There are many symbols of a cold, cruel streak running through Britain today – but for me, the most galling is the ascent of Paul McKenna. Yes, I know that set against David Cameron's assault on our social fabric, it seems trivial to complain that we have turned a glowering stage hypnotist into our best-selling self-help guru. But the two are symptoms of the same disease. The "advice" doled out by McKenna is pure Thatcherite chicken soup for the soul – and a recipe for more pain.

McKenna begins his latest mega-seller, I Can Make You Happy, by telling his stressed-out, advice-hungry readers: "You are about to have a life-changing experience... I'm going to show you a number of techniques that will help you become much happier very soon." After offering a few tricks where you "visualise" your problems and imagine them getting smaller – thanks, Paul! – he offers a core piece of advice.

Are your friends unhappy? Are they going through a hard time, and can't get their life right? Then you must shun them. McKenna says your unhappy friends will only "end up spending all their time talking about their problems," and "endless sympathy won't help them or you." So the answer is easy: "Cut him or her out of your life entirely."

McKenna says every friendship should be subjected to a cost-benefit analysis – a happiness spreadsheet, if you like. You need to ask: "Does this person take my energy up or does he/she/they take my energy down? After I've seen him/her, do I generally feel better or worse?" If your friends aren't boosting your energy levels or your mood, amputate them, fast.

Imagine living by this advice. Imagine being the kind of person who reacts to a friend's suffering and depression by dumping them. Imagine knowing your friends would do the same to you. Imagine promoting this as a way to live. It's a vision of a social hell, where even in your most intimate relationships, your job is to be "energising" and "upbeat," lest you get booted.

McKenna reduces friendship – one of life's most enriching experiences – to the experience of channel-hopping, switching to another superficial "friend" the moment the relationship acquires any texture or pain or grief. When you feel great, it's easy to find somebody to party with. But if I think about the times I have most valued my friends, and felt most proud to be a friend, it's precisely when it wasn't easy. It's when our lives were touched by some of the worst things that life throws out, and we helped each other through it – even if it, yes, "lowered my mood."

And all the scientific research into happiness shows McKenna is entirely wrong. For example, Professor Elizabeth Dunn of the University of British Columbia conducted an experiment where she gave her subjects $20 and randomly assigned them to two groups. One had to spend the money selfishly on themselves, and the other had to give it to somebody else – a friend or relative who they felt needed cheering up. The people who helped out their friends were dramatically happier.

Yet McKenna offers the perfect advice-bromide for a Cameroon Britain – because what is the Government's programme but McKenna's advice on a national scale? Cameron is slashing spending for all those "unhappy" people who "take our mood down" – the homeless, the disabled, the elderly, the weak. Just as McKenna urges us to shun our weakest friends, Cameron is shunning our weakest citizens.

But behind all this crude celebration of sociopathy, there is a better way to live. It's called kindness, and friendship, and a little human decency. They are the greatest anti-depressants anybody ever invented – and in the end, they are the only thing that really will Make You Happy.

j.hari@independent.co.uk; twitter.com/johannhari101