The contrasting political trajectories of Tunisia and Egypt—the first and second countries out of the Arab Spring gate—have received much attention lately. Tunisians have exhibited more of a spirit of compromise, which has facilitated visible progress toward the sort of genuine democracy the country had lacked since independence. Recent political news from Tunisia has included the voluntary stepping down from power of the Islamist Ennahda party in favor of a non-partisan cabinet, and near-completion of the writing of a new constitution in which Islamists and secularists have found middle ground in a relatively (though not always) smooth process. Meanwhile in Egypt, generals who seized power in a coup against the elected president, Mohamed Morsi, seem to find a new way each week to tighten a repressive grip on the country.

Various possible explanations can help to explain the contrasting histories of these two North African countries. One can look at demographics and economic and social structures. Tunisia is smaller than Egypt, it has a more diverse and more successful economy, and its population is both more religiously homogeneous and overall more secular. Perhaps the leading proximate cause, however, of the different political course of the two nations over the past three years is the status and nature of each country's military before any of the upheaval began.

The Egyptian military has long had a dominant and disproportionate political role. Since a military coup overthrew King Farouk in 1952, Egypt has essentially been under military leadership, even though the leadership succession of Nasser, Sadat, and Mubarak took off their uniforms and called themselves presidents. Hosni Mubarak was ousted when he was because that is when the rest of the Egyptian military decided he was no longer useful to them.

In Tunisia, the military has enough cohesion, respect, and clout for its actions (or inaction, in not carrying out certain orders) to have played an important role in the ouster of President Zine el-Abidine Ben Ali. But it has no tradition, anything like that of its Egyptian counterpart, of ruling itself. The sorts of events that have taken place in Egypt over the past year would be inconsistent with its culture.

One can extend this typology by contrasting both Tunisia and Egypt with the country in between: Libya. As with many other institutions or supposed institutions in Libya under the regime of Muammar Qadhafi, what passed for a military was little more than an extension of Qadhafi's personal and highly centralized rule. The military therefore was not a significant factor in either ousting Qadhafi or in providing a foundation for a new political order.

These observations do not point, of course, to much of anything that the United States or any other democratically-minded outsider can do about what is going on politically today in these countries. But it suggests some things to look for in armies and politics, not just in North Africa but elsewhere. In Turkey, perhaps Reccip Erdogan's most positive contribution to his country, notwithstanding his own authoritarian streak, will be that he appears to have stared down the generals sufficiently well that another Turkish military coup seems far less conceivable now than it was just a few years ago. This is a sign that even a historically grounded political culture of a military can change. Pakistan, which has recently completed a peaceful transition from one set of civilian leaders to another, will also be interesting to watch over the next several years to see if there really has been a definitive break in that country's tradition of alternating military and civilian rule.

Back in Egypt, a current much-discussed question is whether the military chief, General Abdel Fattah el-Sisi, will run for president. If he does, that would certainly confirm continuation of the pattern that dates back to the coup against Farouk. But if he doesn't, that would not necessarily indicate much of a break in that pattern. For a model, one can look at yet another country of the Maghreb: Algeria. It has a long-serving (and physically ailing) civilian president Abdelaziz Bouteflika, who from time to time demonstrates his own political initiative. But ask Algerians who really runs the country and the answer is le pouvoir, a collective gray eminence that consists primarily of military brass but more broadly is a sort of military-industrial-intelligence complex. If a civilian and not el-Sisi were to become Egypt's next president, this might represent a system similar to that in Algeria.