High Quality Content by WIKIPEDIA articles! Interventionism is a term for a policy of non-defensive (proactive) activity undertaken by a nation-state, or other geo-political jurisdiction of a lesser or greater nature, to manipulate an economy or society. The most common applications of the term are for economic interventionism (a state`s intervention in its own economy), and foreign interventionism (a state`s intervention in the affairs of another nation as part of its foreign policy).