Sorry about the confusion, I mean to say that even though the Against Malaria Foundation observes evidence of the effectiveness of its interventions all of the time, and this is good, the founders of the Against Malaria Foundation had to choose an initial action before they had made any observations about the effectiveness of their interventions. Presumably, there was some first village or region of trial subjects that first empirically demonstrated the effectiveness of durable, insecticidal bednets. But before this first experiment, the AMF also presumably had to rely merely on correct reasoning without corroborative observations to support their arguments. Nonetheless, their reasoning was correct. Experiment is a way to increase our confidence in our reasoning, and it is good to use it when it's available, but we can have confidence at times without it. I use these points to argue that people successfully reason without being able to test the effectiveness of their actions all of the time, and that they often have to.

The more general point is that people often use a very simple heuristic to decide whether or not something academic is worthy of interest: Is it based on evidence and empirical testing? 'Evidence-based medicine' is synonymous with 'safe, useful medicine,' depending on who you ask. Things are bad if they are not based on evidence. But in the case of existential risk interventions, it is a property of the situation that we cannot empirically test the effectiveness of our interventions. It is thus necessary to reason without conducting empirical tests. This is a reason to take the problem more seriously, for its difficulty, as opposed to the reaction of some others, which is that the 'lack of evidence-based methods' is some sort of point against trying to solve the problem anyway.

And in the case of some risks, like AI, it is actually dangerous to conduct empirical testing. It's plausible that sufficiently intelligent unsafe AIs would mimic safe AIs until they gain a decisive strategic advantage. See Bostrom's 'treacherous turn' for more on this.