Should we always tell the truth? Kant found himself in trouble for saying “yes” to this. He argued that it would undermine the value and reliability of truth telling to say “maybe”. But should Corrie Ten Boom have told the truth to Nazis searching her flat where Jewish refugees huddled in her hiding place, or should Oscar Schindler have told the truth as to why he needed to employ young children in his factory in Nazi Germany? Clearly the answer is “no”.

Kant produced the example of the crazy knifeman. Suppose a friend is hiding in your house and a crazy knifeman comes to the door. He asks “is Bertie hiding in there?”, apparently, said Kant we should reply “yes”! Otherwise, if Bertie has fled through the back door into the woods and the knifeman finds him there and kills him, we will be morally responsible having told the lie.

Kant got himself in this tangle because he failed to recognise that absolutes need to be broken when a proportionally strong reason can be found for so doing. Here it’s obvious to us that saving your friend from harm is more important than truth-telling. There has to be a hierarchy of values – saving a life trumps truth telling any day.

But what of feelings? Should I always tell you exactly what I think of the colour of your wallpaper, the state of our relationship, if you are irritating me or even how you treat your girlfriend?

Aristotle would answer “it depends”. It depends whether it is prudent to do so. It depends whether you will so hurt their feelings that they will never ask you to tea again, whether it builds the relationship, whether blunt, unfeeling, me-centred honesty is really wise – as Aristotle puts it, we need the right amount of honesty on the right issue, in the right context, using the right words. Prudent honesty is the virtue.

There are many ways of hinting there is something seriously wrong with me. Doctors are now being trained in the human touch – a gentle, sensitive, compassionate way of caring – hopefully we will never have to face the cold, blunt, unfeeling sort of truth when we’re at our most vulnerable.

Prudent honesty is a virtue, blunt honesty a vice – sometimes we gently have to exercise our right to silence.