Can ethical norms be justified by rational arguments alone?

Modern societies are to a large extent secular, their way of life being only vaguely related and sometimes even in contrast with the religious ethics of the past. Although many people still consider themselves Christians, Jews, Muslims, or Buddhists and stick to the traditional norms of behaviour, they do not understand these as inspired by or based on religion, but claim that it is just "reasonable" to behave the way they do. This attitude is for the most part a result of the Enlightenment, which put rational arguments higher than any traditionally accepted norm and demanded that everything had to conform to that standard.

So how can ethical norms be justified rationally? Because of the high rank occupied by science in modern societies, many people tend to think that it can also be used to decide what is right and what is wrong. But science consists in collecting and analysing facts and has certain limits. One of the leading figures of the Enlightenment, David Hume, argued convincingly that what "ought to be" cannot be deduced from what "is", so ethical norms cannot be justified scientifically. Later, Immanuel Kant attempted to use purely rational arguments to establish a system of ethics, but the result of his endeavours was of a very general nature: the "categorical imperative" gives no more than a rule of how to judge the validity of other rules and is inadequate for deciding relevant practical questions. Further examples could be given here of unsuccessful attempts to put ethics on a rational basis. None of them has been unanimously accepted. The title of a much discussed book by a contemporary philosopher, John Mackie, is characteristic of this situation: "Ethics - Inventing Wright and Wrong".

In the end, we are left with what we had before: ethical norms have always been established and upheld by religions, and it is not inconceivable that this should continue to be so in the future. Interestingly the prescriptions for living given by different religions are very similar to each other. If this were not the case, the World Parliament of Religions would not have been able to decide on a common Declaration on World Ethics as it did in Chicago in 1993. The question is, of course, whether the very general principles agreed upon by way of an inter-religious dialogue are sufficient to deal with the very complex problems of this and the next centuries. Be that as it may, it must be emphasised that a religious basis for ethics does not preclude the use of rational arguments. The latter will always be needed to apply norms to practical question, to weigh conflicting demands of different norms and to help avoid the fanaticism and bigotry that has pervaded so much of the past.

One area in which important contributions can be expected from religions is our attitude towards nature and man's role in it. Whereas the Enlightenment saw man as endowed with certain capacities to make nature subservient to himself and adjudged him the right to do so (an approach nowadays wrongly considered typical Christian), more recently it has become fashionable to consider nature's own rights and deny man any particular station. Thus, anthropocentrism has been replaced by physicocentrism. Religious concepts would seem to show a way out of this juxtaposition, as they see both man and nature originating in a sphere beyond this material world. Without appreciation of their sacredness, therefore, no progress in the value discussion can be expected. An inter-religious dialogue on this topic would probably help to identify what is needed if this general idea is to be made practically applicable for questions of sustainable development.