Today's conspiracism stems mainly from the instability of the late 1960s and early '70s--a period of both uncontrolled violence (assassinations, urban riots, political protests turned bloody) and anti-government ideology (the left challenged laws regulating speech, sex, and drug use; the right fought busing, the Warren court, and the welfare state).
The 1960s and '70s saw many turbulent events.
World Peace was globally attained some time during the late 16th century.