<unk>  or causation denotes a logical relationship between one event (called cause) and another event (called effect) which is the direct  consequence (result) of the first.
While this informal understanding will suffice in everyday usage, the philosophical analysis of<unk>  or causation has proved exceedingly difficult. The work of philosophers to understand<unk>  and how best to characterize it extends over millennia. In the western philosophical tradition explicit discussion stretches back at least as far as Aristotle, and the topic remains a staple in contemporary philosophy journals. Though cause and effect are typically related to events, other candidates include processes, properties, variables, facts, and states of affairs; which of these comprise the correct causal relata, and how best to characterize the nature of the relationship between them, has as yet no universally accepted answer, and remains under discussion.
According to Sowa (2000), up until the twentieth century, three assumptions described by Max Born in 1949 were dominant in the definition of<unk> :
However, according to Sowa (2000), "relativity and quantum mechanics have forced physicists to abandon these assumptions as exact statements of what happens at the most fundamental levels, but they remain valid at the level of human experience."
It should be noted here, however, that physicists themselves never denied<unk>  or stated that<unk>  is violated in quantum mechanics or relativity. Vice versa, any experiment designed to show violation of<unk>  so far failed to do so.
Causality
Design of experiments
Admissible decision rule
Unblinding
Scientific consensus
Sample size
Agent study
Attrition 