A dispute between Parliament and President João Bernardo Vieira in Guinea-Bissau appears as though it will boil over. The three main parties in parliament--the former only ruling party PAIGC, the main opposition PRS of former president Kumba Yalá, and the other opposition party PUSD--have agreed on some sort of "pact of national unity," the main point of which, undoubtedly, is to dismiss the PM Aristides Gomes, a Vieira ally, and impose their own candidate on Vieira, who does not have his own party.
While Guinea-Bissau has (for no really good reason) been a long-time special interest of mine, the question this dispute raises is broader: why on earth have so few African countries tried a parliamentary system? Even as the continent converted to democracy in the 1990s, very few chose a parliamentary system.
A bit of history: essentially all the former British colonies started as parliamentary systems. Zimbabwe, Zambia, Malawi, Kenya, Tanzania, Uganda, Nigeria, Ghana, The Gambia, Sierra Leone, Mauritius, Botswana, the Seychelles--all adopted a Westminster-style system with first-past-the-post voting after independence. In almost all, the prime minister eventually decided he wanted to be president, the post of Governor-General was eliminated, and a parliamentary system became a presidential one, generally around the same time as opposition parties were also banned. This repeated over and over, from Nkrumah in Ghana to Kaunda in Zambia, Mugabe in Zimbabwe to Banda in Malawi to Kenyatta in Kenya. On the other hand, the former French colonies were presidential systems from the start, imitating the Fifth Republic.
And today, even as new constitutions have been drawn up or constitutions revised, parliamentarism remains untried except in a few cases. South Africa has adopted an essentially parliamentary system, as has Namibia; Botswana has retained its system since independence (though without a change in ruling party); Ethiopia has adopted parliamentarism, but its democratic credentials are very questionable, especially after 2005. The most notable attempted reform was Kenya, where Mwai Kibaki's National Rainbow Coalition swept to power promising to establish a parliamentary system (President Kibaki promptly discarded most of the promise, and the watered-down constitutional amendments were rejected in a referendum).
More countries have adopted proportional representation, though most are presidential democracies. Many of the French-speaking former colonies, in particular, have proportional representation (a by no means complete list includes Senegal, Togo, Benin, Burkina, Mali, and Niger). SA and Namibia also adopted PR, and Burundi and Rwanda use PR. The rest (especially the ex-British colonies) have retained FPP.
It seems as though ethnic politics could be one key reason for the leaning toward FPP. Parties which can win, regionally, in FPP among their own ethnic group have no incentive to let broader-based parties emerge as competitors and may prefer their guarantees under the existing systems. This does not explain the tendency toward presidential systems, however. One would think the advantages of a parliamentary system--in particular, nonfixed government service that allows for non-confidence votes--would carry the day at least in some cases, were democracy to be the primary objective.
So then, the question is--Who wants a fixed, independent executive, and why? The existing elites may be the answer. Perhaps the fixed presidential term creates more perceived stability. Remember, too, that the president is therefore responsible for most patronage, especially distribution of foreign aid and top jobs--and with weak political parties, he can form personal coalitions in the legislature to support him. Therefore, support flows to the president, who dispenses patronage, and elites do not have to worry about the party that they support losing a parliamentary election; support is transferred to the new president, and things continue as before.
Secondly, many (though not all) transitions were begun by existing strongmen. Rawlings in Ghana, Kerekou in Benin, Diouf in Senegal, Kaunda in Zambia, Banda in Malawi, Moi in Kenya, Museveni in Uganda, Kagame in Rwanda, Chissano in Mozambique, and others all hoped to win reelection to their positions in the new, more open system. Abolishing the importance of their own job was not on the agenda. (Again, the exception was Ethiopia, but we see how the possible threat to Meles Zenawi's rule turned out...).
In South Africa and Namibia, where PR-parliamentary systems were adopted, there has been less risk to elites--the winners were clearly known in advance (the liberation movements, ANC and SWAPO, have dominated despite highly proportional systems). If presidentialism is the side effect (yet also cause) of instability, perhaps as democracy starts to take root in some countries, insecurity diminishes, and (not necessarily linked) economic institutions become more secure, we will see a push for parliamentarism or at least the adoption of PR in some countries where FPP is still in charge.
As for Guinea-Bissau, donors (who must be called upon for anything relevant to happen) are, not surprisingly, uneager to fund a new election, so it seems likely that some sort of solution will be worked out. If not, of course, the military could always step in again.