If your mood changes every month, and if you die in any month where your mood turns to suicide, then to live 83 years you need to have one thousand months in a row where your mood doesn’t turn to suicide. Your ability to do this is aided by the fact that your mind is internally divided; while in many months part of you wants to commit suicide, it is quite rare for a majority coalition of your mind to support such an action.
In the movie Lord of the Rings, Denethor Steward of Gondor is in a suicidal mood when enemies attack the city. If not for the heroics of Gandalf, that mood might have ended his city. In the movie Dr. Strangelove, the crazed General Ripper “believes the Soviets have been using fluoridation of the American water supplies to pollute the `precious bodily fluids’ of Americans” and orders planes to start a nuclear attack, which ends badly. In many mass suicides through history, powerful leaders have been able to make whole communities commit suicide.
In a nuclear MAD situation, a nation can last unbombed only as long as no one who can “push the button” falls into a suicidal mood. Or into one of a thousand other moods that in effect lead to misjudgments and refusals to listen to reason, that eventually leads to suicide. This is a serious problem for any nuclear nation that wants to live long relative to number of people who can push the button, times the timescale on which moods change. When there are powers large enough that their suicide could take down civilization, then the risk of power suicide becomes a risk of civilization suicide. Even if the risk is low in any one year, over the long run this becomes a serious risk.
This is a big problem for world or universal government. We today coordinate on the scale of firms, cities, nations, and internationals organizations. However, the fact that we also fail to coordinate to deal with many large problems on these scales shows that we face severe limits in our coordination abilities. We also face many problems that could be aided by coordination via world government, and future civilizations will be similarly tempted by the coordination powers of central governments.
But, alas, central power risks central suicide, either done directly on purpose or as an indirect consequence of other broken thinking. In contrast, in a sufficiently decentralized world when one power commits suicide, its place and resources tend to be taken by other powers who have not committed suicide. Competition and selection is a robust long-term solution to suicide, in a way that centralized governance is not.
This is my tentative best guess for the largest future filter that we face, and that other alien civilizations have faced. The temptation to form central governments and other governance mechanisms is strong, to solve immediate coordination problems, to help powerful interests gain advantages via the capture of such central powers, and to sake the ambition thirst of those who would lead such powers. Over long periods this will seem to have been a wise choice, until suicide ends it all and no one is left to say “I told you so.”
Divide the trillions of future years over which we want to last over the increasingly short periods over which moods and sanity changes, and you see a serious problem, made worse by the lack of a sufficiently long view to make us care enough to solve it. For example, if the suicide mood of a universal government changed once a second, then it needs about 1020 non-suicide moods in a row to last a trillion years.
From your mass suicide link, most of the historic examples occurred when a community lost a battle and chose suicide over capture. Mass suicide that only kills the losing side won't result in extinction.
However, it's conceivable that a losing side might try to kill not only themselves, but everyone. E.g. the Guadeloupe example; if the former slaves could have taken all the French troops with them, they conceivably would have.
However, we already have that danger on the world stage, with the US and Russian nuclear capabilities. Maybe we should try to minimise the number of actors with that capability, which could be done with a world government?
> increasingly short periods over which moods and sanity changes
Governments include measures to protect against this. E.g. mood and sanity may change, but it needs to stay changed for 4 years to get a majority supporting the new mood and sanity into Congress.
Also these changes don't randomly flip to extremes.: they are more like random walks in the presence of various force gradients. So the odds for a well designed government to become able to commit suicide is much smaller than your presentation suggests.