Pick your person and you get your reasons.
1. An army should be loyal to the government, as option 1. If there's no trust in the government and the system, regardless of who's in charge, you're not going to get an army with people who think dying to defend it is a reasonable proposition. Undermine the system, breed distrust, weaken the response in time of crisis.
2. An army should be loyal to the population in a territory, as option 2. If there's no cohesion because Person A identifies more with his tribe or clan than as an Afghan, then defending the territory isn't a reasonable proposition. In other words, "Afghan" is #2 or 3 or 4 on the "importance of identities" ladder. Breed distrust of other groups (or simply discount them as lesser in importance) and you weaken the response in time of crisis.
This is made worse if the soldier thinks that while *he* may be loyal to the population others are emphatically *not* so disposed. Then you simply get a sense of betrayal. This means that collapse in one area can beget collapses in others as a sense of basic fairness intrudes and produces a "screw them, even if it means screw me".
The government helped #1 by being corrupt. #2 is historically the norm in the territory.
3. We can add some things, as well. There's a tendency to ignore a powerful asymmetry: If you're a loser Taliban and get arrested and detained by your enemy, you'll be treated okay for the most part and your friends/family/clan left relatively undisturbed as you wait for an amnesty, and until then you can still qualify for whatever aid there is available. If you're a loser government soldier and get arrested by your enemy, you might be killed after being arrested, your friends and family will be punished, and amnesty = ransom or the result of conversion and going to fight for the Righteous and Pure. I would say this is a cultural tradition, but it's only really the last 60 or so years this kind of bloodthirst has arisen. In the '60s there was a kind of jihad when tribal balances of power were upset by increased migration and education on the part of one or two tribes. Otherwise, most vendettas are about regaining the status quo ante--that can involve transfer of women, money, property, execution of men. Those are mostly ruled out, so now the fighting isn't about balance but absolute power--which is frequently a prelude to tyranny. For that we can thank Qutb and the Ikhwan, and for those we have a bit of Western liberalism, a bit of Nazi thought, and a touch of Marxism-Leninism to thank.
But this asymmetry means you'd better damn well be seen by the victor as having supported the victor when it counted, esp. if the victor is given to more retribution. It also means that the government can't afford for cracks to appear because that gives rise to considerations of who's going to win and what's going to happen to your family and clan.
This gets you Afghanistan, it gets you Libya and Syria, and it gets you the collapse of the USSR.
= new reply since forum marked as read
