Howard Jacobson: If you think that Prozac works, then it doesn't really matter what the experts say

What scientists never understand is that human beings aren't governed by science

So somebody at the University of Hull reckons depression drugs don't work. How can this be if the people who take them say they do? Depression for most of us is a say-you-are, say-you-aren't condition. "I have of late lost all my mirth," says Hamlet. What are you going to do – tell him he's wrong?And if talking dirty to his mother restores his humour, what are you going to do then? Tell him he's still wrong.

If I eat cardboard boxes to make myself feel more cheerful and cardboard boxes make me feel more cheerful, then cardboard boxes work. Quod erat demonstrandum. Never mind that it's scientific nonsense. What scientists never understand is that human beings aren't governed by science.

I gave a paper at the University of Hull years ago. Nothing to do with depression. Except in the sense that the experience depressed me. Not the University of Hull's fault, mine. I was hung up on Henry James's late, late masterpiece The Golden Bowl at the time and harangued people on the subject in language even more convoluted than late, late Henry James's. Sometimes, to irrefutably make my point, I would split the infinitive in as many as three places.

I could get away with this at some universities, but not at Hull. By the end of my talk the only person left in the room was me. Deeply depressing, as I have said, but it never occurred to me to go on Prozac. Granted, it hadn't been invented yet, but even if it had I would not have taken it. These were the Sixties when we were all depressed as a matter of course.

The hopeful times are always the worst. After the euphoria, the slump. I woke feeling weary, stale, flat and unprofitable every morning from my 16th birthday to my 25th. "Vile" was the word I used to describe my condition. "How you feeling?" friends would ask. "Vile," I'd say. They understood. They felt vile as well. It had never been suggested to us that we should feel otherwise. Along with most other human rights, the right to live in permanent high spirits had not yet been promulgated.

Maybe dope was the Prozac of the times. But people didn't acknowledge they were taking it to cure depression. You got high to stay high which is subtly different from getting high in order not to be low.

My point, anyway, is that you can't tell people what does or doesn't work if it works for them. This isn't a defence of the great heartless pharmaceutical rip-off, everyone who profits from which I'd happily see behind bars. We're simply talking reasoning here. Prozac might not do chemically what it says on the label it does, but if the depressed person is less depressed after he's taken it, it does enough for him. So what if a placebo does the same thing. We should be thankful there's more than one way of feeling better.

I agree it would be cheaper if we just handed out placebos all round, but a placebo, by its nature, works only if you don't know it's a placebo. So what we're really taking about is mass deception. Necessary and benign mass deception predicated on several million individual instances of self-deception. Not the pills that are at fault, but us. We're the ones who aren't telling the truth. We aren't as depressed as we claim to be, most of us, we just think we are. That's why it shouldn't surprise us when a cardboard box proves effective. But if we think we are, then we are. And if a sugar pill makes us think we aren't, we aren't.

I tried being judgemental about this once. "You aren't actually depressed," I said to the person I happened to be married to at the time. "You just think you're depressed."

"So you tell me the difference, you moron," was her answer. "It depresses me to think I'm depressed, therefore I'm depressed. Now pass me the pills."

I passed her the pills. It depressed me to think she thought she was depressed, though what depressed me still more was her calling me a moron. "My calling you a moron wouldn't affect you so badly if you weren't already depressed," she told me. Her suggestion was that I join her in dependency. She painted me a picture of an idyllic marriage. The two of us popping Prozac together in the sunshine, she forever smiling, I pharmaceuticalised into the perfect husband, easier to get on with, lighter of heart, and less of a moron.

"I'll have some of those pills you gave my wife," I told the doctor. It took a while to persuade him I genuinely needed them. Which raised the question of whether anyone, apart from depressives proper, genuinely needs them. "Reason not the need," I said. He told me to come back and see him in a fortnight. "And how are you now?" he asked when I returned. "Vile," I told him. He took my blood pressure, looked down my throat, then shone a torch into my ears. No depression he could find. It took me six months to get a single Prozac out of him. And even then only after he read the reviews of a book I'd just published and felt sorry for me. "You'll feel worse before you feel better," he warned. But I knew that from my wife who was still feeling worse two and a half years into the treatment.

You do feel worse before you feel better, so something that is not just auto-suggestion must be going on. And then indeed you do feel better, though whether you're feeling better than you were before you started taking Prozac or just better than you were after you started taking Prozac is difficult to determine.

But I do remember singing in the shower for a few weeks. Not just arias – I had always sung arias in the shower – but whole operas. The trouble is all the operas I know are tragic and break my heart. The bastards shoot Cavaradossi, Rigoletto finds his daughter in a sack, Mimi's tiny hands finally refuse to warm, and you're meant to come out of the shower with a face like Bambi's.

In the end I gave up the Prozac, got divorced, and went back to workaday cheerlessness and single arias. We make these decisions for ourselves. It's not for us to tell the world's Prozac users to pull themselves together. We don't know what it's like inside another person's head. I don't doubt half the pills popped aren't necessary, and the other half might just as well be boiled sweets, but since no man can be called happy until he's dead, whatever helps until then, helps.