It happened today - July 5, 2015 On July 5, back in 1946, the bikini was introduced. And about time, you may say. What the world needs is more scantily clad young women.

Oddly, today that sentiment would be as politically incorrect as the suggestion that in that case maybe more modest swimwear would be in order. It is a sign of how far we have come since such a revealing garment could be banned in many places, condemned by the Vatican, and generally shunned in the United States until the 1960s, Brian Hyland’s 1960 “Itsy Bitsy Teenie Weenie Yellow Polka-Dot Bikini”, daring “beach blanket” movies with Annette Funicello and Frankie Avalon, and so on into the psychedelic explosion.

Speaking of explosions, the bikini was named for Bikini Atoll in the Pacific, where the U.S. was conducting atomic bomb tests. French designer Louis Reard hoped it would cause an “explosive commercial and cultural reaction”. And in time it did; it’s remarkable that Reard originally had to hire an exotic dancer to model it, but back then those two-pieces that did exist from the 1930s in Europe, a halter top and shorts, definitely covered the navel. (It’s also remarkable that Reard’s competitor Jacques Heim had come up with a similar but less risqué suit he called the “atome” – nuclear was rather more chic back then than since.)

Now the bikini is revealing in many ways. Including, said the deathly dull economist nerd, in illustrating a classic problem in game theory. In order to attract male attention at the beach, a girl gains a lot including a reputation for unconventionality by showing just a bit more skin than her rivals. They must keep up and a kind of arms race develops in which bathing suits get smaller and smaller.

Now at first glance, or stare, you’d think only men win this competition. Women are basically forced to undress in public. Now I know, I know, you think I’m being a prude. There’s nothing wrong with a G-string and pasties and only in unenlightened days of yore were they regarded as strip club attire. (Or should I say “Gentleman’s club”, in deference to a convention of so describing places no gentleman would go?) But the truth is that typical bathing suits now are tiny, uncomfortable and require aggressive waxing. And not that great for men.

As suits shrink, tastes become jaded. Jane Wyman was thought to look hot in halter top and shorts in 1935 (see the Wikipedia picture) and it’s hard to believe so many men could have been wrong including, in fact, Ronald Reagan, who once married her. If we now think such an outfit drab, it means we are world-weary and numb. And that’s not good.

Even if you think I’m being stuffy, concede for purposes of argument that the Incredible Shrinking Bikini is bad for both genders. (At the very least, it has helped inspire men to wear thongs, many of whom ought to be hauled off by the fashion police without delay.) What then can be done?

The girl who wears a slightly more modest suit simply loses male attention (or female in these enlightened times) and acquires a reputation for stuffiness. A bikini can shrink gradually but it can’t expand gradually. There’s a one-way ratchet effect there.

If the same is true in all kinds of areas of social life, if a slight relaxation of conventional rules on anything from swimwear to hairstyle to tattoos and piercings is easy to achieve, year on year, but impossible to stop or reverse, we’ll wind up with it all hanging out, glittering, blue-green or pink, deafening and coarse, impossibly wild by the standards of a few decades back and yet to our jaded eyes tired and unimpressive. And yet there will be no easy way back. Women could firmly insist on wearing considerably more modest suits and turn the tide. But it cannot happen millimetre by millimetre.

Finally, if this sort of process happens in ways that are harmful to social stability and possibly to government budgets as well, there’s clearly a dangerous trap here. If the old idea of welfare as bad for character can be whittled away by slowly expanding entitlements, but cannot be restored by slowly shrinking them, why, we might end up with massive government deficits and debts and a populace lacking the self-control to support politicians willing to make dramatic changes.

Again, you may say I’m imagining things. But if you compare the excitement the bikini first generated, the scandal and controversy even, with the apathy it now inspires, how thrilling men once found the garment and how ho-hum they now find it, it’s hard not to believe that there is a one-way ratchet both in swimwear and our capacity to find it exciting. And the Incredible Shrinking Bikini might be a metaphor for much that is happening inexorably around us to no one’s advantage.