Manners makyth man. Etiquette's just nonsense

The idea of social cohesion is under threat from modern eating practices

It's all right to eat with your fingers in a restaurant now, according to the revised guide to modern table manners produced by that arbiter of etiquette, Debrett's. This will not exactly come as news to anyone who frequents their local curry house or has noticed the dearth of cutlery in McDonald's.

But it is, no doubt, very welcome to the owners of Pizza Express who commissioned the new guide as they introduce calzone to their menus. This folded pizza can be eaten with the fingers, the posh person's primer pronounced, even though, with all that oozing cheese, it is the pizza most likely to make a mess – the state of affairs Debrett's insists is most to be avoided at even informal tables.

Only someone who mistook the cosy anachronisms of Downton Abbey for the real world would object to the dismissal of some of the more arcane social conventions surrounding the dining room. Jane Austen had great fun with the snobbery of placement. Remember the consternation in Pride and Prejudice when the heroine's younger sister returns as a married woman and is elevated in precedence to sit nearer to their father?

Then there are the old snobberies about whether we should say pudding or dessert, but certainly not sweet, which is terribly déclassé. Or the unspeakable faux pas of continuing to eat after the Queen has put down her cutlery; haven't we all been there?

Codes of behaviour surrounding food have been in place ever since the Maxims of Ptahhotep were written by a pharoanic steward in Egypt 45 centuries ago. Human history has been distinguished thereafter by two distinct approaches. Etiquette is designed to exclude those outside the inner circle. Manners, by contrast, are designed to include, by putting others, even social inferiors, at their ease. To spot the difference contrast the Edwardian dowager hostess who ate slowly, spinning out her meal until she was sure her most tardy guest was finished, with the harridan stepmother who earlier this year wrote to her son's betrothed telling her not to start eating before everyone else or take additional helpings before being invited.

Styles of courtesy change with the years. Manners are a sign of the tines – for all those old fogeys who know what tines are (the prongs of a fork). To eat peas politely, by the way, they should be crushed onto the fork – with the tines pointing downwards; never scooped, just as you should never tilt your soup bowl towards you. It is also rude to take photographs while eating, one guide says. Photographs! In our house we were too busy with other things. "No singing at the table" was one of my father's rules, which reveals something of the natural proclivities of the Vallely clan.

Everyone and everywhere is very different on this. Never eat, or pass anything at table, with your left hand, in Africa or the Middle East; that hand being reserved for wiping your bum. There are all manner of singularities. In Japan you should use the reverse end of your chopsticks to retrieve food from the communal bowl, not the end which has been in your mouth. In Cambodia if you finish everything on your plate it means you want more; in Japan it's rude not to clear your bowl.

Much of this is arbitrary. In England food is served from the right but drink from the left. Fish bones may be extracted from the mouth with the fingers, but every other unpleasant object should be removed with the fork. Cutlery should be placed on the outer rim of the plate between bites, and never – heaven forfend – rested like a gangplank between plate and table. Napkins should be used to dab the mouth but never to wipe it, says the updated Debrett's guide.

All this is bollocks but gives confidence to those who know it and know others know it. This is the world of Debrett's New Guide to Etiquette and Modern Manners, which, inter alia, informs us that men should use black ink in their fountain pens while blue is more "suitable for women". Only schoolboys use blue-black. Where this leaves my Diamine Teal is unclear.

But there is more to manners than convention. The word companion – cum, with; panis, bread – comes from the Latin for someone with whom you eat. It is the idea of social cohesion that is most under threat from modern eating practices. Some neighbours recently sold their dining table as they never used it now; they eat on trays in front of the telly. Worse still, they do not even do that together. They feed at different times, as suits, the husband in the living room, the wife in the kitchen, the teenager before his computer. The breaking of bread is shrunken to shovelling solipsism.

The majority of Britons no longer eat together as a family, several surveys have shown. Even when they do, four in 10 think nothing of using a smart phone to text or check emails while at table. This is more than just a decline in companionability, civility or grace; it represents a weakening of bonds that are fundamental to the essence of society. Manners makyth man, said the great 14th century educationalist, William of Wykeham. People are made, not born, the philosopher said, and they are made by their relation to others. Ubuntu, the Africans call it.

That is what counts. And whether we use cutlery or fingers is neither here nor there.