It is not just the world's great religions and traditions that for long time have put forward certain moral rules that guide the behaviour of communities. A number of liberal thinkers have also been on a constant and sincere search for the concepts and principles that form the basis of a just and objective moral order.

In spite of this, today we still hear or read about different moralities and styles of moral conduct that are not acceptable to the majority of people. There are people who do not share the same set of values, or use a different value scale, and therefore give very little importance to several principles that other people hold in great esteem .

It is generally agreed that no one should inflict cruelty on another or violate his person. Crimes such as murder, robbery, rape, arson, slander are not open to discussion; they are evil actions, and we feel perfectly justified in telling that to our children. However, people seem to be willing to turn a blind eye - or even condone - other so-called peccadillos such as back-biting, marital infidelity, cheating, and such like.

Quite a few people believe they can lead an honest life simply by avoiding exploitation and deception. But when it comes to other matters, they insist that the individual should be free to choose and determine his own actions. The ultimate criterion is what makes them happy, here and now.

This approach cannot be correct or desirable since basing decisions on subjective likes and dislikes leads to nothing but crass moral relativism. But there is no denying that this modern conception of morality has become one of the hot issues of contemporary ethical debate today.

Nevertheless, well-meaning people are convinced that morality is not simply a man- made invention that depends on the whim of the individual or the current fashion. They believe it should be based upon certain fundamental constants of human nature, and have objective norms which the conscience has to comply with. In plain language, there should be some absolute and universal rules, by which to distinguish right from wrong.

Conscience judges the moral quality of our actions, and searches for the right thing to do. But it is not self-sufficient; there needs to be illumination and guidance from the outside and this reinforces that argument that the basic principles of morality are constant and universal.

These principles of morality are the ultimate measure of every positive law and the factor that gives it binding force. Laws made by human legislators are only good if they are in harmony with moral principles. Natural law, as the pre-Chistian philosophers described this principle, is what the reasonable, balanced human being, in every culture and situation, would judge good and right.

Every person- in order to realise his dignity and achieve his ultimate end as a human being - should live in harmony with the objective moral order. And that means abiding by the fundamental moral norms. Natural law has for many centuries been the yardstick used to measure this.

However, it is important to heed Jacques Maritain's words of caution: "Men recognise the natural law, with greater or lesser difficulty, and in different degrees and always in danger of error, here as in other matters. The only practical knowledge, which all men have naturally and with certainty in common, is that they should do good and avoid evil." In other words, the golden rule "avoid doing to others what you do not want to be done to yourself" comprises all that human reason may teach men about their own moral behaviour.

But this in itself is not enough to stave off the dangers posed by moral relativism, where some people act according to their whim. The limits of human reason are painfully evident and that is why Christian teaching is as valuable now as it was at any other difficult moment in history.