There's a story I remember being told by a friend when I was at school. Back in the 1970s, the actor Clint Eastwood – known for playing be-stubbled, hard-bitten heroes – was being interviewed on television by the Irish chat show host Terry Wogan.

"So come on, Clint," Wogan asked him chummily. "How is it that you're so cool?" To which Eastwood responded by taking out a cigarette, flicking it up in the air, striking a match on the heel of his shoe, and then lighting the cigarette while catching it between his lips on its descent. After taking the first puff, he growled, "I dunno, Terry. I guess it just happened that way."

Deep waters

When I was told that story, I thought it was about the coolest thing I'd ever heard. So my first advice to anyone who wishes to know how to be cool is: take up smoking, learn a party trick, and maybe develop a trademark growl.

I'm kidding. So what is my first advice? These are deep waters. You don't want to plunge right in. Before we go any further, there are four immediate questions raised by the very idea of the book I've written bearing the brazen title of How to Be Cool, and they are these: 1. What is cool? 2. Where did it come from? 3. Has it changed? 4. Can it be taught?

"Cool" can't really be defined but it has something to do with style and something to do with emotional composure (aka "keeping your cool"). It arose out of the New York jazz music scene and was taken up by Hollywood in the 1950s in movies featuring cool characters played by the likes of James Dean and Marlon Brando. The attitude became so popular with the young that the word "cool" came to mean little more than "good". Yet in certain contexts it still retains something close to its earlier meaning.

Cool isn't a 20th century invention but it is a 20th-century phenomenon. It earned a name only in the 20th century when, for a perfect storm of reasons, an anti-establishment attitude began to exert an extraordinary mass influence among the young. This was an unprecedented cultural shift, which amounted to the rise of a new value system to rival those offered by morality or worldly success. We'd had rich. We'd had good. Now here was cool, which was something completely different.

Seething defiance at the root

The question of where cool came from is one that scholars have tried to answer literally, which is to say geographically. The art historian Robert Farris Thompson, for example, has a theory that its true origin was a quality called itutu (a blend of cool-headedness, playfulness and generosity) that was developed by the Yoruba and Ibo peoples of West Africa. It was carried to America in the 19th-century slave ships, where it hardened into a stance of silent but seething defiance.

Then, amid the burgeoning jazz music scene of 1930s New York, there was (we are told) a practice in some clubs of throwing open the windows in the early hours of the morning to let the cool air in, and blow away the smoke of a thousand cigarettes. As a result, the small-hours jazz playing style, which tended to be pretty laid-back, became known as "cool jazz". And later that "cool-ness"' somehow got linked to the rebellious attitude that was rooted in West African itutu.

None of this impresses me much. The meaning of a word isn't defined by origin but by usage. And in any case, where do they take us, these hypothetical theories that are at least partly based on anecdote? More interesting, I think, is to consider where cool came from in the sense of what caused it. What were the conditions, the catalysts?

This isn't, thank God, an academic study, providing rigorous proofs and scrupulous sources. A really thorough account of the rise of cool would need to be practically a roadmap to 20th-century culture. It would include every B-road, byway and lay-by. All we're aiming to do here is to find the right motorway and stick to it.

For the record, though, a comprehensive catalogue of the "inciting incidents" (to use a screenwriting term) that combined to create cool would include not only the suppressed resentment of the cotton-picker (American slavery) and the relaxed intensity of musical improvisation (jazz and blues), but also the breezy confidence of the flapper (first-wave feminism) and the conservative prosperity of post-war America, which gave the young something to rebel against (juvenile delinquency).

The historian Paul Fussell suggested that the horrors of the First World War had such a traumatic impact on the western psyche that, ever afterwards, the dominant cultural and philosophical mode became one of irony, which avoided emotion and rejected the old value systems.

Nowhere else to exist

Coolness, to extend Fussell's thesis, was to the Second World War what irony was to the First. Let's say that it was irony with style.

In an influential essay published in 1957, the celebrity novelist Norman Mailer argued that coolness was a philosophical position: a bleak existential reaction to the barbarity of the Holocaust on the one hand, and the fear of nuclear catastrophe on the other. With an unforgivable past and an unliveable future, there was nowhere left to exist but in the present. Mailer refers to this, rather startlingly, as the search for "orgasm". One of the dangers of writing about cool is that it's easy to get carried away. But, as often with Mailer, in the general cut and thrust of his theory, he may have had a point.

So, has it changed?

From its origins as a term to signify the opposite of warm (a cool breeze), the word has progressed and digressed through a bewildering range of meanings.

Here's a list, which I offer in roughly chronological order. We've had flapper cool, jazz cool, blues cool, Beatnik cool, Hollywood cool (aka juvenile delinquency cool), rock 'n' roll cool, hippy cool (aka counterculture cool), punk cool, yuppie cool, hip hop cool, grunge cool, hipster cool and geek cool.

Cool refuses to be defined. It hates labels, even designer ones. And even cool people can sometimes get it wrong. The comedian Lenny Bruce liked to tell the story of the time he saw a guy with a beard in a coffee shop and went up to him and said, "What's shaking, baby?" The man turned out to be a rabbi. And rabbis can't be cool, can they?

Not easily, no. In whatever era we're talking about, coolness defines itself in opposition to convention and authority. But here's the thing. If it succeeds – which is to say, if it catches on, as cool caught on in the 20th century – then it becomes more conventional, and therefore proportionately less cool.

Classic cool

Does this then mean that cool is dead? I don't think so.

If you accept that cool defines itself in opposition to convention, then it will be around for as long as convention is around. And convention isn't going anywhere. Or at least, it isn't going far. Convention will always revert, sooner or later, to its natural position, which is to align itself with a value system that prioritises the security of health and home, the rewards of monogamous commitment, and the prospect of a steady job.

