How do we tell right from wrong? Christianity offers answers to this question, and so do most philosophers. But how much of the answer depends on faith? Can reason along provide a way forward? Or do we need a combination of the two?

It is quite clear that there is no single "Christian ethic" being practiced in the world today. People who call themselves Christians have a wide variety of opinions about the issues that face us and even the larger Churches disagree about what is right and what is wrong. Papers on "world issues" are among the most popular at GCSE in the UK and opportunities to study ethical issues appear on specifications around the world. Anybody who has tackled questions on abortion and euthanasia, marriage and divorce, war or the environment will know that there are Christians on both sides of each debate. Some are strongly "pro-life" and believe that being involved in any death is wrong, while others preach compassion and say that in some situations an early termination or assisted suicide may be the best option. Some believe that marriage is a sacrament and that divorce is impossible while others accept that marriages end and that divorce is sometimes better than living in misery. Some are pacifists while others support even pre-emptive strikes against nations suspected of having weapons of mass destruction or harbouring terrorists. Some believe that it is our responsibility to protect all forms of God's creation while others believe that animals and plants were given to human beings for our benefit.

How do Christians make moral decisions then? Why do they hold such diverse opinions and disagree so passionately about some issues?

Ethics in the Old Testament

Jesus was Jewish. Jewish ethics were founded on obeying the laws given to them by God in the Torah. The central commandments are absolute. "You shall have no other God before me", "you shall not make for yourself an idol", "you shall not make wrongful use of the name of the Lord your God", "remember the Sabbath day", "honour your father and mother", "you shall not murder", "you shall not commit adultery", "you shall not steal", "you shall not bear false witness", "you shall not covet" ... There are no ifs or buts. However a number of the commandments are open to interpretation.

What is murder? Would it preclude the killing of an embryo or unborn child? Would it rule out suicide? Would it make all war impossible?

What does "you shall not bear false witness" mean? Lying about somebody in court is probably out, but what about white lies or withholding information, allowing somebody to believe something that isn't true?

Even the early biblical community must have been confused. The commandments are repeated in a slightly modified form in the book of Deuteronomy and are expanded upon with more than 600 further laws throughout the Torah. If one followed all the laws in the first five books of the Bible literally (as Hasidic Jews try to do) then life would be very difficult. Everything would be affected - food (kosher food only, no meat and milk together etc.), clothes (no mixed fibres or immodest dress), work (none from Friday sunset to Saturday sunset, no exploiting workers, no dubious financial practices), housing (if your house gets mildew you must disassemble it and turn the stones over in the sun until they are dry before rebuilding it) and so on.

The ethics of Jesus

The question of how literally to take the law was one which preoccupied Jesus. His attitude to the law was a constant cause of dispute with the Scribes and Pharisees (Jewish lawyers who tried to make sure that the whole community obeyed the law so that God would look favourably on them again, would restore the covenant and drive out Israel's enemies, the Romans). Jesus believed that they couldn't see the wood for the trees, that they were so obsessed with the minutiae of the laws that they had lost sight of the purpose of the law and its spirit. Jesus taught that "you shall love the Lord your God with all your heart..." and "you shall love your neighbour as yourself". Human beings are not automatons; we are free and can make choices. The law exists to affirm human freedom - if we could not choose we would not need guidance on what to do. Human beings are not God's slaves; we can have a real relationship with him. One who loves God naturally chooses to act in the spirit of the law. Having said that, Jesus said most clearly that he had not come to alter "one jot or iota" (the two smallest letters in the Hebrew alphabet) of the law; to say that Jesus did not value the commandments, whether the 10 or the 613, would be wrong. For Jesus, love of God and love of neighbour would necessarily lead to following the law, but it would make the conflicts which beset most people in their everyday life null.

The spirit of the law vs the letter of the law

For example, Jesus was asked why he and his disciples had worked on the Sabbath, something prohibited by the fourth commandment. He healed a boy and the disciples picked ears of corn to chew on as they were walking from place to place. Jesus was angry with the Pharisees for focusing on the action without seeing the context. Yes it was right to observe the Sabbath - but not when doing so became so all-consuming and mechanistic as to detract from doing God's work or worshipping Him properly.

Bernard Hoose, one of my colleagues at Heythrop, uses a good example. A father is building a wall and sees his son trying to pull bricks from the bottom before the cement sets. The father, anxious to preserve his son's life, says sternly ‘never pull bricks out of the wall!' A short time later the wall collapses and buries someone. Should the son obey his Father or save the trapped person? It is a stupid question. Obviously saving the person would be in the spirit of the law and the son would be wrong to obsess about the letter.

