Catherine Hakim is a sociologist at the London School of Economics, who has written a book called Honey Money. "The world smiles at good-looking people, and they smile back", is its subtitle, and it goes on to posit this theory: that we have erotic capital, and this divides into six categories: beauty; sexual attractiveness; social skills like grace, charm and discreet flirtation; liveliness, which is a mixture of physical fitness, social energy and good humour; social presentation, including dress, jewellery and other adornments; and finally, sexuality itself, competence, energy, imagination.

We meet in Covent Garden, over fancy tapas. She arrives and says, "I must go and brush my hair," which she really needn't have done, because I don't buy her theory. I don't care what someone's hair looks like, I find hair neither impedes nor accelerates a discussion about ideas. I did not say so, thank God, even in jest, otherwise our encounter could have been even worse than it was.

Erotic capital, according to the book, can be used by women and men, but as a result of the "male sex deficit" – men want sex much more than women, a "new social fact that social scientists have mostly sidestepped" – women have more scope to exploit it. "In sexualised, individualised modern societies," she writes, "erotic capital is becoming more important and more valorised, for men and women. However, women have a longer tradition of developing and exploiting it." And yet, for all our noble history of accessorising and being lively, we have never as a sex been encouraged to exploit it, because of the "patriarchy". "Patriarchal ideologies have systematically trivialised women's erotic capital to discourage women from capitalising on it – at men's expense." Furthermore, "unfortunately, radical feminists today reinforce patriarchal 'moral' objections to the deployment of erotic capital." And "one reason why erotic capital has been overlooked is that the elite cannot monopolise it, so it is in their interest to belittle it and sideline it." Hakim is keen to stress that her thesis is "evidence based" and nothing to do with prejudice or ideology, and finishes her introduction with this rallying cry: "why not champion femininity rather than abolish it? Why does no one encourage women to exploit men whenever they can?"

Anyway, she's back. Her hair looks great. She sits down. The tables are quite close together, and we start talking about this sex deficit. She has presented a wealth of studies that show men want to get laid more within their relationship, that celibacy is far more common among women, that masturbation and use of erotic material are far more common among men, that men are more unfaithful and more frustrated, report more sexual desire, across a whole range of countries. The only thing I think might complicate her conclusion – that men are randier than women, and why won't we all just accept it – is that this area is culturally quite freighted. There are certain expectations, going back centuries, of male sexuality being rampant and ungovernable, and equal and opposite expectations of female sexuality. This might – call me crazy – impact upon the way that men and women report, express and prosecute their sexual desire. There are lesser issues on the same spectrum, like, for instance, that women are under-represented in the making of pornography, so might be under-represented in the consumption of it, without this necessarily leading to the conclusion that we're not interested in sex (in the book, she dismisses the idea of one's response to porn being determined by whether your sex is represented as the spectator or the object as "nonsensical"). My alternative view is supported by Hakim's finding that "in the absence of distorting social constraints, there appear to be no sex differences in sexual interest among younger people, up to around the age of 30." Her conclusion – that women lose interest after they've had kids, because their attention has switched to child-rearing – could conceivably be countered by the idea that the women under 30 in these sex surveys, being younger, might have evolved further from the social constraints that might colour the answers of older women. It's just a thought. The majority of the studies come from the early 90s; she mentions "smaller, repeat studies" in Britain that occurred this century, but the only reference is "reported in medical journals". The Finnish and Australian studies were conducted this century, but most of the time, where there is a 21st century reference, on closer inspection it turns out to be about some other element of sex, only tangentially related to the male sex deficit (pricing in prostitution; the thoughts of a blogger who likes to shag a lot, whose inclusion marks a new weird point in the art of indexing; some figures on sexless marriages, which could just as easily demonstrate both parties would like to have sex, just not with each other). In short, a large part of her supporting evidence is 20 years old and since, by her own admission, different ages give different readings, it strikes me that this picture of the horny male and the frigid, babysitting female might not be the end of the story. So I ask her, very mildly I swear, whether or not she thinks that women might, when they talk about their sexuality, still be labouring under a bit of cultural baggage.

Immediately, she starts barking at me; she tells me I'm using value-laden language, and that I've got to get over the idea that people can't change. "Look at Muslims! They turn against their cultural expectations within one generation of arriving here!" The people on the next table to us get up and move. I would argue that it's a lot easier to get over cultural expectation when you have the warm bath of a different culture, that you live in, ready to step into. But I don't say any of that because I'm worried that one or both of the people who have just moved might be Muslims, and there's always a chance she might start barking again.

