On this subreddit the rules state that the line between current events and history is drawn at 20 years. Is this distinction commonly accepted in the formal study of history? What factors are taken into account when deciding what is "too recent" for historical study?
Hi! This sub's "20 year rule" is an arbitrary cutoff that applies to this subreddit only; various areas of study will have their own cutoffs.
/u/restricteddata illustrates the issue in this post [META] Why is the restriction on current event posts set at 20 years? What makes that amount of time important?, which incidentally includes links to a few earlier threads on the subject, and here's a fuller discussion of the rule Rules Roundtable #5: The Current Events/Modern Politics/"20 Year" Rule