I first noticed it in a restaurant. The place was strangely quiet, and at one table a group seemed deep in prayer. Their heads were bowed, their eyes hooded and their hands in their laps. I then realised that every one, young and old, was gazing at a handheld phone. People strolled the street outside likewise, with arms crooked at right angles, necks bent and heads in potentially crippling postures. Mothers with babies were doing it. Students in groups were doing it. They were like zombies on call. There was no conversation.

Every visit to California convinces me that the digital revolution is over, by which I mean it is won. Everyone is connected. The New York Times last week declared the death of conversation. While mobile phones may at last be falling victim to etiquette, this is largely because even talk is considered too intimate a contact. No such bar applies to emailing, texting, messaging, posting and tweeting. It is ubiquitous, the ultimate connectivity, the brain wired full-time to infinity.

The MIT professor and psychologist Sherry Turkle claims that her students are close to mastering the art of sustaining eye contact with a person while texting someone else. It is like an organist playing different tunes with hands and feet. To Turkle, these people are "alone together … a tribe of one". Anyone with 3,000 Facebook friends has none.

The audience in a New York theatre now sit, row on row, with lit machines in their laps, looking to the stage occasionally but mostly scrolling and tapping away. The same happens at meetings and lectures, in coffee bars and on jogging tracks. Children are apparently developing a dexterity in their thumbs unknown since the evolution of the giant sloth. Talk is reduced to the muttered, heads-down expletives brilliantly satirised in the BBC's Twenty Twelve.

Psychologists have identified this as "fear of conversation". People wear headphones as "conversational avoidance devices". The internet connects us to the entire world, but it is a world bespoke, edited, deleted, sanitised. Doubt and debate become trivial because every statement can be instantly verified or denied by Google. There is no time for the thesis, antithesis, synthesis of Socratic dialogue, the skeleton of true conversation.

There is now apparently a booming demand for online "conversation" with robots and artificial voices. Mobiles come loaded with customised "girlfriends". People turn to computerised dating advisers, even claim to fall in love with their on-board GPS guides. A robot seal can be bought to sit and listen to elderly people talk, tilting its head and blinking in sympathy.

We have, says Turkle, confused connection with conversation – "the illusion of companionship without the demands of relationship". Human friendship is rich, messy and complicated. It requires patience and tolerance, even compromise. As we push other people off into a world of question and answer, connection and information, friendship becomes ersatz virtuality.

In his history of conversation, Stephen Miller points out that "most Americans are nowadays concerned more with improving their sex life than their conversation life". Even the phone is passé. Those who used to call a friend in trouble now send a text. Phone calls are to register urgency or shout anger, with corresponding loss of nuance and sensibility. From Mailer to Eminem, the modern cultural hero is expressionist. He or she has "attitude", and to prove it uses the F-word as often as possible.

Miller notes that public discourse is dominated by contention, by "intersecting monologues". Anger, lack of inhibition, "letting it all hang out" are treated as assets in public debate, in place of a willingness to listen and adjust one's point of view. Politics thus becomes a platform of rival angers. American politicians are ever more polarised, reduced to conveying a genuine hate for each other.

Likewise, the lack of tolerance in American Christianity can be as frightening as it can in Islam. When I once professed support for IVF, a man glared across the table, tight-jawed, and asked: "What does it feel like to be a mass murderer?" With such people there is no conversation, only a tiptoeing from the room.

All that said, the death of conversation has been announced as often as that of the book. Samuel Johnson and David Hume worried that the decline of political conversation would lead to violent civil discord. George Orwell concluded that "the trend of the age was away from creative communal amusements and toward solitary mechanical ones". The philosopher Michael Oakeshott professed himself desperate to "rescue the art of conversation". Somehow we have muddled through.

The "post-digital" phenomenon, the craving for live experience, is showing a remarkable vigour. The US is a place of ever greater congregation and migration, to parks, beaches and restaurants, to concerts, rock festivals, ball games, religious rallies. Affinity groups frantically seek escape from the digital dictatorship, using Facebook and Twitter not as destinations but as portals, as route maps to human contact.

A hundred online universities are no substitute for a live campus any more than Facebook is a substitute for sex or Twitter for debate. Gatherings such as Burning Man and Coachella have revived the medieval pilgrimage, with tens of thousands crossing mountains and deserts to spend from $100 to $1,000 a weekend to commune with like-minded souls. They talk. They even converse.

Somewhere in this cultural morass I am convinced the zest for human contact will preserve the qualities that Plato and Plutarch, Johnson and Hume identified as essential for a civilised life, qualities of politeness, listening and courtesy. Those obsessed with faddish connectivity and personal avoidance are not escaping reality. They are not TS Eliot's misanthropic Prufrock, "a pair of ragged claws / Scuttling across the floors of silent seas". Deep down they still crave friendship. They just want a better class of talk.

With that in mind, my editor has asked me to offer up a few practical suggestions and conversational cautions.

How to open a good conversation:

1) Immediately show an interest in the other person.

2) Try to extract an opinion of some sort, and reasons for it. Never disagree with it openly, but try to construct a dialogue based on it.

3) Never ask intimate questions, unless invited to do so.

4) Always be the one to change the subject if the going gets rough.

5) Try to leave the conversation in good repair should it be interrupted.

Five of the worst conversational openings:

1) You must be very busy these days.

2) Do you live round here?

3) Do you have any children?

4) Will it never stop raining?

5) Gosh, this party is boring.

• Add your suggestions below the line or tweet us @commentisfree with the hashtag #conversation