Another question that was continually presented to Jesus was that of how to treat those who had broken the law. From the beginning Jesus associated with sinners. He said, "does a doctor come to minister to the sick or the healthy?" He saw himself as one giving others a second chance, a baptism, a rebirth into a new spiritual life. Jesus' message was always that there was a way back from sin, through repentance, positive redeeming action and grace, but this seemed to go against the teaching of the Torah.

Keeping the law as a community

For the Jewish people their relationship with God was corporate - the covenant was between the people as a whole and God, not between God and each individual. Because of this, the health of the relationship depended on everybody doing the right thing - you had to be your brother's keeper or else you along with everybody else would suffer from God's displeasure. As far as the Jewish teachers were concerned, the truth of this way of looking at God and ethics was borne out by the exile. Many people sinned so all people were punished, many people were righteous during the exile so all the people were restored. They saw it as everyone's responsibility to prevent the consequences of God's displeasure reoccurring - by demanding and enforcing justice. Only God could be merciful, and they hoped he would be, but human beings had to follow the law.

Forgiveness and godly love

Jesus turned things round. He observed that only God can know the inmost secrets of our hearts, only God can know what really happened and if we are truly sorry. If human beings pursue justice without forgiveness, we deny others the opportunity to atone for their sins and deny God his absolute right to judge. When Jesus taught forgiveness he did not give sinners a licence to reoffend - he commanded the woman caught in adultery to "go and do not sin again". He did not deny the punishments that God would mete out to sinners - just think of the parable of the rich man and Lazarus, with the rich man burning in the furnace, unable to get out to warn his family (Luke 16:19-31). For Jesus, forgiveness meant giving those who truly repent a chance to atone for sin through positive action.

One of the most misquoted and confusing passages in the New Testament is 1 Corinthians 13, a reading often used at weddings but describing a kind of love at odds with the sort associated with white dresses, red roses and Cupid's arrows. St Paul describes agape, pure non-preferential love, not eros (sexual love) or philios (brotherly affection). Jesus commanded his disciples "love one another as I have loved you" (John 13:34) and by this he meant not that the disciples should form a tight-knit exclusive "band of brothers" but that they should love and welcome all people, whether friend or enemy, as Jesus had. They should turn the other cheek to attackers, give their coats to thieves and forgive 70 times seven times. Agape, Christian love, is the true love of God. It does not think of self but puts God in the centre of life - therefore it rejoices in the right and rejects the wrong. Nobody who loves God could accept actions which offend His law. They would wish always to live in an honest relationship with God, acting freely in the spirit of his commandments.

Paul's explanation of Jesus' teaching on love has been misinterpreted to mean that Jesus taught that we should simply "love and do what you will". Some early Christian groups took and ran with this message when they started to like lives dominated by eating, drinking and casual sex saying "yes, we love, lots". For Jesus and Paul, one truly in a state of agape with God could not but love all humanity and could not will anything that would be against God's will and thus against the common good.

Solving modern dilemmas - Situation ethics

Joseph Fletcher (1905-1991), an American professor and Episcopal (Anglican) priest, wrote a book called Situation ethics in 1966. He noted that Christians, like the Pharisees who Jesus rebuked, had become unable to see the wood for the trees and were obsessing about the minutiae rather than living in the spirit of Christianity. Fletcher's argument is persuasive; he uses powerful examples to get his point across. One such is the story of a group of refugees escaping a murderous army in Africa by night. A mother with a new baby has to decide whether to smother it to stop its cries giving away the whole group or to protect her child and see the whole group, including the child, captured and killed. Fletcher suggests that the loving mother would smother her child - he condemns any ethical system which would condemn this action as legalistic, not person-centred and contrary to the Christian principle of love as he understands it.

However the upshot of Fletcher's theory is that it is very easy for individual Christians to justify doing what they want. For this reason, because it puts far too much emphasis on the individual's right and ability to choose what is right, both the Roman Catholic and the Anglican Churches dismissed Situation ethics as a system of making Christian decisions and labelled the book dangerous, as it may discourage people from wrestling with the difficult choices that being a Christian demands.

Why is the Church so determined not to accept situation ethics? It is, after all, a version of the most commonly used and widely accepted ethical system, utilitarianism.

Utilitarianism, product of the Industrial Revolution

Utilitarianism was born out of the social confusion caused by the Industrial Revolution and the Enlightenment. Ancient communities were broken up as thousands flocked to work in factories, which were often set up near supplies of raw materials, miles from the basic services workers needed. There were few churches and fewer schools, representation in parliament was almost non-existent and there was no real police force. People from all over the British Isles and the Empire were jumbled together under stressful conditions and, as might be expected, the results were not pretty.

