Katherine Butler: What made mothers so superior?

Have you got kids? Careful how you phrase it if the answer is no and you're a woman, especially one whose biological clock has been ticking for a bit.

The correct answer should you wish to avoid an awkward silence or, worse, sympathy should probably be: "No", followed immediately by "Not yet!", or, "I'd love to have had them, but sadly...". (That one shuts the discussion instantly with its hint of tragic medical impossibility, or that you were left at the altar and never recovered.) Don't, under any circumstances, reply cheerfully as you sip your Prosecco that in fact you are happy with no kids but would the questioner like to see pictures of your Jack Russell terrier.

Because, to have failed to be a mother, or as the folksy parlance dictates, "a mum", is to be caught without your flak jacket in a conflict zone. You may well get splattered in the crossfire, whacked by the maul of a giant furry paw, or trampled under the weight of a terrifying mama bear, she-elephant or whatever the next political species invented by conservative political strategists in the US might be.

The mama grizzly made her debut in American politics this summer, and if you like scary movies watch the video in which Sarah Palin launched the concept. To rousing music, ordinary women are shown making placards, gathering in parish halls, as if preparing to march in their millions on Washington, while Palin, in her strangely compelling Fargo gosh darnit, ya know voice, claims that all over the US there's "a mom awakening". These women who are supposedly "risin' up" seem at first to represent something positive. But then Palin explains the threat: "Here in Alaska, I always think of the mama grizzly bears who rise up on their hind legs when somebody's coming to attack their cubs, to do somethin' adverse towards their cubs. You don't want to mess with the mama grizzlies!" So naturally the band of conservative women candidates the Alaskan Queen is backing in next month's mid-term elections are known as the mama grizzlies. Leaving aside the nauseating sentimentality, and the illogicality of a supposed maternal uprising over child-friendly Obama policies from healthcare reform to better pay for teachers, the mama grizzly, in cynical marketing terms, is a stroke of genius.

Palin has identified a powerful and universal myth, but it's one we should be wary of importing into British politics. The crux of her video is when she anticipates the question why we should listen to her lady-bears just because they have given birth. Palin's logic is simply: "Because moms kinda just know when somethin's wrong." So that's it. Mothers have special powers, privileged access to some kind of innate, intuitive wisdom that is denied to the childless.

This elevation of the mom has little to do with feminism. No, Palin's women are warriors, who possess a sixth sense thanks to their elevated oestrogen levels perhaps; they are already tough and strong. The female grizzly is nothing if not one of the fittest survivors in the wilds, and the mom cast as this primeval, sometimes violent creature is deliberate.

All this would be merely entertaining from a distance if similar mom-power tactics weren't filtering so swiftly into our own political discourse. Increasingly you can't begin to aspire to a political career until you have queued up to be interrogated by Mumsnet, Netmums or somebody wielding a Bugaboo.

The tirelessly selfless mother is so morally unimpeachable a figure that only a very brave or foolhardy politician would dare to question the authority that supposedly flows from the role. But how far can this be taken? How long before we see the Tory ennoblement of the television presenter Kirstie Allsopp so that she can begin running the country, which is what readers of one women's magazine recently voted for on the basis that she "understands mums". Implicit in this bogus narrative about mum-wisdom is that mothering is so instinctual that only another mother – even better if, like Kirstie, she's rich and well connected – can truly understand where it comes from.

The Coalition leaders are falling over one another to do penance for having upset the angry mums. It can only get worse as savage spending cuts kick in and the frenzy for scarce public money, like food for bear cubs in the frozen wastes of Alaska, intensifies. But the message political leaders are sending is offensive to and neglectful of the millions who have not personally burdened the state with any child-related costs but who, never having had babies, are assumed to be too irresponsible, heartless or maybe downright weird to be allowed near any form of policy-making.

I wonder, though, how much these militant über-mothers are thinking beyond their own individual families when they demand that the political classes listen to them. Terms like soccer mom in the US were, after all, coined for the kind of middle-class mother who would knock another mother's eye out if it ensured her own little emperor got picked for the team.

For all women, mothers included, the mum-power narrative is a regression. Women have long fought to be defined on their own terms, not by their marriages. So why are they so eager suddenly to be defined by motherhood?

Michelle Obama stepped up to the frontline in the debate this week, presenting herself as "Mom-in-Chief" at a rally in Wisconsin. "More than anything else, I come at this as a mom," she told the crowd. "My first priority has been making sure that my girls are happy and healthy and adjusting to a very interesting new life in the White House." Of course you have to decode this depressing twaddle. Michelle is being wheeled out as the Democrats' secret weapon as her husband struggles in the polls. But in raising a paw, she's accepting the rules of engagement in the mommy wars, a conflict no woman needed ever to sign up for.