The Army’s active duty end-strength—the number of troops at the end of a fiscal year—is about to go from 490,000 to 450,000. Army leaders, such as former Army Chief of Staff Ray Odierno, have lamented the reductions and have claimed that further personnel cuts will leave the service too small to deal with unexpected crises. A number of commentators, analysts, and politicians have echoed these concerns. One of those analysts, Michael O’Hanlon of the Brookings Institution, argues for a larger Army in a new book. Judging from his recent blog post on the issue, O’Hanlon’s case for enlarging the service is flawed in important ways.

O’Hanlon lays out a scenario in which a war between India and Pakistan escalates and nuclear weapons are used. U.S. troops need to be deployed to South Asia to conduct stability operations. Given the geography, population size, and devastation involved in this scenario, the size of the Army today would be insufficient to conduct effective stability operations. Therefore, he reckons, the Army needs to be larger.

O’Hanlon concedes that his hypothetical nuclear war in unlikely. However, because the scenario is not, in his estimation, “crazy or implausible,” and America probably couldn’t “sit it out if it happened,” O’Hanlon concludes that “it would be a big mistake” to “design the future American Army without factoring in such possibilities.”

There are at least two problems with this argument for enlarging the Army.

First, any number of scenarios requiring large number of U.S. troops could be considered plausible—in the sense that there’s some possibility they might come to pass. O’Hanlon provides a map that includes a “major domestic disaster” in the continental United States, operations to protect the Baltic States against Russian aggression, peacekeeping operations in Syria, conflict on the Korean Peninsula, and others. All these are plausible scenarios. But there are countless plausible scenarios, and the Army can’t and won’t prepare for all of them. Force design need not factor in all plausible scenarios because it’s impossible.

The possibility of a war in South Asia, particularly one that involves nuclear weapons, is not at all implausible. But it is implausible that the United States ought prepare its military to respond to it. O’Hanlon is right that stability operations on the subcontinent would require a great deal of manpower. He estimates the number of troops that would be needed in the “low hundreds of thousands.” Not only would they have to contend with devastation wrought by the nuclear conflict, but also with the preexisting factions within both India and Pakistan that would be vying for power over a vast geographic expanse. Preparing for such a scenario would quickly chew up the bandwidth of even an enlarged ground force, leaving little spare capacity for flare ups in the other potential trouble spots where O’Hanlon thinks the Army might be needed some day.

And this leads to the second problem with O’Hanlon’s argument. Even with increased manpower, the Army is unlikely to seriously prepare for hypothetical post-nuclear stability operations.

RAND military analyst Carl Builder has argued that the Army prizes its end-strength as a sign of the service’s health. But, as Andrew Krepinevich observed in the 1980s, end-strength was meant to serve a specific organizational goal. This goal was the “Army Concept.” The “Concept” was the Army’s preferred way of waging war following World War II. Krepinevich wrote:

The Army’s perception of how wars ought to be waged and is reflected in the way the Army organizes and trains its troops for battle. The characteristics of the Army Concept are two: a focus on mid-intensity, or conventional, war and a reliance on high volumes of firepower to minimize casualties—in effect, the substitution of material costs at every available opportunity to avoid payment in blood.

The Army Concept is something the service has pursued during both flush times and periods of budgetary contraction. In the 1980s, when the defense budget skyrocketed as a result of Ronald Reagan’s defense buildup, the Army designed its forces around conventional conflict with the Soviet Union in Central Europe. Krepinevich notes that instead of learning lessons from the Vietnam War and training forces for counterinsurgency missions, the Army helped set up political barriers that would decrease the likelihood of future deployment to Vietnam-style counterinsurgency missions. In the 1990s, as funding decreased following the collapse of the Soviet Union, the Army planned its modernization program around the notion of conventional conflict with countries such as North Korea and Iraq.

Even as the service conducted two counterinsurgency campaigns in the 2000s, supplemental war funding allowed the Army to focus its force planning on the conventional conflicts that have always been its priority.

With some exceptions, stability operations have been anathema to the Army. The service largely considered them “MOOTW” (military operations other than war). As “lesser included” activities, the Army believed it could conduct these operations—if policymakers compelled them to—using the same forces planned for conventional warfare. At the end of the last decade it looked like that might change, but the 2012 Defense Strategic Guidance once again defined them as lesser operations.

O’Hanlon may grapple with these issues more fully in his book than he does in his blog post. But the fact remains that resource limitations exist at any budget level. There will never be enough money or manpower to prepare for all plausible scenarios. Given its history, the Army is most likely to dedicate increased resources to its favored mission. Even if O’Hanlon’s desired expansion comes to pass, the Army might not be any more prepared to undertake the stability mission he proposes—even with increased manpower. Calls to increase Army end-strength for reasons that conflict with organizational prerogatives are more likely to waste resources that could be used elsewhere than they are to lead the army to become better prepared for an indefinite number of “plausible” scenarios.