To your man, it's quite straightforward: honesty just isn't always the best policy. Well he would say that, wouldn't he? Keith Blanch tries to explain

You want to know the truth? Men lie - occasionally, compulsively, desperately. We certainly don't have a monopoly on lying - I've seen women pull off some whoppers - but we men, over centuries of tinkering, have developed hardy, scrutiny-resistant strains. In the interests of furthering intergender understanding, I talked real men into identifying, and explaining, their biggest lies.

1. 'Yes, that dress looks fine on you.'
Why he tells it: hassle avoidance

Men employ these 'forgivable fibs' not just to avoid hurting you ('Of course you don't look fat in that outfit'), but to make their lives easier ('I think that wallpaper looks great') and to steer clear of trouble ('I guess Cindy Crawford's "sexy" in a conventional kind of way, but she's not my cup of tea').

'Lies at this level are a way to cushion the shock of two individuals interacting with each other,' says Arthur L. Kovacs, PhD, a psychologist in Santa Monica, California. It's not that your man doesn't care what you wear or what the living room looks like - he does. It just doesn't matter as much to him as it apparently does to you, and often he'll decide that voicing his real opinion is not worth the cost of disrupting an otherwise pleasant car ride or spending another half hour at Ikea.

The bottom line: we lie because we love you. (If one of our mates asked us to help choose wallpaper, we'd say, 'Why don't you photocopy my arse five hundred times and put that up?')

2. 'I can fix it.'
Why he tells it: ego protection

Whether it's home repair, barbecuing, or wiring plugs, there are certain domains men feel compelled to know everything about. If a man cannot fix his own power tool, he must lie and declare it beyond repair, because if he admits defeat and lets his wife fix it, he's officially banished from the Real Man club forever. That's the way it feels, anyway - and that's why, every year, otherwise perfectly competent chartered accountants get their fingers cut off in power saw accidents.

Being visibly proficient at the man basics cuts to the core of our identity. These 'I can fix it' lies tend to lessen with time, as couples start to divide tasks and responsibilities along realistic lines of personal strengths and weaknesses rather than traditional gender roles. But take it slow. 'Reassure him that he's lovable for who he is, and that he doesn't need to solve every problem,' advises Kovacs. 'There's no shame in realistically evaluating each other's skills and sorting out who should do what.'

3. 'I was not looking at her breasts.'
Why he tells it: to achieve a delicate balance between marital harmony and four million years of biological conditioning

No matter how long you've been together, I guarantee your man hasn't stopped being attracted to other women. You can't promise to stop liking chocolate - only to stop eating it. When a good-looking woman walks by, he notices. If her skirt is momentarily caught in a crosswind, even a legally blind man will get whiplash.

Men are responding to millions of years of biological conditioning. Why bother lying? Because it's obvious our looking bothers you. 'This is what I call a "blessed lie",' says Kovacs. 'Men are given more licence to acknowledge a wandering eye, but at the same time, we always have to treat our woman as if she's the only thing in our field of vision.'

I once dated a woman who discreetly pointed out the awesome cleavage of a girl standing next to us. I was thrilled, and not just by the view. With that one self-confident gesture, my date relieved my subconscious worry of being caught checking out other girls. She's now my wife. (OK, she did a lot of other cool stuff, too.)

4. 'Nothing's wrong.'
Why he tells it: so that he can lick his wounds in private

Sadness, depression, disillusionment. Correct me if I'm wrong, but for women, a man's loneliness seems to offer an ideal consoling/bonding opportunity. If only men felt the same way. For us, your heartfelt concern only confirms that our personal weakness is now blatantly visible. And that's why, when pressed by a loved one to unburden our souls, we quickly pull our heads back in our shells. Remember that, for men, to bleed is noble, to refuse an Elastoplast divine. In the psychological realm, this sometimes means lying and dissembling to avoid 'The Dreaded Talk'. Should you ever offer a shoulder to cry on? Yes. 'If I think there's a solution to be found, I'm glad to talk to my wife about it,' says Jerry, 31. 'She's pretty insightful. But if I can't change the situation, for God's sake just let me go out to the garage and bang some boards together or something.'

5. 'I tried to call you.'
Why he tells it: self-defence

All men secretly think they're saints - or exceedingly nice guys, anyway. We can't understand how women could ever be disappointed with us, given the glorious single life we've willingly given up. So when you get angry because your husband didn't call, or he turned up late, the excuses kick in. You're complaining about a small, specific crime; his lie is his way of saying, 'But doesn't it matter that my intentions were pure?'

'Whenever I do something wrong, my wife totally overreacts and gets hostile,' says Jason, 34. So, essentially, lying is damage control. When we sense undue distress, we assume our petty crime can't account for it all. Rather, your complaint must be the tip of an iceberg of criticism, and a simple apology may be admitting to more than we bargained for. If we confess to forgetting to phone you when out with the boys, will you take it to mean we didn't think about you once all evening, or that we were glad to be away from you? Far safer simply to pretend that the phone went dead.

6. 'I don't want to have sex unless you want to.'
Why he tells it: to avoid seeming like a sex-crazed monkey

Women love sex - with the right person, in the right mood and armed with the right underwear. Men's love of sex is unconditional. When unburdened by physical problems or moral restraints, the typical man can happily have sex any time, any place. He doesn't have to be in a good mood, or like the person, or 'feel right about it', or know her name. Even porn movie dialogue doesn't turn men off. What does that tell you?

Men aren't insensitive to the dismaying effect our lust can have on the women we love. So we do our best to smooth over the rough edges. If you're not in the mood, we'll hide our disappointment so you won't think we're raging sex maniacs. If you're averse to our new idea involving handcuffs, a lingerie catalogue and a balloon full of porridge, we'll quickly pretend we were kidding so you won't think we're perverts. (And if we feel too tired for sex, we may 'perform' anyway so you won't cast your eye in the direction of the milkman.)

It's tough for men today. We're required to be sublimely romantic and respectful, and to ask for permission before touching your nose. But we're also expected to be harder than nuclear physics, last longer than a libel trial, be ready for action whenever you are and give you wild orgasms every time.

Juggling all these concerns, a man will lie to you in the bedroom whenever he thinks the truth would: (a) make him seem like an oversexed animal; (b) make him seem undersexed; or (c) offend you and get his horizontal privileges cut off. And we don't want anything cut off now, do we?

7. 'I'm the best, baby.'
Why he tells it: to make you glad you married him

Virtually all men engage in a little creativity when describing their bravery and fortitude, the wildness of their past exploits, or their critical role at work. We're just making sure you never forget what a superlative man you married. 'I think women expect you to talk yourself up,' says Kenneth, 34. 'It's your duty to give her great stories.'

More important, embellishing our personal histories gives a small but regular booster shot to that ever-susceptible male ego. It's hard for the average man to accept his averageness - to drive his average car to his average job, take home his average salary, and so forth - especially when TV ads are blasting us with exciting images of exceptional people. If stretching the truth helps justify our unique importance to the planet, great. (This doesn't apply to me, of course: I'm legitimately extraordinary. Have a seat and I'll tell you all about it.)

It's harmless, in moderation. Is it important to him that you believe he 'forced them' to fire him? Don't worry, he's normal. Is it important to him that you believe he's the CEO of IBM? You're in trouble (unless, of course, he is the CEO of IBM).