We all know that killing people is wrong.

In the wake of a anniversary of VE day, it may be as well to get one argument out if the way first of all. People may try to kill me of my family and friends, by way of crime, vendetta, terrorism or war. In these cases I have a duty of defence which if need be, overrides my duty not to kill. Even in such circumstances I have a duty not to kill more than is necessary. Radical pacifists and others may argue that all killing is wrong in all circumstances, and that violent defence leads to the perpetuation of violence. We may applaud their witness to non-violence, while noting that it departs from the common view, that reasonable self-defence against violent attack is permitted in national and international law, and accepted as morally right by most decent people – which is what I mean by “we all know.”

The exception I have introduced above does not lead me to approve all killings by, for example, British armed forces. If Britain enters a violent dispute in promotion of its own trade advantage or retention of its remaining empire, its armed forces are not fighting in defence of its people, and are therefore engaged in illegal killing. It’s easy for governments to excuse this sort of killing because they say it is in the national interest, but improper use of violence turns its trained defenders into hired killers.

The conviction that killing is wrong means that even in cases of for example terrorism, minimum effective violence should be used, so that perpetrators may be taken alive and tried by law. We want to maintain our respect for human life even if a particular human may be a killer. There is some evidence that armed police squads are being used more often than before against potentially violent criminals, a habit which unfortunately means that on occasion unarmed suspects are also killed. While almost all citizens support the police, there is justifiable worry that policing by consent may be substituted with policing by force.

It should be noted that the argument which supports defensive violence by individuals or nations, has also been used to justify the kind of armed struggle against injustice seen in South Africa, or more controversially, in Northern Ireland. Sections of populations who see themselves as oppressed, having exhausted all peaceful means of change, claim the right to kill in defence of their rights. Some such movements have restricted their violence to members of the security forces, others such as the IRA have killed ordinary citizens. The IRA claimed that its war on the UK was similar to Mandela’s struggle against Apartheid. I think that most people reject this as spurious, and would limit their approval of deadly violence to occasions where oppressive forces are actually threatening lives.

We all know that killing is wrong and would extend the meaning of the term to cover situations where the death of a person is the result of criminal carelessness, neglect, torture, beatings, or enforced exposure to life-threatening conditions.

But how so we know this moral truth? It’s clear that we know it through civil and/or religious tradition. In Scotland we know it through the legal tradition of the European civilisation mediated through the civil society of lowland Scotland. No amount of pro-Celtic argument can disguise the fact that Scottish clans viewed killing the members of other clans for the sake of honour as acceptable into the 18th century. We also came to know it through the Christian tradition, in particular the Ten Commandments and the teaching of Jesus, the latter indeed forbidding any violence of word or deed.

I am saying that we do not know this essential moral truth by some kind of universal intuition, or innate instinct: we have to learn it.

Why then do we not teach it?

In places of education we teach all manner of things for the benefit of individuals and society, but nowhere, as far as I know, do we teach moral truth about killing. Surely this is an astonishing carelessness. Perhaps the reasonably recent dominance of the Christian tradition in British society allowed educators to assume that most people would be exposed to its teaching on killing, but it is clear that this assumption is out of date. The absence of any serious teaching of this morality may turn out to be dangerous, especially in a world where climatic interruptions of settled patterns of life will be more frequent. Would we like to live in a society where we don’t all know, or perhaps very few of us know, that killing people is wrong?

Meantime, Christian Churches might consider it more important to teach children, teenagers and adults that it’s wrong to kill, rather than dubious narratives from its Bible that suggest the opposite.