JANE JACOBS, in her lifetime of thinking brilliantly about the rise and fall of cities, has arrived perhaps inevitably at the subject of empires, their rise and fall. In the current Atlantic she has coined the phrase ''transactions of decline'' to explain what goes wrong.
She takes as an example Camp Lejeune, the Marine Corps base in North Carolina. She asks us to imagine the bumper-to-bumper traffic of trucks rumbling all day past the sentry gates, bringing in freight loads of peanut butter, business machines, mattresses, chain-link fences, light bulbs, spaghetti. And, of course, weapons.
But what then passes out through those gates - what export of goods or raw materials to match those that come in? Nothing that can be eaten or worn or plugged in - or even liquidated for cash. By the ordinary laws of exchange, we have an economic non sequitur that can be tolerated up to a point, like the welfare state - another Jacobs example. But if this case of no quid for an awful lot of quo grows too distancing, the mother country that the garrison state is supposed to protect (and the welfare state to reward) will topple into bankruptcy.
''Transactions of decline'' - the phrase for a seesaw with only one rider - is so catchy that a Jacobs reader soon wanders outside of her thesis, and beyond economics itself. Certainly other transactions seem to be in confusion, if not decline. Parents are not sure what their bargain is with their children, or vice versa. Both parties complain of an ''imbalance of trade.'' Men and women are also being famously wary not to make commitments that lead to ''deficit spending'' of time and energy - bicycling for two while one's tandem partner coasts.
''Only connect,'' E.M. Forster wrote at a time when transactions were not in decline. But the thing Miss Jacobs has noticed is that, in times of difficulty, people do not connect. A certain social rhythm is lost, and the human enterprise tends to fall into a jerky state of discontinuity, at cross-purposes with itself.
The simplest connection becomes complicated into a classic problem. How does an individual - producing his driver's license and two other forms of identification - ''only connect'' to his often suspicious community? For that matter, how does he ''only connect'' to himself?
What a corresponding disarray our inner transactions are in, if Miss Jacobs wished to build that thesis! Publicly we threaten to go broke trying to meet the demands of the military state and the welfare state, both at once. Privately we seem to be workaholics and hedonists simultaneously - an overtime card in one hand, a Playboy key in the other. We are full of selective ''life styles,'' but where's the pattern?
Is it just a game of metaphors to tie public confusions to private confusions? Or does it mean something that both we and our institutions seem to play like pieces of music, incapable of deciding upon a time signature or even a key?
This meaninglessness, the German theologian Wolfhart Pannenberg argues, is, alas, the meaning of modern times. Nothing so sets us apart as our inability - or our fear - to relate the parts of a whole because, he speculates, wholeness is a premise that involves God and we are determined to be the first secular civilization.
And so, for one reason or another, we have more of the bits and pieces than ever before, and in our theories, as in our practices, we cannot or will not make them meet. We are left with answers for which we have no matching questions. We are left with inventions for which we have, as yet, no use. We explain more and more while understanding less and less. Our transactions are indeed in decline.
But, as Pannenberg doubtless knows, we're not ready to give up yet. For now, we seem prepared to feed all the ''information'' into the computer and wait - almost in the posture of prayer - for a connection to appear.