Marx and Engels described the conditions in Manchester, where 4.4 per cent of children died before their fifth birthday, rates of infectious diseases was four times higher than in surrounding areas and crime rates high. They railed against an unfair system that was seemingly designed to keep the poor poor and the rich rich. Employers judged employees for being illiterate when they had no opportunity to learn and worse, judges judged people guilty against laws they did not know about or understand. Why is it wrong to steal bread to feed a starving baby from a rich person's kitchen where it will not be missed? Thousands were deported to Australia or worse for similar crimes.

Bentham's ethical calculation

Jeremy Bentham (1748-1832), a wealthy lawyer and politician, saw the awful and unfair conditions and tried to do something about them. He campaigned tirelessly for the law to be rationalised and for opportunities to be extended to all. Looking back to the Greek philosopher Epicurus, he believed that all human beings share a desire for pleasure and to avoid pain. From this he determined the basis of a new ethic, later dubbed utilitarianism, "always act so as to produce the greatest happiness for the greatest number of people". Of course even Bentham knew that things are really not so simple. Are all pleasures equal? How should we measure pleasure? How should we really go about calculating the right action? Bentham's answers, that "all things being equal, poetry is as good as pushpin," that pleasure can be measured according to its "intensity, duration, fruitfulness, extent, purity, certainty and nearness," and that we can make moral decisions by simply applying a "hedonic calculus", namely "pleasure over pain times number equals right action", are the subject of much controversy, even today.

In the nineteenth century Bentham's system was radical and the subject of a good deal of mockery. Most educated people doubted ordinary people's ability to make rational decisions and certainly resented being told that their own cultivated pleasures should be counted the same as the rustic amusement of peasants. Back then democracy was a dirty word and the idea that each person should count for the same in a hedonic calculation - whether the Queen or a cotton-mill employee - was scandalous. But before we laugh and say how much things have changed, ask yourself how you might react if there was a choice between saving a respected doctor and three convicts, or how Western governments make choices about the environment or war - is one African life really treated as being equal with an American life?

Christian objections to utilitarianism

Thus far it is quite easy to see why most Christians would reject utilitarianism. Maximising the happiness in society does not necessarily mean promoting what is right. Looking at the front pages of tabloid newspapers and the covers of glossy magazines will show that a lot of what is popular is not in line with Christian principles, which value the sanctity of life, the rule of law and giving people a second chance. More people might be made immediately happy than sad if we permitted paedophiles to be publicly tortured - but that doesn't mean that it would be right to permit it. Situation ethics risks being classed with basic utilitarianism. On first reading it seems that a situationist could allow anything, given appropriate circumstances. Thus like utilitarianism it puts great weight on the individual to calculate what is right for themselves, trusting that their own understanding of the situation is complete, accurate and objective. Of course, we know that individual understanding is flawed and therefore that prediction causes a major problem for consequentialist systems of ethics that depend on knowing what an outcome will be.

John Stuart Mill - pursuing happiness and higher goals

John Stuart Mill was one who disagreed with Bentham on some of the key questions. Mill's utilitarianism suggests that there are some absolute values to which we should aspire beyond the basic pursuit of pleasure as it is usually understood. Mill claims that we achieve real pleasure through pursuing justice, truth, beauty, right - but we are unlikely to be grinning along the way. Mill represents a bringing together of two usually opposed ways of thinking - that of Fletcher (though that may be unkind), Bentham and the simple utilitarian which places simple happiness above all else, with that of Kant, Aristotle, Aquinas and many others who see that true human fulfilment lies in pursuing higher goals, even if there may be suffering along the way. In Mill though we can see that the two ways of thinking do not have to be opposed - the latter is just a different way of looking at and applying the former.

Kant and human function

Immanuel Kant's ethics are often caricatured as "duty ethics" but this leads to gross misunderstandings. The English word "duty" conjures up lists of arbitrary chores and is associated with punishments. In German and Greek, the words "Pflichte" and "deontos" (though translated into English as "duty") actually refer to a function of something's being. "Deontos" is actually the participle of the verb "einei", to be, and so means "of being". For example, a seagull's function is to fly - a seagull that cannot fly is somehow less than fully a seagull and condemned to be unfulfilled, disappointed and disappointing. For Kant our human function is to be rational and free - a human being who is irrational or enslaved in thought or deed is less than fully human, unfulfilled. Like Aristotle, Kant's ethics are designed to support human flourishing, both on an individual and a corporate level.

