I think how we think about the breakdown of Arusha ultimately depends on our own speculation of the events of April 6, 1994. The question of who shot down the plane that night, killing two presidents, (and who may have helped them -- cough cough the French cough), remains as much the subject of conspiracy theory and guesswork as fact.

What we do know, is that in the hours following the assassinations Col. Bagosora had formed a crisis committee, taken control of the Presidential Guard, (the core of the Rwandan army), erected road blocks throughout Kigali, including using Interhamwe units, and begun to isolate, and eventually eliminate moderate opponents. This is epitomized by the assassination of PM Agathe Unwilingiyimana, the constitutional successor to President Habyarimana, early in the morning of April 7th.

So, whoever was responsible for Habyarmana's death, some if the immediate beneficiaries were the anti-Arusha Hutu-Power extremists in the Rwandan military and government. It is also the case that the Interhamwe, established and armed by Col. Bagosora, supposedly as local defence committees against RPF invasion, played a crucial role in securing the country for the Hutu-Power clique, starting April 6th.

This is all an extremely roundabout way of getting to your initial question, which was on the political logic for the events of 1994. What I hope my brief summary of some of the events of April 6th have demonstrated was that there existed an individual logic of immediate power and advancement for those who were the principle advocates of conflict and Hutu-Power. Advocating compromise, peace and moderation is an extremely unpopular and dangerous proposition.

As for a larger political logic for the genocide, it's clear that any logic is grounded in a particular Hutu-Power ideology, and only makes sense within that ideological framework. I think genocide generally requires the adoption of an altered worldview. For example, by way of comparison, take the events of the Holocaust. Does it make sense for the German state to devote significant resources towards the destruction of Europe's Jewish population? From a perspective outside of Nazism, of course not. However, if your political worldview is premised on the belief that European Jewry us responsible for the degeneration of civilization, the economic subjugation of Germany, the rise of Bolshevism, ect., only then does the destruction of Europe's Jewish population, even at the expense of the war effort, make sense. In the same vein, if you were an adherent of Hutu-Power, the threat of the RPF is always secondary to the threat posed by a degenerate Tutsi population ready to resume their racial domination and enslavement of the Hutu population. To adherents of Hutu-Power, Kagame and the RPF were only a symptom of a larger racial struggle for survival.