Breht and Alyson talk about this in their episode on Socialism: Utopian and Scientific when they talk about how Marxism is a science. Breht brought up some events that could falsify key pillars of Marxist thought (around 1:25 in)
- Anarcho-capitalism gets established
- If liberal democracy is able to resolve class conflict
- A non-Marxist left ideology is able to lead and defend a world revolution
- Fascism and imperialism is rooted out of liberal society
Any of these events happening would crush key views of Marxism.
Foreign aid is when the poor people of a rich country give money to the rich people of a poor country!