Kant's categorical imperative was clearly inspired by the Gospels which shaped his upbringing. He gave six versions of the imperative in the Groundwork for the metaphysics of morals but basically they boil down to the Christian Golden Rule (which has equivalents in most other religious traditions): Love one another and do unto others as you would like to be done to. For Kant this equated to acting rationally on a single principle, recognising that there is no difference between oneself or those we prefer and any other human person, acting justly and treating all people as valued equals in every situation.

For Kant there is no way we can know God exists, but positing his existence is the best way of making sense of a world which makes sense. There can be no reason for the world to be as fair and ordered as it appears to be unless it is sustained by a single principle of goodness. Kantian ethics are not religious but accepting our common humanity and the call of duty, our common human nature, arises from an acceptance of the world as an ordered and beautiful place that didn't just arise by accident. On Kant's tombstone is inscribed a line from his works: "Two things ever fill me with awe: the starry skies above me and the moral law within me". For Kant there was a fundamental connection between the two, the exterior and the interior, the huge scale and the small. He was searching for a "theory of everything" which would explain this connection but, like so many scientists today, struggled to put it into words.

Kant's ethic is often dismissed as being cold, unfeeling - and so it is in a way. Yet for Kant every decision must be made freely out of a love of the law and a non-preferential love for humanity. Yet it is important to remember that however detached, disinterested, objective the decision-making process must be, it must be motivated by love. Thus Kant's ethic is not a million miles from that of Jesus and Paul in the New Testament. To act on love is not to do what you want; it is to follow the demands of the law and to consider the interests of all people equally. Kant, Jesus and Paul would surely agree that it is not possible to condone murder, theft or lying in a spirit of love. Christian love, agape, is tough - and certainly a million miles away from trying to promote smiley faces.

Natural moral law

Another tradition, which has long tried to establish a single, clear Christian ethic, is natural moral law. To understand the system we must look back to the work of Aristotle.

For Aristotle all things can be understood in four ways, or through four "causes" as he put it. Everything has material causes, ingredients, efficient causes, agents which bring together the ingredients, a formal cause, a shape or recipe, and a final cause, a purpose or reason for being. Taking the example of an oak tree - the material causes are carbon, hydrogen, oxygen and so on, the efficient causes are acorn, sun, rain etc. The formal cause is having a trunk, branches and knobbly leaves and the final cause is to live, grow and eventually reproduce. For Aristotle human beings are the same. We have material causes - carbon, oxygen, sulphur and so on. We have efficient causes - parents, food, shelter etc. We have a formal cause (two arms, two legs - but more freedom and the potential to make moral choices) and we have a final cause, to live, learn, procreate and pass on our learning in a peaceful society. For Aristotle good things fulfil their final causes - good actions contribute to things doing so, they enable things and people to flourish. Bad things are destructive and prevent that.

Aquinas - what is a ‘good' life?

Aquinas developed the Aristotelean principle and concluded that the primary precepts of natural law (the common characteristics of a good life) were to live peacefully, to be reasonably prosperous, to procreate, acquire wisdom through philosophy and pass on wisdom and express gratitude through praise. He argued that all actions which generally contributed to the primary precepts are good and those which generally take away from the primary precepts are bad. These are the secondary precepts of natural law - not to murder, steal, lie etc. The primary precepts also suggest that some forms of behaviour are virtuous and others full of vice. Virtues tend, for Aquinas, to occupy the middle ground between extremes of vice. For example it is virtuous to be courageous but vice lies in both being rash and in being cowardly.

According to Aquinas, people do not tend to do something that they know consciously to be wrong. Most evil is done through the pursuit of apparent goods - that is, we might steal to feed our family under the impression that satisfying the hunger of children is a greater duty than obeying the law and respecting the property of others. He argued that the intention is important, as well as the action itself and its consequences, though clearly the intention may be difficult to establish. Today Catholic ethics are still broadly Thomist in character. Though there are many neo-naturalist theories of ethics (described under Natural law in this section) Catholics still tend to accept St Thomas' Primary Precepts and Virtues as the basis of their ethic.

In conclusion then it is clear that while there is diversity within Christian ethics, there is also a thread of unity. The vast majority of Christians hold to the sanctity of life, the need for human beings to flourish and to act with love. The differences come in the definition of what is a human person, how human beings best flourish and what the principle of love really is. None of these issues are easy to resolve, however Christians would be more likely to come together if they addressed the central philosophical issues directly in open debate, rather than focusing on their different opinions on applied issues.