This is so wrong in so many ways. I will focus on the military side of things, but the problem is the same for police and other folks who think that only members of the particular profession can understand their profession:
- First, and, most obviously, civilian control of the military means that civilians have the final say on what the military does. If you don't like that, don't live in a democracy as this is a fundamental aspect of any democracy. Want the military to be entirely autonomous? Go to a military dictatorship. That sounds like a simplification, but it is a basic reality. In democracies, the civilians rule. Saying that civilians should do whatever folks with military experience tell them is fundamentally problematic. Yes, civilians with military experience can have valuable perspectives but that does not make them only people who can offer opinions or make decisions.
- Second, the idea that the military has a monopoly on expertise (not to mention wisdom) is a myth.
- It used to be the case when few civilians studied the military, but that time has come and gone. There are plenty of people across a variety of professions and disciplines that study the military. Some have experience in uniform, some don't. It is probably better for all concerned that a diversity of experiences and attitudes and background are deployed to study something, including the military, than just those who wore the uniform.
- There are plenty of military people who have lousy judgement who should not be consulted for expertise (Tommy Franks is the easy cheap shot, but to be fair I wouldn't trust Wesley Clark either). There are damn near infinite numbers of folks with military experience who have lousy judgement, just as there are similar numbers of non-military folks who have lousy judgement. Having a combat infantry badge means that one has probably seen combat (not all badges are equally earned), but not that each badge-wearer is better than any civilian expert or the average civilian expert.
- This idea made more sense when the military did mostly simple tasks--taking hills and such (stylized reality--war is and always has been complex). But the more armed forces are grappling with complex stuff (nuclear war, peacekeeping, counter-insurgency, etc), the more they are operating outside of their expertise and require outside inputs.
- Third, being a tree makes one good at seeing the trees but not the forest. So, the idea that a military person can see the forest and the trees really depends on what they have experienced, how they have trained, where they were deployed, what education they have received, and how much they have thought about stuff (hint: reacting that civs cannot understand requires no thinking/expertise/education).
- Fourth, there is a particular tendency for males to use this "argument" against women, which makes it not just dumb and anti-democratic but misogynist, too.
To twist a classic saying, if war is too important to be left to the generals, then studying the armed forces is too important to be left to the armed forces.