So who lives, who dies?

The sinking of the Costa Condordia brings to mind the following questions. If there were, or might be, fewer places on lifeboats than there were people in peril aboard a sinking ship, who should be given preference? What rule should those seeking to escape follow? What rule should those who are in authority on the ship try to enforce?

The rule that women and children should go first, associated most dramatically with the sinking of the Titanic, is highly dubious. It embodies two principles one “sexist” and the other “ageist”, neither of which seems appropriate.

Do women and children have a greater moral right than other people to have priority in these circumstances? Do those who are not women or children have a moral duty to give priority to those who are? It is far from clear that they do.

The crew should not try to escape before they have ensured that all the passengers have been led to safety. The members of the crew ought to follow this rule because they agreed to do so when they accepted their jobs. The moral duty goes with the job. They voluntarily accept the benefits of the job. They ought to accept the attendant burdens. It might not be fair that the members of the crew have such a moral duty but whether people have particular moral rights and duties and whether it is fair that they have them are separate questions.

We have a moral right to life in the sense that other people have a moral duty not to take our lives from us wantonly. However, we do not have a moral right to all that is required to keep us alive. We do not have a moral duty to provide other people with all that they require to stay alive.

Hence, in a situation where they are, say, two people and only one place in a lifeboat, neither person has a moral right to the place.

Similarly, neither person is morally obliged to stand aside to let the other person take it even although this action deprives the other of a place and, thereby, of life. It might be splendid if one of them foregoes the opportunity of trying to take the place but he or she does not have a moral duty to do so. No matter how morally praiseworthy it might be, self-sacrifice is not morally obligatory in the envisaged circumstances.

To allow someone to go before you in such circumstances is akin to an act of charity. If you choose to be charitable, it is your own business on whom you choose to bestow your charity. A man on the sinking ship might choose to let a woman or a child go before him but he is not obliged to.

Such a gesture might be admirable but it would be no more admirable to let a women or a child go before you than to let a man do so.

Would it be a better outcome if women and children rather than men were to be saved in such a maritime disaster? It is not obvious that it would be. More importantly, with regard to the rule that the passengers should adopt, it is not obvious that it matters what would be the morally best outcome in such circumstances.

To say that, were it to occur, something or other would be the morally preferable outcome is not the same thing as saying that we ought to bring that outcome about. There can be a relevant moral difference between that which happens and that which is done. For instance, it might, all things considered be for the best if some particular ill and elderly relative were to die. However, it does not follow that someone or other has a duty to kill her. We all might have a duty not to kill her and some people might have the added duty of trying to ensure that she is not killed.

Even if it would be a better outcome if younger people rather than older people were saved, it does not follow that older people have a moral duty to let younger people go before them on to the lifeboats.

In any case, it is not obvious that it would be the morally best outcome if the younger people were saved rather than the older one. Why would it be better? It might be said that, in utilitarian terms, it would be less harmful if the older rather than the younger people died since the younger people have more years of potential happiness before them.

This is not very convincing. What if some or all or the children on board were known to be terminally ill? Would we be comfortable in saying that such sick children should be last in the queue for places in the lifeboats?

In such utilitarian terms, there is no justification for making a distinction between children and adults. Those who are 90 years old should give precedence to those who are only 89 no less than adults should give way to minors.

On average, women live longer than men. Is this a reason for saying that it would be better for women rather than men to be saved?

In some circumstances, favouritism is not only morally permissible, it is morally obligatory. Parents who treat their own children in all respects the same as they treat all other children would hardly be good parents.

In other circumstances, particularly where they are acting in an official or quasi-official capacity, people have a duty to act impartially and others have a right to receive impartial treatment from them. Someone in authority such as the captain of a ship would appear to be in such a position.

I would suggest that the captain and his crew have an obligation to treat the passengers impartially. That might mean helping those of whatever age and sex to muster on deck. However, it is not consistent with giving preferential treatment to women or to children.

Suppose that the captain of a sinking ship discovered that there were, say, only ten places available on the life raft of his doomed and heavily populated vessel.

Suppose that it is his responsibility to decide how these places should be allocated. What should he do? It is not his responsibility to try to estimate what would be the best moral outcome. Apart from anything else, he could have no way of estimating what that might be.

If it were practical to do so, he should treat his passengers impartially by giving them all an equal chance of survival and draw ten names at random from the list of passengers.

Often, when there is no good reason for making a particular decision that has to be made, a reason that is not a bad one will suffice. A random choice in these circumstances is not a bad reason.

It would be unreasonable for the crew of the ship to try to enforce the rule of “women and children first” in a situation where passengers run a serious risk of dying if they do not secure an early place in a lifeboat. The maintenance of orderly queues is what the crew should aim for.

First come, first served, is the rule that the crew should try to enforce. It is also a reasonable rule for those who are seeking a place on the lifeboats to follow.

Were it a matter of life and death, I think that I ought to stand aside and let my wife have the only remaining place in a lifeboat rather than me. I hope that I would.

However, I do not feel that I ought to stand aside and let someone else’s wife or child have it. Regard for one’s self-interest is not the same as selfishness. It is entirely reasonable and honourable.

• Hugh McLachlan is professor of applied philosophy in the Glasgow School for Business and Society at Glasgow Caledonian University