In 1972, the Pioneer 10 space probe ventured out, bearing images from Earth to distant galaxies.

To convey a sense of who humans are, we sent up a map showing our location in the galaxy and drawings of a man and a woman.

Apparently, we thought it important the aliens know human beings come in two kinds. And not just any two kinds: We didn't send drawings of a fat man and a thin man, or a tall woman and a short woman. Nor did we attempt to send one androgynous silhouette, like those eerie sexless mannequins at some of the artier clothing stores.

If any aliens have received those images by now, they know more about humans than many of us know about ourselves!

Today, one common view — perhaps even the default view at the ritzier colleges and newspapers — holds that the assumption behind the Pioneer 10 pictures is just wrong: The difference between men and women is trivial. It's interesting when you happen to be watching a Tracy/Hepburn movie but easy to ignore whenever it might prove inconvenient.

La difference doesn't make much difference when you don't want it to. Men and women are basically interchangeable, and that's great, because it means we operate under far fewer constraints.

This viewpoint spills out from the political realm through the theological and into the intensely personal. If men and women are interchangeable, children do not need a mother and a father; two mothers or two fathers will do just as well. If men and women are interchangeable, women should be ordained. If men and women are interchangeable, cultures need not develop and maintain courtship practices that recognize the sexes' differing risks and vulnerabilities.

Americans might be especially prone to this anti-gender worldview. We romanticize the unconstrained individual: the Lone Ranger. We hate the thought that accidents of birth — whether you're born a boy or a girl — should restrict your life's possibilities. We especially fear being constrained by our bodies, because every fleshly constraint is a premonition of death, the final limit our physicality places on our ambitions. Moreover, we live in a young nation born of revolution. It's only natural that we're skeptical of received wisdom and open to radical innovation.

But if Americans are unusually vulnerable to anti-gender thinking, there are two groups of people who should be unusually attuned to the meaning and value of la difference: writers and believers in a creator God.

Poets, playwrights and novelists can look back through the history of their craft and see a parade of vivid, compelling characters: Hektor, Medea, the Wife of Bath, Falstaff, all the way up through Molly Bloom and Mickey Sabbath.

And all these characters would be unimaginable in a world where gender meant little.

Many of the great characters break societal conventions; they don't conform to what their culture considered the proper roles of men and women. (After all, the clash between role and desire, or between individual and society, generates the drama that the great stories need.)

But their manhood or womanhood matters.

Medea's break from convention is shocking, horrifying — and the horror is especially great because a mother has slain her own children, a woman has taken up a knife. The men are intensely men, the women intensely women; and sexual difference, unlike (for example) class and ethnic divisions, persists at high intensity in radically different ages and countries.

From ancient Roman comedies to Gone With the Wind, He does not behave like She.

On a deeper level, literature relies on the symbolic use of real objects and features of our world. Writers rely on a belief that things in the world have particular meanings that can be understood, in at least some cases, across cultures.

The world is itself a kind of symbolic dictionary — that's the feeling writers get when they know they've hit upon the exact right image, the exact right word. When a lamppost or a sparrow turns up in a poem and you know it couldn't have been anything else, the writer has tapped into that inherent meaning in physical things. This intuitive sense understands that a sparrow doesn't convey the same symbolic meaning as a peacock; and it also knows that there is a far deeper difference in meaning between a man and a woman. Trying to write a man where the poem needs a woman would lead to results even more ridiculous than if Shakespeare had written, “There's a special providence in the fall of a peacock.”

And this belief in creatures as words in a symbolic language is also the natural perspective of anyone who believes in a creator God. For us, God is the one who speaks the words that make up the world, and by speaking them brings them into being. If man and woman are especially important, unique words, we would expect creation narratives to reflect that fact. And so they do: “Male and female he created them.”

If we hate constraint that much, we can pretend that sexual difference makes little difference. It will cloud our eyes as we read great literature. It will blind us to the fingerprints of God impressed into the world around us. It will warp our politics and our private lives. It's anti-poetic and deeply unromantic.

Which would you rather be — an autonomous mannequin or a word spoken by God?

Eve Tushnet writes from Washington, D.C.