CHICAGO (MCT) — It's a cold calculus, trying to estimate the cost of a war.

What is an Iraqi life worth? The life of an American GI? It's no easier estimating the value of removing Saddam Hussein from power than it is calculating the sum cost of lifetime health care for a host of disabled American soldiers.

When politicians talk about the war's costs in terms of lives and treasure, they don't necessarily expect someone to actually pull out a spreadsheet and start running the numbers. But that is what has happened with the Iraq war. And as we approach the five-year anniversary of the initial March 20, 2003, "shock and awe" aerial assault on Baghdad, it is worth noting an important shift in the accounting of the conflict's cost.

Those who opposed the war are finding that the costs far exceeded anything they would have expected, or might have argued, at the time the conflict started. The most notable and authoritative such argument is put forward by Nobel Prize-winning economist Joseph Stiglitz, who puts an eye-grabbing, ultimate bottom line on the seemingly endless U.S. commitment to Iraq: at least $3 trillion. That's trillion, with a "T."

Those who argued during the run-up to war that armed conflict would be more economical than the cost of containing Saddam have shifted fields. Instead of arguing, as some once did, that America's Iraq adventure might actually turn a profit once the country's vast oil wealth began to flow, they now put forward a more nuanced argument.

On a purely fiscal basis, they now acknowledge, the war has been at best a wash. But looked at as a total package — taking into account the benefits of removing a tyrant from power and thrusting Iraq into its post-Saddam period, however bloody and chaotic — they say armed intervention was still the more attractive alternative.

A trio of University of Chicago economists sought to estimate the cost of containing Saddam had there been no U.S.-led invasion. Their 2006 paper pegged it at $700 billion over an unspecified period of years.

That estimate figures in the extra U.S. military equipment and manpower that would have been needed to keep Saddam within his borders and keep his hands off Kuwait. It includes the cost of weapons inspection programs, of economic boycotts, of oil that would remain in the ground, and a rate of premature Iraqi deaths ranging from 10,000 to 30,000 per year, based on Saddam's bloody track record and mismanagement of the country.

"When people talk about the cost of war, as an economist, you have to ask, 'In comparison to what?"' said Kevin Murphy, one of the University of Chicago economists.

Though he faults President Bush for errors in execution, he believes war was the better option.

"I don't hear Joe Stiglitz saying the best world is the world where Hussein stays around as long as possible because it costs too much to make him leave," Murphy said. He has a fair point. Stiglitz spends little time contemplating either the economic or moral consequences of allowing Saddam to remain in power. Perhaps that is because Stiglitz cannot take his eyes off the financial and human catastrophe that is unfolding before the nation's eyes.

Bringing important new scholarship to the book, "The Three Trillion Dollar War: The True Cost of the Iraq Conflict," Stiglitz and co-author Linda Bilmes spend little time contemplating what-ifs. Instead, they turn a calculating eye to the economic consequences of the American military invasion. — and to the vital policy considerations presented by both its financial and human costs. There is the expected, grim accounting that any actuary might calculate. The cost of 4,000 American troops' lives, for example, runs to roughly $28 billion. War outlays have added $1 trillion to the national debt and could run to $2 trillion over time, the authors calculate.

One of the most important calculations is an aspect of the war often ignored by the politicians and pundits who are not quite as handy with a calculator as Stiglitz is: The staggering, long-term toll of veterans' health care, disability benefits and Social Security disability pay. Add them up, and even in a best-case scenario they amount to $371 billion, according to the authors' calculations.

Stiglitz expected his calculations would come under criticism, as they have. But he said the larger purpose — putting some price tag on the cost — is important.

"The public ought to have some accounting of the costs," he said in an interview.

"Obviously, after Pearl Harbor, you wouldn't sit down and say, 'How are we going to respond?"' Stiglitz said. "But this was a war of choice. We didn't have to go to war. We had a choice of timing, and a choice of whether to go to war at all."

The debate is not purely among economists, obviously. But even among political scientists who supported the war, Stiglitz's view is starting to take hold.

Michael O'Hanlon, a security expert at the Brookings Institution who runs a project that compiles all manner of data on present-day Iraq — from military and civilian deaths to commodity costs to public opinion — said he cannot ignore the negatives: a huge increase in violence in Iraq, the lack of political stability, the inability to find weapons of mass destruction and oil prices at $110 a barrel.

O'Hanlon supported the initial American invasion, and gave carefully delineated backing to the troop surge a year ago. Today, though, "common sense ultimately pushes me toward the Stiglitz view if I had to look at just the bottom line," O'Hanlon said.

The question for Americans, ultimately, no longer is whether going to war made sense. Today, as we head toward the presidential election, the question is whether we keep U.S. troops in Iraq or start bringing them back.

Based on governmental budget figures, several economists have put the cost of the Iraq war at $12 billion a month. Stiglitz figures the actual cost probably is at least twice that.

And putting a final fiscal argument to the test, Stiglitz invokes a tenet of economics that is hammered home at the University of Chicago business school itself: The fallacy of the "sunk cost."

People throw good money after bad, in hopes of recovering what they first invested, even though every new dollar just perpetuates a lost cause.

Five years into the war, Americans must decide whether we are caught up in a sunk-cost fallacy. But in this case, the cost is not counted just in dollars and cents. It is tallied in the impact on American security, and in the cost of American and Iraqi lives.