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A communist acquires the death note. How quickly can it be used to build global communism?
(hexbear.net)
Bonus question: How many names would one need to right down?
Real bad luck some chud hog like Light Yagami found the Death Note before anyone else did. By killing only criminals reported on in the news, he effectively made himself into a weapon of execution that could be freely wielded by the cops at almost entirely their own discretion. I wish the anime would have explored that idea a bit more, but I'll settle for the very pathetic way Light Yagami got caught by a 12 year old, threw a tantrum, and then died. That was unironically a great ending.
So say a communist found it instead. How much damage could this baby do to the global capitalist nightmare we live under?
There are just 2,700 billionaires in the world.
And their inheritors
And their inheritors inheritors
And their inheritors inheritors inheritors
Until they're gone.
That's maybe 10k-20k, eliminating the organising class of capitalism. Forcing all of their assets into the possession of the states in which they reside.
Then eliminate the bourgeoise parties, and the bourgeoise party memberships. Leave behind only the socialist parties.
With no bourgeoise class and no political or ideological leadership the right would catastrophically collapse. The only political leadership that would exist would be socialist. The remaining petty-bourgeoisie might try to cobble something together in the chaos but without the existing political infrastructure of the bourgeoise parties it would be a weak mess.
20k to eliminate the bulk of the global bourgeoisie. 15k-200k per country to eliminate the bourgeoise political infrastructure, much much less in countries with lower populations.
The goal here isn't to eliminate reactionaries but to eliminate the political infrastructure upon which they and the right are organised. You do that and you win by being the only ones that could reasonably be considered a viable option.
EDIT: You may need to do something about militaries. Many of them might attempt to assume emergency military rule, being the only ones organised enough to do so. I think a few thousand in each military is probably all you need though, if you end all the commanders and officers then there's nobody capable of doing any organising.
EDIT2: If you started with the countries neighbouring socialist countries then they would flip very easily and successfully with the support of their neighbours, they could happily come in and help provide political infrastructure in the emergency. You could then just paint the map, country by country.
EDIT3: Upon further thought, this is basically the Jakarta Method but applied against the capitalists.
You could get rid of every right wing media personality, writer, thinker, and ideologue while leaving the political structure intact. Good luck winning elections when every campaign writer and advertising manager you hire dies of inexplicable exploding head syndrome.