with the power to be creative. We are capable of making decisions which are really awful; and the corollary is that we can also make decisions which are really brilliant, and play our own part in making the world a little bit more like the Kingdom of God.