What this means is that there will always be a central core of cool, which defines itself against this central core of convention. I guess you could call it Classic Cool. 

Finally, can cool be taught?

The great myth of cool is that it's effortless.  And anyone repeating the self-serving myth of effortless cool, I would congratulate for understanding the First Rule of Coolness, which is to deny that there are any rules. But then I would point them in the direction of some of those who are widely regarded as the coolest of the cool.

It's not effortless after all

In almost every case, it's clear that they themselves learnt from cool role models, sometimes quite deliberately. Early in his career, Paul Newman was thought to be copying James Dean. James Dean was thought to have copied Marlon Brando. Muhammad Ali confessed that he had been inspired by the flair and flamboyance of the boxer Jack Johnson. David Bowie wrote songs acknowledging his admiration for Andy Warhol and Bob Dylan.

As a young man, the aspirant author Hunter S. Thompson typed out the entirety of Ernest Hemingway's novel A Farewell to Arms. That's right. He typed the whole thing out, word for word, punctuation mark for punctuation mark, in the hope of learning what it felt like to write a cool masterpiece. There was nothing effortless about that.

One last question: who is the coolest person ever?

There's a story told by the Greek historian Herodotus, in which the rich King Croesus asks the wise Solon, "Who is the happiest of men?" He's hoping that Solon will reply, "You, Croesus", since he was so stinking rich. But Solon (an Ancient Greek version of an anti-capitalist) wasn't having any of it. He starkly declared that the happiest of men was some guy Croesus had never heard of: an ordinary citizen named Tellus. Tellus, apparently, had lived to see all his grandchildren survive infancy. He then perished nobly in battle.

Personally, I'm with Solon up until the part about dying in battle. But he does make a good point, which is relevant to us here. The likeliest thing, of course, is that the coolest person who ever lived is someone we've never heard of.

Five of the real deal

Children: A naturalness, A lack of self-consciousness. The absence of the desire to judge. The ability to exist in the present, as if the past hadn't happened and the future were nothing to fear. A readiness to laugh and forgive. A lack of side. Near freedom from sexuality. An experimental approach to food and drink. Lack of interest in hygiene. An instinct for play. Imagination. Trust. Children have just got it. No-one taught them. They aren't putting it on. I don't know how long it lasts. Maybe in some cases, you lose it the first time you're attracted to a member of the opposite sex. Or it might happen when you engage in competitive sports, the first time you want to win. At the age of four or five, a little later. But it's clear some people keep it a lot longer, and there are a few who never let it go.

Solitude: If solitude were a species, it would be listed as endangered. Mot of us these days carry our mobile phones around with us. We're never too far from a wifi signal. If you listen, you can usually hear sounds of human life, laughter in the next room, or the revving of an engine. So it's tempting to conclude that we're somehow afraid of solitude. Yet three of the world's major religions - Islam, Christianity and Buddhism - were created after a period of solitude on the part of their founders. And many great authors - John Bunyan, Ludwig Wittgenstein, Cervantes, Carl Jung - have sought out or endured their equivalent of 40 days in the wilderness. Reading is a form of solitude. As is meditation or gong for a walk. As, often, is a journey. It's often supposed that those who spend time alone do so because they're ill at ease in company. But in fact it's as often true that those who are most at ease in company are most likely to be comfortable alone. 

Socrates: In Athens in the 5th century BC, a fat, balding, extremely ugly man wandered around barefoot interviewing self-important people such as philosophers and politicians. He confessed to knowing nothing about anything, and insisted that he merely wished to learn. Yet the strange thing was, as the chat proceeded, it became clear the interviewee was the ignorant one, while the fat man actually seemed pretty clued up. This was Socrates, employing his "dialectical method" of question-and-answer, which is one of the cornerstones of western philosophy.

Hedy Lamarr: Try to think of a handful of people who have excelled in two entirely unconnected fields. A prime minister with his own boutique fashion line, say. Or perhaps an NBA championship-winning basketball player who was also a chess grandmaster. It isn't easy but one who should undoubtedly appear on any such list is the Hollywood sex symbol Hedy Lamarr, who took time out from playing smouldering femmes fatales to invent an unjammable missile-guidance system for use by the Allies in the Second World War. Billed as "the most beautiful woman in the world", she was bored by the boozing and the schmoozing required to sustain her career. In her spare time, Hedy liked nothing more than to hunker over her drafting table and invent things. (Her devices included a traffic light and a tablet for creating a carbonated drink.) In 1940, working with the avant-garde composer George Antheil, she came up with a "spread spectrum" system for directing torpedoes. The US Defense Department didn't adopt the new technology at the time, but dug it out in the 1960s. A version of Hedy's system is now used in all wireless communication, including mobile phones and wifi.

Being uncool: It isn't cool to be too cool just as it isn't charming to be too charming. If you're too charming, people suspect they're being manipulated. If you're too cool, it doesn't seem real. You need the behavioural equivalent of a Persian flaw, the deliberate break in the pattern that Persian carpet-makers are said to weave into their designs because only God is entitled to create something perfect. Beau Brummell's vanity. Marlene Dietrich's lisp. Tennessee Williams moustache. Humphrey Bogart's use of wigs. Jesse Owens' self-promotion. Marlon Brando's obesity. Bob Dylan's appearance in the film Hearts of Fire. If you take it all too seriously, you can't achieve it. There has to be a part of you that doesn't care about cool, that 's willing to be utterly uncool. Otherwise, you don't stand a chance. 

This is an edited extract from How To Be Cool: The 150 Essential; Idols, Ideals and Other Cool S*** by Thomas W. Hodgkinson, Icon Books, $27.99. Hodgkinson is also the author of How To Be Cultured.