Unfortunately, we don’t understand the exact mechanism for many (most?) available medication. Correlation != causation. Which is why you need to do randomized

Unfortunately, we don’t understand the exact mechanism for many (most?) available medication. Correlation != causation. Which is why you need to do randomized testing and try and account for other causative factors. But if you give a bunch of people a medication and they stop dying, you can pretty much say this is valuable and start giving it to people.