So instead, I just accept the sex deficit as fact. Let's talk about something else. She writes: "In societies and periods when women have limited access to economic, social and human capital, [erotic capital] is crucial for them – which may be why women have traditionally worked harder at it." Possibly, then, as women's capital in those other areas increases, their reliance on erotic capital should fall? She rolls her eyes, as if she cannot believe she's suffering the indignity of such a foolish conversation. "Should!" she exclaims. I'm being an Anglo-Saxon puritan. She really doesn't have my number at all, but no matter. She's not here to interview me. I didn't mean "should" as in "ought to, for some moral, puritanical reason". I meant "one might reasonably assume… like, if cloud cover correlates with rainfall, when clouds dissipate, rainfall should decrease." But never mind! Our food is going cold. I feel a bit sick, to be honest. The waitress looks to me to be too scared to come and take it away

I accept, or at least I stop arguing, that whatever a woman's economic agency and position in society, she should still make a big fandango about her sexual playfulness and exquisite taste in shoes. Let's talk a bit about those six elements of erotic capital. I ask whether or not all of them are indivisible from sex on some level. People like flirtatiousness because it conveys some possibility, it's not just a coquettish, Renaissance thing that you do, for politeness, like holding open a door. She fixes me with an angry eye: "Now we finally come down to it. I'm surprised it's taken so long." She sounds a little bit like Darth Vader. "You understand erotic capital as sexual capital. I'm saying 'no'. I say 'no', several times in the book. Facial beauty is not about sexuality. Sex appeal, yes, is about sexuality. Sexual competence, yes, is about sexuality. But physical liveliness, being able to tell jokes, that is not about sexuality. Dress sense, ability to present yourself, these are not about sexuality."

"But surely you know from your life that these things that make you attracted to someone, sexually, are exactly the things you describe? You know, liveliness is part of it."

"In a work setting, and in a whole lot of other social settings, someone who is lively is attractive without necessarily being sexually attractive. Someone who dances well is attractive to look at, even if you don't particularly want to have sex with them. I'm saying that there are six elements of which only one is purely sexual, and the second one, sex appeal, is only partly to do with sex. Four of them have nothing to do with sexual attraction. There are several theorists whom I note and mention who think the only thing that matters is sexual capital, the only thing that matters is sexual attractiveness. They happen to be gay. In the gay community, this is absolutely the case. The gay community is not interested in talk, not interested in getting to know you. It's interested in sex in a much more straightforward and simple way."

Well, of course a homophobic rant is always an unexpected treat on a Monday lunchtime. "Hang on a sec, gay people don't choose partners on the basis of their personality?"

"I'm simply reporting what I have read and been told by people who know more about this, and have written more about it than I have. And I'm simply saying that sociality features less strongly in the gay community."

"You just said the gay community is not interested in talk. I think that needs a little more flesh on its bones."

"I'm not going to go into the gay community. You want to trip me up. You are trying to trip me up all the time."

Well, this distracted me, otherwise I would have had a number of follow-up questions, like, for instance, in what regard is sex appeal only "partly" to do with sex? And if none of the others have anything to do with sex, in what regard are they erotic? How does it differ from just having a personality?

We move on to China: she seems to view their appraisal of erotic capital quite positively. "The paper I'm particularly interested in was a study limited to women, in Shanghai – that said there were much higher returns, double the level in North America, to looking attractive, and the second thing was that attractiveness was definitely related to expenditure on clothing and cosmetics." I ask whether it's her view that China takes a more honest approach to attractiveness and its place in the economy. "You keep using these value-laden words, I don't understand the language you use. Perhaps you'd like to rephrase your question in a non-value-laden way."

"OK, you did say earlier that you thought China was normal and North America was abnormal. That you thought the American response to erotic capital had been perverted by puritanism. So perhaps you could expand a bit upon that?"

"I think it's true generally of Anglo-Saxon puritan cultures, and that includes Britain – and the rest of the world values erotic capital and therefore you might say it was normal rather than abnormal. Abnormality is the Anglo-Saxon response. The research evidence is from Britain and America so it's difficult to generalise from."

"So tell me a bit about how the puritan hegemony came about in Anglo-Saxon cultures?"

"Well, I think it has a lot to do with Christianity."

"You don't think Islam has had just as much an effect on prudishness?"

She starts to speak very slowly. I believe she's attempting to convey that I am the stupidest person she's ever met. "No. Because Islam is not common in puritan cultures. In fact, they are abominated by Christianity for the last 2,000 years."

"Yes. I understand that. I am asking, if Christianity managed to imbue Anglo-Saxon cultures with this prudishness, why did the moral strictures of any other religious system not imbue their cultures?"

More sighing. "Puritanism doesn't arise in others. It's a Christian sect. It's a Christian development."

"Well, a huge amount of sexual restrictiveness arises in other religions. But you don't think that has had any impact on their surrounding cultures?"

