Is the U.S. military experiencing a readiness crisis? Conservative national security analysts and hawkish legislators say yes, and blame the reductions in planned Pentagon spending from the 2011 Budget Control Act. Left-leaning national security analysts dismiss these claims or counter that any readiness crisis is the product of wasteful spending for the benefit of defense contractors. Framing military readiness as a policy matter in this way provides little hope of understanding the nature of the U.S. military’s current or future readiness problems.

A new round of this debate, with entirely different participants, has just recently begun. Retired Army General David Petraeus and Michael O’Hanlon of the Brookings Institution kicked the debate off with a Wall Street Journal op-ed decrying alarmism over the state of military readiness and declaring the so-called “crisis” a “myth.” The response came in the form of an op-ed at Defense One by retired Army General Carter Ham, now head of the Association of the U.S. Army—who argues that the Army may be ready for operations today against the likes of the Islamic State, but not for a “full-spectrum war against a foe like North Korea.” Instead of bringing ideological axes to grind, the debate between Petraeus and O’Hanlon on the one hand, and Ham on the other, is about the problem of near-term readiness versus long-term, and the readiness of a single service versus that of the military as a whole. While the limits of the op-ed form leave little room for either side to make a robust empirical case, they each in their own way provide insight into how to better understand the readiness problem.

Of course, both pieces also have their problems. Petraeus and O’Hanlon cite a number of “inputs” meant to indicate the health of the U.S. military. They describe defense spending that remains at near records levels; the fair, or in some cases historically high, combat-capability ratings of some equipment; and a return to training for “full-spectrum” operations after a decade-long focus on counterinsurgency. But, as Todd Harrison of the Center for Strategic and International Studies explained in his 2014 study of how the U.S. military measures readiness, these inputs are not linearly related to the output of readiness. For his part, Ham falls back on a fuzzy notion of future “risk” to rebut Petraeus and O’Hanlon. “Today’s Army is too small,” he writes, “to meet its national security objectives without risks.” Seeing as the future is unknowable, risk always exists, and knowing the optimum amount of troops to mitigate it is likely to always prove impossible.

But when taken in combination, the two pieces get at fundamental problems in assessing readiness: Who needs to be ready? For what type of war? For when? Petraeus and O’Hanlon highlight the relative health in the near-term of multiple services. They are not blind to future challenges though, and laud Secretary of Defense Ashton Carter’s attempts to spur technological innovation and imply that modest increases in the defense budget might be necessary. Ham, on the other hand, bemoans the long-term decline of the size of a single service due to ongoing “budget uncertainty.” He complains that the “Total Army”—including active-duty, reserve, and Army National Guard—will only meet what the National Commission on the Future of the Army considered its “minimally sufficient” manpower level.

Who is right? Should investments, even if modest, be made in sustaining the near-term readiness of the force? Should funding for innovation be prioritized instead? Which service’s budget should be the top priority? Should the Army’s funding be increased to address potential manpower shortages in a futile attempt to eliminate future risks? Or should the Pentagon take advantage of the fact that it has multiple armies, navies, and air forces across its different services that could cover for shortfall in the others? As Harrison notes in his paper, “Near-term readiness, by definition has a short shelf life… Investments in long-term readiness, such as new technologies and capabilities have the potential to yield value for decades to come.” Does that mean near-term readiness should be sacrificed for long-term investment?

The answer to all these questions is yes, no, and maybe. Different bureaucracies will value different things at different times and will generally make policy incrementally. That is a good thing. Redundancies can cover shortfalls in one area or mitigate the risks when one service or another is unprepared. But, as Harrison argues, when the services adopt a mission or set of missions, they need to be adaptable in their pursuit of readiness. He proposes a system that constantly tests new readiness hypotheses that can show where readiness resources are most needed, or where goals need to changes when resources are unavailable. Despite what General Ham might think, budget uncertainty is a fact of life when the political process distributes resources. Understanding that the who, what, and when of readiness will always be moving targets will provide a better basis for defining and measuring readiness than will ideological mudslinging contests.