Why is it that, day after not-quite-summery day, otherwise practical, savvy, street-smart and generally tasteful women insist on slipping slabs of rubber on their feet and slapping around the city? Yes, I’m talking about flip-flops, that utterly irrational fashion trend that seems frozen in an eternal crest. Why won’t they go away?

Let’s dwell, for a moment, on the many pitfalls of summer leisure wear doing double duty as urban glitz. Dirty feet, obviously, are the No. 1 disadvantage, and I don’t mean just smudges of urban grime. Then, too, consider the bleats of “ouch” on crowded subways, as countless toes get mashed by the inconsiderate owners of heavier, more practical footwear. The city’s crowded, remember, and naked toes hold their vulnerable temptations for sadists, fetishists and inconsiderate clods alike.

Then there’s the problem of rain and the slurpy sound of skin sliding around on sopping rubber. True, impracticality has never been a barrier to fashion – if anything, it’s more of a prerequisite. But here I must ask, in the service of what? I can understand why women might balance on towering spike heels or take a cab because they lack the stability and muscle tone to actually walk anywhere in the designer sandal of the moment. Apart from the snob factor, the “I can afford this and you can’t,” quotient, there’s the literal height such footwear can confer, as well as the advantage of the sexily elongated leg.

But flip-flops convey no such edge – if anything, they’re levelers, literally. With their thin soles, they expose every woman’s true height. And it’s impossible for most of us to distinguish between the haute version and dime-store generic. Designers have tried to dress them up with gold bands and plastic flowers, but they all put their wearers on the same unstable footing.

Some ugly footwear trends have a practical dimension that justifies their lack of grace. Office workers are willing to pair suits with sneakers for the sake of a well-oiled commute because pumps can be stowed in a briefcase. For a little while after 9-11, many women refused to stay hobbled by preposterously pointy shoes and opted instead for clunky wedges that kept them grounded and ready to run.

But what accounts for ugly, uncomfortable thongs, as they were once known? I think they represent an existential “No!” to the basic premises of city life. They deny humdrum urban reality in favor of an Edenic fantasy of eternal leisure. They scream “I don’t really want this job.”

At a time when American women are working longer and longer hours, wearing flip-flops to the office represents an assertion of the right to have fun. “I may be confined to my cubicle right now,” they proclaim, “but I can leave for the beach at a moment’s notice.”