"I haven't written a book about sexual activity and sexual cultures outside the western world."

"But it strikes me that you're basically saying America and Britain and anybody else with an Anglo-Saxon belief structure, their course has been perverted, so they've arrived at a position that is wrong. And that is the result of Christianity. I'm interested, if that is what you mean, in why Christianity should be the only religion to pervert the course of culture, when all religions, well, most religions, have militant, sexually illiberal factions."

"That I don't know. Ask people who are specialists in religion. I'm not a specialist in religion."

"You can't use Christianity as your rationale, and then refuse to engage in why it would exert so singular an influence."

"I'm not using it as a rationale, I'm saying, fact: it is a fact that the countries where Christianity holds sway have had a down on sexuality, pleasure, and things to do with the body. It's there in the literature. People who know more about this than I do have said so."

"Do you think the reason we don't allow women to capitalise on their erotic resources is because we disapprove of sex?"

"Sorry. Who is disapproving of sex?"

"Anglo-Saxon cultures."

"I don't think I say that anywhere."

"You just did."

(Actually, she also says it in her book: "The Puritan ethic did a lot more than promote capitalism. It seems to have ruined sex for a lot of people in the western world". Evidence base? That I'd like to see.)

"I don't think I've read anywhere that people disapprove of sex. There is a generally negative attitude in the Puritan Christian culture toward pleasure, sexuality, aesthetic enjoyment, things that are not purely of the mind."

Yet again, we are not getting anywhere. She disowns her views then restates them with abandon. She gets incredibly cross. I am slightly too old to capitulate just because someone is unpleasant to me. This you might call my unerotic capital.

We have a number of other skirmishes, about Berlusconi, Jordan, David Beckham, Christine Lagarde, Rebekah Brooks and children. In her book, she lays into a number of feminists, saving her peculiar dismissiveness for "Anglo-Saxon feminism".

"French and German feminists reject Anglo-Saxon victim feminism in all its guises," she writes. I ask, in the spirit of genuine interest, who she means by French and German feminists, since it would seem to be pertinent whether she's talking about Elisabeth Badinter or Virginie Despentes, Catherine Millet or Julia Kristeva.

She reacts with disgust to the question – "you keep asking me for names. I'm not going to give you names!" – as if I'm asking for tittle-tattle. In the book, it turns out she is referring to Badinter, so it's weird that she won't discuss her, and to Luce Irigaray (who is actually Belgian, but let's not be pedantic), or at least this statement of hers: "What we need for our future civilisation, for human maturity, is a sexed culture." No serious reader of Irigaray would take this to mean she supported "erotic capital". Irigaray described her own career thus: a first phase, in which "I showed how a single subject, traditionally the masculine subject, had constructed the world according to a single perspective"; a second phase, in which she defined "those mediations that could permit the existence of a feminine subjectivity – that is to say, another subject." And the third she sees as "trying to define a new model of possible relations between man and woman, without submission of either one to the other." Broadly, then, and at a much more theoretical level, Irigaray fashioned the point that Hakim earlier described as "nonsensical" in relation to porn: that the two sexes could not be judged and discussed and measured within parameters that had been framed by only one of those sexes. I mean, look, it's quite an intricate point of academic feminism; you don't have to agree or disagree with it. But it has sod all to do with Hakim's "social science", and the idea that it constitutes a "rejection of Anglo-Saxon victim feminism" is a basic misunderstanding. Elsewhere, the comparisons are sloppy: "Some of the most taboo-breaking and positive books about female sexuality were written by French women: The Story Of O, The Diary Of Anaïs Nin… These texts form a sharp contrast with equivalent moralising novels by Englishmen, such as Moll Flanders and Vanity Fair." Except that the first was published, by a woman, in 1954, and the second was published, by a woman, in 1966. Whereas those "equivalent", moralising novels were published by men, respectively, in 1722 and 1847. Sharp contrast? You might just as well find a sharp contrast between the sexual standards in Shakespeare and the Venerable Bede.

After the interview, Hakim rang the editor, posing two questions: was it my idea to interview her, or the desk's? And was I in the middle of a marital breakdown? Clearly, she'd cooked up a dark motive, whereby my husband was ditching me for someone with superior erotic capital, and I'd tracked her down with the direct purpose of disagreeing with her. This tickled me; if I were a spurned ex seeking revenge, I would definitely not do it via a social scientist. And if I were to do it via a social scientist, I'd choose one with a bit more going on.

• Honey Money, by Catherine Hakim, is published by Allen Lane at £20. To order a copy for £16, visit the Guardian Bookshop.Catherine Hakim will be discussing her book at London's Southbank Centre on 26 September.