From Hume's problem of induction, it is intuitive to me that, for example, 'taking aspirin in the past has relieved my headaches' is insufficient to say with certainty that 'taking an aspirin in the future will relieve my headaches'. This is because we are relying on the assumption that future events will be similar to past events. Furthermore, if we say that future events will be similar to past events because past future events were similar to past past events, then we are again relying on the assumption that the future will be like the past. I am not making a criticism of this problem. I am making a criticism only of the first half. That is, how do I know that it was indeed the aspirin that relieved my headaches in the past? Can it be demonstrated that two past (successive) events had a causal relationship to each other? So far, in my research, philosophers and scientists tend to look at causality in two ways. However, neither of these address the past, or the existence of causality itself. From this article, it is stated that we can establish causality (X causes Y) in three steps. Problematically, the article addresses point 2 only with hypothesis testing. Furthermore, the article tries to address present causal relationships, not past ones. Is it merely taken as an axiom that causal relationships have existed? Are there any resources on the topic? Is there any example of two successive past events, A and B, which we can say with certainty that A caused B? If so, Why?